EPA 832-R-06-005 SEPTEMBER 2006
Emerging Technologies

for

Biosolids Management

Offi ce of Wastewater Management

U.S. Environmental Protection Agency

Washington, D.C.
Emerging Technologies September 2006

ii Biosolids Management

Emerging Technologies for Biosolids Management

EPA 832-R-06-005

September 2006

Produced under U.S. EPA Contract No. 68-C-02-111

Prepared by the Parsons Corporation

Fairfax, Virginia

Technical review was provided by professionals with experience in biosolids management. 

Technical reviewers of this document were:

Michelle Hetherington and Michael Moore, Orange County Sanitation District, Fountain Valley, 

California

Robert Pepperman, Environmental Group Services, White Marsh, Maryland

Timothy G. Shea, CH2M Hill, Herndon, Virginia

Lori Stone, National Biosolids Partnership, Alexandria, Virginia

Robert Reimers, Tulane University, New Orleans, Louisiana 

Paul Rom, Black & Veatch, Chicago, Illinois

Recycled/Recyclable

Printed with vegetable-based ink on paper that contains a minimum of 50 percent postconsumer fi ber content chlorine free.

Electronic copies of this handbook can be downloaded from the

U.S. EPA Offi ce of Wastewater Management web site at:

www.epa.gov/owm
Biosolids Management

September 2006 Emerging Technologies

iii

Preface

The U.S. Environmental Protection Agency (U.S. EPA) is charged by Congress with 

protecting the nation’s land, air, and water resources. Under a mandate of environmental 

laws, the Agency strives to formulate and implement actions leading to a balance between 

human activities and the ability of natural systems to support and sustain life. To meet 

this mandate, the Offi ce of Wastewater Management (OWM) provides information and 

technical support to solve environmental problems today and to build a knowledge base 

necessary to protect public health and the environment well into the future.

This publication has been produced under contract to the U.S. EPA by Parsons Corporation 

and provides information on the current state of development as of the publication date. 

It is expected that this document will be revised periodically to refl ect advances in this 

rapidly evolving area. Except as noted, information, interviews and data development 

were conducted by the contractor. It should be noted that neither Parsons nor U.S. EPA 

has conducted engineering or operations evaluations of the technologies included. Some 

of the information, especially related to embryonic technologies, was provided by the 

manufacturer or vendor of the equipment or technology and could not be verifi ed or 

supported by full-scale case study. In some cases, cost data were based on estimated 

savings without actual fi eld data. When evaluating technologies, estimated costs, and 

stated performance, efforts should be made to obtain current information. 

The mention of trade names, specifi c vendors, or products does not represent an actual 

or presumed endorsement, preference, or acceptance by the U.S. EPA or the Federal 

government. Stated results, conclusions, usage, or practices do not necessarily represent 

the views or policies of the U.S. EPA.
Emerging Technologies September 2006

iv Biosolids Management
Biosolids Management

September 2006 Emerging Technologies

v

Contents

 Page

Executive Summary ..................................................................................................ES-1

1. Introduction and Approach................................................................................ 1-1

1.1 Introduction .....................................................................................................................1-1

1.2 Approach .........................................................................................................................1-2

1.2.1 Information Collection and New Process Identifi cation .....................................1-3

1.2.2 Initial Screening Technologies ...........................................................................1-4

1.2.3 Development of Technology Summary Sheets ...............................................1-11

1.2.4 Evaluation of Technologies .............................................................................1-11

1.3 Guidance Document Format and Use .......................................................... 1-13

1.4 Chapter References ........................................................................................... 1-14

2. Conditioning............................................................................................................ 2-1

2.1 Introduction .....................................................................................................................2-1

2.2 Technology Assessment ..................................................................................................2-1

3. Thickening............................................................................................................... 3-1

3.1 Introduction .....................................................................................................................3-1

3.2 Technology Assessment ..................................................................................................3-1

4. Stabilization ............................................................................................................ 4-1

4.1 Introduction .....................................................................................................................4-1

4.2 Technology Assessment ..................................................................................................4-1

5. Dewatering .............................................................................................................. 5-1

5.1 Introduction .....................................................................................................................5-1

5.2 Technology Assessment ..................................................................................................5-1

6. Thermal Conversion ............................................................................................. 6-1

6.1 Introduction .....................................................................................................................6-1

6.2 Technology Assessment ..................................................................................................6-1
Emerging Technologies September 2006

vi Biosolids Management

Contents

 Page

7. Drying........................................................................................................................ 7-1

7.1 Introduction .....................................................................................................................7-1

7.2 Technology Assessment ..................................................................................................7-1

8. Other Processes .................................................................................................... 8-1

8.1 Introduction .....................................................................................................................8-1

8.2 Technology Assessment ..................................................................................................8-1

9. Research Needs .................................................................................................... 9-1

9.1 Introduction .....................................................................................................................9-1

9.2 Research Needs .............................................................................................................9-1

9.2.1 Analysis and Reduction of Risk Associated with Certain Benefi cial Use 

Practices ...........................................................................................................9-2

9.2.2 Utilization of the Potential of Biosolids to Yield Energy .....................................9-2

9.2.3 Improved Operation, Performance and Effi ciency of Biosolids Treatment 

Processes ........................................................................................................9-3

9.2.4 Research Needs ...............................................................................................9-3

9.2.5 Chapter References ..........................................................................................9-3

Appendix A .....................................................................................................................A-1

A.1 Introduction .................................................................................................................... A-1

A.2 Trade Associations ......................................................................................................... A-1
Biosolids Management

September 2006 Emerging Technologies

vii

List of Tables

 Page

Table 1.1 Summary of Biosolids Technologies ............................................................. 1-6

Table 1.2 Descriptive Evaluation Criteria .................................................................... 1-12

Table 2.1 Conditioning Technologies – State of Development ..................................... 2-1

Table 3.1 Thickening Technologies – State of Development ........................................ 3-1

Table 4.1 Stabilization Technologies – State of Development ...................................... 4-1

Table 5.1 Dewatering Technologies – State of Development ....................................... 5-2

Table 6.1 Thermal Conversion Technologies – State of Development ......................... 6-2

Table 7.1 Drying Technologies – State of Development ............................................... 7-1

Table 8.1 Other Processes – State of Development..................................................... 8-1

Table 9.1 Research Needs Technologies: State of Development ................................. 9-2

List of Figures

 Page

Figure 1.1 Summary of Wastewater Solids Management in the U.S. ............................ 1-2

Figure 1.2 Flow Schematic for Guide Development....................................................... 1-3

Figure 2.1 Evaluation of Innovative Conditioning Technologies ..................................... 2-2

Figure 3.1 Evaluation of Innovative Thickening Technologies ....................................... 3-2

Figure 4.1 Evaluation of Innovative Stabilization Technologies ..................................... 4-2

Figure 5.1 Evaluation of Innovative Dewatering Technologies ....................................... 5-2

Figure 6.1 Evaluation of Innovative Thermal Conversion Technologies ........................ 6-2

Figure 7.1 Evaluation of Innovative Drying Technologies .............................................. 7-2

Figure 8.1 Evaluation of Other Innovative Processes .................................................... 8-2
Emerging Technologies September 2006

viii Biosolids Management

ABR anaerobic baffl ed reactor

AGF anoxic gas fl otation

ATAD autothermal thermophilic aerobic digestion

ASCE American Society of Civil Engineers

AWWA American Water Works Association

BOD biochemical oxygen demand

BTU British thermal unit

CBFT3 Columbia biosolids fl ow-through thermophilic treatment

CFR Code of Federal Regulations

CIP capital improvement program

COD chemical oxygen demand

cP centipoise

CWMP comprehensive wastewater management plan

DAFT dissolved air fl otation thickening

DC direct current

DCWASA District of Columbia Water and Sewer Authority

EPRI Electric Power Research Institute

ERS energy recovery system

FELL Focused Electrode Leak Locator

g/ac/day gallon per acre per day

gpcd gallon per capita per day

gpd gallon per day

GTI Gas Technology Institute

HAPs hazardous air pollutants

HIMET high methane process

IEUA Inland Empire Utilities Agency

JWPCP Joint Water Pollution Control Plant

kg kilogram

kWh kilowatt-hour

MFP master facilities plan

List of Abbreviations
Biosolids Management

September 2006 Emerging Technologies

ix

MGD million gallons per day

MLSS mixed liquor suspended solids

MSO molten salt oxidation

NOAA National Oceanic and Atmospheric Administration

NPDES National Pollutant Discharge Elimination System

OCS oxygen combustion system

O&M operation and maintenance

OWM Offi ce of Wastewater Management

POTW publicly owned treatment works

PSI pound per square inch

RHOX reheat and oxidize process

RP recycling plant

SRF State Revolving Fund

SRT solids retention time

SSDML sewage sludge digestion and metal leaching

SW southwest

SWSSD Southwest Suburban Sewer District

TPAnD temperature-phased anaerobic digestion

tpd ton per day

U.S. United States

U.S. EPA U.S. Environmental Protection Agency

USDA U.S. Department of Agriculture

VAR vector attraction reduction

VS volatile solids

VSR volatile solids reduction

WEF Water Environment Federation

WERF Water Environment Research Foundation

WWTF wastewater treatment facility

WWTP wastewater treatment plant

List of Abbreviations
Emerging Technologies September 2006

x Biosolids Management
Biosolids Management

September 2006 Emerging Technologies

ES-1

Executive Summary

Biosolids (sewage sludge) are the nutrient-rich organic materials resulting from treatment 

and processing of wastewater residuals. U.S. Environmental Protection Agency (U.S. 

EPA) estimates that the publicly owned wastewater treatment works (POTW) generate 

over 8 million tons (dry weight) of sewage sludge annually. Figure 1.1 summarizes how 

this material is managed. The technologies in this document help reduce the volume of 

residuals, and produce biosolids that can be used, help improve soil fertility and tilth, while 

decreasing the use of inorganic fertilizers, and promote the conservation of energy.

This document provides information regarding emerging biosolids management 

technologies organized into three categories based on their stage of development:

Embryonic – Technologies in the development stage and/or tested at laboratory or 

bench scale. New technologies that have reached the demonstration stage overseas, but 

cannot yet be considered to be established there, are also considered to be embryonic 

with respect to North American applications. 

Innovative – Technologies meeting one of the following qualifi cations: (1) have been 

tested at a full-scale demonstration site in this country; (2) have been available and 

implemented in the United States (U.S.) for less than 5 years; (3) have some degree 

of initial use (i.e. implemented in less than twenty-fi ve utilities in the U.S;. and (4) are 

established technologies overseas with some degree of initial use in the U.S.

Established – Technologies widely used (i.e. generally more than 25 facilities throughout 

the U.S.) are considered well established.

The document also provides information on each technology—its objective, its description, 

its state of development, available cost information, associated contact names, and 

related data sources. For each innovative technology, this document further evaluates with 

respect to various criteria, although it does not rank or recommend any one technology 

over another. Research needs are also identifi ed to help guide development of innovative 

and embryonic technologies and improve established ones.

References

U.S. EPA. Offi ce of Solid Waste. Biosolids Generation, Use, and Disposal in the United 

States. EPA 530-R-99-009 (1999).
Emerging Technologies September 2006

ES-2 Biosolids Management
Biosolids Management

Chapter

1-1

1.1 Introduction

Wastewater treatment processes produce residuals, also called sewage sludge, as a 

by-product of the treatment processes. Biosolids are the nutrient-rich organic materials 

resulting from the treatment and processing of these residuals. U.S. EPA estimates that 

the publicly-owned wastewater treatment works generate over 8 million tons (dry weight) 

of sewage sludge annually. Figure 1.1 summarizes how this material is managed. The 

technologies in this document help reduce the volume of residuals, produce biosolids 

that can be used, help improve soil fertility and tilth, while decreasing the use of inorganic 

fertilizers, and promote the recovery of energy.

To meet the challenge of keeping progress in wastewater pollution abatement ahead 

of population growth, changes in industrial processes, and technological developments, 

U.S. EPA is providing this document to make information available on recent advances 

and emerging techniques. The goal of this document is straightforward—to provide a 

guide for persons seeking information on innovative and embryonic biosolids treatment 

technologies. The guide lists processing technologies, where available assesses their 

merits and costs, and provides sources for further technological information. This document 

is intended to serve as a tool for wastewater facility owners and operators. It should 

be noted that neither Parsons nor U.S. EPA has conducted engineering or operations 

evaluations of the technologies included. The information provided is from the vendors 

and/or practitioners; no detailed verifi cation of vendors’ claims has been undertaken.

Introduction and Approach

1
Emerging Technologies September 2006

1-2 Biosolids Management

Figure 1.1 – Summary of Wastewater Solids Management in the U.S.

(Source: U.S. EPA 1999)

Emerging technologies typically follow a development process that leads from laboratory 

and bench-scale investigations to pilot studies and, subsequently, to initial use or “full-scale 

demonstrations” before the technology is considered established. Not all technologies 

survive the entire development process. Some fail in the laboratory or at pilot stages; others 

see limited application in the fi eld, but poor performance, complications, or unexpected 

costs may cause them to lose favor. Even technologies that become established may 

lose favor in time, as technological advances lead to obsolescence. In short, technologies 

are subject to the same evolutionary forces present in nature; those that cannot meet 

the demands of their environment fail, while those that adapt to changing technological, 

economic, and regulatory climates can achieve long-standing success and survival in the 

market.

1.2 Approach

To develop this guide, the investigators sought information from a variety of sources, 

identifi ed new technologies, prepared cost summaries, and evaluated technologies 

deemed to be innovative. 

Other Disposal

1%

Land

Application

41%

Advanced

Treatment

12 %

Other Beneficial

Use

7%

Incinerated

22%

Landfilled

17%
Biosolids Management

September 2006 Emerging Technologies

1-3

This method is described below and in Figure 1.2.

Figure 1.2 Flow Schematic for Guide Development

1.2.1 Information Collection and New Process Identifi cation

Information collection on new technologies provided the foundation for subsequent work. 

To identify new biosolids processing technologies, investigators gathered information 

from a variety of sources, including the following:

Published Literature – An extensive literature review was performed to identify new 

technologies, and to evaluate their performance and applications. Specifi cally, the review 

focused on relevant Water Environment Federation (WEF) and American Society of Civil 

Engineers (ASCE) conference proceedings, as well as other publications from these and 

other organizations.

“Gray” Literature – Vendor-supplied information, Internet research, and consultants’ 

technical reports were the primary sources of gray literature.

Collect Information

Identify Process

Prepare Process

Summary Sheets

Prepare Process

Evaluation Matrix

Screen

Established No Further Action

Embryonic

Innovative

No Further Action

Embryonic or Innovative

Screen
Emerging Technologies September 2006

1-4 Biosolids Management

Technical Associations – Investigators contacted a variety of professional and 

technical associations in the United States, including members of WEF, to identify 

emerging wastewater treatment technologies.

Interviews and Correspondence – Individuals known to the project investigation 

team, including consultants, academics, and municipal wastewater treatment plant owners 

and operators, were consulted.

Technologies identifi ed through searches of the above sources were screened to determine 

their classifi cation as described below.

1.2.2 Initial Screening Technologies

This project focuses on emerging technologies that appear to be viable, but have not yet 

been accepted as established processes in the United States. Specifi c screening criteria 

used to defi ne the state of development for processes are described in the following 

paragraphs. This screening resulted in:

 25 Embryonic Technologies

 31 Innovative Technologies

Embryonic – These technologies are in the development stage and/or have been tested 

at laboratory or bench scale. New technologies that have reached the demonstration stage 

overseas, but cannot yet be considered to be established there, are also considered to be 

embryonic with respect to North American applications. 

Innovative – Technologies that meet one of the following criteria were classifi ed as 

innovative:

They have been tested as a full-scale demonstration; 

They have been available and implemented in the United States for less than fi ve 

years;

They have some degree of initial use (i.e. implemented in less than 25 municipalities 

throughout the United States); or,

They are established technologies from overseas. 

Established – In most cases, these processes are used at more than 25 full-scale facilities 

in North America; but there are some exceptions based upon specifi c considerations. The 

established category may include technologies that are widely used although introduced 

more recently in North America. In some cases, an established technology such as 

Anaerobic Digestion may have been modifi ed or adapted resulting in a new, innovative 

technology such as Thermally Phased Anaerobic Digestion. Due to the extensive number 

of established technologies and variations in each technology, established technologies 

are only listed. None are described in depth in this document and Technology Summary 

sheets are not provided for established technologies. 








Biosolids Management

September 2006 Emerging Technologies

1-5

The focus of this document is on Innovative Technologies along with some coverage of 

Embryonic Technologies as well. Early in the development process (laboratory stage), 

data are usually insuffi cient to prove or disprove technology viability at full scale; available 

information on these embryonic technologies is presented in this document. Technologies 

on the other end of the developmental scale, those defi ned as established in North 

America, are excluded from the detailed assessments on the assumption that they are 

proven, although still relatively new.

The differentiation between technologies established in Europe or Asia and those that 

have reached similar status in the United States can be critical since technologies have 

been applied successfully in other countries have not always fl ourished here. Because the 

viability of imported technologies is not guaranteed, established processes from overseas 

are classifi ed as innovative technologies for this project unless they have been proven in 

North American applications.

Some technologies fall into a “gray area” between the embryonic and innovative categories. 

Technologies that fall into this category are incorporated into the innovative category. The 

screening assessment is summarized in Table 1.1.
Emerging Technologies September 2006

1-6 Biosolids Management

Technology and Advancement(s)

Potential Benefi t* 

as Compared to Established Technologies

Low Capital CostLow Annual CostsReduces Solids or ThickensProduces Class A BiosolidsReduces OdorBenefi cial Use(Non Agriculture)

Chapter 2 Conditioning

Established

Chemical Conditioning

Heat Conditioning

Innovative

Cell Destruction

Chemical (MicrosludgeTM) z z

Ultrasonic z z

Embryonic

Cell Destruction Biological (BIODIET®) z z

Electrocoagulation z

Enzyme Conditioning z

Chapter 3 Thickening

Established

Centrifuge

Flotation Thickening

Gravity Belt Thickening

Gravity Thickening

Rotary Drum Thickening

Innovative

Flotation Thickening – Anoxic Gas zzz z

Membrane Thickening zzz

Recuperative Thickening zzz

Embryonic

Metal Screen Thickening z z

Table 1.1 – Summary of Biosolids Technologies
Biosolids Management

September 2006 Emerging Technologies

1-7

Technology and Advancement(s)

Potential Benefi t* 

as Compared to Established Technologies

Low Capital CostLow Annual CostsReduces Solids or ThickensProduces Class A BiosolidsReduces OdorBenefi cial Use(Non Agriculture)

Chapter 4 Stabilization

Established

Aerobic Digestion

Autothermal Thermophilic Aerobic Digestion (ATAD)

Alkaline Stabilization

Advanced Alkaline Stabilization

Anaerobic Digestion

Dual Digestion

Two-Stage Mesophilic

Composting

Pasteurization

Solidifi cation

Synox

Innovative

Aerobic Digestion

Aerobic/Anoxic zzz

Anaerobic Digestion

Anaerobic Baffl ed Reactor (ABR) zzz

Columbia Biosolids Flow-Through – Thermophilic Treatment 

(CBFT3) zzzz

High Rate Plug Flow (Bio Terminator 24/85) zzz

Temperature Phased Anaerobic Digestion (TPAND) zzzz

Thermal Hydrolysis (CAMBI Process) zzzz

Thermophilic Fermentation (ThermoTechTM) zzzz

Three-Phase Anaerobic Digestion z z

Two-Phase-Acid/Gas Anaerobic Digestion zzzz

Vermicomposting zz z

Embryonic

Aerobic Digestion

Simultaneous Digestion and Metal Leaching z

Table 1.1 – Summary of Biosolids Technologies (Contd)
Emerging Technologies September 2006

1-8 Biosolids Management

Technology and Advancement(s)

Potential Benefi t* 

as Compared to Established Technologies

Low Capital CostLow Annual CostsReduces Solids or ThickensProduces Class A BiosolidsReduces OdorBenefi cial Use(Non Agriculture)

Anaerobic Digestion 

Ozone Treatment z

Ferrate Addition z z

Disinfection

Irradiation z z

Neutralizer® z z

Chapter 5 Dewatering

Established

Belt Filter Press

Centrifuge

Chamber Press

Drying Beds

Auger-Assisted

Natural Freeze-Thaw

Vacuum-Assisted

Vacuum Filters

Innovative

Drying Beds

Quick Dry Filter Beds zzz

Electrodewatering zzz

Metal Screen Filtration

Inclined Screw Press zzz

Textile Media Filtration

Bucher Hydraulic Press zzz

DABTM System zzz

Geotube® Container zzz

Embryonic

Electro Dewatering

Electroacoustic zzz

Electroosmotic zzz

Table 1.1 – Summary of Biosolids Technologies (Contd)
Biosolids Management

September 2006 Emerging Technologies

1-9

Technology and Advancement(s)

Potential Benefi t* 

as Compared to Established Technologies

Low Capital CostLow Annual CostsReduces Solids or ThickensProduces Class A BiosolidsReduces OdorBenefi cial Use(Non Agriculture)

Membrane Filtration zzz

Membrane Filter Press

Textile Media Filtration

Simon Moos zzz

Tubular Filter Press zzz

Thermal Conditioning and Dewatering

Mechanical Freeze-Thaw z

Chapter 6 Thermal Conversion

Established

Combustion

Fluidized-Bed Furnace

Multiple-Hearth Furnace

Oxidation

Wet Air Oxidation

Innovative

Combustion

Reheat and Oxidize (RHOX) zz z

Oxidation

Supercritical Water Oxidation z z

Vitrifi cation

Minergy z z

Embryonic

Combustion

Molten Salt Incineration z z

Oxygen Enhanced Incineration z z

Fuel Production

Gasifi cation z

Sludge-to-Oil z

SlurryCarbTM zzz z

Table 1.1 – Summary of Biosolids Technologies (Contd)
Emerging Technologies September 2006

1-10 Biosolids Management

Technology and Advancement(s)

Potential Benefi t* 

as Compared to Established Technologies

Low Capital CostLow Annual CostsReduces Solids or ThickensProduces Class A BiosolidsReduces OdorBenefi cial Use(Non Agriculture)

Oxidation

Deep-Shaft Wet Air Oxidation (VERTADTM) zzz

Plasma Assisted Sludge Oxidation z z

Vitrifi cation

Melting Furnace z z

Chapter 7 Drying

Established

Direct Drying

Flash Drying

Indirect Drying

Innovative

Belt Drying z zz z

Direct Microwave Drying z zz z

Flash Drying z zz z

Fluidized Bed Drying z zz z

Embryonic

Chemical Drying z zzzz

Multiple Effect Drying

Carver-Greenfi eld (Not a viable technology)

Chapter 8 Other Processes

Innovative

Cannibal Process zzz

Lystek zz z

Injection into Cement Kiln zzz zz

Table 1.1 – Summary of Biosolids Technologies (Contd)

* Potential Benefi ts require confi rmation on a case-by-case basis. May enhance existing facilities, replace existing 

facilities, or offer an alternative choice for new facilities. For existing facilities, analysis of invested costs to date 

must be considered.
Biosolids Management

September 2006 Emerging Technologies

1-11

1.2.3 Development of Technology Summary Sheets

Technologies defi ned as embryonic or innovative are summarized on an individual 

Technology Summary sheet. Each process includes the following information:

Objective – Description of the goal of the technology.

State of Development – Where and how the technology has been applied (i.e. 

laboratory study, demonstration scale, full scale, etc.).

Description – A brief overview of the technology.

Comparison to Established Technologies – A brief comparison to established 

technologies that serve the same function in biosolids management. 

Available Cost Information – An approximate range of capital and operation and 

maintenance (O&M) (on an annual basis) costs, and assumptions made in developing 

them. Annual O&M costs typically include labor, equipment replacement and/or parts, 

energy, and chemicals. For many of the technologies, suffi cient information was not 

available for detail annual costs so general values are presented.

Contact Names – Names, addresses, and telephone numbers of contacts (vendors 

and practitioners) with additional information on the technology.

Key Words for Internet Search – Words used to enhance Internet searches for 

more information.

Data Sources – References used to compile the technology summary. 

1.2.4 Evaluation of Innovative Technologies

Technologies defi ned as innovative in the initial screening were subjected to a detailed 

evaluation presented in tabular format. Each technology was evaluated with respect to 

the descriptive and comparative criteria described below. Descriptive criteria include:

State of Development – Describes the stage of development for each technology, 

ranging from demonstration stage to full-scale operations.

Applicability – Qualitatively assesses where the technology is designed to be 

used.

Benefi cial Use – Describes the potential for the technology to produce a 

biosolids product suitable for benefi cial use (e.g. agriculture, construction, or power 

generation).
Emerging Technologies September 2006

1-12 Biosolids Management

Potential Benefi ts – Considers the benefi ts gained (e.g., capital or operational 

savings, reduces odor, produces Class A biosolids, etc.) from implementation of the 

technology.

Designations for each descriptive criterion are presented in Table 1.2.

Table 1.2 Descriptive Evaluation Criteria

Criterion Designation Description

 State of Development B Bench scale

P Pilot scale

 I Full-scale industrial applications, with demonstration or pilots for 

municipal sewage sludge

 O Full-scale operations overseas

D Full-scale demonstration in North America

 N Full-scale operations in North America

 Applicability I Industrywide

 F Few plants

 S Primarily small plants

L Primarily large plants

 Benefi cial Use A Agriculture

 C Construction

 P Power

 Potential Benefi ts C Low or lower capital costs

O Low or lower annual costs

V Reduces solids or produces thicker product Concentrations

 A Produces Class A biosolids

M Reduces odors

F Produces high nutrient fertilizer

R Benefi cial use (nonagricultural)

Comparative criteria are general attributes that the technology may possess relative to 

attributes of established technologies in the same category (e.g., conditioning etc.), for 

the same criteria. The innovative technologies may be rated positive, neutral or negative 

compared to expectations for established technologies. These criteria include:

Impact on Other Processes – Describes the degree to which the existing facilities 

will be disturbed.

Complexity – Considers the construction method and operation of the technology. 

Air Emission – Considers the potential for air emissions including odor.

Benefi cial Use – Considers the potential to produce a product that allows for more 

benefi cial use options.
Biosolids Management

September 2006 Emerging Technologies

1-13

Energy – Considers the potential to directly produce power or to produce a product 

that has characteristics that make it suitable for energy generation.

Footprint – Considers the requirement for land to support the construction of the 

technology at full-scale.

Environmental – Considers other factors associated with the technology that may 

produce environmental impacts or enhance environmental conditions.

The criteria and ratings were applied to each innovative technology and the results are 

presented in matrix format. Where available information was insuffi cient to rate a technology 

for a criterion, no rating is given. The project team and reviewers assessed each technology 

based on the limited information gathered and their collective judgment, experience, and 

opinions. Results of the evaluation are presented in subsequent chapters.

1.3 Guidance Document Format and Use

The majority of the document is divided into chapters based upon general technologies. 

One chapter is dedicated to each of the following categories:

Conditioning (Chapter 2)

Thickening (Chapter 3)

Stabilization (Chapter 4)

Dewatering (Chapter 5)

Thermal Conversion (Chapter 6)

Drying (Chapter 7)

Other Processes (Chapter 8)

Each chapter overviews the technology included, discusses the state of development 

for each, presents an evaluation matrix for innovative and embryonic technologies, 

and concludes with a Technology Summary sheet for each innovative and embryonic 

technology.

The technology summaries and evaluation matrices are the cornerstones of each chapter, 

giving a broad overview of the innovative technologies. Neither the summaries nor the 

matrices should be considered defi nitive technology assessments. Rather, they should 

be considered stepping stones to more detailed investigations.

The fi nal chapter, Chapter 9, discusses research needs related to biosolids 

management.

This document should be updated from time to time. Technologies were reviewed in mid2006.
Emerging Technologies September 2006

1-14 Biosolids Management

1.4 Chapter References

U.S. EPA. Offi ce of Solid Waste. Biosolids Generation, Use, and Disposal in the United 

States. EPA 530-R-99-009 (1999).

U.S. EPA. Offi ce of Water. Clean Watersheds Needs Survey 2000 Report to Congress. 

EPA 832-R-03-001 (2003)
Biosolids Management

Chapter

2-1

2

Conditioning

2.1 Introduction

Conditioning processes enhance biosolids characteristics for subsequent processing. 

This chapter focuses on the latest developments in conditioning technologies.

2.2 Technology Assessment

Table 2.1 summarizes the state of development of conditioning technologies.

Recent technology innovations in the area of conditioning now include electro-coagulation, 

ultrasonic disintegration, and enzyme addition as well as a combination of conditioning 

processes. These processes aim at modifying the organic and inorganic characteristics 

of biosolids critical to other following processes. Conditioning is typically linked to other 

processes and the purpose of conditioning is based upon the goals of these other 

subsequent processes. Often the results achieved by conditioning are seen in the 

subsequent processes rather than the conditioning process itself.

Figure 2.1 includes an evaluation of the emerging technologies identifi ed in this report. 

Summary sheets for each innovative and embryonic technology are provided at the end 

of this chapter.

Established Innovative Embryonic

Chemical Conditioning

Heat Conditioning

Cell Destruction

Chemical (MicroSludgeTM)

Ultrasonic





Cell Destruction

Biological (BIODIET®)

Electrocoagulation

Enzyme Conditioning



Table 2.1 – Conditioning Technologies—State of Development
Emerging Technologies September 2006

2-2 Biosolids Management

Figure 2.1 – Evaluation of Innovative Conditioning Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Chemical Cell Destruction

(MicroSludgeTM)

D I V,O N/A \ T \ T S \

Ultrasonic Cell Destruction O I V,O N/A \ T \ T S \

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

2-3

Technology Summary

Chemical Cell Destruction (MicroSludgeTM)

Objective:

Destroy the cell membranes of microbes in waste 

activated sludge to increase the performance of 

anaerobic digestion. Increase the amount of biogas 

generated from anaerobic digestion of biosolids.

State of Development: Innovative

The fi rst full-scale MicroSludgeTM chemical biocell destruction 

demonstration was conducted at the Chilliwack Wastewater 

Treatment Plant (WWTP) near Vancouver, Canada in 2004. A 

second full-scale demonstration started at the Los Angeles County 

Sanitation Districts Joint Water Pollution Control Plant in October 

2005. Neither is currently operating. 

Description:

TWaste-activated sludge from the secondary clarifi er enters a central unit where caustic chemicals (NaOH) are added. The mixture 

is held for one hour to weaken cell membranes and signifi cantly lower viscosity. As described by the developer of MicroSludgeTM, 

the technology employs an industrial-scale high-pressure homogenizer or “cell disrupter” to provide an enormous and sudden 

pressure drop to lyse the bacterial cells in the sludge. The processed sludge is liquefi ed, mixed with primary sludge, and 

anaerobically digested to produce stabilized biosolids and biogas.

The central unit of the process is a high-pressure cell disrupter that subjects waste-activated sludge to a large abrupt pressure 

drop. The sludge in the cell disruption valve is accelerated up to 300 meters per second (1,000 feet per second) in approximately 

2 microseconds. The sludge then impinges on an impact ring, disrupting the cell membranes, and liquefying the waste-activated 

sludge.

Comparison to Established Technologies:

Similar to conventional chemical conditioning only in that chemicals are added to the solids with the goal of breaking 

cellular bonds. The caustic additive is not similar to chemicals traditionally used such as ferrous or aluminum salts.

Available Cost Information:

Approximate Capital Cost: $1.7 million to $2 million 

Approximate O&M Costs: $68 to $119 per dry ton of activated sludge

The above range, provided by the vendor, is for a MicroSludgTM System 50 capable of processing approximately 

50,000 U.S. gallons of thickened waste-activated sludge per day. According to the vendor, larger systems would cost 

proportionately less per dry ton to operate. These costs do not include installation costs.

The operating cost estimate, again provided by the MicroSludgeTM vendor, includes electricity, chemicals, and maintenance. 

The above O&M cost estimate is for processing activated sludge to a range of 4 – 7% total solids. The estimate assumes 

electricity is purchased at $0.07/kilowatt-hour and chemicals costs are $0.21/pound. Electricity is the largest single 

operating cost contributor. Power consumption between 

500 – 1,000 kWh/ton dry solids is required for this process.

Vendor Name(s):

Paradigm Environmental Technologies, Inc.

200, 1600 West 6th Avenue

Vancouver, BC

Canada V6J 1R3 

Phone: 604-742-0360

Website: www.paradigmenvironmental.com

Practitioner(s):

The following were sites of technology demonstration but are not 

current practitioners:

Chilliwack Wastewater Treatment Plant

8550 Young Road

Chilliwack, British Columbia V2P 8A4

Joint Water Pollution Control Plant, Los Angeles County 

Sanitation Districts

Carson, CA
Emerging Technologies September 2006

2-4 Biosolids Management

Chemical Cell Destruction (MicroSludgeTM) (Contd)

Key Words for Internet Search:

MicroSludgeTM, anaerobic digestion, cell lysis, chemical pretreatment, volatile solids reduction, sludge, biosolids

Data Sources:

Rabinowitz, B. and R. Stephenson “Full-Scale Demonstration of Waste-Activated Sludge Homogenization at the Los 

Angeles County Joint Water Pollution Control Plant.” Proceedings of the WEF/AWWA Joint Residuals and Biosolids 

Management Conference, Cincinnati, Ohio, (12 – 15 March 2006). 

Paradigm Environmental Technologies, Inc. (2006). Personal e-mail communication with Director of Marketing, Filipe 

Figueira, on 12 May 2006.

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

2-5

Ultrasonic Cell Destruction

Objective:

Increase the rate at which anaerobic digestion of solids 

occurs; improve sludge settling; facilitate denitrifi cation, 

promote recovery of biogas for energy production.

State of Development: Innovative

The full-scale technology has been used at the Bad Bramstedt 

Sewage Works, Germany, in Kävlinge, Sweden ( 2002) and at 

Mangere Wastewater Treatment Plant, New Zealand (2005). 

Description:

Acoustic waves are applied to solids prior to digestion to attain extremely high pressures and temperatures within the biosolids. 

This results in the implosion of gas bubbles, which produces shear stresses that break up surfaces of bacteria, fungi, and other 

cellular matter. Different disintegration objectives can be achieved using either high- or low-frequency waves. The vendor claims 

that the process has been shown to increase cell disruption, reduce anaerobic digestion time, reduce sludge quantity and raise 

biogas production. Typically, this process is applied to waste activated solids, not primary solids.

Comparison to Established Technologies:

Ultrasonic disintegration is meant to enhance traditional anaerobic digestion by increasing the rate of fl oc and cell 

disintegration. Since hydrolysis can be a rate-limiting factor in anaerobic digestion, the claim is that ultrasonic disintegration 

increases the digestion rate, volatile suspended solids concentration, and gas production. 

Available Cost Information:

Approximate Capital Cost: $265,000

Approximate O&M Costs: $10,000 – $20,000 per year

Capital cost is based on a 5 – 8 million gallon per day facility treating 30% of the sludge produced per day. Operation 

and maintenance costs derived from a test plant in Riverside, southern California. Operation and maintenance cost 

assumptions include supervision, parts, and power. Current energy prices will signifi cantly impact power-related expenses.

Vendor Name(s):

EIMCO® Water Technologies

2850 S. Decker Lake Drive

Salt Lake City, UT 84119

Phone: 801-526-2342

Fax : 801-526-2910

E-mail: info@eimcowater.com

Sonico LLC (North America)

3020 Old Ranch Parkway, Suite 180

Seal Beach, CA 90740

Phone: 562-314-4231

Practitioner(s):

The following was the site of a demonstration system but is not a 

current practitioner:

Orange County Sanitation District

P.O. Box 8127

Fountain Valley, CA 92728-8127

Technology Summary
Emerging Technologies September 2006

2-6 Biosolids Management

Ultrasonic Cell Destruction (Contd)

Key Words for Internet Search:

Ultrasonic cavitation, ultrasonic disintegration, Sonolyzer, biosolids, sludge

Data Sources:

Vendor-supplied information

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

2-7

Biological Cell Destruction (BIODIET®)

Objective:

Promote biological disintegration of organic matter in 

organic sludges to water and carbon dioxide, thereby 

reducing sludge volume.

State of Development: Embryonic

This technology is primarily marketed in Japan for highly organic 

industrial (i.e. food processing) sludges. Currently marketed as 

BIODIET®.

Description:

Activated sludge is diverted from the settling tank to a vessel where a chemical agent is added. The agent has strong oxidizing

power, causing the cell walls of the bacteria to become weak and breakdown. The processed bacteria are then returned to the 

activated sludge unit where they decompose into carbon dioxide and water. The BIODIET® process is intended for organic sludges 

only; volume reduction will be impacted by the amount of inorganic material in the sludge.

Comparison to Established Technologies:

Not similar to any established technologies. 

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Detailed information is not available but the vendor’s website presents anecdotal information 

showing a cost savings of over 50% using BIODIET® compared to conventional methods of 

managing industrial waste.

Vendor Name(s):

Plant Engineering Division

Kankyo Engineering Company, Ltd.

1-9-8 Higashikanda, Chiyoda-ku

Tokyo 101-0031 Japan

Phone: 81-3-3862-1611

Fax : 81-3-3862-1617

E-mail: general@k-eng.co.jp

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

BIODIET®, Japanese wastewater treatment, sludge

Data Sources:

Japanese Advanced Environment Equipment. BIODIET®. Global Environment Centre Environmental Technology Database 

NETT21. (2002).

T. Hagino, S. Gohda, H. Yoshida. “A Sludge-Thickening-Dehydrating System Featuring Single Polymer Conditioning” The 

Abstract of Ebara Engineering Review. (1999).

Vendor-supplied information.

Technology Summary
Emerging Technologies September 2006

2-8 Biosolids Management

Technology Summary

Electrocoagulation

Objective:

Increase the rate at which anaerobic digestion of solids 

occurs; improve sludge settling; facilitate denitrifi cation, 

promote recovery of biogas for energy production.

State of Development: Embryonic

Electrocoagulation has been used for mining and metals industry 

applications since the 1900s. The wastewater treatment plant 

at the Vancouver Shipyards (British Columbia) has been using 

electrocoagulation for 4 years to successfully remove heavy 

metals and emulsifi ed oils. The system does not, however, remove 

antifreeze or solvents, nor can it treat soluble biochemical oxygen 

demand (BOD) and other organic constituents of sewage.

Powell Water Systems, Inc. markets electrocoagulation technology 

for domestic wastewater treatment and claims anywhere from 

85 to 99.99% removal of several wastewater constituents, including 

heavy metals, phosphates, fats and oils, insoluble BOD, and Total 

Coliforms. 

Description:

Electrocoagulation uses an electrical current to dissolve a sacrifi cial anode and thereby introduce chemically reactive aluminum 

into the wastewater stream. These positively charged aluminum ions are attracted to the very fi ne negatively charged ions and 

particles in suspension. The resulting agglomerations of particulates increase in size until they no longer remain in suspension. 

Simultaneously, gases formed by hydrolysis form very fi ne bubbles that associate with the particulates and buoy them up to the 

surface of the treated wastewater for removal by fl otation.

Comparison to Established Technologies:

Not similar to any established technologies

Available Cost Information:

Approximate Capital Cost: $451,000 (500 gpd system) $1,520,000 (3,000,000 gpd system)

Approximate O&M Costs: $678 per day (500 gpd system) $2,791 per day (3,000,000 gpd system)

Capital cost estimates are for the Powell electrocoagulation unit only, and they do not take into account additional 

construction costs that may be necessary to install the unit. Operation and maintenance costs include electricity, labor, 

replacement blades, and maintenance.

Vendor Name(s):

Powell Water Systems, Inc.

19331 Tufts Circle

Centennial, CO 80015-5820

Phone: 303-627-0320

Fax : 303-627-0116

E-mail: scottpowell@powellwater.com

Website: www.powellwater.com 

Practitioner(s):

Vancouver Shipyards Co. Ltd.

North Vancouver, B.C.

Canada V7P 2R2

Phone: 602-988-6361

Fax: 604-990-3290

Email: info@vanship.com
Biosolids Management

September 2006 Emerging Technologies

2-9

Electrocoagulation (Contd)

Key Words for Internet Search:

Electrocoagulation, conditioning, dewatering, biosolids, sludge.

Data Sources:

Stephenson, R., B. Tennant, D. Hartle, G. Geatros. “Vancouver shipyards treat emulsifi ed oily wastewater using 

electrocoagulation.” Watermark Newsletter of the British Columbia Water & Waste Association. (2003).

Vendor-supplied information.

Technology Summary
Emerging Technologies September 2006

2-10 Biosolids Management

Technology Summary

Enzyme Conditioning

Objective:

Degrade organic material to increase the dewaterability 

of biosolids and, in some cases, to reduce odors and 

aid in digestion processes.

State of Development: Embryonic

Enzymes have shown promising results in breaking down fats and 

oils in meat industry pretreatment facilities, as well as in reducing 

odors, solvents, and chemical oxygen demand (COD) in aeration 

tanks, lagoons, and biosolids digesters. There has also been 

research with promising results showing signifi cant increase in 

percent solids from conventional dewatering of enzyme-treated 

solids. 

Description:

Mixtures of enzymes, specialized nutrients (i.e. humic acids, amino acids) and often aerobic and anaerobic bacteria cultures are 

added to thickening and digestion systems that produce enzymes specially engineered to degrade organic materials converting 

them into carbon dioxide and water. Reported advantages include limited damage to biological treatment systems and cost savings

as the enzymatic reaction will continue to occur over several days.

Comparison to Established Technologies:

Enzyme destruction of cells is not similar to any established processes.

Available Cost Information:

Approximate Capital Cost: $31 per pound of enzyme solution

Approximate O&M Costs: Not available

The manufacturer of Enviro-Zyme® recommends various amounts of solution depending on the amount of sludge to be 

treated. For example, 1 pound is needed to treat 1 to 5 tons of sludge, 2 pounds are required for 6 to 25 tons of sludge, and 

so on.

Vendor Name(s):

Eco-Cure, Inc.

1525 Casa Buena Drive Suite D

Corte Madera, CA 94925

Phone: 415-924-8450

Email: jimkritchever@yahoo.com

Website: www.eco-cure.com

Envoguard

298 Kings Mill Rd York, PA 17403

Phone: (800) 297-8266

Email: info@envoguard.com 

Website: www.envoguard.com

Enviro-Zyme® International, Inc.

P.O. Box 169

Stormville, NY 12582

Phone: 800-882-9904

E-mail: info@envirozyme.com

Practitioner(s):

See websites for practitioners: 

www.eco-cure.com/enzymeinfodert.htm 
Biosolids Management

September 2006 Emerging Technologies

2-11

Enzyme Conditioning (Contd)

Vendor Name(s) (Contd):

Vendor Name(s):

The Moorhead Group, Inc

108 Don Lorenzo Court

Aptos, CA 95003 

Phone 831-685-1148 

Fax 831-685-1259

info@moorheadgroup.com

www.moorheadgroup.com 

NRP, Inc.

2948 N. W. 60th Street

Fort Lauderdale, FL 33309

Phone: 954-970-7773

Fax: 954-970-7778

hschure@nrp-inc.com

www.nrp-inc.com

Suez

www.suez.com

Western Bio-Tec Services

1265 W. 16th Street

Long Beach, CA 90813-1381

Phone: 949-456-0058

Email: westernbiotec@aol.com

Website: www.westernbiotec.com

Key Words for Internet Search:

Enviro-Zyme, enzyme conditioning, odorants, ACE, Agricycle Catalyst Enzyme, WESBAC, Biolysis-e.

Data Sources:

Vendor-supplied information.

Dursun, D., A Ayol, S.K. Dentel. “Pretreatment of Biosolids by Multi-Enzyme Mixtures Leads to Dramatic Improvements in 

Dewaterability.” Proceedings of the WEF Residuals and Biosolids Management Conference 2006: Bridging to the Future, 

Cincinnati, OH (12–14 March 2006).

Toffey, William E., Matthew Higgins. “Results of Trials and Chemicals, Enzymes and Biological Agents for Reducing 

Odorant Intensity of Biosolids.” Proceedings of the WEF Residuals and Biosolids Management Conference 2006: Bridging 

to the Future, Cincinnati, OH (12–14 March 2006).

Technology Summary

Biosolids Management

Chapter

3-1

3

Thickening

3.1 Introduction

The goal of thickening is to increase the concentration of solids. Thickening enhances 

treatment processes that follow such as stabilization, dewatering, and drying. This chapter 

focuses on the latest developments in thickening technologies.

3.2 Technology Assessment

Table 3.1 summarizes the state of development of thickening technologies.

Recent technology developments in this area focus on various methods to increase solids 

concentrations such as anoxic gas fl otation, membrane thickeners and recuperative 

thickeners. These technologies can help reduce chemicals and increase the effi ciency 

of subsequent processes such as digestion. Some odor reduction during thickening also 

has been recognized. 

Figure 3.1 includes an evaluation of the innovative technologies identifi ed in this report. 

Summary sheets for each innovative and embryonic technology are provided at the end 

of this chapter.

Established Innovative Embryonic

Centrifuge

Flotation Thickening

Gravity-Belt Thickening

Gravity Thickening

Rotary Drum Thickening

Flotation Thickening 

Anoxic Gas

Membrane Thickening

Recuperative Thickening



Metal Screen Thickening

Table 3.1 – Thickening Technologies—State of Development
Emerging Technologies September 2006

3-2 Biosolids Management

Figure 3.1 – Evaluation of Innovative Thickening Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Flotation Thickening – Anoxic Gas P I C,O,V,M N/A S \\\ S \

Membrane Thickening N I C,O,V N/A S S \ \ S \

Recuperative Thickening P I C,O,V N/A S \\\ S \

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

3-3

Technology Summary

Flotation Thickening – Anoxic Gas 

Objective:

Thicken contents of an anaerobic digester to reduce 

volume of solids to dewater and transport. Increase 

digester capacity.

State of Development: Innovative

The technology was used for over a year at the Salmon Creek Plant 

in Burien, King County, Washington. Volatile solids were increased 

from approximately 50% to 71%; resulting in a 34% reduction in 

volume of solids to be hauled off site. In addition, odors from the belt 

presses and the amount of polymer required for dewatering were 

both reduced. Plant operations, which used to experience frequent 

foaming incidents, improved; there were no foaming incidents while 

the technology was employed. The process is also used to treat dairy 

and potato processing wastes in the U.S.

Description:

This totally-enclosed process involves separating and thickening solids removed from anaerobic digestion using digester gas to 

fl oat solids which are removed and returned to the digester. The technology is typically employed as an enhancement to existing 

conventional digesters. Solids are concentrated to 6 – 10%. All gases are discharged back to the anaerobic digester or to a biofi lter.

Comparison to Established Technologies:

Similar to Dissolved Air Flotation Thickening (DAFT), however, uses digester gas instead of air.

Available Cost Information:

Approximate Capital Cost: $7.50 per dry lb (at 6-8% solids, or $1.90 per gallon) processed per day

Approximate O&M Costs: $8.00 per dry ton of biosolids processed for polymer

Capital costs include associated equipment (saturator, controls, polymer feed, inlet/outlet pumps) and will vary with the 

surface loading rate to the separators. The quoted costs are based on processing 200 pounds of dry solids per square foot 

per day. According to the vendor, each gallon processed per day through an AGF will reduce feed through digester by 1.5 to 

2.0 gallons per day. 

Operational costs include a polymer requirement of 4 pounds per dry ton of biosolids processed at $2.00 per pound. 

However, total polymer use may decrease. 

Cost information supplied by vendor. 

Vendor Name(s):

Environmental Energy Engineering Company

6007 Hill Road NE

Olympia, WA 98516

Phone: 360-923-2000

E-mail: dennis@makingenergy.com 

www.makingenergy.com 

Practitioner(s):

The following hosted a demonstration project but is not a current 

practitioner:

Southwest Suburban Sewer District (SWSSD)

Salmon Creek Wastewater Treatment Plant

431 Ambaum Blvd. SW

Burien, WA 98166

Phone: 206-244-2202

Fax: 206-433-8546

E-mail: millercreekWWTP@aol.com
Emerging Technologies September 2006

3-4 Biosolids Management

Flotation Thickening – Anoxic Gas (Contd)

Key Words for Internet Search:

Anoxic gas fl otation, AGF, biosolids, Salmon Creek WWTP, King County Washington

Data Sources:

King County Applied Wastewater Program. “AGF – Anoxic Gas Flotation.” Demonstration project evaluation. (2000).

Burke, D.A. “Application of AGF (Anoxic Gas Flotation) Process.” Environmental Energy Company. (2000) Vendor-supplied 

information 

Burke, D.A “Producing Exceptional Quality Biosolids through Digestion, Pasteurization, and Redigestion”. Biosolids 2001: 

Building Public Support Conference Proceedings Water Environment Federation/AWWA/CWEA Joint Residuals and 

Biosolids Management Conference. (2001).

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

3-5

Technology Summary

Membrane Thickening

Objective:

Thickening of waste-activated sludge.

State of Development: Innovative

Membrane thickeners are operating in several locations throughout 

the U.S. Full-scale facilities are in use in Dundee, Michigan and 

Fulton County, Georgia among other locations.

Description:

A basin with suspended biomass and a membrane system that provides a barrier for the solid-liquid separation. These membranes 

can be used in an aerobic environment to achieve separation of liquid from biomass. Anaerobic environments have plugged 

membranes too quickly in tests. Therefore, aerobic environments are needed for oxygen mixing. Thickening to over 4% solids has 

been reported. Flux through the membrane is reduced to half the value for membranes used in activated sludge basins.

The different types of membranes are described as modular and they are of the following types: tubular, hollow-fi ber, spiral wound, 

plate and frame, and pleated cartridge fi lters.

Comparison to Established Technologies:

Similar to MBRs for wastewater treatment. Membranes for thickening require a smaller footprint than many established 

thickening technologies.

Available Cost Information:

Approximate Capital Cost: $125,000 for a one-train system with two cassettes.

Approximate O&M Costs: Not provided by vendor.

Vendor Name(s):

Enviroquip, Inc.

2404 Rutland Drive, Suite 200

Austin, TX

Phone: 512-834-6019

Website: www.enviroquip.com 

Infi lco Degremont - U.S. Headquarters

P.O. Box 71390 

Richmond, VA 23255-1390 

8007 Discovery Drive 

Richmond, VA 23229-8605 USA

Phone: (804) 756-7600

Website: www.infi lcodegremont.com/membrane_

fi ltration.html

Mitsubishi International Corporation

333 South Hope Street West, Suite 2500

Los Angeles, CA 90071

Phone: 213-687-2853

Website: www.micusa.com

Practitioner(s):

Village of Dundee Wastewater Treatment Plant

596 E Main St 

Dundee , MI 48131-1208

Phone: 734-529-3001

Fulton County Public Works Department

Cauley Creek Water Reclamation Facility

141 Pryor Street, Suite 6001

Atlanta, GA 30303

Phone: 404-730-7442

www.co.fulton.ga.us/public_works_projects/index_new_pubwks1.

html 

See www.zenon.com/resources/case_studies/wastewater/ for 

additional practitioners.
Emerging Technologies September 2006

3-6 Biosolids Management

Membrane Thickening (Contd)

US Filter/MEMCOR

4116 Sorrento Valley Blvd.

San Diego, CA 92121

Contacts for regional offi ces that provide information on MEMCOR are 

available at 

www.usfi lter.com/en/Product+Lines/Memcor_Products/Contacts/memcor_us_

contacts.htm

Veolia Water Solutions & Technologies

L’Aquarène 

1 place Montgolfi er 

94417, Saint Maurice 

France 

Phone: +33 (0)1 45 11 55 55 

Website: www.veoliawater.com

Zenon Environmental Services, Inc.

3239 Dundas Street West

Oakville, Ontario

Phone: 905-465-3030

Fax: 905-465-3050

Website: www.zenon.com

Key Words for Internet Search:

Membrane thickening, biosolids membrane treatment, sludge separation

Data Sources:

Metcalf and Eddy. Wastewater Engineering Treatment and Reuse. 4th Edition. (2003).

Vendor-supplied information.

Technology Summary

Typical membrane unit

Overview of the Cauley Creek WRF 

Fulton County, GA

MBR Technology at Cauley Creek WRF 

Fulton County, GA
Biosolids Management

September 2006 Emerging Technologies

3-7

Technology Summary

Recuperative Thickening 

Objective:

Reduce biosolids volume, enhance biosolids 

destruction and gas production; reduce dewatering and 

benefi cial use/disposal costs.

State of Development: Innovative

Recuperative thickening was the subject of a full-scale test at the 

Spokane, Washington, Advanced Wastewater Treatment Plant from 

September 2000 to May 2001. Two benefi ts were reported in the 

study: (1) Use of existing dissolved air fl otation capacity allowed 

implementation with essentially no capital cost; (2) Co-thickening with 

waste-activated sludge showed no increase in thickening labor or 

power costs. Polymer use increased for thickening and decreased 

for dewatering. Recuperative thickening of 25% of the digesting 

solids increased solids retention time in the anaerobic digesters from 

15.7 days to 24.0 days. Anaerobic digestion volatile solids reduction 

increased from 50% to 64%. Recuperative thickening did not affect 

effl uent quality.

Description:

Digested biosolids are removed from the anaerobic digestion process, thickened, and returned to the anaerobic digestion process. 

Anoxic gas fl otation is one type of recuperative thickening process, and it is described earlier in this chapter.

Comparison to Established Technologies:

Technology allows for the use of existing biosolids process equipment and does not have the additional capital costs 

associated with other innovative technologies that require greater capital investments. 

Available Cost Information:

Approximate Capital Cost: Not provided by vendor.

Approximate O&M Costs: Not provided by vendor.

Capital and operations and maintenance cost estimates will vary depending on what thickening equipment currently exists 

at a treatment facility. According to the Spokane study, the net result was a net reduction of polymer requirements by 15% 

with an annual savings of $28,000. Biosolids production (wet weight) was reduced 22% with a resultant annual savings of 

$85,000. There is no specifi c equipment to be purchased.

Vendor Name(s):

Not applicable (procedural variation not requiring 

specifi c equipment)

Practitioner(s):

The following hosted a demonstration project but is not a current 

practitioner:

Spokane Advanced Wastewater Treatment Plant

4401 North A.L. White Parkway

Spokane, WA 99205

Phone: 509-625-4600
Emerging Technologies September 2006

3-8 Biosolids Management

Recuperative Thickening (Contd)

Key Words for Internet Search:

Recuperative thickening/thickener, anaerobic digestion

Data Sources:

Reynolds, D.T., M. Cannon, T. Pelton. “Preliminary Investigation of Recuperative Thickening for Anaerobic Digestion.” 

WEFTEC Paper. (October 2001).

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

3-9

Technology Summary

Metal Screen Thickening 

Objective:

This equipment performs conditioning and thickening in 

one basin

State of Development: Embryonic

According to Ebara Corporation, a pilot test was conducted in a 

24-hour operation biosolids treatment facility for a period of about 1 

year. Test results indicated a sludge treatment rate of about 200 kg 

dissolved solids per hour.

Description:

This system employs a set of slit screens with 1-millimeter openings. The screens are installed in a mixing tank. Sludge is thickened 

by cross-fl ow fi ltration through the screens. According to the vendor, this system is designed to prevent clogging (which often 

occurs with simple screening under atmospheric pressure) with low differential pressure through the submerged screens.

Comparison to Established Technologies:

Not similar to any established technologies.

Available Cost Information:

Approximate Capital Cost: Not provided by vendor.

Approximate O&M Costs: Not provided by vendor.

Vendor Name(s):

Not applicable (procedural variation not requiring 

specifi c equipment)

Practitioner(s):

The following hosted a demonstration project but is not a current 

practitioner:

Spokane Advanced Wastewater Treatment Plant

4401 North A.L. White Parkway

Spokane, WA 99205

Phone: 509-625-4600

Key Words for Internet Search:

Recuperative thickening/thickener, anaerobic digestion

Data Sources:

Reynolds, D.T., M. Cannon, T. Pelton. “Preliminary Investigation of Recuperative Thickening for Anaerobic Digestion.” 

WEFTEC Paper. (October 2001).

Biosolids Management

Chapter

4-1

4

Stabilization

4.1 Introduction

Biosolids are stabilized to reduce pathogens, eliminate offensive odors and inhibit, reduce 

or eliminate the potential for putrefaction that leads to odor production. Stabilization also 

reduces attraction to vectors. Stabilization processes may produce Class A or Class B 

biosolids, depending on the level and type of stabilization provided. This chapter focuses 

on the latest developments in stabilization technologies.

4.2 Technology Assessment

Table 4.1 summarizes the state of development of stabilization technologies.

Recent technology developments in this area include several adaptations to the anaerobic 

digestion process. Temperature-Phase Anaerobic Digestion (TPAnD), Two-Phase Acid/

Gas, and Three-Phase Anaerobic Digestion are included as innovative technologies. 

Figure 4.1 includes an evaluation of the innovative technologies identifi ed. Summary 

sheets for each innovative and embryonic technology are provided at the end of this 

chapter.

Established Innovative Embryonic

Aerobic Digestion 

Autothermal Thermophilic 

(ATAD)

Alkaline Stabilization

Advanced Alkaline Stabilization

Anaerobic Digestion

Dual Digestion

Two-Stage Mesophilic

Composting

Pasteurization

Solidifi cation

Synox







Aerobic Digestion 

Aerobic/Anoxic Digestion

Anaerobic Digestion

Anaerobic Baffl ed Reactor

Columbus Biosolids Flow-Through

Thermophilic Treatment

High-Rate Plug Flow (BioTerminator 24/85)

Temperature Phased Anaerobic Digestion

Thermal Hydrolysis (CAMBI Process)

Thermophilic Fermentation (ThermoTechTM) 

Three-Phase Anaerobic Digestion

Two-Phase Acid Gas Anaerobic Digestion 

Vermicomposting





















Aerobic Digestion 

Simultaneous Digestion and 

Metal Leaching

Anaerobic Digestion

Ozone Treatment 

Disinfection

Ferrate Addition

Irradiation

Neutralizer®











Table 4.1 – Thickening Technologies—State of Development
Emerging Technologies September 2006

4-2 Biosolids Management

Figure 4.1 – Evaluation of Innovative Thickening Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Aerobic/Anoxic Digestion D F C,O,V N/A S \ \ S S \ Enhances aerobic 

digestion

Anaerobic Baffl ed Reactor (ABR) D F C,O,V N/A \\\\\\

Columbus Thermophilic Treatment 

(CBFT3) N I C,O,V A S T \ S \ S Retrofi ts to produce Class A

High-Rate Plug Flow BioTerminator 

24/85 P I C,O,V N/A S T \ \ T \ Requires screening and 

degritting

Temperature-Phased Anaerobic 

Digestion N I C,O,V A S T \ S \ S

Thermal Hydrolysis

(CAMBI Process) D L C,O,V N/A STTS \ \ Odor issues

Thermophilic Fermentation

(ThermoTechTM) I F C,O,V N/A S T \ S S \

Three-Phase Anaerobic Digestion N I C,O,V A S \ \ STS

Two-Phase Acid/Gas Anaerobic 

Digestion N I C,O,V A S \ \ SSS Low capital cost

Vermicomposting N S C,O,V A S S \ STS

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

4-3

Technology Summary

Aerobic/Anoxic Digestion 

Objective:

Improve denitrifi cation and enhance aerobic digestion.

State of Development: Innovative

Full-scale aerobic/anoxic operation has been evaluated at treatment 

plants in Castle Rock, Colorado; Paris, Illinois; and Clyde, Ohio. In 

each case, the result was nearly complete nitrifi cation and the ability 

to maintain approximately neutral pH values, enhanced digestion, 

near-complete nitrifi cation, and nitrogen removal.

Description:

Aerators in an aerobic digester cycle on and off so that denitrifi cation occurs under the anoxic conditions produced when the 

aerators are turned off. Aerobic/anoxic digestion results in denitrifi cation, which can provide approximately neutral pH that enhances 

nitrifi cation, aerobic digestion, and nitrogen removal. Effective pathogen destruction is also observed. Aerobic/anoxic operation 

at several facilities has allowed the facilities to maintain approximately neutral pH values, enhanced digestion, near-complete

nitrifi cation, and nitrogen removal.

Comparison to Established Technologies:

Similar to aerobic/anoxic wastewater treatment nutrient removal technologies. Aerobic/anoxic sludge digestion has been 

shown to improve sludge dewaterability, fi ltrate quality, and pH control compared to aerobic digestion alone.

Available Cost Information:

Approximate Capital Cost: Process involved conversion of existing facilities. Vendor does not have unit capital costs.

Approximate O&M Costs: Not provided by the vendor.

Vendor Name(s):

Enviroquip, Inc.

2404 Rutland Drive, Suite 200

Austin, TX 78758

Phone: 512-834-6000

Fax : 512-834-6039

Practitioner(s):

Plum Creek Wastewater Authority

4255 N US Highway 85

Castle Rock, CO 80108

Phone: 303-688-1991

Fax: 303-688-1992

Key Words for Internet Search:

Aerobic-anoxic, biosolids, sludge

Data Sources:

Daigger, G.T. and E. Bailey. “Improving Digestion by Prethickening, Staged Operation, and Aerobic-Anoxic Operation: Four 

Full-Scale Demonstrations.” Water Environment Research. (May/June 2000).
Emerging Technologies September 2006

4-4 Biosolids Management

Technology Summary

Anaerobic Baffl ed Reactor (ABR)

Objective:

Reduce sludge production by encouraging anaerobic 

biological degradation of the primary sludge in the 

primary treatment tank.

State of Development: Innovative

A full-scale pilot plant at Orange County Sanitation District was used 

to evaluate the performance of an ABR in Southern California. Fullscale prototypes have been constructed in the United Kingdom. 

The appropriateness of the ABR for on-site primary sanitation in lowincome communities in South Africa also has been evaluated.

Description:

An anaerobic baffl ed reactor (ABR) consists of alternating hanging and standing baffl es that compartmentalize the reactor and 

force liquid fl ow up and down from one compartment to the next. The compartmentalized design separates the solids retention time 

from the hydraulic retention time, making it possible to anaerobically treat wastewaters at short retention times (4 – 10 hours).

Comparison to Established Technologies:

Similar to baffl ed wastewater treatment basins used as a sequence of complete mix reactors. ABR systems have been 

shown to provide higher resilience to hydraulic and organic shock loads, longer biomass retention times, and lower sludge 

yields than other high rate anaerobic treatment systems. According to Orange County Sanitation District, volatile solids 

reduction was not clear from the test data. High BOD in effl uent was observed.

Available Cost Information:

Approximate Capital Cost: $400,000 to retrofi t a 4-MGD rectangular primary clarifi er with ABR

Approximate O&M Costs: $10,000 per year

Costs are expected to vary based on rectangular versus circular retrofi t.

Vendor Name(s):

Atkins Water

3020 Old Ranch Parkway

Suite 180

Seal Beach, CA 90740

Phone: (562) 314-4231

Email: rupert.kruger@atkinsglobal.com 

Practitioner(s):

The following hosted a pilot project but is not a current 

practitioner:

Orange County Sanitation District

10844 Ellis Avenue 

Fountain Valley, CA 92708-7018

Phone: (714) 962-2411

Email: forinformation@ocsd.com 

Key Words for Internet Search:

Anaerobic Baffl ed Reactor, ABR, volatile solids reduction, biosolids
Biosolids Management

September 2006 Emerging Technologies

4-5

Anaerobic Baffl ed Reactor (ABR) (Contd)

Data Sources:

Foxon, K.M., S. Pillay, T. Lalbahdur, N. Rodda, F. Holder and C.A. Buckley. “The anaerobic baffl ed reactor (ABR): An 

appropriate technology for on-site sanitation.” Water SA 30:5 (2004)

44-50.

Kruger, R. and J. Brown. “Large-scale pilot trial of anaerobic baffl ed reactor: Assessment of key performance parameters 

and cost-benefi t analysis of full-scale retrofi t.” Proceedings of the WEF/AWWA Joint Residuals and Biosolids Management 

Conference, Nashville, Tennessee. (17-20 April 2005)

ABR installation. Photo courtesy

of Atkins Water, 2006.

Schematic of ABR unit (Foxon, et al., 2004)

Cross-section of ABR (Kruger and Brown, 2005)

Technology Summary
Emerging Technologies September 2006

4-6 Biosolids Management

Technology Summary

Columbus Biosolids Flow-Through Thermophilic Treatment (CBFT3)

Objective:

Low-cost way for converting from Class B to Class A 

biosolids production. 

State of Development: Innovative

Columbus Water Works (CWW), Georgia, completed a pilot-scale 

study of CBFT3 in June 2003 which showed successful production 

of Class A biosolids at digestion temperatures of 53°C > 6 days and 

60°C for 30 minutes with a very specifi c treatment train. This has 

received site-specifi c approval for Class A biosolids production. In 

addition, testing for Helminth and viruses continue.

Description:

The CBFT3 design consists of a conventional, complete-mix, continuous-feed thermophilic anaerobic digester followed by a long, 

narrow plug-fl ow reactor. Mesophilic digestion is then used to minimize odors in the fi nal product. The construction of a plug-fl ow 

reactor prototype was completed in February 2004, and ongoing studies are testing its effectiveness. Estimates indicate that the 

CBFT3 conversion process could save from $0.6 million for a 5 MGD plant up to $19 million for a 200 MGD plant. Patent rights of

this process were given to the Water Environment Research Foundation (WERF) in 2005.

Comparison to Established Technologies:

An improved process from conventional anaerobic digesters potentially capable of yielding Class A biosolids.

Available Cost Information:

Approximate Capital Cost: $12,000,000 (for a 90 MGD facility)

Approximate O&M Costs: Not available.

Capital cost estimate is based on construction loan for the South Columbus Water Resource Facility, Georgia. Maintenance 

activities are completed on an “as-needed” basis, a minimum of once annually. 

Vendor Name(s):

Developed by the Columbus Water Works with:

Brown and Caldwell

4700 Lakehurst Court, Suite 100

Columbus, OH 43016

Phone: (614) 410-6144

Fax: (614) 410-3088

Practitioner(s):

Columbus Water Works

1421 Veterans Parkway, P.O. Box 1600

Columbus, GA 31901

Phone: 706-649-3400 

Fax: 706-327-3845

Email: mailbox@cwwga.org 

Website: www.cwwga.org

Key Words for Internet Search:

Columbus Biosolids Flow-Through Thermophilic Treatment, CBFT3, Columbus Water Works
Biosolids Management

September 2006 Emerging Technologies

4-7

Columbus Biosolids Flow-Through Thermophilic Treatment (CBFT3) (Contd)

Data Sources:

Esters, K. “Columbus Water Works honored for technique that turns human waste into safe fertilizer.” Water Industry News. 

(22 February 2005). 

Water Environment Research Federation (WERF). “Columbus Retrofi ts Plants to Achieve Low-Cost Class A Biosolids.” 

Compiled by Roy Ramani in WERF Progress Newsletter –Vol 15: Issue 3. (Summer 2004)

Willis, J. and P. Schafer. “Upgrading to Class A Anaerobic Digestion: Is Your Biosolids Program Ready to Make the Move?” 

Public Works Magazine. (1 January 2006).

Technology Summary
Emerging Technologies September 2006

4-8 Biosolids Management

Technology Summary

High-Rate Plug Flow BioTerminator 24/85

Objective:

Reduce total suspended solids of feed sludge by 85% 

in 24 hours. Generate methane that can be recovered 

and used for energy 

State of Development: Innovative

Pilot studies of the BioTerminator system have been conducted at 

wastewater treatment plants in Daphne, Alabama; Galveston, Texas; 

Baton Rouge, Louisiana; and Fort Smith and Little Rock, Arkansas. 

Based on pilot study results, the BioTerminator appears to achieve 

exceptional total and volatile solids destruction. The fi rst full-scale 

application of the BioTerminator technology is scheduled to be 

installed at the Daphne, Alabama WWTP in 2007.

Description:

The BioTerminator 24/85 anaerobic digester consists of a plug fl ow insulated tank with a patented arrangement of baffl es. The 

tanks are rectangular in shape with a maximum capacity of 10,000 gallons. 

A plant requiring more than the 10,000 gallon feed capacity would need to employ multiple reactors. Prior to entering the tank, 

the sludge may need to be screened and/or degritted, and will have to be heated to 35°C (95°F). For some sludges, a minimal 

amount of carbon supplement, typically sugar, is added as a microbial stimulant. For mixed primary and secondary sludges, 

sodium bicarbonate is fed if necessary to maintain proper pH. 

A portion of the methane generated by the process is used to preheat the sludge (<25%, depending on climate) and the rest may 

be fl ared or used to recover energy value. Additional descriptions of the various system components are provided in Burnett 

(2005).

Comparison to Established Technologies:

According to the vendor, the BioTerminator requires much shorter retention time and achieves a greater reduction in total 

solids in comparison to a well-operated conventional anaerobic digester. Studies are underway to support these claims.

Available Cost Information:

Approximate Capital Cost: $1.2 million for fi rst 10,000 gpd reactor and equipment skid

$400,000 for subsequent two reactors, if added

Approximate O&M Costs: $15,000/year for chemicals and $4,000/year electricity

Recoverable energy value of methane, if used, would offset O&M costs

Vendor Name(s):

Shaw Environmental & Infrastructure, Inc.

17 Princess Road

Lawrenceville, NJ 08648

Phone: 609-895-5340

Practitioner(s):

Information on practitioners is available at 

www.bioterminator.com/casestudies.phtml. 

Key Words for Internet Search:

Anaerobic digester, volatile solids, mesophilic, plug fl ow, solids reduction, BioTerminator
Biosolids Management

September 2006 Emerging Technologies

4-9

High-Rate Plug Flow BioTerminator 24/85 (Contd)

Data Sources:

Burnett, C. “Pilot test results of the BioTerminator high-rate plug fl ow anaerobic digester.” Proceedings of the WEF/AWWA 

Joint Residuals and Biosolids Management Conference, Nashville, Tennessee. (17–20 April 2005).

The website www.totalsolidsolution.com provides information on this technology although this company is no longer a 

vendor for the BioTerminator system.

Also visit www.shawwatersolutions.com.

Technology Summary
Emerging Technologies September 2006

4-10 Biosolids Management

Technology Summary

Temperature-Phased Anaerobic Digestion (TPAnD)

Objective:

Improve the quality of biosolids by combining 

thermophilic and mesophilic anaerobic digestion.

State of Development: Innovative

The Western Lake Superior Sanitary District in Duluth, Minnesota 

uses the TPAnD system to process solids resulting from the 

treatment of 40 mgd of wastewater. The technology is also used at 

Madison, WI and in Orange County and Los Angeles in CA.

Blue Plains Advanced Wastewater Treatment Plant is planning to 

construct an egg-shaped TPAnD digester facility. The results of 

studies performed by Virginia Tech comparing a TPAnD system, a 

two-stage thermophilic system, and two mesophilic conventional 

digesters recommended that DC WASA continue to pursue TPAnD 

as a process option for their new anaerobic digestion facility.

Description:

Temperature-phased anaerobic digestion (TPAnD), also referred to as thermophilic/mesophilic digestion, is a promising process 

option for the wastewater treatment facilities due to its higher performance and ability to control product odor. The process employs 

thermophilic (>55°C) conditions in the fi rst phase of digestion followed by mesophilic (35°C) conditions in the second phase of 

digestion.

Comparison to Established Technologies:

A combination of thermophilic digestion and mesophilic digestion processes. By their combined use, the performance is 

enhanced over either individual process.

Available Cost Information:

Approximate Capital Cost: $4,700,000

Approximate O&M Costs: Not available.

Capital cost is based on the 2004 estimated cost to install a new 2,465 m3 temperature-phased anaerobic digester, 

associated piping upgrades, and upgrades to a secondary digester at the Ravensview Water Pollution Control Plant in 

Kingston, Ontario.

Vendor Name(s):

Not applicable

Practitioner(s):

Western Lake Superior Sanitary District

2626 Courtland St.

Duluth, MN 55806

218-722-3336

Website: www.wlssd.com 

Key Words for Internet Search:

Anaerobic digestion, temperature phased, Blue Plains wastewater
Biosolids Management

September 2006 Emerging Technologies

4-11

Temperature-Phased Anaerobic Digestion (TPAnD) (Contd)

Data Sources:

J.L. Richards & Associates, Ltd. Ravensview WPCP Secondary Treatment and Capacity Upgrades Class EA Update. 

Technical Memo No. 5 - Biosolids Management Upgrades. Prepared for Utilities Kingston. (May 2004).

Inman D.C., S. Murthy, P. Schafer, P. Schlegel, J. Webb, J.T. Novak. “A comparative study of two-stage thermophilic, singlestage mesophilic, and temperature-phased anaerobic digestion.” Proceedings of the WEF 2005 Residuals & Biosolids 

Specialty Conference, Nashville, Tennessee. (17–20 April 2005). 

Water Environment Federation Residuals and Biosolids Committee. “High-Performance Anaerobic Digestion (White 

Paper)”. Water Environment Federation, Alexandria, Virginia. (January 2004)

Technology Summary
Emerging Technologies September 2006

4-12 Biosolids Management

Technology Summary

Thermal Hydrolysis (CAMBI Process)

Objective:

Biosolids mass reduction; increased production of 

biogas.

State of Development: Innovative

This process was used full scale in 2002 at the Nigg Bay Wastewater 

Treatment Plant in Aberdeen, Scotland, and is installed at additional 

wastewater treatment facilities across Europe, Australia and Japan. 

In Europe, it is also used by pulp manufacturers.

Description:

Prior to digestion, sludge is dewatered to 15%–20% solids and fed through a hydrolysis vessel. The process involves the oxidation 

of sludge under elevated temperature (approximately 320°F) and pressure (approximately 100 psi). Under these conditions, 

pathogens are destroyed and cell structures in the sludge breakdown, releasing energy-rich compounds. 

Following hydrolysis, sludge is fed to an anaerobic digester where it readily breaks down, resulting in high volatile solids destruction 

(approximately 65%) and increased biogas production compared to conventional anaerobic digestion.

Odor issues need to be addressed for this process

Comparison to Established Technologies:

Similar to established technology by Zimpro Wet Air Oxidation process. Increased biogas production from hydrolyzed 

sludge. 

Available Cost Information:

Approximate Capital Cost: $6,000,000

Approximate O&M Costs: $360 per dry ton treated

Capital and O&M costs are for the installation and 2000–2001 estimated operational costs of the CAMBI process at the 

5 MGD Hamar Wastewater Treatment Plant, Norway. Operational costs include operating the treatment plant, disposal of 

waste biosolids, personnel costs, overhead costs, depreciation, and interest. The Hamar plant accepts biosolids from other 

treatment plants.

Vendor Name(s):

RDP Technologies, Inc.

2495 Boulevard of the Generals

Norristown, PA 19403

Phone: 610-650-9900

E-mail: pchristy@rpdtech.com 

Practitioner(s):

North of Scotland Water Authority

Denburn House

25 Union Terrace

Aberdeen, Scotland AB10 1NN

Phone: 845-743-7437

For additional practitioners see 

www.cambi.com/sludge_frame.asp

Key Words for Internet Search:

Thermal hydrolysis, CAMBI Process, biosolids, sludge

Data Sources:

Stevens, D., Kelly, J., Liston, C., Oemeke, D. Biosolids Management in England and France. Water, 29(1):56–61. The 

Journal of the Australian Water Association. (2002).

Wilson, S. Panter, K. (2002). Operating Experience of Aberdeen CAMBI Thermal Hydrolysis Plant Proceeding of CIWEM/

AQUA Enviro 7th European Biosolids and Organic Residuals Conference. (November 2002).

Vendor-supplied information
Biosolids Management

September 2006 Emerging Technologies

4-13

Technology Summary

Thermophilic Fermentation (ThermoTechTM)

Objective:

Converts sewage sludge and residuals into fertilizergrade product by thermophilic fermentation process.

State of Development: Innovative

ThermoMasterTM plants in Canada convert food wastes into a highprotein animal feed supplement and wastewater treatment sludges 

into fertilizer material. This technology is not being actively marketed 

by the vendor at this time.

Description:

ThermoTechTM is a microbial organic waste digestion technology originally developed to create animal feed supplement from 

relatively high-solids-content food wastes. The process has been modifi ed for wastewater sludge and materials with a lower solids 

content. In the ThermoMasterTM process, autoheated aerobic digestion is operated at a relatively short residence time of 30 hours 

to maximize single-cell protein production using the infl uent waste material as a substrate. The solids from the digestion process 

are then dried and pelletized. 

Limited information was available on this technology as the vendor is no longer focusing its efforts on marketing this technology.

Comparison to Established Technologies:

Fermenting provides a number of benefi ts over established technologies, including a 20% increase in protein content and 

minimal energy requirements (as the process creates its own heat). Residuals are transformed into salable products in less 

time and with smaller space requirements.

Available Cost Information:

Approximate Capital Cost: $15,000,000 – $50,000,000 for a 400-tpd facility

Approximate O&M Costs: Not available.

Vendor Name(s):

ThermoTechTM Technologies

204-195 County Court Boulevard

Brampton, Ontario L8E 5V9 Canada

Phone: 905-451-5522 or 561-2662

Fax : 905-451-5833

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

ThermoTechTM, ThermoMasterTM, waste digestion, autoheated aerobic digestion

Data Sources:

Glenn, Jim. “Nutrient Niches: Marketing Food Residuals As Animal Feed.” Biocycle. (April 1997) 43-50.

PR Newswire. “ThermoTechTM Ventures, Inc. Signs US Dollars 200 Million Commitment to Secure Long-Term Debt 

Financing to Build and Operate ThermoMaster Mark II Plants.” (2 March 1999).
Emerging Technologies September 2006

4-14 Biosolids Management

Technology Summary

Three-Phase Anaerobic Digestion

Objective:

Increase dewaterability, produce Class A biosolids for 

direct land application, increase biogas production, and 

reduce odors.

State of Development: Innovative

Three-phase anaerobic digestion was implemented full scale at the 

Inland Empire Utilities Agency (IEUA) Regional Water Recycling 

Plant No. 1 (RP-1) in San Bernardino County, California, in 

November 2000.

Description:

This anaerobic digestion system operates using three phases. The fi rst phase is a volatile fatty acid digester operating at a 

temperature of 35°C. The second is an anaerobic thermophilic gas digester operating in the range of 50°C to 56°C. The third 

phase is not heated but remains above 35°C. IEUA received U.S. EPA’s approval for Class A Biosolids per Alternative 4 of CFR 

503. The following operating parameters apply:

• Phase 1-Minimum HRT of 2 days ( monthly average) at temperatures greater than 35°C;

• Phase 2-Minimum HRT of 14 days (monthly average) at temperatures greater than 50°C;

• Phase 2-Minimum HRT of 10 days (daily minimum) at temperatures greater than 55°C;

• Phase 3-Minimum HRT of 4 days (monthly average) at temperatures greater than 35°C.

Comparison to Established Technologies:

Three-phase anaerobic digestion reportedly results in improved pathogen destruction and very high volatile solids reduction 

and gas production as compared to single stage anaerobic digestion.

Available Cost Information:

Approximate Capital Cost: Not available.

Approximate O&M Costs: $60 per wet ton treated

Operational and maintenance costs for IEUA include chemicals, labor, miscellaneous materials, power used, natural gas 

consumed, and power that was generate in its RP-1 facility (a credit). O&M costs do not include laboratory or monitoring 

costs, collection system or pretreatment costs, any administrative costs, contract labor or professional fees and services. 

IEUA estimated it saved $270,000 in energy costs during the fi rst 2 years of operation.

Vendor Name(s):

None identifi ed.

Practitioner(s):

Inland Empire Utilities Agency

Recycling Plant 1 (RP-1)

2450 E. Philadelphia Avenue

Ontario, California 91761

Phone: 909-993-1800

Fax: 909-947-2598

City of Tacoma Wastewater Management 

2101 Portland Avenue

Tacoma, WA 98421

Key Words for Internet Search:

Three-phase anaerobic digestion, thermophilic digestion, Inland Empire Utilities Agency, IEUA, biosolids
Biosolids Management

September 2006 Emerging Technologies

4-15

Three-Phase Anaerobic Digestion (Contd)

Data Sources:

Lee, S.A., D.D. Drury, C.A. Baker, J.S. Bowers, R.H. Nienhuis. “Three-Phase Thermophilic Digestion Disinfects Biosolids.” 

Biosolids Technical Bulletin. Water Environment Research Federation. Vol. 8: No. 6. (2003).

Salsali H.R., and W.J. Parker. “An Evaluation of 3 Stage Anaerobic Digestion of Municipal Wastewater Treatment Plant 

Sludges.” Proceedings of the WEF Residuals and Biosolids Management Conference 2006: Bridging to the Future, 

Cincinnati, OH (12–14 March 2006).

Technology Summary
Emerging Technologies September 2006

4-16 Biosolids Management

Technology Summary

Two-Phase Acid/Gas Anaerobic Digestion

Objective:

Increase methane production and shorten biosolids 

digestion time. 

State of Development: Innovative

Patented process developed by Dr. Samnabuth Ghosh during his 

tenure at Gas Technology Institute (GTI, also known as Institute of 

Gas Technology). It has been in operation for more than 10 years 

at a 12 MGD wastewater treatment plant in DuPage County, Illinois. 

The treatment generates suffi cient methane to power a 1.5 mega 

watt generator.

Full-scale projects are either installed or underway in Denver, Dallas, 

Hampton Roads and Baltimore.

Description:

Two-phase anaerobic digestion utilizes an acid stage and a gas stage to break down biosolids. Hydrolysis reactions along with 

acidifi cation and acetifi cation occur in the acid phase digester where the pH is in the range of 5.5 to 6.0 because of the volatile fatty 

acid fermentation. The second (gas) stage is where high quality (>650 BTU per cubic foot) methane gas production occurs.

The two-phase anaerobic digestion process (called the HIMET or high-methane process) is based on physically separating two 

different groups of bacteria into two separate tanks and maximizing their growth by maintaining optimum conditions in each tank

for that particular group of bacteria. The fi rst group, the acidogenic bacteria, is grown in the acid phase digester where the pH is in 

the range of 5.5 to 6.0 because of the volatile fatty acid fermentation. The second group, the methanogenic bacteria, is grown in the 

methane digester where the pH is naturally much higher and where residence time can be between 7–10 days, depending upon 

the waste characteristics. The acidogenic bacteria will not thrive in the methane reactor as most of its feed material is used in the 

acid digester; the methanogenic bacteria cannot thrive in the acid digester as the retention time is too short and the pH is too low.

Comparison to Established Technologies:

This process is similar to fermentation processes. According to one vendor, upsets in conventional anaerobic digesters 

are often attributable to the methanogenic bacteria, which are diffi cult to grow and are sensitive to overloads. Two-phase 

digestion is resilient to changes in feed volume and composition because the acidogenic bacteria are hardy and do well 

under extreme loading conditions. It is also claimed that the technology minimizes or eliminates foaming problems.

Available Cost Information:

Approximate Capital Cost: Not available.

Approximate O&M Costs: Not available.

Vendor Name(s):

Vendor Name(s):

GTI

1700 S. Mount Prospect Road

Des Plaines, IL 60018

Phone: 847-768-0500

Fax: 847-768-0501

E-mail: environscienceandtech@gastechnology.org

Practitioner(s):

Woodridge – Greene Valley Wastewater Facility

7900 South Route 53

Woodridge, IL 60517

Email: Kbuoy@dupageco.org 

Phone: 630-985-7400

Website: www.dupageco.org/publicworks/

Key Words for Internet Search:

Two-phase anaerobic digestion, two-stage anaerobic digestion, biosolids, sludge
Biosolids Management

September 2006 Emerging Technologies

4-17

Two-Phase Acid/Gas Anaerobic Digestion (Contd)

Data Sources:

Kelly, H.G. Emerging Technologies in Biosolids Treatment. Dayton & Knight Ltd., West Vancouver, Canada. (2003).

GTI. “HIMET – A Two-Stage Anaerobic Digestion Process for Converting Waste to Energy.” Company website: 

www.gastechnology.org. (September 2004).

DuPage County, Illinois, Department of Public Works website. (2005). Woodridge-Greene Valley Wastewater Facility. 

Available online at www.dupageco.org/publicworks/generic.cfm?doc_id=880.

Technology Summary
Emerging Technologies September 2006

4-18 Biosolids Management

Technology Summary

Vermicomposting

Objective:

Achieve pathogen reduction, produce a land 

application-quality compost from biosolids. 

State of Development: Innovative

In July 2004, the fi rst full-scale vermicomposting facility in the 

United States was commissioned for the township of Granville, 

Pennsylvania. This facility, which treats approximately 70 dry tons 

annually, processes aerobic digested biosolids.

Description:

Earthworms, added to biosolids, break down organic material and produce a fi ne-grained castings, considered by some to have 

greater value as a soil amendment than traditional composts. Generally operated in a semi-continuous fl ow. The earthworms stay 

in the bed with no need to restock regularly; generally, the worm population is self regulating and will increase to the point where 

available food and space constrain further expansion. The process must be monitored for such parameters as moisture content 

and temperature but is not labor-intensive. Flow of solids into the system is then adjusted to optimize living conditions for the 

worms. The castings are known to contain plant growth regulators and other substances that make them an effective form of biofertilizer and bio-pest control agent. 

A full-scale demonstration in Orange County, Florida, showed greater reduction of indicator pathogens in biosolids composted 

with, versus without, the addition of worms. The Manure Management Program, Cornell University, is currently researching 

vermicomposting of animal manure.

Comparison to Established Technologies:

Vermicomposting involves earthworms and microorganisms working together. In contrast to conventional aerobic 

composting, it does not involve a thermophilic stage to achieve stabilization. As with other non-enclosed composting 

technologies, vermicomposting does have a fairly large footprint similar to aerated static pile composting. 

Available Cost Information:

Approximate Capital Cost: $1,600,000 

Approximate O&M Costs: $495,000

Vendor Name(s):

Vermitech USA Inc.

100 Helen Street

Lewistown, PA 17044

Phone: 717-994-4885

Website: www.vermitech.com

Email: shaun.ankers@vermitech.com 

Practitioner(s):

Township of Granville

Junction Wastewater Treatment Facility

100 Helen St.

Lewistown, PA 17044

Email: lcraig@granville-twp.org 

Phone: 717-242-1838

Key Words for Internet Search:

Vermicomposting, vermiculture, municipal waste, biosolids, sludge
Biosolids Management

September 2006 Emerging Technologies

4-19

Vermicomposting (Contd)

Data Sources:

Eastman, Bruce R. “Achieving Pathogen Stabilization Using Vermicomposting”. Biocycle Journal of Composting. 

(November 1999). 62-64.

Slocum, Kelly. “Pathogen Reduction in Vermicomposting.” Worm Digest. Issue 23. (1999).

Vendor-supplied information

Technology Summary

Granville Township, PA vermicomposting facility 

(Photo courtesy of Granville Township)
Emerging Technologies September 2006

4-20 Biosolids Management

Technology Summary

Simultaneous Digestion and Metal Leaching (SSDML)

Objective:

Increase the pathogen reduction and metals solubility 

during the digestion process.

State of Development: Embryonic

A 2003 pilot-scale study found that the SSDML process was 

successful in obtaining acidity and oxidation-reduction potential 

levels within a sludge bioreactor that were greater than necessary 

for solubilization of toxic metals. Nutrient levels (N, P, K) in the 

decontaminated sludge were preserved throughout the process. The 

study also found the process to be effective in reducing odors and 

indicator bacteria in the sludge.

Description:

The simultaneous sewage sludge digestion and metal leaching (SSDML) process involves the addition of elemental sulfur to 

biosolids during aerobic digestion. After several days, the pH of the mixture is very low (about 2), which is conducive to increasing 

the solubility of toxic metals within the biosolids.

Comparison to Established Technologies:

Not similar to other established technologies.

Available Cost Information:

Approximate Capital Cost: Not available.

Approximate O&M Costs: Not available.

Vendor Name(s):

Institut National de Recherche Scientifi que

Universite du Quebec

2700 rue Einstein

C.P. 7500

Sainte-Foy, Quebec G1V 4C7

Phone: 418-654-2617

E-mail: tyagi@inrs-ete.uquebec.ca 

Practitioner(s):

No practitioner at this time

Key Words for Internet Search:

Metals leaching, SSDML, aerobic digestion, biosolids, sludge

Data Sources:

Blais, J., N. Meunier, G. Mercier, P. Drogui, and R.D. Tyagi. “Pilot Plant Study of Simultaneous Sewage Sludge Digestion 

and Metal Leaching.” Journal of Environmental Engineering. 130:5 (2004) 516-525.
Biosolids Management

September 2006 Emerging Technologies

4-21

Anaerobic Digestion with Ozone Treatment

Objective:

Break down organic matter in biosolids to increase the 

effectiveness of anaerobic digestion.

State of Development: Embryonic

The Vranitsky and Lahnsteiner (2002) laboratory-scale study found 

that the average degradation rate of organic matter increase to 65%, 

as compared to 45% in a conventional (non-ozonated) system. The 

study also showed an increase in biogas production of 30%–40% 

due to the added biological disintegration from the ozone addition. 

The achieved removal rate of carbon and nutrients decreased, but 

remained within regulatory requirements.

Description:

Anaerobically digested biosolids are diverted from the digester to a reaction tank where they are exposed to low levels of ozone. 

One experiment by Vranitsky and Lahnsteiner (2002) showed that only 0.06 g of ozone per gram of dissolved solids was necessary 

to destroy the biological activity of the digested biosolids. The ozonated biosolids are then sent to the thickening tank and then 

back to the digester where they are mixed with both ozonated and non-ozonated biosolids. The biosolids either exit the digester to 

be dewatered, or they are again diverted back to the ozone reactor. The ozone generation is based on corona discharges that are

capable of transforming molecular oxygen into ozone.

Comparison to Established Technologies:

Not similar to other established technologies.

Available Cost Information:

Approximate Capital Cost: Not available.

Approximate O&M Costs: $1700 per million gallons treated

Operational cost estimate is based on a model wastewater treatment plant treating approximately 5 million gallons per day 

using an ozonation plant unit capable of producing 42.3 pounds of ozone per hour.

Vendor Name(s):

American Air Liquide

2700 Post Oak Blvd., Suite 1800

Houston, TX 27056

Phone: 800-820-2522

Website: www.us.airliquide.com

Practitioner(s):

No practitioner at this time

Key Words for Internet Search:

Ozone treatment, ozonation, biosolids, sludge

Data Sources:

Vranitsky, R., J. Lahnsteiner. “Sewage sludge disintegration using ozone – a method of enhancing the anaerobic 

stabilization of sewage sludge.” Proceedings of the European Biosolids and Organic Residuals Workshop, Conference and 

Exhibition. (2002).

European Environmental Press. “Europe: Using Ozone to Reduce Sludge.” (2005)

Water and Wastewater.com. Available online at

www.waterandwastewater.com/www_services/news_center/publish/article_00540.shtml. March 31.

Vendor-supplied information

Technology Summary
Emerging Technologies September 2006

4-22 Biosolids Management

Ferrate Addition

Objective:

Stabilization and disinfection of wastewater solids as 

well as enhancement of biosolids products increasing 

benefi cial use potential.

State of Development: Embryonic

Pilot-scale investigation was conducted using solids from a 

Washington DC area wastewater treatment plant.

Description:

Ferrate is a powerful oxidizing chemical with a higher reactivity than traditional oxidants. As a liquid, ferrate can be injected into 

the process stream without the addition of special mixing equipment. One study by the USDA showed dosing dewatered solids 

with ferrate inactivated 99.9% of E. coli. The resulting pH of the disinfected solids is generally between 12 and 13 depending on 

dose. Ferrates also have been shown to have an affi nity to react with sulfi des, mercapitans and alkyl amines, all odor-producing 

compounds common in wastewater solids.

Comparison to Established Technologies:

Depending on use of the ferrate, the process can be compared to various processes where a chemical is added to 

wastewater solids to increase the potential for benefi cial use.

Available Cost Information:

Approximate Capital Cost: Not provided by the vendor.

Approximate O&M Costs: Ferrate liquid is available for approximately $2 per pound

Vendor Name(s):

Ferrate Treatment Technologies, LLC

6432 Pine Castle Blvd, Unit #2C

Orlando, FL 32809

Phone: 407-857-5721

Fax : 407-826-0166

E-mail: calig@ferrate.biz

Website: www.ferratetreatment.com 

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Ferrate, biosolids, sludge

Data Sources:

Chao, A. Quality Improvement of Biosolids by Ferrate (VI) Oxidation of Offensive Odour Compounds.” IWA Publishing 

Journal Online at www.iwaponline.com/wst/03303/wst033030119.htm. 8 August 2006.

Kim, H. P. Millner, V. Sharma, L. McConnell, A. Torrents, M. Ramirez, C. Peot. “Ferrate: Nature’s Most Powerful Oxidizer: 

It’s Potential As a Disinfection Treatment for Thickened Sludge.” Research Notes published at 

www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=190364. 8 August 2006.

Reimers, R.S., V.K. Sharma, S.D. Pillai, and D.R. Reinhard. “Application of Ferrates in Biosolids and Manure Management 

with Respect to Disinfection and Stabilization.” WEF/AWWA Joint Residuals and Biosolids Management Conference 2005, 

Nashville, Tennessee (17-20 April 2005).

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

4-23

Irradiation

Objective:

Biosolids disinfection

State of Development: Embryonic

Beta and gamma irradiation have been tested for at least 20 years 

based on the promise of their low space requirement; however, 

to date irradiation methods have not been implemented on a 

continuous full-scale basis at any wastewater treatment plants in the 

United States. 

Description:

Irradiation destroys organisms by altering the colloidal nature of cell protoplasm. Gamma rays are high-energy photons produced

by certain radioactive elements; beta rays are electrons accelerated in velocity by electrical potentials in the vicinity of 1 million 

volts. Both types of radiation destroy pathogens; however, the effectiveness of beta radiation is dependent on the dose. A dose of 

1 megarad or more at 2°C will reduce pathogenic viruses, bacteria, and helminthes to below detectable levels. Lower doses may 

successfully reduce bacteria and helminth ova but not viruses. Gamma rays from isotopes such as 60Cobalt and 137Cesium (at 

1 megarad at 20°C) can penetrate substantial thicknesses and are easier to expose to sludge. Beta rays have limited penetration

ability and therefore are introduced by passing a thin layer of sewage sludge under the radiation source. Because these processes, 

when used alone, do not reduce nuisance odors and the attraction of vectors, they are considered supplementary to typical 

stabilization and pathogen treatment processes.

Comparison to Established Technologies:

Low space requirement is an advantage irradiation offers. However, irradiation does not “stabilize” sludge to satisfy vector 

attraction reduction (VAR) requirements of U.S. EPA. An alternate approach is to incorporate the biosolids material into the 

soil within 8 hours, or lime can be added, an established method of vector attraction management.

Available Cost Information:

Approximate Capital Cost: Not available.

Approximate O&M Costs: Not available.

Vendor Name(s):

No vendors at this time

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Ferrate, biosolids, sludge

Data Sources:

Pennsylvania Department of Environmental Protection. Training Course. “Biosolids – Characteristics and Treatment.” 

(1998). Available online at www.dep.state.pa.us/dep/biosolids/training/index.htm

Technology Summary
Emerging Technologies September 2006

4-24 Biosolids Management

Neutralizer®

Objective:

Disinfection of wastewater solids.

State of Development: Embryonic

The process has been tested in the laboratory on aerobically 

digested, anaerobically digested and raw solids. It has also been pilot 

tested at the Lagoon Wastewater and Sludge Facility, St. Thomas, 

U.S. Virgin Islands. Research has demonstrated the reduction of 

fecal coliforms and viral densities to below detectable limits and the 

viability of helminth eggs to 0%. The process has been tested on 

both raw and digested solids.

Description:

Neutralizer® is a sequenced batch process. First, chlorine dioxide is added to solids as they are fed into a mixing tank. Continuous 

mixing is provided during this initial two-hour contact time. Next, sulfuric acid is added to acidify the solids to a pH of between 2.3 

to 3.0. Then sodium nitrite (which converts to nitrous acid at this pH) is added to the tank. The tank is completely fi lled to eliminate 

head space. The pressure in the tank builds to between 15 and 25 psig due to the acidifi cation of the solids and generation of 

nitrous acid gas. The material is held for another two hour period with continuous mixing. After the two hour period, the pH of the 

material can be adjusted to create a biosolids favorable for benefi cial use.

Comparison to Established Technologies:

Similar to Synox process but uses chlorine dioxide and nitrous acid instead of ozone. Chlorine dioxide is less expensive 

and more reliable than ozone.

Available Cost Information:

Approximate Capital Cost: varies with application; contract vendor for specifi c cost information

Approximate O&M Costs: varies with application; contract vendor for specifi c cost information

Vendor Name(s):

BioChem Resources

3540 Agricultural Center Drive

St. Augustine, FL 32092

Phone: 904-607-2223

Fax : 904-607-9224

E-mail: ws@biochemresources.com 

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Neutralizer®, biosolids, sludge

Data Sources:

Reimers, R.S., L.S. Pratt-Ward, H.B. Bradford, F.P. Jussari and W. Schmitz. “Development of the Neutralizer® Process for 

Disinfection and Stabilization of Municipal Wastewater Residuals.” WEF/AWWA Joint Residuals and Biosolids Management 

Conference 2006, Cincinnati, Ohio (12–14 March 2006).

Technology Summary
Biosolids Management

Chapter

5-1

5

Dewatering

5.1 Introduction

Dewatering removes water from biosolids making them easier and less expensive to 

transport, dry, compost, or incinerate. Dewatering is most often accomplished by drying 

beds or a physical process that separates water from the solids via presses or centrifuges. 

Often chemicals are used to enhance the processes. This chapter focuses on the emerging 

dewatering technologies.

5.2 Technology Assessment

Table 5.1 summarizes the state of development of dewatering technologies.

Physical separation techniques have dominated the practice of dewatering for decades. 

Recent advancements in dewatering use electricity rather than, or in combination with, 

mechanical devices. Electroacoustical, electroosmotic, and electrodewatering are three 

such processes. Membrane and tubular fi lter presses have had some reported success in 

overseas dewatering applications; however, these technologies have yet to gain popularity 

in the United States. Two more dewatering systems, DAB and Simon Moos, may be 

promising technologies for small wastewater treatment plants and septage dewatering 

applications.

Figure 5.1 includes an evaluation of the innovative technologies identifi ed. Summary 

sheets for each innovative and embryonic technology are provided at the end of this 

chapter.
Emerging Technologies September 2006

5-2 Biosolids Management

Figure 5.1 – Evaluation of Innovative Dewatering Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Quick Dry Filter Beds N S C,O,V N/A S \ \ S S \

Electrodewatering B,P F V N/A S \ \ T \ \

Inclined Screw Press N I V,R N/A S S \ S T \

Bucher Hydraulic Press O S C N/A S S \ S \ \

DABTM System N S C,O N/A \ S \ S S \ Similar to thickening

Geotube® Container N F C,O,V N/A S \ \ S \ \

Established Innovative Embryonic

Belt Filter Press

Centrifuge

Chamber Press

Drying Beds

Auger-Assisted

Natural Freeze-Thaw

Vacuum-Assisted

Vacuum Filters







Drying Beds

Quick Dry Filter Beds

Electrodewatering

Metal Screen Filtration

Inclined Screw Press

Textile Media Filtration

Bucher Hydraulic Press

DABTM System

Geotube® Container











Electrodewatering

Electroacoustic

Electroosmotic

Membrane Filtration

Membrane Filter Press

Textile Media Filtration

Simon Moos

Tubular Filter Press

Thermal Conditioning and Dewatering

Mechanical Freeze-Thaw











Table 5.1 – Dewatering Technologies—State of Development

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

5-3

Quick DryTM Filter Beds

Objective:

Drying biosolids to a higher solids percentage – 

30%–60% dry cake

State of Development: Innovative

Drying beds with a difference in the drainage system and under bed 

construction.

Description:

The Quick Dry fi lter bed process consists of a series of pipes laid on the base of a bed to provide drainage and to presaturate water 

to enter the bed before the sludge is applied. These pipes are then covered with 20–25 mm rock. A honeycomb grid is placed on 

the base rock, fi lled with 10–15 mm rock and covered with a fi nal layer of sand to complete the bed. The Quick Dry process also 

includes a fl occulation system (RapidFloc Mixer), an in-line polymer preparation system that injects polymer into the fl occulation 

device, and a self-contained harvesting unit. 

Deskins Quick Dry fi lter bed is based on rapid gravity drainage with further water removal by natural solar evaporative processes. 

The Quick Dry media prevents compaction of the fi ltering media in conventional sand drying beds. Saturation of the bed forces 

out any air that has been trapped in the fi lter media and allows the sludge to fl ow evenly across the bed surface to achieve 

maximum distribution. When the underdrain is opened, a vacuum or siphoning effect is created and causes the rapid dewatering 

of the sludge. Along with this cracking or “opening up” of the sludge occurs and allows air to circulate around the cake and further 

increase drying. Around 90% of the water will exit in 12 hours and the sludge will continue to drain while it is on the bed. Results of 

several trials produced a cake of 45%–60% dry.

Comparison to Established Technologies:

Compares favorably with mechanical dewatering systems such as a belt fi lter press or centrifuge. Performs better than 

existing drying beds. Dewaters solids to greater than 50% within 5–7 days on a footprint about 30% of the size of standard 

drying beds.

Available Cost Information:

Approximate Capital Cost: Not provided by vendor.

Approximate O&M Costs: Not provided by vendor.

Vendor Name(s):

F D Deskins Company, Inc.

23 Fairway Drive

Alexandria, Indiana 46001

Phone: 765-724-7878

Fax : 765-724-7267

E-mail: deskins@netdirect.net 

Practitioner(s):

McAllen Public Utilities

4001 N Bentsen Road

McAllen, TX 78504-9790

City of Casey

108 Main Street

Casey, IL 62420

Technology Summary
Emerging Technologies September 2006

5-4 Biosolids Management

Quick DryTM Filter Beds (Contd)

Key Words for Internet Search:

Deskins, Quick Dry fi lter bed, polymer mixing, fl oc

Data Sources:

Evans, Anthony. Biosolid Reduction and the Deskin Quick Dry Filter Bed. Australia Water Industry Operators Association 

Annual Conference Proceedings (220) www.wioa.org.au/conf_papers/02/paper10.htm

Fraser, Ross. Latest Advance in Solids Dewatering.

Technology Summary

Deskins Quick Dry Filter Bed

Rapid Flocculation Mixer

Polymer Preparation Unit

Dried Solids Harvesting Unit
Biosolids Management

September 2006 Emerging Technologies

5-5

Electrodewatering

Objective:

Enhance conventional dewatering using electric 

current.

State of Development: Innovative

Electrodewatering has been attempted by a variety of groups 

since the 1920s. A bench-scale demonstration was conducted by 

the Electric Power Research Institute (EPRI). An electroacoustic 

dewatering process using electric and ultrasonic fi elds that improved 

water removal over a conventional belt fi lter press by approximately 

8% was demonstrated. Until recently, very little work has been 

done to develop a suitable system capable of meeting full-scale 

requirements, or to optimize such a system.

Description:

A direct current (DC) voltage is applied to the biosolids mixture. The application of the current in the initial stages of dewatering 

causes particles to migrate to the electrode of opposite charge (i.e., electrophoresis). Once a cake is formed, electroosmosis 

occurs as ions migrate to the appropriate electrode to compensate for particle charges. Electrodewatering can be combined 

with conventional fi lter presses. According to a recent study by the Water Environment Research Foundation (WERF), the cost 

benefi t of electrodewatering is likely to be greatest for sludge that does not respond well to traditional pressure fi ltration. The study 

demonstrated that the novel electrodewatering technique is applicable to a wide range of sludges and indicated that performance

might be limited for sludges with high conductivities.

Comparison to Established Technologies:

Not similar to any established technologies. May be combined with fi lter presses to enhance the thickening of highly 

conductive sludges.

Available Cost Information:

Approximate Capital Cost: Approximately $5.25 million to retrofi t 30 belt fi lter presses. 

Approximate O&M Costs: $5,100 –$24,200 per dry ton 

Operation and maintenance costs include electricity ($70–$140 per dry ton), labor ($9–$29 per dry ton), and maintenance 

($5,000–$24,000 per dry ton). Cost savings anticipated over conventional dewatering costs.

Vendor Name(s):

Waste Technologies of Australia

Environmental Biotechnology CRC Pty Ltd

Suite G01 Bay 3 Locomotive Workshop

Australian Technology Park

Everleigh NSW 1430

Phone: +61 (0) 2 9209 4963

Website: www.wastetechnologies.com

Practitioner(s):

Electric Power Research Institute (EPRI)

3412 Hillview Avenue

Palo Alto, CA 94304

Phone: 800-313-3774

E-mail: askepri@epri.com

Website: www.epri.com 

Technology Summary
Emerging Technologies September 2006

5-6 Biosolids Management

Electrodewatering (Contd)

Key Words for Internet Search:

Electrodewatering, EPRI, biosolids, sludge

Data Sources:

Electric Power Research Institute (EPRI). “Emerging Environmental Technologies: An Analysis of New Treatment 

Technologies for the California Energy Commission.” Palo Alto, California, California Energy Commission, Sacramento, 

California. 1007411. (2003).

Water Environment Research Foundation (WERF). “Demystifying the Dewatering Process: New Techniques and 

Technologies Shed Light on a Complex Process.” WERF Progress Newsletter. WERF, Alexandria, Virginia. (April 2006). 

Available online at: www.werf.us/press/spring06/dewatering.cfm.

Vendor-supplied information.

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

5-7

Inclined Screw Press

Objective:

Provide cost-effective dewatering with simplifi ed 

operations and lower polymer usage.

State of Development: Innovative

The City of Old Town, Maine installed the fi rst permanent inclined 

screw press in the United States in 2003 as part of a major plant 

upgrade. In the fi rst year of operation, the inclined screw press 

successfully met its design criteria and demonstrated that it is a 

viable and cost-effective dewatering option. Inclined screw presses 

have since been installed in Utah and other installation projects are 

underway.

Description:

Liquid sludge (mixture of primary and secondary solids at 11⁄2 to 2%) is pumped to a fl occulation reactor. A polymer is introduced 

through a dosing ring in the feed sludge line and is mixed with the sludge in a static inline mixer.

Flocculated sludge overfl ows into an inclined screw (~20°) rotating inside a stainless steel, wedge wire screen (200 micron). As the 

sludge is advanced up the rotating screw, fi ltrate fl ows out through the screen. The frictional force at the sludge/screen interface 

coupled with increased pressure caused by the outlet restriction produces the dewatered sludge cake. The screw fl ights are 

provided with a brush for continuous internal cleaning of the screen. The screen basket is also cleaned periodically with spray water 

from the outside. Spray bars rotate around the basket, but within the enclosure of the press. 

A lower and wider section of the basket serves as predewatering zone where free water drains by gravity. A second section of the 

basket with a reduced diameter serves as a pressure zone. Here the sludge is compressed between narrowing fl ights of the screw. 

The pressure in the pressure zone is controlled by the position of a cone at the discharge end of the basket. The dewatered sludge 

is driven through a gap between the cone and the basket. The dewatered sludge cake (at about 20% to 25% solids) drops on a 

conveyor or directly into a dumpster. 

Two or three screw presses can be installed in parallel, with a single feed pump, polymer station, and fl occulation reactor.

Comparison to Established Technologies:

The slow rotational speed results in less noise, vibration and overall wear, reducing anticipated long-term maintenance 

costs. The unit is constructed of stainless steel and is fully enclosed, reducing the corrosion potential and assisting with 

containing odors and improving working conditions. In addition, the operation of the unit is fully automated, reducing 

operational costs as compared to more traditional technologies.

Available Cost Information:

Approximate Capital Cost: Not Available

Approximate O&M Costs: Not available

Vendor Name(s):

Huber Technology, Inc.

9805 North Cross Center Court, Suite H 

Huntersville, NC 28078 

Phone: 704-949-1010 

Fax: 704-949-1020

www.huber-technology.com

Practitioner(s):

City of Old Town 

Pollution Control Facility

150 Brunswick Street

Old Town, Maine 04468

Phone: 207-827-3970

Fax: 207-827-3964

Technology Summary
Emerging Technologies September 2006

5-8 Biosolids Management

Inclined Screw Press (Contd)

Key Words for Internet Search:

Inclined screw press, dewatering, biosolids, sludge, City of Old Town Maine

Data Sources:

Atherton, P.C., R. Steen, G. Stetson, T. McGovern, and D. Smith. “Innovative biosolids dewatering system proved a 

successful part of the upgrade to the Old Town, Maine water pollution control facility.” Proceedings of the 2005 WEFTEC: 

The Water Quality Event, Washington, DC. (30 October – 2 November 2005) 6650-6665.

Technology Summary

Schematic of Incline Screw Press. 

Image courtesy of Huber Technology, Inc., 2006

Installed incline screw press at Old Town Water Pollution 

Control Facility. (Atherton et al., 2005)
Biosolids Management

September 2006 Emerging Technologies

5-9

Bucher Hydraulic Press

Objective:

Increase cake solids content in biosolids with 

lower energy requirements than typical dewatering 

processes.

State of Development: Innovative

The Bucher hydraulic de-juicing press was tested side-by-side 

with the existing belt fi ler presses on digested biosolids as well 

as digested manure at the Inland Empire Utilities Agency (IEUA) 

Regional Plant Number 1 (RP-1). The press was also tested at 

the Big Bear Area Regional Wastewater Authority for dewatering 

undigested oxidation ditch sludge.

The Bucher press is widely used in Europe and North America in 

food and beverage processing applications. Industrial-scale trials 

of hydraulic press sludge dewatering also have been conducted at 

solids treatment plants in Switzerland and Germany.

Description:

The Bucher press is a hydraulic dejuicing press consisting of a cylinder and a moving piston that squeezes the sludge allowing 

the water to pass through several fi lter elements made of porous cloth material. The sludge cake is retained inside the cylindrical 

shell. After the sludge enters the cylinder, it is continuously squeezed by the piston, thereby achieving a high degree of mechanical 

dewatering. Filtrate can be collected and discharged to the wastewater system.

Comparison to Established Technologies:

Side-by-side testing results with a belt fi lter press indicated that a hydraulic press can improve the biosolids and manure 

cake solids content by more than 25% compared to the belt fi lter press. The chemical conditioning requirements for the 

hydraulic press were similar to the belt fi lter press.

Available Cost Information:

Approximate Capital Cost: Not provided by vendor.

Approximate O&M Costs: Not provided by vendor.

Vendor Name(s):

Atkins Water

3020 Old Ranch Parkway, Suite 180

Seal Beach, CA 90740

Phone: 562-314-4231

Email: rupert.kruger@atkinsglobal.com 

Practitioner(s):

The following tested the technology but is not a current 

practitioner.

Inland Empire Utilities Agency

Recycling Plant 1

2450 E. Philadelphia Avenue

Ontario, California 91761

Phone: 909-993-1800

Fax: 909-947-2598

Technology Summary
Emerging Technologies September 2006

5-10 Biosolids Management

Bucher Hydraulic Press (Contd)

Key Words for Internet Search:

Hydraulic press, dewatering, sludge

Data Sources:

Kolisch G., M. Boehler, F.C. Arancibia, D. Pinnow, W. Krauss. “A new approach to improve sludge dewatering using a semicontinuous hydraulic press system.” Water Science Technology, 52:10-11(2005) 211-8.

Soroushian, F., Y. Shang, E.J. Whitman, and R. Roxburgh. “Biosolids and manure dewatering with a hydraulic de-juicing 

press.” Proceedings of the WEF/AWWA Joint Residuals and Biosolids Management Conference, Cincinnati, Ohio

(12–15 March 2006).

Technology Summary

Bucher Hydraulic Press. (Soroushian et. al., 2006)
Biosolids Management

September 2006 Emerging Technologies

5-11

DABTM System

Objective:

Provide low-cost, low-maintenance dewatering.

State of Development: Embryonic

More than 20 DABTM systems are operating around the world; seven 

are located in Quebec. Several are operating in Sweden, where 

the technology originated. DABTM system installed at the Bowhouse 

Wastewater Treatment Works in Scotland has been operating 

successfully for 7 years.

Description:

The DABTM dehydration unit consists of a conical gravity fl ow fi ltration-drainer mechanism that separates sludge liquids and solids, 

removing most of the free water from the sludge and producing a 90% solids product. The drainer consists of a double-walled 

cylinder of fi ne mesh fi lter medium on a stainless steel frame. 

The mechanism is immersed in fl occulated sludge. The fi ltrate fl ows by gravity in the space between the medium. Additional 

batches of fl occulated sludge are added to the cone. The extra weight compresses the sludge at the base of the silo, increasing 

solids concentration. The fi lter medium is kept clean by an internal high-pressure jet system. Batches can be added several times a 

day, and thickened sludge withdrawn from the base of the tank. Depending on climate, it is not necessary to install the DABTM unit 

in a building. 

Comparison to Established Technologies:

Similar to an Imhoff tank with a vacuum fi ltration step to further reduce the water content of the solids.

Available Cost Information:

Approximate Capital Cost: $150,000 for a 10-m3 unit to $175,000 for a 25-m3 unit. 

Approximate O&M Costs: $8–$12 per m3

 of sludge treated.

A 10-m3

 unit can dehydrate up to 130 m3/day (34,000 gal/day) of septic tank sludge, a 25 m3 unit can treat up to 

240 m3

/day (63,000 gal/day). Note: costs vary with currency conversion rate; consult with vendor for current cost 

information. Construction and installation requires 2 to 3 months.

Vendor Name(s):

GSI Environment

855 Pépin

Sherbrooke, Québec J1L 2P3

Phone: 819-829-2717

Fax: 819-829-2717

E-mail: sherbriije@gsienv.ca

Practitioner(s):

No practitioner at this time. 

Scottish Water

P.O. Box 8855

Edinburgh, Scotland EH10 6YQ

www.scottishwater.co.uk 

Key Words for Internet Search:

DABTM dewatering, GSI Environmental Quebec, biosolids, sludge.

Data Sources:

Vendor-supplied information 

Rand, Chris (Editor). “East of Scotland Water cuts treatment costs.” Published online in Engineeringtalk by Simon-Hartley 

at www.engineeringtalk.com/news/sim/sim102.html. (21 August 2000).

Technology Summary
Emerging Technologies September 2006

5-12 Biosolids Management

Technology Summary

Geotube® Container

Objective:

Provide on-site, low-maintenance, cost-effective 

dewatering.

State of Development: Innovative

Geotextile tubes have been used in the past to contain and dewater 

dredge materials from shipping harbors. Studies in California, 

Georgia, Ohio, and New Hampshire have shown improved 

dewatering of fi ne grained sewage sludge, successful containment of 

odors during dewatering, reduction in effl uent suspended solids, and 

cost savings resulting from the use of Geotube® containers.

Description:

Geotube® brand geotextile tubes are comprised of high-strength polypropylene fabric and are fabricated to the project’s 

requirements. The tube is fi lled by a pumping system conveying sludge material. The geosynthetic tube retains fi ne-grain fi ll 

material while allowing effl uent water to permeate through the tube wall. With the addition of a chemical conditioning agent (i.e., 

a polymer), excess water drains from the Geotube® container through the geotextile resulting in effl uent that is, according to the 

manufacturer, clear and safe enough to be returned to the plant. Volume reduction within the container allows for repeated fi lling. 

After the fi nal cycle of fi lling and dewatering, retained fi ne grain materials continue to consolidate by desiccation because residual 

water vapor escapes through the geotextile. The dried biosolids are removed from the tube when retained solids meet dryness 

goals.

Comparison to Established Technologies:

A recent study of a Geotube® installation at a Midwestern WWTP stated that, compared to the previous year’s belt press 

operations, the Geotube® dewatering system required little to no operation and maintenance time. A belt press or centrifuge 

requires full-time monitoring and constant adjusting with fl uctuating infl uent conditions. However, if suffi cient time is not 

available for a Geotube® system to dewater stored biosolids, a mechanical dewatering technique may be required. With a 

belt fi lter press, biosolids are open to the air where they can release odors or spill off the belt, and belt presses are often 

noisy. The closed-loop Geotube system reduces odors, the potential for spills, and general biosolids handling. Geotube®

systems can be run through all seasons as long as the polymer delivery lines do not freeze. Mechanical dewatering 

systems are often in climate-controlled buildings and freezing is not an issue.

Available Cost Information:

Approximate Capital Cost: Approximately $0.03/gallon of biosolids for the fi rst 150,000 gallons. Includes one 60-ft-circumference by 100-ft-long Geotube® container, a polymer make-down system, 1,350 pounds 

of polymer, bench testing, and technical assistance during start-up.

 Approximately $0.02/gallon of biosolids for 250,000 gallons more. A more shear-resistant 

polymer and an additional 60-ft by 100-ft Geotube® container were added to the system 

described above for the subsequent 250,000 gallons of biosolids.

Approximate O&M Costs: Not Available.

Excavation, transportation, and disposal of dried solids were not included in calculation of project costs, as these costs 

would fl uctuate depending on the percent solids in the containers and fi nal mass disposed of at the landfi ll.
Biosolids Management

September 2006 Emerging Technologies

5-13

Geotube® Container (Contd)

Vendor Name(s):

Miratech

A Division of Ten Cate Nicolon

3680 Mount Olive Road

Commerce, Georgia 30529

Phone: 706-693-1897

Fax: 706-693-1896

Website: www.geotubes.com 

Practitioner(s):

Saticoy Sanitary District

1001 Partridge Drive, Suite 150

Ventura, CA 93003-0704

Phone: 805-658-4605

City of Cambridge WWTP

Cambridge, OH

Phone: 740-432-3891

The vendor’s website includes case studies for several 

practitioners.

Key Words for Internet Search:

Geotube containers, geotextiles, thickening and dewatering, polymers, biosolids, sludge

Data Sources:

Mastin, B.J. and G.E. Lebster. “Dewatering with Geotube® Containers: A Good Fit For A Midwest Wastewater Facility?” 

Proceedings of the WEF/AWWA Joint Residuals and Biosolids Management Conference, Cincinnati, Ohio. 

(12–15 March 2006).

MiratechTM Division, Ten Cate Nicolon. 2006. Company website, www.geotubes.com. 

WaterSolve, LLC. 2006. Company website, www.gowatersolve.com/geotube.htm.

Technology Summary

Geotube® Container at Cambridge WWTP after 

being fi lled with 250,000 gallons of biosolids. 

(Mastin and Lebster, 2006).

The phases of Geotube® Container operation. Image from Watersolve, LLC, 2006.
Emerging Technologies September 2006

5-14 Biosolids Management

Electroacoustic Dewatering

Objective:

Enhance dewatering of biosolids by combining 

electrical fi elds and ultrasound waves.

State of Development: Embryonic

Batelle Laboratories has conducted bench-scale studies on 

electroacoustical dewatering, and as a result have designed a 

commercial prototype belt fi lter press.

Description:

The combination of electrical fi elds and ultrasound waves has been shown to enhance dewatering. The electrical fi eld allows for 

increased electrophoresis and electroosmosis, and the acoustical force of the ultrasound waves help maintain electrical continuity 

throughout the biosolids. It has also been shown in bench-scale studies that the ultrasonic waves decrease specifi c energy 

consumption, increase the fi ltration rate, and reportedly help keep the cathode clean.

Comparison to Established Technologies:

Tests of the prototype on four different types of wastewater sludges showed solid contents were increased by 3.4% to 

10.4% over conventional dewatering, with fi nal solids concentrations of 23% to 29%.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: $19 to $27 per ton of dry solids

Operational cost estimate is based on the energy costs for a bench-scale study by Batelle Laboratories.

Vendor Name(s):

OilTrap Environmental 

(markets Electro-Pulse)

2775 29th Avenue SW

Tumwater, WA 98512

Phone: 360-943-6495

Fax : 360-943-7105

E-mail: support@oiltrap.com

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Electroacoustic dewatering, Electro-Pulse, electrodewatering, biosolids, sludge

Data Sources:

Abu-Orf, M., Muller, C.D., Park, C., and Novak, J.T. “Innovative Technologies to Reduce Water Content of Dewatered 

Municipal Residuals.” Journal of Residuals Science & Technology. 1:2 (2001) 83-91.

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

5-15

Electroosmotic Dewatering

Objective:

Enhance conventional dewatering using electric 

current.

State of Development: Embryonic

This phenomenon has been successfully used in the ceramics 

industry for product dewatering, as well as in the construction 

industry for soil dewatering at building foundations. Researchers 

have used this process on a bench scale to dewater a variety 

of agricultural products, including animal manure, without the 

drawbacks of thermal water removal.

Description:

This technology uses an imposed electric fi eld to force ionic particles in a biosolids mixture to migrate to their attractive electrodes.

Comparison to Established Technologies:

Not comparable to established technologies.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Not available 

Practitioner(s):

The following tested this technology but is not a current 

practitioner.

Electric Power Research Institute (EPRI)

3412 Hillview Avenue

Palo Alto, CA 94304

Phone: 800-313-3774

E-mail: askepri@epri.com

Key Words for Internet Search:

Electroosmotic dewatering, electrodewatering, biosolids, sludge.

Data Sources:

Electric Power Research Institute (EPRI). “Emerging Environmental Technologies: An Analysis of New Treatment 

Technologies for the California Energy Commission.” Palo Alto, California. California Energy Commission, Sacramento, 

California. 1007411. (2003)

Technology Summary
Emerging Technologies September 2006

5-16 Biosolids Management

Membrane Filter Press

Objective:

Increases percent of solids in biosolids cake.

State of Development: Embryonic

According to one vendor of membrane fi lter press technology, their 

press has been used in the following industries: chemical processing, 

pharmaceuticals, food product and ingredient manufacturers, wine 

and juice producers, industrial waste dewatering and recycling.

Description:

Membrane fi lter presses operate on what the manufacturer calls the “variable chamber principle.” The liquid biosolids are pumped 

into a chamber. The clear fi ltered liquid passes through the fi lter cloth against a drainage surface built into the plate, just like on 

a conventional fi lter press. Once the fi ltration step has been completed, the fl exible membrane, or diaphragm, is infl ated with 

pressurized fl uid, typically water, thereby compressing the formed fi lter cake. The fi nal cake discharge volume is reduced in the 

process.

Comparison to Established Technologies:

Not comparable to established technologies.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Komline-Sanderson Engineering Corp.

12 Holland Avenue

Peapack, NJ 07077

Phone: 800-225-5457

Fax : 908-234-9487

E-mail: info@komline.com 

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Membrane fi lter press, biosolids sludge

Data Sources:

Vendor-supplied information

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

5-17

Technology Summary

Simon Moos

Objective:

On-site dewatering for septic tanks and small 

wastewater treatment plants.

State of Development: Embryonic

According to the manufacturer, the Simon Moos technology has 

been successfully demonstrated to pump and dewater septic tanks, 

grease traps, wastewater treatment plants, and various types of 

industrial sludge.

Description:

The Simon Moos System consists of a dewatering container and a built-in or a separate pump and dosing plant. Dewatering of 

sludge is achieved by the injection of polymer into the sludge as it is being pumped by the sludge pump or pressed through the 

cyclone of the system’s pump and dosing plant into the dewatering container. During this operation, polymer amounts are adjusted 

to achieve the best sludge fl occulation possible. Once separated, the water fl ows through a special set of fi lter nets installed inside 

the container and out drain ports located on each side of the container. Solids remain inside the container until accumulation 

requires dumping and disposal.

Comparison to Established Technologies:

Not comparable to established technologies.

Available Cost Information:

Approximate Capital Cost: Not provided by vendor

Approximate Capital Cost: Not provided by vendor

Vendor Name(s):

Simon Moos Maskinfabrik A/S

Kallehave 33, Horup

DK-6400 Sonderborg, Denmark

Phone: +45 74 41 0 51 

Fax : +45 74 41 52 08 

E-mail: MW@simonmoos.com 

Practitioner(s):

Nykøbing Falster Wastewater Treatment Plant

Denmark

Key Words for Internet Search:

Simon Moos, mobile dewatering, biosolids, sludge.

Data Sources:

Vendor-supplied information
Emerging Technologies September 2006

5-18 Biosolids Management

Tubular Filter Press

Objective:

Dewater and thicken inorganic sludges.

State of Development: Embryonic

The tubular fi lter press has primarily been used for dewatering 

of mining waste waters. One pilot study showed that chromium 

discharge to the environment in mine wastewater could be nearly 

eliminated by concentrating the pollutants in the dried cake. The 

tubular fi lter press also has been used to treat drinking water in 

South Africa.

Description:

Sludge is pumped at a high velocity through a series of tube-shaped fi lter presses constructed of proprietary fabric. Cake from the 

tube walls is then dislodged by a roller cleaning and the cake, in the form of fl akes, is simultaneously transported out of the tubes, 

drained, and conveyed to a collection hopper.

Comparison to Established Technologies:

Not comparable to established technologies.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Explochem

P.O. Box 400

Ferndale, 2160, Gauteng, South Africa

Phone: +27 11 888-3926

Fax : +27 11 888-3942

E-mail: micheleb@explochem.co.za

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Tubular fi lter press, South African wastewater treatment, biosolids, sludge

Data Sources:

Coopman’s, E.P.A., H.P. Schwarz, M.J. Pryor. “The dewatering of a mining sludge containing hexavalent chromium using a 

tubular fi lter press – a South African development.” Water Supply. 1:5-6 (2001) 371-376.

Vendor-supplied information.

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

5-19

Technology Summary

Mechanical Freeze-Thaw

Objective:

Increase the dewaterability of sludge without chemical 

additives.

State of Development: Embryonic

Pilot-scale demonstrations of nonmechanical freeze/thaw drying 

beds have been successful in New York State. The mechanization of 

the process in order to speed up the freeze/thaw cycles is still being 

studied.

Description:

In freeze-thaw dewatering, the sludge is frozen using commercially available freezer equipment. The frozen sludge is crushed 

and allowed to thaw naturally. Freezing alters the chemical bonds between the solids in the sludge and the water, making the 

sludge more easily dewatered. The conditioned sludge is then processed using conventional sludge dewatering equipment. 

Conditioning the sludge increases the amount of water that can be removed from the sludge. Testing has shown this technology to

be particularly successful with inorganic (e.g., alum and ferric iron) sludges.

Comparison to Established Technologies:

Similar to drying beds with refi nements (addition of freezer equipment) which improves sludge dewatering.

Available Cost Information:

Approximate Capital Cost $250,000 – $1,500,000

Approximate O&M Costs: $26,000 – $960,000 

The total installed cost of a freeze/thaw system is directly related to the amount of ice produced each day for use in 

the freezing process. Fewer freezer plates will reduce the installation cost. Properly maintained residuals freezing and 

refrigeration systems can be expected to provide many more years of service than the typical 10-year period assumed 

for economic evaluation. Frequently, annual maintenance costs are estimated as a percentage of total plant equipment 

cost, which has generally proven to be realistic and reasonable values. The above ranges of capital and O&M costs were 

estimated for residuals production ranging from 2,500 to 40,000 gallons per day. This process is typically more costeffective in cooler climates where natural freezing may occur.

Vendor Name(s):

Not available 

Practitioner(s):

The following tested the technology but is not a current 

practitioner.

Electric Power Research Institute

3420 Hillview Avenue

Palo Alto, CA 94304

Phone: 650-855-2000

Key Words for Internet Search:

Freeze-thaw dewatering, mechanical freeze-thaw, biosolids, sludge

Data Sources:

Energy Power Research Institute (EPRI). Mechanical Freeze/Thaw and Wastewater Residuals: Status Report. Palo Alto, 

California. TR-112063 (1998)

EPRI. Mechanical Freeze/Thaw and Freeze Concentration of Water and Wastewater Residuals: Status Report. Palo Alto, 

California. WO-671002. (2001)

Biosolids Management

Chapter

6-1

6

Thermal Conversion

6.1 Introduction

Thermal conversion processes are used to signifi cantly reduce volume by oxidizing the 

organic matter in the biosolids. Some treatment plants that use thermal conversion lower 

their energy costs by recovering energy as a part of these processes.

6.2 Technology Assessment

Table 6.1 summarizes the state of development of thermal conversion technologies.

In the past, thermal conversion of wastewater residuals has often been equated with 

incineration. However in recent years, some industries and municipalities have shown 

interest in creating a usable product, such as fuel from their thermal conversion processes. 

Four emerging thermal conversion technologies featured in this chapter—gasifi cation, 

melting furnace, sludge-to-oil and supercritical water oxidation—aim to produce a 

usable end product. Both the reheat and oxidize (RHOX) process and oxygen-enhanced 

incineration have improved conventional incineration by making it more effi cient and/

or reducing air emissions. Molten salt oxidation has been used primarily for industrial 

applications where the wastewater residuals are hazardous, or in areas where biosolids 

must be destroyed.

Figure 6.1 includes an evaluation of the innovative technologies identifi ed. A summary 

sheet for each innovative and embryonic technology is provided at the end of this 

chapter.
Emerging Technologies September 2006

6-2 Biosolids Management

Established Innovative Embryonic

Combustion

Fluidized-Bed Furnace

Multiple-Hearth Furnace

Oxidation

Wet Air Oxidation







Combustion

Reheat and Oxidize (RHOX)

Oxidation

Supercritical Water Oxidation

Vitrifi cation

Minergy







Combustion

Molten Salt Oxidation

Oxygen-Enhanced Incineration

Fuel Production

Gasifi cation

Sludge-to-Oil

SlurryCarbTM

Oxidation

Deep-Shaft Wet Air Oxidation (VERTADTM)

Plasma Assisted Sludge Oxidation

Vitrifi cation

Melting Furnace

















Table 6.1 – Thermal Conversion Technologies—State of Development

Figure 6.1 – Evaluation of Innovative Thermal Conversion Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Reheat and Oxidize (RHOX) I I O,V N/A \ \ S S \ S

Supercritical Water Oxidation P,O F V,A A STSSSS

Minergy I F V,R C \ T \ TTS

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

6-3

Reheat and Oxidize (RHOX)

Objective:

Decrease fuel usage and air emissions from biosolids 

incineration furnaces.

State of Development: Innovative

The fi rst RHOX installation at a wastewater treatment plant used 

a shell and tube heat exchanger to preheat the scrubbed gasses 

on their way to the afterburner. This unit, located in Willow Grove, 

Pennsylvania, has operated for almost 10 years.

Description:

Hot (1,500°F) afterburned gases are passed down through a bed of ceramic forms. In doing so, the heat content of the gas is 

transferred to the ceramic mass and the gas is cooled (to about 250°F) for discharge to the atmosphere. Cold, dust-free gas from 

the afterburner pollution control equipment is passed up through another bed of ceramic forms, which has previously been heated

with afterburner gas. Here, the cold gas is preheated to a temperature approaching the afterburner requirement by extracting 

the heat previously stored in the mass of ceramic forms. A small quantity of fuel is burned in the afterburner to reach the required 

temperature. The hot and cold gases pass back and forth through two or more beds to achieve preheating and cooling.

Comparison to Established Technologies:

Technology designed to reduce emissions. Not similar to any other established technology.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Chavond-Barry Engineering Corporation

400 County Road 518, P.O. Box 205

Blawenburg, NJ 08504

Phone: 609-466-4900

Fax : 609-466-1231

Practitioner(s):

Upper Moreland Hatboro Joint Sewer Authority

2875 Terwood Road

Willow Grove, PA

Additional practitioners are available from the vendor.

Key Words for Internet Search:

RHOX process, sludge, biosolids, reheat, oxidize

Data Sources:

Vendor-supplied information

Technology Summary
Emerging Technologies September 2006

6-4 Biosolids Management

Supercritical Water Oxidation

Objective:

Reduce the volume of biosolids using the physical 

properties of water.

State of Development: Innovative

Application of the process in industrial and wastewater treatment 

facilities is ongoing. The fi rst two units were installed at the Harlingen, 

Texas, wastewater treatment facility in July 2001 for use in a pilot 

study.

Description:

Water is heated and pressurized above the critical point [374°C and 3,191 pounds per square inch (psi)] and the solubility of 

organic substances and oxygen into water is signifi cantly increased. Supercritical water oxidation technology takes advantage of 

this characteristic to completely decompose organic substances. This technology produces a high-quality effl uent and is capable of 

producing Class A biosolids. Supercritical water oxidation also may be referred to as “hydrothermal oxidation.”

Comparison to Established Technologies:

Not similar to established technologies.

Available Cost Information:

Approximate Capital Cost: $3,500,000

Approximate O&M Costs: $160—$295 per dry ton

Capital and O&M costs are for the system installed at the Harlingen Water Works System wastewater treatment facility in 

July 2001. O&M costs include seven major components: oxygen (55.3%), natural gas (12.5%), labor-operators (12.4%), 

electrical (8%), solids disposal (6%), maintenance (5%), and expendable chemicals (0.5%).

Vendor Name(s):

HydroProcessing LLC

3201 Longhorn Blvd., Suite 101

Austin, TX 78758

Phone: 512-339-9981

E-mail: info@hydroprocessing.com

Practitioner(s):

The following was the site of a demonstration facility but is not 

currently a practitioner:

Harlingen Water Works System

134 East Van Buren

Harlingen, TX 78550

Phone: 956-430-6100

Fax: 956-430-6111

www.hwws.com

Key Words for Internet Search:

Supercritical water oxidation, SCWO, biosolids, sludge

Data Sources:

Bartholomew, R. Conversion of Biosolids: An Innovative Alternative to Sludge Disposal. Pennsylvania Department of 

Environmental Protection. (October 2002).

Kelly, H.G. Emerging Technologies in Biosolids Treatment. Dayton & Knight Ltd., West Vancouver, Canada. (2003)

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-5

Minergy

Objective:

Convert biosolids into construction material and 

industrial feed stocks that are inert and marketable.

State of Development: Innovative

Minergy’s GlassPack® Demonstration Unit in Winneconne, 

Wisconsin, built in 2000, is a 12-dry-tons-per-day commercial-scale 

system available to demonstrate Minergy’s GlassPack® technology. 

Solids from several wastewater treatment plants have been 

processed at the facility on trial bases. There are operational systems 

using pulp and papermill sludges.

Description:

Minergy gives the following description of the three-zone operation of the GlassPack vitrifi cation system:

Zone 1 Melting and Combustion. Feedstock that has been predried to approximately 90% solids or more is injected along with 

air or synthetic air into the Zone 1 chamber. In this zone, the organic component of the sludge is completely combusted, liberating 

a signifi cant amount of heat energy. In a closed-loop oxygen-enhanced application, this energy release results in temperatures of 

approximately 2,400° to 2,700°F. At these high temperatures, the mineral (ash) component of the feedstock melts to form a pool of 

molten glass at the bottom of the Zone 1 chamber. The high-temperature environment provides very high destruction effi ciencies of 

any organic compounds that may be contained in the feedstock.

Zone 2 Phase Separation. Phase separation of the molten glass and exhaust gas occurs by gravity draining the molten glass from 

Zone 1 through a drain port on the bottom of the Zone 2 chamber. The molten material drops into a quench tank and is cooled into 

the glass aggregate product. The exhaust gas is directed out of Zone 2 through a refractory-lined duct into Zone 3. 

Zone 3 Gas Cooling. The exhaust gas from Zone 2 is 2,400°F to 2,700°F and is cooled through dilution mixing with lower 

temperature gases obtained external to the melter. Reducing the temperature offers two important cost-saving advantages. 

This system can eliminate refractory-lined ductwork exterior to the melter and can cool carry over particulate below its softening 

point, thus eliminating ductwork fouling. The temperature of the Zone 3 exit gas is dependent on the selection of heat recovery

technology, but is typically in the range of 700° to 1,400°F. Higher exit gas temperature can provide for higher effi ciencies in heat 

recovery systems.

Comparison to Established Technologies:

Similar to the Melting Furnace, an innovative technology. Minergy claims the GlassPack® process eliminates the need 

to co-fi re fuel to achieve vitrifi cation and provides signifi cant environmental air emissions improvement over current 

combustion technologies due to the closed-loop design. In contrast to traditional incineration-type techniques, ash disposal 

is not necessary because the fi nal end product is a glass aggregate that has many uses including sandblasting grit, roofi ng 

shingle granules, and asphalt paving.

Available Cost Information:

Approximate Capital Cost: $104,000

Approximate O&M Costs: $97,000

Cost estimates are for 7.5-ton-per-day glassifi cation unit coupled to a thermal dryer with a minimum size of 20 dry tons per 

day. Estimates are from a cost analysis performed for Eastern Municipal Water District, California, and assume a 20-year 

life cycle and the costs associated with providing adequate facilities for this time period.

Vendor Name(s):

Minergy Corporation

1512 S. Commercial Street

Neenah, WI 54956

Phone: (920) 727-1919

E-mail: info@minergy.com 

www.minergy.com 

Practitioner(s):

Minergy Corporation Vitrifi cation Technology Center

200 Tower Road

Winneconne, WI 54986

Minergy Corp. Fox Valley Glass Aggregate Plant

231 Millview Drive

Neenah, WI 54956

Technology Summary
Emerging Technologies September 2006

6-6 Biosolids Management

Minergy (Contd)

Key Words for Internet Search:

Vitrifi cation, Minergy, glassifi cation, GlassPack®, biosolids, sludge

Data Sources:

Baudhuin, T, T. Carroll, and R. Paulson. 2005. Vitrifi cation: A Sustainable Biosolids Management Alternative. Proceedings of 

the WEFTEC: The Water Quality Event, Washington, D.C. 

(30 October – 2 November 2005) 659-666.

Kilian, R.E., A.C. Todd, A.K. Wason, M. Luker, J. Jannoni, J.D. Wall. (2003). “How to Put One Egg in Multiple Baskets.” 

EMWD’s Regional Biosolids Management Approach Makes Sense. Proceedings of the WEF/AWWA/CWEA Joint Residuals 

and Biosolids Management Conference, Baltimore, Maryland, USA. (19-22 February 2003).

Vendor website

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-7

Molten Salt Incineration

Objective:

Eliminate or reduce biosolids volume.

State of Development: Embryonic

This treatment system is favored for wastes contaminated with both 

chlorinated organics and heavy metals such as cadmium, chromium, 

zinc, etc. Industrial applications of this technology have been in use 

on a small scale since the 1950s.

Description:

The Molten Salt Oxidation (MSO) process uses a sparged liquid bed of alkaline salt contained in a reaction vessel. The process 

is based on the catalytic action of alkaline molten salts for the oxidation of organic materials. The molten salt bed acts as a heat 

transfer and reaction media. Suffi cient heat is liberated by the oxidation reaction to maintain the molten salt bed at a temperature of 

900° to 1,000°C.

Comparison to Established Technologies:

Not similar to established technologies.

Available Cost Information:

Approximate Capital Cost: Not available 

Approximate O&M Costs: $1,150/metric ton treated (Australian dollars)

Generally, the cost of treatment with this technology is relatively high because of the high capital cost of the equipment, the

labor requirements, and the high energy cost. The cost per ton depends on the feed rate of the contaminant to the furnace. 

The above O&M cost estimate was provided for hazardous waste sludges at a feed rate of 1,000 kilograms per hour, and 

it does not include effl uent treatment costs, residuals and waste shipping costs, handling and transport costs, analytical 

costs, and site restoration costs.

Vendor Name(s):

None identifi ed

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Molten salt oxidation, sludge

Data Sources:

CMPS&F Environmental. Appropriate Technologies for the Treatment of Scheduled Wastes. Review Report Number 4. 

(November 1997)

Technology Summary
Emerging Technologies September 2006

6-8 Biosolids Management

Oxygen-Enhanced Incineration

Objective:

Improve the performance of biosolids and industrial 

sludge furnaces.

State of Development: Embryonic

Praxair, Inc., claims successful operations in both municipal and 

industrial incineration applications with its Oxygen Combustion 

System (OCS).

Description:

A small amount of oxygen is added through an annulus around the fuel tube of the furnace to promote fl ame stability and consistent 

destruction effi ciency during variations in feed material. Typical temperatures with air combustion are about 3,000°F (1,649°C), 

whereas temperatures with conventional oxygen-enriched systems can rise to 5,000°F (2,760°C), thereby reducing incomplete 

combustion.

Comparison to Established Technologies:

Reaches higher temperatures than conventional oxygen-enriched furnaces.

Available Cost Information:

Approximate Capital Cost: Not provided by vendor. 

Approximate O&M Costs: Not provided by vendor.

Vendor Name(s):

Praxair, Inc.

39 Old Ridgebury Road

Danbury, CT 06810

Phone: 716-879-4077

Fax : 716-879-2040

www.praxair.com 

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Praxair, oxygen-enhanced incineration, oxygen injection, biosolids, sludge.

Data Sources:

Vendor-supplied information.

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-9

Gasifi cation

Objective:

Reduce the volume of biosolids and produce gas that 

can be used to generate electricity.

State of Development: Embryonic

Recovery of biomass-derived gas for use as a fuel source has 

been used for industrial, wood and agricultural wastes in the United 

States for more than 50 years. It was used for production of coal 

gas for over 200 years. However, gasifi cation of biosolids is a new 

application and there are no full-scale facilities operating in the 

United States. Industrial sludges have been successfully gasifi ed at 

facilities in the United States. In 2002, the Balingen Sewage Works, 

Germany, started operation of a sewage sludge gasifi cation plant 

as a demonstration study. Since 2004, it has been operating as a 

full-scale facility.

Waste to Energy Limited (United Kingdom) has patented a 

gasifi cation system for the production of electricity. The company 

conducted a demonstration project with Anglian Water in the 

United Kingdom, and reports having an agreement with Kwikpower 

International to build biosolids gasifi cation plants in Morocco.

Description:

The gasifi cation process converts sludge or biosolids into a combustible gas, referred to as synthesis gas, or “syngas,” which can 

be recovered. While incineration fully converts the input waste into energy and ash, gasifi cation heats the material under controlled 

conditions, deliberately limiting the conversion so that combustion does not take place directly. Syngas can be used as a fuel to 

generate electricity and heat. The fuel value of Syngas is not typically as high as that of digester gas, perhaps 60% of digester gas 

energy values. 

The gasifi cation process takes place in two steps: pyrolysis and partial combustion. Pyrolysis is the degradation of biosolids in 

the absence of air, into a gas and a black, carbon-rich substance called “char.” In the second reaction, the char is gasifi ed by 

partial combustion in the presence of oxygen or air to produce the syngas described above. Due to the concentrating effect of the 

constituents in the original biosolids, the remaining char will require disposal, probably in a landfi ll. 

Comparison to Established Technologies:

Similar to pyrolysis of other organic substances such as coal gasifi cation.

Available Cost Information:

Approximate Capital Cost: Not provided by the vendor

Approximate O&M Costs: Not provided by the vendor 

Studies have shown that gasifi cation is technically feasible, but project costs are typically higher than conventional 

alternatives and not based on any full-scale operations. Data on true capital cost and operating costs for “real-world” 

applications are unavailable. Vendor-supplied literature suggests one kilogram of waste will typically produce one kilowatt 

of electricity and two kilowatts of heat. At this time, no full scale facilities are operating in the United States to verify these 

claims in actual operations. 

Technology Summary
Emerging Technologies September 2006

6-10 Biosolids Management

Gasifi cation (Contd)

Vendor Name(s):

Waste to Energy Limited

Borley Green

Sudbury, England CO10 7AH

Phone: +44 1787 373007

Fax : +44 1787 373535

E-mail: info@waste-to-energy.co.uk

www.wastetoenergy.co.uk 

US Centrifuge

4011 Championship Drive

Indianapolis, IN 46268

Phone: 800-899-2040

www.uscentrifuge.com 

Kopf AG

Stützenstrasse 6

72172 Sulz-Bergfelden

Germany

www.kopf-ag.de 

info@kopf-ag.de

Practitioner(s):

Anglian Water

P.O. Box 770

Lincoln, England LN5 7WX

Phone: +44 1522 341922

www.anglianwater.co.uk 

Key Words for Internet Search:

Sewage sludge, gasifi cation, waste-to-energy, bioenergy.

Data Sources:

KMK Consultants Limited. City of Toronto Biosolids and Residuals Master Plan. In association with Black & Veatch Canada. 

(September 2004).

Gasifi cation Technologies Council website. www.gasifi cation.org

Water Environment Federation, Bioenergy from Wastewater Treatment – A Clean, Affordable Energy Source. Alexandria, VA 

(2006).

Vendor-supplied information

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-11

Sludge-to-Oil

Objective:

Produce a commercially marketable oil product from 

biosolids.

State of Development: Embryonic

ThermoEnergy Corporation, in conjunction with another contractor, 

operated a 5-MGD sludge-to-oil demonstration project in Colton, 

California, for two years. The project closed in November 2000 and 

the vendor is focusing on other technologies. 

EnersludgeTM process was built at the Subiaco WWTP, Perth, 

Australia, in 1999. It operated for 4 months before being shut down 

when the oil product was deemed unsuitable for diesel engines.

Description:

This technology uses an enhanced pyrolysis process that through specifi ed pressures and catalysts can produce lightweight oils of 

varying viscosities. 

One such process is the ThermoFuel process marketed by ThermoEnergy Corporation in Little Rock, Arkansas. The company 

claims ThermoFuel allows wastewater treatment plant operators to meet all water quality standards, produce a product that meets

Class A biosolids standards, and improve process effi ciency at a lower cost without increasing the size of the plant. 

Comparison to Established Technologies:

Not similar to established technologies.

Available Cost Information:

Approximate Capital Cost: $3,000,000 

Approximate O&M Costs: Not available 

Capital cost estimate is based on the approximate cost of the 5-MGD Colton, California, demonstration project described 

above.

Vendor Name(s):

ThermoEnergy Corporation

323 Center Street, Suite 1300

Little Rock, AR 72201

Phone: 501-376-6477

E-mail: technology@thermoenergy.com

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Sludge-to-oil, biosolids-to-oil, ThermoEnergy, ThermoFuel

Data Sources:

Kelly, H.G. Emerging Technologies in Biosolids Treatment. Dayton & Knight Ltd., West Vancouver, Canada. (2003)

Vendor-supplied information.

Technology Summary
Emerging Technologies September 2006

6-12 Biosolids Management

SlurryCarbTM Process

Objective:

Convert biosolids into a renewable fuel. For a dried 

product, a drying process must be added.

State of Development: Embryonic

Construction is scheduled to start in 2006 on a 675 wet tons per 

day facility in Rialto, California, that will incorporate the SlurryCarbTM

process plus biosolids drying. The dried product from the facility, 

scheduled to begin full-scale operations in 2008, is intended to be 

used as fuel by a cement kiln. It is estimated that the facility will 

produce 140 dry tons of product per day.

Description:

Cake of between 20 and 30% solids are fi rst macerated to create a feedstock of particles of less than 1⁄2 inch. The 

macerated solids are pressurized to above the saturated steam pressure, heated to approximately 450°F (232°C) and then 

fed to a reactor where temperature and pressure are maintained. The elevated pressure and temperature cause the cells to 

rupture and release carbon dioxide gas. This “carbonization” step causes the solids to lose their affi nity for water. Following 

this carbonization step, the material is put through a centrifuge to separate off the liquid fi ltrate. Trace contaminants are 

removed from the fi ltrate and the purifi ed water is recycled to the slurry preparation phase of the process or discharged. 

The carbonized material can then be dewatered to greater than 50% solids. The dewatered product can either be managed 

directly as slurry or further dried. The vendor reports plans to use the fi nal product as a fuel supplement in operations such 

as cement manufacturing and pulverized coal boilers.

Comparison to Established Technologies:

The SlurryCarbTM process operates at a lower temperature and pressure, and for a shorter reaction time, than pyrolysis. 

It produces an energy-rich carbon product, but no gases or oils like pyrolysis. The SlurryCarbTM process also operates 

at a lower temperature and pressure, and for a shorter reaction time than typical wet air oxidation, and no air is added 

to partially oxidize the organics in the biosolids. SlurryCarbTM also differs from the Carver-Greenfi eld® process in that the 

SlurryCarbTM process does not add anything to the biosolids and does not evaporate water. However, if a dried product is 

necessary, evaporative drying would have to be added. Drying will probably be required due to very limited use for a 

50% solids slurry.

Available Cost Information:

Approximate Capital Cost: Not provided by the vendor

Approximate O&M Costs: Not provided by the vendor

Vendor Name(s):

EnerTech Environmental, Inc.

675 Seminole Ave., Suite 207

Atlanta, GA 30307

Phone: 404-355-3390

Fax: 404-355-3292

Email: slurrycarb@enertech.com

Website: www.enertech.com 

Practitioner(s):

City of Rialto

Public Works Department

335 W. Rialto Avenue

Rialto, CA 92376

Phone: 909-820-2608

Email: publicworks@rialtoca.gov 

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-13

Technology Summary

SlurryCarbTM Process (Contd)

Key Words for Internet Search:

SlurryCarbTM, biosolids, sludge, carbonization, renewable fuel

Data Sources:

EnerTech Environmental, Inc. Company Information Packet: The SlurryCarbTM Process. (2006) Available at 

www.enertech.com.

EnerTech Environmental, Inc. “Converting Biosolids to a Usable Fuel: The Emerging Technology of Biosolids Carbonization 

–The Rialto Regional Biosolids Facility.” Presentation to CIWMB, (12 May 2005).

Kearney, R.J. and K.M. Bolin. “Using the New SlurryCarbTM Process Prior to Drying: How to Save Money and Achieve 

Permanent Recycling of Biosolids.” Proceedings of the WEF/AWWA Joint Residuals and Biosolids Management 

Conference, Cincinnati, Ohio. (12–15 March 2006). 

SlurryCarbTM process fl ow diagram from EnerTech Environmental, Inc. (2005)
Emerging Technologies September 2006

6-14 Biosolids Management

Deep-Shaft Wet Air Oxidation (VERTADTM)

Objective:

Increases energy effi ciency and produces Class A 

biosolids.

State of Development: Embryonic

The last trial of this technology related to biosolids was at King 

County’s Renton Wastewater Treatment Plant, Washington.

Description:

Deep-Shaft Wet Air Oxidation is an autothermophilic aerobic digestion process that treats sludge in a subsurface 

autothermophilic reactor that is 250–350 feet deep. The VERTADTM vendor’s website describes three reactor zones that 

function as follows: 

Oxidation Zone: The top of the shaft where the sludge digestion takes place.

Mixing Zone: Feed sludge and air are introduced in this zone. Air provides oxygen and mixing. Solids separation is through 

fl otation thickening.

Saturation Zone: Stabilized biosolids removed from the reactor fl ow through the saturation zone where high temperature 

and long residence time occur.”

High oxygen transfer effi ciency promotes rapid digestion of sludge. Pathogen-free Class A biosolids are produced in four 

days. Thickened biosolids can be dewatered to 30%–35% solids and reduced polymer usage. Offgas is separated and 

treated in a fi xed-fi lm biofi lter.

Comparison to Established Technologies:

Similar to vertical reactors that have been used for wastewater treatment for 25 years. VERTADTM has a small footprint and 

is largely underground. Therefore they are less visible than surface tankage. 

VERTADTM achieves 40% volatile solids (VS) reduction in 4 days in comparison to conventional anaerobic digestion 

systems that require up to 30-day retention times for a 55% VS reduction.

Available Cost Information:

Approximate Capital Cost: Capital cost lower than conventional autothermal thermophilic aerobic digestion (ATAD) plant 

of similar size.

Approximate O&M Costs: Not Available

Low energy requirements: 1.27 kW.hr/kg VS destroyed

Low polymer requirements: 14 lb/ton

Vendor Name(s):

NORAM Engineering and Construction, LTD

Suite 400-200 Granville Street

Vancouver BC V6C 1S4

Phone: 604-681-2030

Fax: 604-683-9164

www.noram-eng.com

Practitioner(s):

The following was the site of a trial facility but is not currently a 

practitioner:

Technology Assessment and Resource Recovery

King County

201 South Jackson Street 

Mail Stop: KSC-NR-0512

Seattle, WA 98104

Phone: (206) 684-1255

Fax: (206) 684-2057

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-15

Technology Summary

Deep-Shaft Wet Air Oxidation (VERTADTM) (Contd)

Key Words for Internet Search:

VERTADTM, deep-shaft, wet air oxidation, biosolids

Data Sources:

Vendor-supplied information.

Flow diagram of typical VERTADTM installation (courtesy of NORAM Engineering)
Emerging Technologies September 2006

6-16 Biosolids Management

Plasma Assisted Sludge Oxidation

Objective:

Signifi cant volume reduction through combustion.

State of Development: Embryonic

The process was pilot tested by LTEE, Hydro-Quebec’s research 

facility, for approximately 2 years using industrial, municipal, and 

farming feedstocks.

Description:

Plasma assisted sludge oxidation uses a rotary oven operating at between 600° and 700°C at atmospheric pressure. The oven 

is equipped with an air plasma arc torch. The plasma arc generates ultraviolet radiation and ionic radicals to sustain oxidation. 

A plasma plume is used to catalyze oxidation of wet sludges at relatively low temperatures. The vendor claims low operating 

temperatures result in high combustion effi ciency. Feed solids can have a solids content as low as 20% but operating effi ciencies 

are directly related to the solids content. The process results in an ash to be used or disposed. Combustion can reach autothermal 

operation if feed solids have a high enough energy value [estimated at 20,000 millijoules per dry ton (mJ/dry ton)].

Comparison to Established Technologies:

Not similar to established technologies.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Fabgroups Technologies, Inc.

1100 St. Amour

St. Laurent, Quebec, Canada H4S 1J2

Phone: 514-331-3712

Fax: 514-331-5656

Email: tmulhern@fabgroups.com 

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

Plasma assisted oxidation, biosolids, sludge

Data Sources:

Mulhern, T. and M. Bacon. “Full Scale Demonstration of Plasma Assisted Sludge Oxidation.” Proceedings of the 2006 WEF 

Residuals and Biosolids Management Conference, Cincinnati, Ohio. (12–15 March 2006).

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

6-17

Melting Furnace

Objective:

Reduce the volume of biosolids and industrial wastes 

by heating them to extremely high temperatures while 

producing potentially usable by-products.

State of Development: Embryonic

Full-scale melting furnaces have been in operation in Japan for more 

than 20 years. This is primarily due to the lack of available space for 

land application or surface disposal of municipal biosolids. Similar 

melting furnaces have been used to melt industrial sludges as well. 

As of 2003, the Ebara Corporation was operating two small plants 

using the Meltox technology that had been in operation for nearly 

4 years. In addition, the Ministry of Housing and Local Government 

in Malaysia decided in 2003 to construct a large TwinRec thermal 

waste treatment plant for municipal waste.

Description:

The Ebara Corporation of Japan has developed the Meltox (called TwinRec in Europe) biosolids melting and ash 

incineration technology. This process melts biosolids at temperatures exceeding 1,300°C and produces a marketable 

by-product. The furnace is fl uidized bed gasifi cation unit comprising a vertical primary combustion chamber, an inclined 

secondary combustion chamber, and a slag outlet section. Biosolids are blown into the furnace with compressed air, where 

they are incinerated and melted during a spiral descent. A plate at the outlet maintains a steady fl ow of slag, which is cooled 

by water or air before discharge. Flue gas is separated and treated to reduce odors and sulfur oxide (SOx) emissions. The 

slag can be used in various ways, such as for fi lling material, tiles for pavement and roads, interlocking blocks, terrazzo 

tiles, and other construction materials.

Comparison to Established Technologies:

Similar to fl uidized bed furnace except that it can operate at higher temperatures. Similar to innovative vitrifi cation furnace.

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

Vendor Name(s):

Ebara Corporation

1-6-27, Konan, Minato-ku

Tokyo, 108-8480 Japan

Phone: +81-3-5461-5585

Fax : +81-3-5461-5784

Website: www.ebara.ch 

Practitioner(s):

A list of practitioners using Ebara Corporation melting furnace 

technologies in Asia is available online at: 

www.ebara.ch/twinrec.php?n=1

Key Words for Internet Search:

Melting furnace, biosolids, sludge, Meltox

Data Sources:

Selinger, A., S. Steiner, K. Shin. “TwinRec Gasifi cation and Ash Melting Technology – Now also established for Municipal 

Waste.” 4th Int’l Symposium on Waste Treatment Technologies. Ebara Corporation, Zurich. (2003)

Japanese Advanced Environment Equipment. Meltox Sludge Melting System. Global Environment Centre Environmental 

Technology Database NETT21. (2002)

Vendor-supplied information.

Technology Summary

Biosolids Management

Chapter

7-1

7

Drying

7.1 Introduction

The objective of the drying process is to remove water from biosolids producing a relatively 

high percent solids, and to reduce weight and volume of the biosolids. This is usually 

accomplished with either a direct or indirect heat source. Drying can produce marketable 

products that meet Class A standards. It also dramatically reduces transportation costs if 

long distance hauling is involved.

7.2 Technology Assessment

Table 7.1 summarizes the state of development of drying technologies. This table includes 

three innovative heat-drying technologies. Belt, fl ash, and microwave drying all have been 

successfully operated in Europe and pilot-tested in the United States. 

Figure 7.1 includes an evaluation of the innovative technologies identifi ed. Summary 

sheets for each technology categorized as innovative or embryonic technology are 

provided at the end of this chapter.

Established Innovative Embryonic

Direct Drying

Flash Drying

Indirect Drying

Belt Drying 

Direct Microwave Drying 

Flash Drying

Fluidized Bed Drying

Chemical Drying

Multiple Effect Drying

Carver-Greenfi eld (case studies have shown technology to 

be not viable in the United States. No technology summary is 

provided.)



Table 7.1 – Drying Technologies—State of Development
Emerging Technologies September 2006

7-2 Biosolids Management

Figure 7.1 – Evaluation of Innovative Drying Technologies

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Belt Drying O S C,O,V,A,R A,P \ \ TSSS

Direct Microwave Drying D I C,O,V,A,R A,P T \ \ S S \

Flash Drying B,P S C,O,V,A,R A,P S \\\\\ Centrifuge and drying 

process in one.

Fluidized Bed Drying O I C,O,V,A,R A,P S \ S \\\

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

7-3

Belt Drying

Objective:

Drying of biosolids to 90% or more solids.

State of Development: Innovative

A BioCon® dryer has been in operation at the Bronderslev WWTP 

in Denmark since 1995. The fi rst operating US facility will be Mystic 

Lake, Minnesota.

A HUBER KULT® dryer for wastewater sludge is under construction 

in Germany. There is also a HUBER KULT® dryer in operation in 

Germany for drying water treatment plant residuals.

Description:

This technology is composed of two or more slow moving belts in series with air supplied through or around the belts. Dewatered

sludge is spread in a thin layer on the fi rst belt to maximize surface area. Preheated air is either blown through the belts or pumped 

into the area surrounding the belts. 

In the BioCon® dryer, temperatures ranges from 350°F at its hottest down to 175°F as the biosolids complete the drying process. 

The residence time in the dryer is more than 60 minutes, thereby exceeding Class A pathogen reduction requirements. An add-on 

process called the Energy Recover System (ERS), uses the fuel value of the dried product to generate energy used in the drying 

process.

Comparison to Established Technologies:

The BioCon® dryer is operated at a low negative pressure to minimize odor and dust generation often associated with 

biosolids drying technologies.

Available Cost Information:

Approximate Capital Cost: Not provided by the vendor.

Approximate O&M Costs: Not provided by the vendor.

Vendor Name(s):

Kruger, Inc.

401 Harrison Oaks Blvd., Suite 100

Cary, NC 27513 

Phone: 919-677-8310 

Fax: 919-677-0082

Huber Technology

9805 North Cross Center Court

Suite H

Huntersville, NC 28078

Phone: 704-949-101

Website: www.huber-technology.com

Practitioner(s):

Mystic Lake, Minnesota

Technology Summary
Emerging Technologies September 2006

7-4 Biosolids Management

Belt Drying (Contd)

Key Words for Internet Search:

BioCon, ERS, Huber Technology KULT®, biosolids, sludge, drying

Data Sources:

Frewerd, B. “Harnessing the Power of Biosolids.” Published by Kruger Inc., a division of Paris-based Veolia Water Solutions 

& Technologies. (2006).

Vendor websites.

Technology Summary

BioCon® Process Flow Diagram (Frewerd, 2006).

KULT® dryer schematic 

(Huber Technology website 8 August 2006).

BioCon® ERS Unit 

(Photo courtesy of Kruger USA).
Biosolids Management

September 2006 Emerging Technologies

7-5

Direct Microwave Drying

Objective:

Remove excess water from waste activated sludge and 

reduce pathogens.

State of Development: Innovative

Burch BioWave® is in use in Ireland and Fredericktown, Ohio. A new 

installation will be on line in Zanesville, Ohio, in fall 2006. 

Description:

Burch BioWave® is a patented continuous fl ow process that uses a duel-fueled microwave system to remove water and pathogens 

from dewatered sludge. The process utilizes a high-effi ciency multi-mode microwave system specifi cally designed to remove 

moisture. Microwaves vibrate water molecules and the resulting friction heats the water. BioWave® uses heated air forced through 

the biosolids to evaporate the moisture released by the microwaves. The air is heated by either natural gas, liquifi ed petroleum gas 

(LPG), or digester gas. 

The equipment comes in various sizes, each with the ability to dry a certain throughput of material. The process is completely 

automated and can dry biosolids with an initial moisture content of 85% to a fi nal product with 10% moisture content. Tests show 

100% pathogen kill without any change in nutrient content. 

Comparison to Established Technologies:

Established drying technologies use natural gas as fuel and rely on convection to heat solids from the outside in along 

with a loss of energy to the environment. In microwave drying, all the materials are heated simultaneously and the heat is 

generated from within the material.

Available Cost Information:

Approximate Capital Cost: $800,000 for system capable of processing 1 dry ton per day

Approximate O&M Costs: Not provided by the vendor.

Equipment provided in cost includes stainless steel applicator unit, four 100-kilowatt microwave transmitters, control panel, 

250,000-BTU gas burner, standard aluminum wave guides, operator training and 1-year system warranty. 

Maintenance cost are low because there are no moving parts. Electricity is more than 90% of the energy used. System is 

80% energy effi cient.

Vendor Name(s):

Burch Hydro, Inc.

17860 Ankneytown Road

Fredricktown, OH 43019

Phone: 800-548-8694

Website: 

www.burchbiowave.com/sections/process/index.asp

Practitioner(s):

Fredericktown, Ohio.

Technology Summary
Emerging Technologies September 2006

7-6 Biosolids Management

Direct Microwave Drying (Contd)

Key Words for Internet Search:

Burch BioWave®, microwave dryer, biosolids

Data Sources:

Vendor-supplied information.

Burch BioWave® dryer installed

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

7-7

Flash Drying

Objective:

Drying of biosolids to 90% or more solids.

State of Development: Innovative

The Centridry® fl ash drying process was evaluated in King County, 

Washington, where it reduced the water content of 20% dewatered 

solids to 60%–70% solids. However, product testing indicated that 

for best usability, the product should also be composted, which 

signifi cantly increases costs. This project was completed in the 

summer of 2001 and King County does not anticipate any further 

testing on this process. Centridry® units have been in operation in 

Europe since 1993.

Description:

Liquid biosolids combined with polymer are pumped into a centrifuge where conventional mechanical dewatering takes place. The 

dewatered biosolids reach a minimum of 25% dry solids, and are discharged into the thermal stage as a fi ne-grained spray.

The biosolids particles are instantly dried upon entering the thermal cyclone chamber in order to prevent them from sticking to the 

walls of the chamber. The particles are then entrained and conveyed in the sweep gas, and exit the chamber in a matter of seconds 

during which time the sludge granules are dried and the temperature of the conveying gas is dramatically reduced. The pneumatic

conveying and drying process continues during the relatively short transport time to a cyclone where the product particles are 

separated and discharged via a rotary valve to the stockpile. 

The sweep gas, drawn through the system via the main ventilator fan, is reheated in the hot gas generator before re-entering the 

dryer loop. Excess gas vapors in the system are drawn off by a small blower, treated in a venturi scrubber to remove residual 

quantities of fi ne dust and volatile components, and discharged for odor treatment.

Comparison to Established Technologies:

Similar to other drying processes; however CentriDry® does not require biosolids to be dewatered prior to entering the unit.

Available Cost Information:

Approximate Capital Cost: Not provided by the vendor.

Approximate O&M Costs: Not provided by the vendor.

Vendor Name(s):

Euroby Limited

Columbia House, Columbia Drive

Worthing, West Sussex BN13 3HD

Phone: +01-903-69-44-00

E-mail: sales@euroby.com

Website: www.euroby.com/centridy.htm

Practitioner(s):

Severn Trent Water STW

Worksop, UK

Key Words for Internet Search:

Centridry®, centrifuge drying, biosolids, sludge

Data Sources:

King County Department of Natural Resources. Regional Wastewater Services Plan – Annual Report. Wastewater 

Treatment Division. (December 2001).

Vendor-supplied information

Technology Summary
Emerging Technologies September 2006

7-8 Biosolids Management

Fluidized Bed Drying

Objective:

Provide a safer, more reliable, more fl exible technology 

for drying digested/undigested municipal biosolids to 

Class A levels.

State of Development: Innovative

Three plants in Europe are currently operating using this technology. 

It is used in other industrial applications in the U.S.

Description:

Mechanically dewatered wet cake is pumped from storage directly into the fl uidized bed dryer, where it comes in contact with 

already-dry granules, building larger granules. The process is done entirely within the fl uid bed itself without the need for recycling/

blending/classifying steps. It is also accomplished within an inert closed loop. Only a minimal amount of gas is exhausted for 

treatment. All heating is done via indirect means with heat exchanger surfaces (tubes) immersed in the fl uidized layer of solids in 

the dryer. Heating confi guration is extremely fl exible and can be accomplished with energy derived from natural gas, digester gas, 

steam, waste heat, and other sources. The end product is ≥90% dry solids, dust free, mechanically stable, and can be used in land 

application or as a fuel and mineral source in cement kilns.

Comparison to Established Technologies:

Not similar to any established biosolids management technologies. This process is established for drying pellets, powders, 

and granules in the chemical and pharmaceutical industries.

Available Cost Information:

Approximate Capital Cost: Approximately $750,000 per ton of water per day evaporated.

Approximate O&M Costs: Approximately 65 to 75 kWh per ton of water evaporated. 

Maintenance costs approximately 3% per year.

Figures are approximate and depend largely on equipment arrangement and structure for the equipment to be located, and 

the amount of wet cake and dry granule storage, which is included. The thermal energy requirement is approximately 1,250 

to 1,300 BTU per pound of water evaporated. Technology is best suited for plants in the 5 to 500+ MGD range, but is cost 

competitive at lower capacities as well.

Vendor Name(s):

Andritz-Ruthner, Inc.

1010 Commercial Boulevard, South

Arlington, TX 76001

Phone: 817-419-1704 Fax : 817-419-1904

E-mail: peter.commerford@andritz.com

Website: www.andritz.com 

Schwing America, Inc.

Material Handling Division

5900 Centerville Road

St. Paul, MN 55127

Phone: 651-429-0999 Fax: 651-653-5481

E-mail: cwanstrom@schwing.com

Website: www.schwing.com

Practitioner(s):

No practitioners of this technology for wastewater solids in the 

U.S. were identifi ed. However, vendors can provide information 

on practitioners in other industries. 

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

7-9

Technology Summary

Fluidized Bed Drying (Contd)

Key Words for Internet Search:

Fluid bed dryer, biosolids, sludge

Data Sources:

Vendor-supplied information and websites
Emerging Technologies September 2006

7-10 Biosolids Management

Chemical Drying

Objective:

Solids are dried through chemical reaction. The dried 

product is mixed with nutrients to enhance the fertilizer 

value of the fi nal product. 

State of Development: Embryonic

There are no installation or pilot facilities of this technology operating 

in the U.S.

Description:

In the chemical drying process, ammonium salts or anhydrous ammonia and concentrated organic acids are mixed with dewatered 

biosolids. The organic acids (e.g., sulfuric acid, phosphoric acid) react with the ammonia in an extremely exothermic reaction.

Sulfates and phosphates are produced in the reaction between the acid and the ammonia. The heat and pressure from the reaction 

sterilize the biosolids and complete the drying process. The reaction of the biosolids with the ammonium salts produces a hard 

granular material. As with other drying processes, the granular material can be combined with plant nutrients to further raise the 

nutritive value of the product. 

Comparison to Established Technologies:

Vendor claims indicate a fi nal product similar to that produced by other drying technologies that is suitable for benefi cial use 

(provided feed solids are of acceptable quality).

Available Cost Information:

Approximate Capital Cost: < $ 4M for a 22 ton (25% solids) per day facility

< $10M for a 100 ton (25% solids) per day facility

Approximate O&M Costs: Not provided by the vendor.

Vendor Name(s):

VitAG, LLC.

2111 Forest View Road

Aiken, SC 29803

Phone: 239-398-6127 Fax : 803-652-2009

E-mail: Jburnham1@aol.com

Unity Envirotech, LLC

1119 Burgundy Circle

Pennsburg, PA 18077

Phone: 215-262-5233 Fax : 904-819-9224

E-mail: RTuttleUFC@aol.com

Practitioner(s):

No practitioner at this time.

Key Words for Internet Search:

VitAG, Unity, biosolids, sludge, chemical drying

Data Sources:

Vendor-supplied information

Technology Summary
Biosolids Management

Chapter

8-1

8

Other Processes

8.1 Introduction

This chapter focuses on other processes that do not fi t clearly into one of the other 

categories in this report.

8.2 Technology Assessment

Table 8.1 summarizes the state of development of other processes. Two of the technologies 

presented in this chapter are designed to signifi cantly reduce either the volume or 

pathogen content of biosolids without all of the steps required by conventional methods. 

The Cannibal® process uses bacteria developed specifi cally to degrade biosolids’ organic 

matter. The Lystek process uses heat and chemicals to produce a liquid biosolids product 

that is suitable for land application and meets Class A requirements. Use of biosolids as 

a fuel in cement kilns is also addressed.

Figure 8.1 includes an evaluation of the innovative technologies identifi ed. Summary 

sheets for each process are provided in this chapter.

Established Innovative Embryonic

N/A Cannibal® Process

Lystek Process

Injection in Cement Kiln

N/A

Table 8.1 – Other Processes—State of Development
Emerging Technologies September 2006

8-2 Biosolids Management

Figure 8.1 – Evaluation of Other Innovative Processes

Process

Evaluation Criteria

DevelopmentApplicabilityPotential BeneComments

fi ts

Benefi cial UseImpact on Other ProcessesComplexityAir EmissionsEnergyFootprintEnvironmental

Cannibal® Biosolids Destruction 

Process

N I C,O,V N/A STS \\\

Lystek Thermal/Chemical Process N I C,O,A N/A \ TSS \ S

Injection in Cement Kiln N F C,O,V,R P S \ \ SSS

Statement of Development

B = Bench scale

D = Full-scale demonstrations in North 

America

I = Full-scale industrial applications, with 

demonstrations or pilots for municipal 

sewage sludge

O = Full-scale operations overseas

N = Full-scale operations in North America

P = Pilot

Potential Benefi ts

A = Produces Class A biosolids

C = Capital savings

O = Operational/maintenance savings

F = Produces high-nutrient fertilizer

M = Minimizes odors

R = Provides benefi cial use (nonagricultural)

V = Sludge volume reduction

Applicability

F = Few plants

I = Industrywide

L = Primarily large plants

S = Primarily small plants

Benefi cial Use

A = Agriculture

C = Construction

N/A = Not Applicable

P = Power

Comparative Criteria

S Positive feature

\ Neutral or mixed

T Negative feature
Biosolids Management

September 2006 Emerging Technologies

8-3

Cannibal® Biosolids Destruction Process

Objective:

Biosolids volume reduction without digestion, 

thickening, dewatering or polymer addition

State of Development: Innovative

A 1 MGD sequential batch reactor wastewater treatment plant 

in Georgia began using the Cannibal solids reduction process in 

October 1998. The plant has purged solids once in fi ve years to 

relieve the plant of extremely fi ne inert material buildup. The plant 

removed 8,000 pounds of wasted biosolids using the process 

between January 2000 and September 2003. Favorable results also 

have been realized at other full-scale operations within the United 

States. This process also has been successful at the Alpine Cheese 

Factory in Holmes County, Ohio, and has been the subject of benchscale research at Virginia Polytechnic Institute and State University.

Description:

A portion of sludge from the main treatment process is pumped to a sidestream bioreactor where the mixed liquor is converted from 

an aerobic-dominant bacterial population to a facultative-dominant bacterial population. Aerobic bacteria are selectively destroyed 

in this sidestream reactor while enabling the facultative bacteria to break down and use the remains of the aerobes and their 

byproducts. 

Mixed liquor from the bioreactor is recycled back to the main treatment process. There, the facultative bacteria, in turn, are outcompeted by the aerobic bacteria and subsequently broken down in the alternating environments of the aerobic treatment process 

and the sidestream bioreactor. 

Trash, grit and other inorganic materials are removed from the process by a patented solids separation module on the return sludge 

line. All of the return sludge is pumped through this module and recycled back to the main treatment process. Only a portion of this 

fl ow is diverted to the sidestream bioreactor for the selection and destruction process.

Comparison to Established Technologies:

Not similar to any established technology

Available Cost Information:

Approximate Capital Cost: Not available

Approximate O&M Costs: Not available

According to the vendor, a 1.5 MGD WWTP could recognize an approximate net operating cost savings of $245,600 using 

the Cannibal process.

Vendor Name(s):

Envirex Products

1901 S. Prairie Ave.

Waukesha, WI 53189

Phone: 262-521-8570

Fax : 262-547.4120

E-mail: RoehlM@usfi lter.com

website: www.usfi lter.com

Practitioner(s):

Alpine Cheese Factory, Inc.

1504 US 62

Wilmont, OH 44689

Phone: 330-359-5454

Fax: 330-359-5049

Technology Summary
Emerging Technologies September 2006

8-4 Biosolids Management

Cannibal® Biosolids Destruction Process (Contd)

Key Words for Internet Search:

Cannibal® process, biosolids, sludge

Data Sources:

Sheridan, J. and B. Curtis. “Casebook: Revolutionary Technology Cuts Biosolids Production and Costs.” Pollution 

Engineering. 36:5 (2004).

Novak, J.T., D.H. Chon, B-A. Curtis, M. Doyle. “Reduction of Sludge Generation using the Cannibal® Process: Mechanisms 

and Performance.” Proceedings of WEF Residuals and Biosolids Management Conference 2006: Bridging to the Future.” 

Cincinnati, OH (12–14 March 2005).

Vendor-supplied information

Technology Summary
Biosolids Management

September 2006 Emerging Technologies

8-5

Lystek Thermal/Chemical Process

Objective:

Biosolids treatment and processing technology for 

production of high solids and pathogen-free product for 

benefi cial use.

State of Development: Innovative

The process has been successfully demonstrated at a full-scale 

pilot facility at the Guelph Wastewater Treatment Plant in Ontario, 

Canada. It was able to produce a Class A biosolids of 12 to 15% 

solids. The product was stored without any change in product quality. 

Description:

The Lystek process is a propriety sequenced batch operation where heat is applied and chemicals added to the feed solids in 

controlled conditions. Retention times are relatively short and the system can be fully automated to control the relevant parameters: 

pH, temperature and time. The resultant product is 12%–15% solids with a viscosity of < 1,500 cP (>2,000,000 cP of the feed) and 

is compatible with standard equipment used for land application. The resulting material retains the pump-ability needed to reduce 

the costs of biosolids handling, storage, transport and land application. The process has been shown to achieve the specifi cations 

required for Ontario NMA Class B biosolids and U.S. EPA Class A biosolids.

Comparison to Established Technologies:

Similar to digestion processes that use additives and heat to reduce pathogens.

Available Cost Information:

Approximate Capital Cost: $1,000,000 – $1,250,000

Approximate O&M Costs: $120 – $145 per dry metric ton 

Capital cost estimates for the Lystek system are for a generic WWTP producing approximately 4,000 dry tons biosolids per 

year, and do not take into account any additional modifi cation costs that may be necessary to integrate the Lystek system 

to the existing wastewater treatment plant. The cost will also depend on the nature of the biosolids produced by the plant. 

Operation and maintenance costs include material and energy

Vendor Name(s):

Lystek International, Inc.

107-279 Weber Street North

Waterloo, Ontario N2J 3H8

Canada

Phone: 519-880-2170

Fax : 519-747-8125

E-mail: info@lystek.com

Website: www.lystek.com

Practitioner(s):

City of Guelph Wastewater Services

530 Wellington Street

Guelph, Ontario N1H 3A1

Phone: 519-837-5629

E-mail: connie.mcdonald@guelph.ca or wastewater@guelph.ca

Key Words for Internet Search:

Lystek, biosolids, sludge

Data Sources:

Singh, A, F. Mosher, O.P. Ward, W. Key. “An advanced biosolids treatment and processing technology for benefi cial 

applications of high solids and pathogen-free product.” 3rd Canadian Organic Residues and Biosolids Management 

Conference, Calgary. (1–4 June 2005).

Technology Summary
Emerging Technologies September 2006

8-6 Biosolids Management

Technology Summary

Injection in Cement Kiln

Objective:

The objective for the wastewater treatment plant is 

cost effective, environmentally sound management 

of biosolids. The objective from the standpoint of the 

cement kiln is to reduce emission of nitrogen oxides 

(NOx) and/or fuel usage.

State of Development: Innovative

The technology is currently used for managing dewatered biosolids 

from a few wastewater treatment plants in California. It is also used 

to manage dried biosolids in a facility in Union Bridge, Maryland. 

A pilot study was conducted at the Maryland facility in 2004 and 

operation of the full scale facility began in 2006 under the terms of a 

six-month test fi re permit. Heidelberg Cement (the parent company 

of Lehigh Cement, the owner of the Maryland facility) has been using 

this technology in Europe for a number of years

Description:

Biosolids are injected into cement kilns at different locations depending on the purpose of the biosolids. Biosolids can be used to 

reduce NOx emission and can serve as an alternate fuel source. 

In reducing NOx emissions, the ammonia present in the biosolids reacts with oxygen to form nitrogen and water. In this application, 

dewatered biosolids are injected into the process at a point where temperatures are between 1600 and 1700° F (870 – to 930° C),

typically, where the exhaust gases leave the kiln. This application is appropriate for preheater/pre-calciner kilns because in these 

plants, the target temperature range occurs at a location where it is feasible to inject the biosolids. In kilns of other designs the ideal 

temperature range occurs within the rotating portion of the kiln, an area where injecting the biosolids is not feasible. In addition 

to providing the means for the chemical reaction, the introduction of the biosolids at the point where exhaust gases leave the kiln 

also creates less favorable conditions for NOx formation by lowering the gas temperature. Through many years of operation, 

Mitsubishi’s Lucerne Valley Cushenberry Plant in California has found that with a commercial injection rate of approximately 10

tons of dewatered biosolids per hour results in a small increase in electric load. That facility has also tested for increase in carbon 

monoxide and hazardous air pollutants (HAPs). There was no signifi cant increase in HAPS. There were some notable increase in 

carbon monoxide emission but emissions remained below acceptable levels of 550 ppm. 

Where biosolids are used to augment fossil fuels, dried biosolids (greater than 90% solids) are fed into the calciner combustion 

zone of the cement manufacturing process. During the initial pilot testing at the Lehigh Cement facility, the biosolids were mixed 

with the pulverized coal fuel. However, NOx emissions increased slightly with the use of biosolids at the Maryland facility, believed 

to be the result of increase rate of combustion. Currently, alternate feed locations are being investigated in an effort to reduce 

NOx emission while maximizing the use of biosolids. Testing of other emissions showed slight decrease in carbon monoxide, total

hydrocarbons and sulfur dioxide.

In both applications there are no addition residuals to manage; ash is bound in the cement product and has been found to be 

compatible with the raw materials used in cement manufacture. However, adequate fan capacity must be provided to deal with 

steam vapor resulting from the use of biosolids in both applications. The vapor is more of a concern when the feed biosolids have 

lower percent solids.

Comparison to Established Technologies:

Not similar to any established technology.
Biosolids Management

September 2006 Emerging Technologies

8-7

Technology Summary

Injection in Cement Kiln (Contd)

Available Cost Information:

Approximate Capital Cost: Not applicable to biosolids generator; capital investment is made by cement kiln operator/

owner. 

Approximate O&M Costs: Cost varies regionally; tipping fees of less than $5 per ton (wet) were quoted in the literature 

but will be infl uenced by the percent solids of the biosolids

Vendor Name(s):

Operators of cement kilns that have accepted biosolids 

include:

Lehigh Cement

7600 Imperial Way

Allentown, PA 18195

Phone: 610-366-4636

Email: emorton@htcnam.com 

Mitsubishi Cement Corporation

5808 State Highway 18

Lucerne Valley, CA

Phone: 760-248-737

Practitioner(s):

Joint Water Pollution Control

24501 S Figueroa Street

Carson, CA 

Synagro-Baltimore LLC

Key Words for Internet Search:

Cement kiln biosolids injection

Data Sources:

Battye, R., S. Walsh, J. Lee-Greco. NOx Control Technologies for the Cement Industry, Final Report. (2000).

Kahn, Robert. “Biosolids Injection: A New Technology for Effective Biosolids Management,“ Undated.

Morton, Edward L. “A Sustainable Use for Dried Biosolids.” Undated.

Cement Industry Environmental Consortium website, www.cieconline.net.

Vendor-supplied information.

Lehigh Cement plant in Union Bridge, Maryland.

(Photo courtesy of Lehigh Cement. 2006.)

Biosolids Management

Chapter

9-1

9

Research

9.1 Introduction

In order to reclassify any technology which is considered to be innovative or embryonic, 

additional research and fi eld demonstration projects are necessary. This chapter focuses 

on specifi c technologies that may have a signifi cant impact on biosolids treatment and 

management, and the relevant research needs in these areas.

9.2 Research Needs

Sound, sustainable biosolids management is based upon controlling and infl uencing the 

quantity, quality and characteristics of biosolids in such a way that negative impacts to 

the environment are avoided and benefi cial uses are optimized. It is recognized that 

each wastewater treatment facility in the United States faces unique circumstances 

resulting in a variety of applicable biosolids management strategies. Biosolids treatment 

technologies are used to achieve benefi cial use to the greatest extent possible. 

Table 9.1 identifi es research needs for especially promising technologies in biosolids 

treatment. Benefi cial use can take advantage of the soil conditioning and fertilizing 

properties of this material or it may include gas and energy production. Substantial 

scientifi c research will enable the benefi cial use of biosolids to continue to expand by 

reducing the uncertainties and data gaps on the potential effects of biosolids exposure 

to human health. Research is used to determine whether current practices need to 

be altered. Emerging and innovative technologies can provide new cost-effi cient and 

effective solutions to biosolids management. Some steps towards completing scientifi c 

research include: “development and standardization of sampling and analytical methods, 

investigation of contaminant fate/transport and exposure routes, potential human health 

effects, risk assessment determinations; evaluation of improvements that may be needed 

in operational practices, technologies, and management practices for biosolids treatment 

and reuse.” (WERF, 2002).
Emerging Technologies September 2006

9-2 Biosolids Management

Technology Type Technology Focus of Investigation

Conditioning None None.

Thickening None None.

Stabilization Temperature-Phased 

Digestion

Confi rm solids reduction and gas production.

Determine SRT needed vs. conventional anaerobic digestion.

Identify operating problems – Thermophile Heating/Heat Recovery.

Two-Phase 

Digestion

Confi rm solids reduction and gas production.

Determine SRT needed vs. conventional anaerobic digestion.

Identify operating problems.

Ferrate Addition Confi rm performance, costs and viable operating parameters.

Neutralizer® Confi rm performance, costs and viable operating parameters.

Dewatering None None.

Thermal 

Conversion

RHOX Process Document improvement in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

Gasifi cation Conduct testing at several locations.

Document improvements in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

Sludge-to-Oil Conduct testing at several locations.

Document improvements in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

Supercritical Water 

Oxidation

Conduct testing at several locations.

Document improvements in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

SlurryCarbTM Conduct testing at several locations.

Document improvements in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

Deep-Shaft Wet Air 

Oxidation

Conduct testing at several locations.

Document improvements in plant capacity and decrease in emissions.

Determine impact on capital and operating costs.

Drying Belt Drying Determine capital and operating costs.

Identify operating problems/confi rm performance.

Direct Microwave 

Drying

Determine capital and operating costs.

Identify operating problems/confi rm performance.

Flash Drying Determine capital and operating costs.

Identify operating problems/confi rm performance.

Fluidized Bed Drying Determine capital and operating costs.

Identify operating problems/confi rm performance.

Chemical Drying Confi rm performance, costs and viable operating parameters.

Cannibal® Document improvements in performance.

Determine impact on capital and operating costs.

Lystek Document improvements in performance.

Determine impact on capital and operating costs.

Table 9.1 – Research Needs Technologies: State of Development
Biosolids Management

September 2006 Emerging Technologies

9-3

Generally, research and technical issues can be grouped into three areas: 

(1) Analysis and reduction of risk associated with benefi cial use practices; 

(2) Utilization of the potential of biosolids to yield energy; and, 

(3) Improved operation, performance, and effi ciency of biosolids treatment 

processes. 

9.2.1 Analysis and Reduction of Risk Associated with Certain Benefi cial Use 

Practices

Fundamental research in this area relates to:

Standardization of sampling and analytical methods for contaminants to assure 

the use of the best measurement methods for particular microbial and chemical 

contaminants. This standardization should also state the best time and place for 

sampling. 

Standardization of risk assessment measures and methods for chemicals and 

pathogens. Risk assessment allows for the evaluation of operational improvement 

practices and technologies. This evaluation would differ from most plant effi ciency 

evaluations by focusing on the treatment practices and the protections they offer 

to human and environmental health. 

Fate and transport of the contaminants during biosolids management practices. 

Emerging chemical contaminants and pathogens, as well as on exposure 

measurements and routes. The potential health risks and effects should be 

addressed to determine the adverse effects of the emerging contaminants.

Resolution of issues that affect the acceptability of Class B biosolids to continue 

in the future.

Reactivation of fecal coliforms in centrifuge dewatered solids, anaerobically 

digested biosolids.

9.2.2 Utilization of the Potential of Biosolids to Yield Energy

Fundamental research in this area relates to:

Research on technologies that can generate or increase the quantity of energy 

from the production of biosolids by-products and gases.

Utilization of process-generated gas to provide energy to offset at least some of 

the energy requirements of wastewater and biosolids treatment technologies.
















Emerging Technologies September 2006

9-4 Biosolids Management

9.2.3 Improved Operation, Performance and Effi ciency of Biosolids Treatment 

Processes

Optimization of the application of chemicals for dewatering and their impact on the 

quality of the fi nal product.

Assessment of the odor potential from biosolids stabilization and dewatering 

techniques and advances to mitigate odor emissions.

New technologies for the production of artifi cial soils and fertilizer components or 

products.

Emergence of high temperature, high-volume solids destruction technologies.

Improvements in energy effi ciency, particularly the use of heat exchangers and 

heat recovery.

9.2.4 Research Needs

The technologies are arranged by type, noting the recommended focus of the investigations 

for each.

Selection of the technologies and their research needs is based upon an assessment of 

the process summaries and evaluations in the previous chapters. Criteria used to select 

the technologies include applicability, judgment about critical assessments needed to 

promote the technology to the next level of development, promise for further development 

and current interest in the technology. 

9.2.5 Chapter References

Water Environment Research Foundation (WERF) (2002).

www.werf.org/funding/researchplan.cfm

WERF (1999) Biosolids Management Evaluation of Innovative Processes.










Biosolids Management

Appendix

A-1

A

Great Lakes By-products Management Association

15743 Hagenderfer Road, Plain City, OH 43064

Phone: 866-309-7946 

Web: http://glbma.org 

Mid-Atlantic Biosolids Association

Web: http://www.mabiosolids.org 

National Biosolids Partnership

601 Wythe Street, Alexandria, VA 22314

Phone: 703-684-2400

Web: http://www.biosolids.org 

North East Biosolids & Residuals Association

P.O. Box 422 Tamworth, NH 03886-0422

Phone: 603-323-7654 

Web: http://www.nebiosolids.org 

Northwest Biosolids Management Association

201 S. Jackson St Seattle, WA 98104-3855

Phone: 206-684-1145

Web: http://www.nwbiosolids.org 

Water and Wastewater Equipment Manufacturers Association (WWEMA)

P.O. Box 17402, Washington, D.C. 20041

Phone: 703-444-1777 

Web: http://www.wwema.org 

Water Environment Federation

601 Wythe Street, Alexandria, VA 22314-1994

Phone: 703-684-2452 

Web: http://www.wef.org 
Emerging Technologies September 2006

A-2 Biosolids Management

Water Environment Research Foundation

635 Slaters Lane, Suite 300, Alexandria, VA 22314

Phone: 703-684-2470 

Web: http://www.werf.org

Air and Waste Management Association

One Gateway Center, 3rd Floor, 420 Fort Duquesne Blvd.

Pittsburgh, PA 15222-1435 

Phone: +1-800-270-3444 

Web: http://www.awma.org/

National Association of Clean Water Agencies

1816 Jefferson Place, NW Washington D.C. 20036 

Phone: 202.833.2672 

Web: http://www.nacwa.org/