United States Environmental

Protection

 Agency

Office of Research and

Development

Washington DC 20460

EPA/540/AR-93/513

September 1995
EPA/540/AR-93/513

September 1995

EPOC Water Inc. Microfiltration Technology

Applications Analysis Report

NATIONAL RISK MANAGEMENT RESEARCH LABORATORY

OFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OH 45268

@ Printed on Recycled Paper
Notice

The information in this document has been funded by the U.S. Environmental Protection Agency under Contract No.

68-CO-0048 and the Superfund Innovative Technology Evaluation (SITE) Program. It has been subjected to the

Agency’s peer review and administrative review, and it has been approved for publication as a U.S. EPA document.

Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.

ii
Foreword

The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation’s land,

air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and

implement actions leading to a compatible balance between human activities and the ability of natural systems

to support and nurture life. To meet this mandate, EPA’s research program is providing data and technical

support for solving environmental problems today and building a science knowledge base necessary to manage

our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental

risks in the future.

The National Risk Management Research Laboratory is the Agency’s center for investigation of

technological and management approaches for reducing risks from threats to human health and the environment.

The focus of the Laboratory’s research program is on methods for the prevention and control of pollution to air,

land, water and subsurface resources; protection of water quality in public water systems ; remediation of

contaminated sites and ground water; and prevention and control of indoor air pollution. The goal of this research

effort is to catalyze development and implementation of innovative, cost-effective environmental technologies;

develop scientific and engineering information needed by EPA to support regulatory and policy decisions; and

provide technical support and information transfer to ensure effective implementation of environmental

regulations and strategies.

This publication has been produced as part of the Laboratory’s strategic long-term research plan. It is

published and made available by EPA’s Office of Research and Development to assist the user community and

to link researchers with their clients.

E. Timothy Oppelt, Director

National Risk Management Research Laboratory

. . . 111
Abstract

This document is an evaluation of the performance of the EPOC Water, Inc. Microfiltration Technology and its

applicability as a treatment technique for water contaminated with metals. Both the technical aspects and the

economics of this technology were examined. Operational data and extensive sampling and analysis information

were carefully compiled to establish a data base against which the vendor’s claims for the technology have been

compared and evaluated. Other information provided by the vendor, and summarized in this report, was also taken

into account in this evaluation. Conclusions concerning the technology’s suitability for use in removing metals from

acid mine drainage were reached, and extrapolations regarding applicability to other sites with different contaminants

and liquid wastes are also provided.

EPOC’s system consisted of a reaction (precipitation) chamber, microfiltration units, dewatering units, and auxiliary

equipment. The microfiltration unit (EXXFLOW) utilizes a unique fabric support operating with a formed-in-place

dynamic membrane. The system also includes a pressurized tubular fabric dewatering unit, the EXXPRESS, which

operates on the same.microfiltration principles. According to the vendor, particulates 0.1 pm in diameter or larger

are removed by the EXXFLOW and the concentrate (reject) slurry can be dewatered in the EXXPRESS. Dissolved

metals present in acid mine drainage water or other contaminated waters first must be precipitated by chemical

treatment to enable removal by filtration.

The EPOC Microfiltration Technology was demonstrated under the U.S. EPA SITE program at the Iron Mountain

Mine Superfund site near Redding, California in May and June of 1992. The water source for most of this

demonstration, acid mine drainage from the Old No. 8 Mine Seep, contained about 3,000 mg/L of total metals,

primarily aluminum and iron, with much smaller concentrations of heavy metals. Chemical precipitation with

various alkalies and recirculation through the EXXFLOW microfiltration unit increased the suspended solids in the

concentrate to about 10,000 to 35,000 mg/L. Further concentration and dewatering with the EXXPRESS achieved

12% to - 30% solids in the filter cakes, rather than the claimed 20% to 40 % , depending on the alkali used for

precipitation. Considerable operating difficulty was encountered with the EXXPRESS unit as configured for the

demonstration. The filter cakes all passed the TCLP.

The permeate from the ON8 seep using the EXXFLOW was of high quality. The metals were successfully

removed, meeting all claims with the exception of aluminum and, occasionally, manganese and iron. Where

elevated concentrations of heavy metals were present (e.g., copper at 170 mg/L), these were consistently reduced

to less than 0.1 mg/L (e.g., copper in permeate: <0.05 mg/L). The permeate turbidity was consistently less than

1 NTU in all cases. The permeate pH was usually in the 9 to 10 range and would probably require acidification

before it could be discharged.

The estimated cost for a 1-yr remediation using two sizes of the EPOC EXXFLOW system was $125.00/1000 gal

($33.50/m3) for the 7 gpm (26.5 L/min) pilot-scale unit with no dewatering of the concentrate, $103/1000 gal

($27.25/m3) with conventional dewatering and $47.40/1000 gal ($12.50/m3) for the 50 gpm (190 Lmin) full-scale

system with dewatering. The EXXPRESS unit was not used in the cost analysis.

This demonstration was conducted for the Risk Reduction Engineering Laboratory (now the National Risk

Management Research Laboratory) in April-July 1992, and work was completed as of September 1993.

i v
Contents

Page

Foreword ............................................................................................iii

Abstract ...................................... . . .....................................................iv

Tables .............................................................................................. vii

Figures ............................................................................................. viii

AbbreviationsandSymbols.............................:...............................~................ ix

ConversionFactors ......................................................................................x.

Acknowledgments .....................................................................................xi

1. Executive Summary ............................................................................ 1

l.l Intorn ................................................................................. 1

1.2 Conclusions ................... ..) ......................................................... 1

1.3 Discussion of Conclusions.. ................................................................... 2

2. Introduction ................................................................................... 4

2.1 The SITE Program. ........................................................................ 4

2.2 SITE Program Report s ....................................................................... 4

2.3 Key Contacts ............................................................................... 5

3. Technology Applications Analysis ...............................................................

3.1 Introduction ..............................................................................

3.2 Conclusions ..............................................................................

3.3 Technology Evaluation .....................................................................

3.4 Ranges of Site Characteristics Suitable for the Technology .............................. .: ..........

3.5 Applicable Wastes for the Technology ................. 1 ......................................

3.6 Environmental Regulatory Impacts ...........................................................

3.7 Manpower Requirements. . .................................................................

3.8 Testing Requirements ......................................................................

6

6

6

7

9

10

11

13

13

4. Economic Analysis ..................... . . . ..C ...............................................

4.1 Introduction ..............................................................................

4.2 Conclusions .............................................................................

14

14

14

4.3 Issues and Assumptions .................................................................... 15

4.4 Basis for Economic Analysis ................................................................ 16

4.5 Results ................................................................................. 20

4.6 Development of a 700 GPM Microfiltration System .............................................. 21

Appendices

A. Process Description ...............................................................................

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

A.2 The Reaction Tank ........................................................................

A.3 EXXFLOW Unit ............................................ ..i ..........................

22

22

22

22

V
Contents (continued)

Page

A. 4 EXXPRESS Unit.. . . . . ..,,..................................a... . . . . . . . . . . . . . . . ..*........ 25

A.5 Sludge Dewatering . . . . . . . . . . . . ..,.........,..............*..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

B. Vendor’s Claim36

B lIntroduc.............................................................................. 26 

B.2 EPOC Microfiltration Technology ............................................................. 26

B.3 Applications of the EPO EXXFLOW/EXXPRESS C Technology .................................... 29 

B.4SystemAdvantage ......................................................................... s 29

C. Demonstration Test Results ........................................................................... 31

C. lIntroductio ............................................................................... n 31

C.2 Site Description ............................................................................ 31

C.3 Wastewater Contamination Characteristics ........................................................ 31

C.4 Review of Site Demonstration ............................................... . ................. 31

D. Case Studies 41

D. 1 Bench Scale Treatability Testing ............................................................ . ... 42

D.2HazardousWasteReduction. ................................................................ . 43

D.3GroundwaterRemediatio .................................................................... n 44

D.4 Zero Discharge of Ceramics Wast ............................................................. e 45

D.5IndustrialWastewate ....................................................................... r 46

vi
Tables

Number

3-1. Effect of EXXFLOW Microfiltration

3-2. Filter Cake Production from EPOC Process

4- 1. Estimated Costs for 7 gpm Pilot-Scale Unit

4-2. Estimated Costs for 50 gpm Full-Scale Unit

B-l. Wastes Compatible with the EPOC System

C-l. EPOC Demonstration Test Runs Performed at IMM Site

C-2. Treated Effluent Quality-Composite Samples

C-3. EPOC Microfiltration Summary

C-4. Filter Cake Output from EPOC EXXPRESS

C-5. Filter Cake Metal Content

D-l. Treatability Test Results

D-2. Removals of Hazardous Constituents

D-3. Concentration Comparison

42

vii
Figures

Number

3-1. Aluminum-Alkalinity Relationship

A-l. EXXFLOW Filtration Technology and Flexible Tube Module

A-2. EXXFLOW Crossflow Microfilter

A-3. EXXPRESS Automatic Sludge Dewatering System

B-l. Typical Vertical Module Configuration

B-2. EPOC Microfiltration Process Schematic

B-3. EXXPRESS Dewatering Schematic

C-l. Iron Mountain Mine Location Map Showing Richmond Portal, Old No. 8 Mine Seep and Other

D-l. Talley Corporation Process Schematic

Page

8

24

24

27

27

. . . vul
Abbreviations and Symbols

CERCLA

gpd

gpm

HSWA

kWh

mg/L

NPDES

PEL

ORD

OSHA

OSWER

NPL

POTW

ppb

ppm

psi

psig

QA/QC

RCRA

SAIC

SARA

scfm

SITE

TCLP

TSD

VOC

Acid Mine Drainage

Comprehensive Environmental Response, Compensation, and Liability Act of I980

gallons per day

gallons per minute

Hazardous and Solid Waste Amendments to RCRA - 1984

kilowatt-hour

milligrams per liter

National Pollutant Discharge Elimination System

Permissible Exposure Limit

Nephelometric Turbidity Units

Office of Research and Development

Occupational Safety and Health Administration or Act

Office of Solid Waste and Emergency Response

National Priorities List

publicly owned treatment works

parts per biiion @/I)

parts per million (mg/L)

pounds per square inch pressure

pounds per square inch, gauge pressure

Quality Assurance/Quality Control

Resource Conservation and Recovery Act of 1976

Risk Reduction Engineering Laboratory

Science Applications International Corporation

Superfund Amendments and Reauthorization Act of 1986

standard cubic feet per minute

Superfund Innovative Technology Evaluation

Toxicity Characteristic Leaching Procedure

Treatment, Storage, and Disposal

Volatile Organic Chemical

ix
Conversion Factors

Area:

Flow Rate:

Length:

Mass:

Volume:

Pressure:

English (US)

lf?

1 in’

1 cfm

1 gal/min

1 gal/min

1 Mgal/d

1 Mgal/d

1 Mgal/d

lft

l in

1 yd

1 lb

1 lb.

lrt’

1 ft)

1 gal

1 gai

1 psia

x Factor

x 9.29 x 10’

x 6.45

x 2.83 x 10’

x 6.31 x 10’

x 6.31~10’

x 43.81

x 3.78 x 10

x 4.38 x 10’

x 0.30

x 2.54

x 0.91

x 4.54 x lor

x 0.454

x 28.31

x 2.83 x 10’

x 3.78

x 3.78 x 103

x 51.71

ft = foot, P = square foot, ft’ = cubic foot

in = inch, in2 = square inch

yd=yard

lb = pound

gal = gallon

gal/min (of gpm) = gallons per minute

Mgal/d (or MGD) = million gallons per day

m=meter,m2 = square meter, m3 = cubic meter

cm = centimeter, cm2 = square centimeter

L = liter

g=gram

kg = kilogram

cfm = cubic feet per minute

L/s = liters/sec

m3/d = cubic meters per day

= Metric

= m2

= cm2

= m’/min

= m’js

= IJS

= Us

= m’/d

= m’/s

= m

= cm

=m

= g = kg

=L

= m3

= L

= m3

= cm Hg
Acknowledgments

This report was prepared under the direction and coordination of Mr. Jack Hubbard, EPA Superfund Innovative Technology

Evaluation (SITE) Project Manager in the National Risk Management Research Laboratory (formerly the Risk Reduction

Engineering Laboratory), Cincinnati, Ohio. Contributing authors were: Mr. Robert Dvorin, Mr. Dan Patel, Mr. Ray

Martrano. Ms. Linda Hunter and Ms. Ruth Alfasso of SAIC.

This report was prepared for EPA’s SITE Program by the Environmental Technology Division of Science Applications

International Corporation (SAIC) under U.S. EPA Contract No. 68-CO-0048.

xi
Section 1

Executive Summary

1.1 Introduction

TheEPOC microfitration technology, using a dynamic

(formed-in-place) membrane to remove, concentrate. and

dewater suspended solids (down to 0.1 micrometer, pm,

diameter), was evaluated on acid mine drainage (AMD) at

the Iron Mountain Mine Super-fund site near Redding,

California. Operating and cost data collected from this

demonstration provide the basis for this evaluation.

Microfiltration allows for removal of very small particles of

suspended solids (to 0.1 um). A dynamic membrane, which

is constantly renewed, is expected to be more resistant to

plugging and fouling, thereby requiring less downtime far

cleaning. The EPOC system used a patented design of

woven textile tubes as the support for the dynamic

membranes.

The dissolved metals in the acid mine drainage were

precipitated with various alkalies in a mechanically mixed

reaction tank physically separated and concentrated in the

EPOC EXXFLOW microfiltration unit, and dewatered in the

EPOC EXXPRESS system. The final products of this

process are the decontaminated water and a small volume of

filter cake containing the contaminants.

This report offers information useful in assessing the

suitability of this process to other similar sites, and includes

additional information (supplied by the developer) relative to

performance on other types of contaminated water.

The primary objectives of this demonstration were to:

I) Assess the ability of the EPOC microfiltration

technology to remove metals present in the acid

mine drainage (AMD) at the Iron Mountain Mine

site, using various precipitating chemicals;

I Evaluate the technology’s capability to dewater the

metals-bearing sludge formed as result of the

treatment of the AMD wastewater.

Assess the quality of the treated water and the dewatered

metals-bearing sludge thus produced, and

1) Develop capital and operating costs for the EPOC

microfiltration technology.

1.2 Conclusions

The results and observations of the SITE demonstration at

Iron Mountain Mine provide the bases for the following

conclusions:

A. When operated at a rate of about 11 L/min (3 gpm) on

acid mine drain water containing about 3000 mg/L of

total metals:

* The EXXFLOW microfiltration system met the

developer’s claims for removal of heavy metals in the

AMD but did not meet the claim for aluminum (1 mg/L)

with all alkalies used as the precipitating chemical.

e The EPOC microfiltration system reduced cadmium,

copper, and zinc in the permeate to <50 ppb each.

* Aluminum was reduced to less than 1 mg/L when

magnesium oxide (Mg0) was used; hydrated lime

(Ca(OH)a or caustic soda (NaOH) produced residual

concentrations of about 15-50 mg/L of aluminum.

* Flow rate, pressure, and a flux of about 2650 L/m’day

(65 gal/ft%lay) were essentially constant for the duration

of each demonstration run (4 to 6 hr), indicating that the

EXXFLOW unit should operate for extended times with

minimal maintenance and cleaning.

* The EXXPRESS dewatering unit experienced serious

operating problems that required operator attention and

prevented effective evaluation.

1
B.

* Dewatered filter cake volume was less than 5% of the

treated water volume in all runs (i.e., water recovery

as permeate was 95% or better).

* None of the filter cakes met the developer’s claims

for solids content. Caustic treatment produced a

sludge cake with about 12% dry solids (claimed:

>20%). Hydrated lime, magnesium oxide . or a

combination of magnesium oxide and caustic soda

treatment resulted in filter cakes containing about

30% dry solids (claimed: >40% with lime).

1) The dewatcred filter cakes, in all runs, passed the

TCLP (toxicity characteristic leaching procedure) test

but were composed primarily of metals other than

those analyzed in the test (e.g., Al, Fe).

@ Based on the demonstration tests, other information,

and the use of other dewatering approaches for the

concentrate, the cost to treat metal contaminated

wastes such as the ON8 acid mine drainage is

estimated at $125/1000 gal ($33/m’) with a 7 gpm

(26.5 L/min) unit with disposal of the reject as a

liquid waste and $103/1000 gal (S27/m3 ) with

dewateaing of the reject stream. For a 50 gpm (190

L/min) system, with dewatering of the reject, the

estimated cost is $47.40/1000 gal ($ 12.50/m3) These .

costs are based on a 90% on-line factor, a total

treatment time of twelve months, and 50% sodium

hydroxide as the treatment chemical. The cost of

caustic is a major cost factor.

When acid mine drainage containing about 20,000 mg/L

of dissolved metals (primarily iron, aluminum, copper,

and zinc) was treated at a rate of 3.8 L/min (1.0 gpm)

with a combination of magnesium oxide and caustic

soda:

Residual metals in the permeate met the developer’s

claims except for iron (which was, nevertheless,

reduced by 99.9%). cadmium, and manganese.

Flux in the EXXFLOW unit was maintained at about

730 IJm2&y (18 ga.l/ftGIay) with a feed

concentration of about 7% w/w suspended solids.

Dewatered filter cake passed the TCLP test for

metals. Dry solids in the dewatered filter cake, 26%,

did not meet the 40% claim. Water recovery was

76%.

C. The EPOC system may have utility in removing metals

and suspended solids from a wide variety of waste and

process streams. The system requires minimal floor

space and probably can surpass other clarification means

where needed to meet discharge requirements. Metalcontaining streams would be well-suited to the process,

and, based on information provided by the developer, oil

emulsions and other solids that do not settle readily may

be good candidates.

1.3 Discussion of Conclusions

A trailer-mounted EPOC microfiltration system with a

design flow rate of 26.5 L/min (7 gpm) but operated at 11

L/min (3 gpm) and 3.8 L/min (1 gpm) was tested at the Iron

Mountain Mine Superfund site. Extensive data were

collected ove r nine demonstration runs of 4 to 6 hr duration

to assess (a) dissolved metals reduction, (b) sludge

dewatering capabilities, (c) operational requirements, and (d)

operating costs. Data generated by this testing serve as the

basis for the preceding conclusions.

A Quality Assurance (QA) program was conducted by SAIC

in conjunction with EPA’s QA program which includes ,

audits and data review as well as corrective action

procedures. This program is the basis for the high quality

of data obtained from the SITE project.

Extensive data were collected on the metals, acidity,

alkalinity, pH, sulfate, and total solids of the water before

and after treatment Suspended solids concentration of the

feed to the microfilter was determined. The dewatered filter

cake was analyze d for moisture, density, pH, metals, and

TCLP (toxicity characteristic leaching procedure) for metals.

The key factors affecting performance of the system were

neutralizing chemical choice and chemical feed rate control.

Caustic soda produced the most hydrated sludge cake, which

is to be expected. Aluminum concentrations in the permeate

remained higher than anticipated when either caustic or lime

was used because it was difficult to control the pH and any

excess alkali redissolved the amphoteric aluminum.

Magnesium oxide, and a combination of magnesium oxide

and caustic, allowed more precise control of pH and this was

reflected in improved aluminum removal.

The EXXFLOW microfiltration unit operated effectively in

producing a permeate with very little residual metals. With

the Old No. 8 Mine Seep water, about 95% of the feed

water could be recovered as permeate meeting all heavy

2
metal objectives. With the Richmond Portal AMD

containing significantly higher concentrations of aluminum,

iron and other metals, permeate water accounted for 76% of

the feed water. Although the several runs were shorter than

planned. the absence of any gradual deterioration in flow

rate, pressure, or flux suggests that the microfiltration unit

would operate over a long time with minimal downtime for

cleaning.

In addition to affecting the nature of the solids and the rate

at which they are produced, the chemical agent apparently

also affected the ease with which the sludge generated in the

EXXFLOWmicrofiltration unit could be further dewatered

in the EXXPRESS unit, The result was that sludge generated

by caustic precipitation could only be dewatered to about

12% solids, while lime or magnesium oxide produced

sludges that could be dewatered to 25% to 32% solids.

The EXXPRESS dewatering unit required frequent attention

and manual cleaning, seemingly because the high

concentration of metal hydroxides did not act hydraulically

within the tubes as expected and the unit plugged. Almost

constant operator attention was required on some runs.

Either this device requires design modification to operate on

heavy loads of metal hydroxide sludges, or it may be more

suited for applications where the nature or quantity of solids

is different.

Costs were estimated for two system sizes and assumed that

approaches other than the EXXPRESS dewateaing unit are

used to process the reject concentrate from the EXXFLOW.

Direct disposal of the reject stream is more costly than

dewatering. accounting for 36% of the pilot-plant costs.

With dewatering, the cost for management of the reject

decreased to 23%. In the full-scale system. dewatering

accounts for 14.2% of the cost. Neutralizing chemical cost

for a given volume of wastewater will remain essentially the

same for any size of treatment system, but could change

significantly with different wastewaters.
Section 2

Introduction

2.1 The SITE Program

In 1986. the EPA’s Office of Solid Waste and Emergency

Response (OSWER) and Office of Research and

Development (ORD) established the Superfund Innovative

Technology Evaluation (SlTE) program to promote the

development and use of innovative technologies to clean

up Superfund sites across the country. SlTE is helping to

provide the treatment technologies necessary to implement

new federal and state cleanup standards aimed at

permanent remedies, rather than quick fixes. The SlTE

program is composed of four major elements: the

Demonstration Program, the Emerging Technologies

Program, the Measurement and Monitoring Technologies

Program, and the Technology Transfer Program.

The major focus has been on the Demonstration Program.

which is designed to provide engineering and cost data on

selected technologies. EPA and developers participating

in the program share the cost of the demonstration.

Developers are responsible for demonstrating their

innovative systems at chosen sites, usually Superfund

sites. EPA is responsible for sampling, analyzing. and

evaluating all test results. The result is an assessment of

the technology’s performance, reliability, and cost.This

information will be used in conjunction with other data to

select the most appropriate technologies for the cleanup of

Superfund sites.

Developers of innovative technologies apply to the

Demonstration Program by responding to EPA’s annual

solicitation. EPA will also accept proposals at any time

when a developer has a treatment project scheduled with

Super-fund waste. To qualify for the program, a new

technology must be at the pilot- or full-scale stage and

offer some advantage over existing technologies. Mobile

and in situ technologies are of particular interest to EPA.

Once EPA has accepted a proposal. EPA and the

developer work with the EPA Regional Offices and state

agencies to identify a site containing wastes suitable for

testing the capabilities of the technology. EPA prepares

a detailed sampling and analysis plan designed to evaluate

the technology thoroughly and to ensure that the resulting

data are reliable. The duration of a demonstration varies

from a few days to several months, depending on the

length of time and quantity of treated waste needed to

assess the technology. After the completion of a

technology demonstration, EPA prepares two reports.

which are explained in more detail below. Ultimately. the

Demonstration Program leads to an analysis of the

technology’s overall applicability to Superfund problems.

The second principal element of the SITE Program is the

Emerging Technologies Program, which fosters the further

investigation and development of treatment technologies

that are still at the laboratory scale. Successful validation

of these technologies could lead to the development of a

system ready for field demonstration. The third

component of the SITE program, the Measurement and

Monitoring Technologies Program, provides assistance in

the development and demonstration of innovative

technologies to better characterize Superfund sites. The

final component, the Technology Transfer Program.

disseminates the information from all the studies to

interested parties in the remediation community in the

form of reports, bulletins, etc.

2.2 SITE Program Reports

The analysis of technologies evaluated in the

Demonstration Program is contained in two documents:

the Technology Evaluation Report and the Applications

Analysis Report. The Technology Evaluation Report

contains a comprehensive description of the demonstration
sponsored by the SITE program and its results. It gives a

detailed description of the technology, the site and waste

used for the demonstration, sampling and analysis during

the test. the data generated, and the quality assurance

program.

The scope of the Applications Analysis Report is broader

and encompasses estimation of other Superfund and

hazardous waste site applications and costs of a

technology based on all available data This report

summarizes the results of the SlTE demonstration, the

vendor’s design and test data, and other laboratory and

field applications of the technology. It discusses the

advantages, disadvantages, and limitations of the

technology as they may pertain to other sites with different

characteristics.

Costs of the technology for different applications are

estimated in the Applications Analysis Report, based on

available data on pilot- and full-scale applications. The

report discusses factors such as site and waste

charactaistics that have a major impact on costs and

performance.

Theamount of available data for the evaluation of an

innovative technology varies widely. Data may be limited

to laboratory tests on synthetic waste, or may include

performance data on actual wastes treated at the pilot- or

full-scale. Nevertheless, there are limits to conclusions

regarding Superfund applications that can be drawn from

a single field demonstration. A successful field

demonstration does not necessarily assure that a

technology will be widely applicable or fully developed to

the commercial scale. The Applications Analysis Report

attempts to synthesize whatever information is available

and draw reasonable conclusions. This document will be

very useful to those considering the technology for

Superfund cleanups and represents a critical step in the

development and commercialization of the treatment

technology.

2.3 Key Contacts

For more information on the demonstration of the EPOC

Microfiltration technology, please contact:

1.

2.

3.

ERA Technical Project Manager concerning the

SITE demonstration:

S. Jackson Hubbard

U.S. ERA Risk Reduction Laboratory

26 West Martin Luther King Drive

Cincinnati, OH 45268

(5 13) 569-7507

Vendor concerning the process:

Scott Jackson

EPOC Water, Inc.

3065 sunnyside. #101

Fresno. CA 93727

(209) 291-8144

For further information concerning The Iron

Mountain Test site:

Rick Sugarek

Remedial Project Manager

U.S. Environmental Protection Agency

75 Hawthorne Street

San Francisco, CA 94105

(4 15) 744-2226
3.1 Introduction

Section 3

Technology Applications Analysis

This section of the report addresses the applicability of the

EPOC Microfiltration process to waste streams that contain

dissolved solids which can be precipitated and removed from

the aqueous phase . This discussion is based upon

information gathered from the SITE demonstration tests

conducted at Iron Mountain Mine in Redding . CA and other

information provided by the vendor. The demonstration tests

provided a data base on which this process can be judged as

to its applicability to this type of waste at other sites,

Additional information for application of the EPOC

microfiltration process at other sites, and with other wastes,

is presented in Appendix D. The Technology Evaluation

Report, a separate EPA document, provides an in-depth

discussion of this SITE demonstration test and the analytical

results.

The EPOC Microfiltration process is based on the ability of

a semi-permeable membrane to retain suspended particulates

while allowing the water and dissolved species to pass

through the membrane. Microfiltration processes typically

remove particles in the O.lpm to l.Opm range. EPOC’s

technology consists of a patented crossflow microfiltration

module using dynamic membrane technology to achieve

filtration separations for particles in the range of O.lpm to

0.2pm . with minimal fouling of the membrane and,

consequently, minimal decrease in flux [throughput] over

time. Suspended solids in the feed water deposit on the

inner surface of porous tubes in the microfiltration module

to form the dynamic membrane, and it is this membrane that

controls the filtration process. Dissolved solids, e.g., metal

ions, are chemically reacted to form particles which can then

be filtered from the host liquid.

3.2 Conclusions

Evaluation” subsection discusses the data generated from the

demonstration test in support of these conclusions.

Dissolved heavy metals can be successfully removed

from the water stream by the microfiltration process

(EXXFLOW) when precipitated with any of several

alkalies.

The system generally met the vendor’s claim for

reduction of heavy metals in the permeate to 4.1

mg/L, but did not consistently meet claims for

aluminum and iron reduction to 4 mg/L. High

concentrations of these two metals in the AMD feed

waters and high alkalinity in the treated water may

have been contributing factors. It must be noted,

however, that some heavy metal concentrations in the

feed water were below the claimed final

concentrations.

The performance of the EXXFLOW microfiltration

system and the quality of the product water are

dependent on the choice of base used for

precipitation.

The quantity and quality of the filter cake is a

function of the base used. The filter cakes from the

EXXPRESS dewatering system did not meet the

vendor’s claims of >20% solids (from caustic) and

>40% solids (from lime).

The system can produce filter cake from these AMD

waters that wilI pass the TCLP requirement.

recognizing that aluminum and iron were the major

constituents in the sludge.

The EXXPRESS dewatering unit required

considerable attention and did not operate effectively

as configured by the vendor for the demonstration.

The following are overall conclusions from the evaluation of

the EPOC Microfiltration process. The “Technology

6
*i

Each waste stream to be treated by the process

requires detailed characterization and selection of

treatment chemicals and additives in order to develop

optimal operating parameters.

The cost for treatment with the EXXFLOW process has

been estimated at about $103/1000 gal with a 26.5

L/min (7 gpm) unit such as the pilot-plant system tested

and decreases to about $47/1000 gal for a 190 L/min

(50 gpm) unit, both coupled with dewatering of the

reject. Chemical cost is a major factor with both units,

but decreases significantly on scale-up. These costs

were developed with a conventional filter press for

dewatering because the EXXPRESS unit could not be

operated effectively during the demonstration.

It was not possible to determine the long term utility or

reliability of the system since run lengths were limited

to about 4 to 6 hours. However, there was little change

in flux over the course of the tests, suggesting that

extended operation of the EXXFLOW unit was feasible.

Adjustment of the product water pH may be required

before discharge, depending upon regulatory

requirements.

The process can be designed as a transportable unit or

a permanent installation. For given sizes of

EXXFLOW/EXXPRESS units, a reasonably wide range

of process flow rates can be accommodated.

The process requires a limited amount of site

preparation before installation, including electric power

and a level area for the unit. Units then can be placed

in operation after a 1 to 2 week shakedown period.

3.3 Technology Evaluation

The following provides a more detailed discussion of the

chemical and operational test results that were used to

develop the foregoing conclusions. A summary of the test

and analytical data is presented in Appendix C. Information

on other applications of this technology along with

performance data is presented in “Appendix D Case

Studies”. The estimated cost to treat waste streams is

presented in detail in Section 4. “Economic Analysis’.

3.3.1 Chemical Test Results

The EPOC Microfiltration technology is designed to remove

suspended solids from liquid wastes. Dissolved

contaminants must first be converted to particulates (of

appropriate size) using conventional technologies. Dissolved

metals. which were the focus of this SITE demonstration

test, can be treated with lime, caustic or magnesium oxide to

precipitate the metals by forming insoluble metal hydroxides

(and/or carbonates). The contaminant metals can then be

removed from the water stream by filtration such as the

EPOC microfiltration system. Other species, such as oils,

can be coagulated or aggregated with or on coagulants and

polyelectrolytes.

The SITE demonstration test was conducted at Iron

Mountain Mine, Redding, CA. This site is contaminated

with several acid mine drainage water sources that contain

heavy metals. Two water sources were tested during the

demonstration, Old No. 8 Mine Seep and Richmond Portal.

Both waste streams are contaminated with high levels of

iron, aluminum, copper and zinc. Several other metals were

present at much lower levels, but were still considered

critical in the evaluation of this technology.

Eight test runs were performed on water collected from the

Old No. 8 Seep using caustic. lime, magnesium oxide, and

a combination of caustic and magnesium oxide as the

precipitating base. A combination of caustic and magnesium

oxide also was evaluated on water from the Richmond Portal

seep. One to three hours were required to reach and maintain

the desired pH (over 9) in the reaction tank before operation

of the EXXFLOW unit was initiated Completed test runs

averaged 4 to 5 hours during which grab and composite

samples were collected of the raw feed, permeate, and filter

cake. These samples were analyzed for metals to determine

removal efficiencies. Other parameters were also measured

to evaluate, for example, solids content of the filter cakes.

Caustic soda or lime treatment resulted in metals

concentration well below the developer’s claims, except for

aluminum (and manganese), in the permeate from the

EXXFLOW microfiltration unit.

The treated water pH and alkalinity were extremely sensitive

to small changes in alkali feed rate, particularly with the

soluble sodium hydroxide. A feed rate of 9 g/L of caustic

(100%) was targeted and maintained while the reaction

vessel was being filled and treated at a nominal 12 L/min (3

gpm) rate; at this rate an excess of 0.1 g/L (about 1%)

would produce 100 mg/L excess alkalinity. In field tests

during the caustic runs, aluminum in grab samples increased

from 2.5 ppm at a pH of 8.3 to 100 ppm at pH 12 while the

alkalinity was 26 ppm and 740 ppm, respectively.

Aluminum in lime-treated water was about 18 ppm at a pH

of about 10.5 and alkalinity of 90 ppm, and less than one

ppm at an 8.8 pH and 44 ppm alkalinity. The amphoteric

character of aluminum at elevated pH is well known.

Figure 3-1 shows the relationship between treated water,

aluminum content and alkalinity. Alkalinity may be a more

7
Table 3-I. Effect of EXXFLOW Microfiltration

Fig. 3-1 Aluminum-Alkalinity Relationship

important factor than pH based on the grab sample results

for caustic and limetreatment. Basedon this limited

information, at other sites it may be necessary to measure

akalinity and choose the precipitating alkali andtherateof

introduction so that removal of aluminum (and possibly zinc)

is maximized.

Magnesium oxide provided more reliable control due to its

much lower solubility at elevated pH, but required a longer

time for equilibrium to be reached. Total metal reduction

was about two orders of magnitude with magnesium oxide.

Some metals, such as copper, were reduced four orders of

magnitude.

In some of the tests, residual concentrations of some metals

in the permeate were below published solubilities, perhaps

due to added benefits attributable to the dynamic membrane,

as repotted in other microfiltration studies.

Table 3-1 compares metal concentrations, p H and alkalinity

in the feed waters with those in the permeate from the Old

No. 8 Seep. Similar results were observed in the single test

run using the Richmond Portal seep. Tables C-2 and C-3 in

Appendix C provide more detailed information about the test

runs.

The filter cake characteristics during operation of the

EXXPRESS varied with the alkali used for precipitation.

Solids content was 12% (w/w) with caustic, not up to the

claim of 20% w/w solids. With lime, the demonstration

produced 30% w/w, not the anticipated 40% w/w solids. In

addition, the cake masses actually recovered during the

demonstration runs were considerably less than would be

predicted based on run volume, metals removal, and

dewatered cake characteristics (Table 3-2). The lower solids

content in the filter cakes would be reflected in larger

volumes requiring disposal.The relatively low volume runs

(600 to 900 gal) and the large water and sludge inventory in

the system (400 to 500 gal in the reaction tank and feed

tank) apparently allowed for hold-up of heavy sludge within

the system. This was confirmed by visual examination of

the conebottomed reaction vessel at the end of individual

runs: considerable solids were observed to be present.

Table 3-2. Filter cake production from EPOC process

3.3.2 Operational Test Results

For this process, the important operating parameters are the

treatment chemical. pH in the precipitation/reaction tank,

residence time in the reaction tank, EXXFLOW flux rate,

and filter press (EXXPRESS) control. With other

wastewaters. there may be other parameters that can affect

the performance of the unit. For the demonstration tests,

8
EPOC evaluated each AMD waste stream and selected

operating parameters and treatment chemicals based upon

bench-scale treatability tests.

Three treatment chemicals were selected for evaluation at

Iron Mountain: hydrated lime, i.e., calcium hydroxide or

Ca(OHh. sodium hydroxide (50% liquid caustic soda.

NaOH). and magnesium oxide (MgO). Tests were also

conducted using a combination of sodium hydroxide and

magnesium oxide. Each of these chemicals yielded very

different operating and sludge characteristics.

Prcdemonstration shakedown runs were performed by EPOC

using hydrated lime. This established the unbuffered quality

of this water. In both the predemonstration and the

demonstration tests, treated water pH was extremely

sensitive to very small changes in chemical feed rate, and

very tight control was required to prevent pH excursions of

as much as a full unit. The volume and characteristics of

the sludge formed presented operating problems, particularly

with the EXXPRESS dewatering system, which required

considerable attention, including frequent short downtime for

manual cleaning.

With sodium hydroxide, the first chemical evaluated during

the actual demonstration testing, reaction rates were quick

and pH control again was difficult to maintain with highly

variable pH results for the permeate during the start-up

period of each of the two runs. The sludge generated from

the process was very thin and there was some difficulty

during the shakedown activities with EXXPRESS unit

operation. EPOC evaluated the problems and made

adjustments to the EXXPRESS operation in an effort to

improve sludge production for the scheduled test.

Throughout the demonstration tests, sludge was produced at

moderate rates (about 40-50 Ib/hr) and never dewatered to

the anticipated 20% solids content

With magnesium oxide as the base, reaction rates were much

slower. Approximately 2 hours were required to raise the

pH to 8; the low solubility of magnesium hydroxide limits

the pH to about 9. This facilitated pH control in the reaction

tank and the permeate samples. With good control of pH

during precipitation, enhanced removal of aluminum from

the permeate from the EXXFLOW was observed. However,

sludge recovery for the MgO runs was very low and

difficulty was again encountered with operation of the

EXXPRESS unit for dewatering during the demonstration

test runs. In addition, the physical properties of the sludge

produced with MgO were such that it was not possible to

form a “chip” or filter cake particle with the EXXPRESS.

Instead of adhering to the tube walls. the sludge was easily

washed back into suspension when the tubes were opened

for draining. Consequently, the EXXPRESS reject continued

to concentrate and plug the tubes even as EPOC attempted

to vary the flux in the press.

In all cases, the EXXFLOW flux remained essentially

unchanged at 2650 Wm24ay (65 gal/feday) over the course

of each test run. While the runs were not as long as

planned, a fall-off in flux would usually occur during the

early period if plugging were taking place: that was not the

case with these wastewaters and the EXXFLOW unit.

3.4 Ranges of Site Characteristics Suitable for

the Technology

3.4.1 Site Selection

The EPOC microfiltration system is readily transportable by

truck. The unit size and configuration can be tailored to the

needs of the waste stream and the available area on the site

or in the treatment plant. The system can either be designed

as one large unit or as several replicate modules, depending

on site and other needs.

The demonstration test unit (nominal 26 L/min. 7 gpm.

capacity) was transported on a trailer approximately 18 ft

long and 8 ft wide. This pilot-scale unit was transported to

the demonstration test site by a pickup truck over narrow

dirt roads. Any site accessible by an ordinary automobile

should be accessible to this size unit provided that the roads

have sufficient clearance. Larger units would be transported

as several individual modules.

3.4.2 Topographical and Area Requirements

A level and stable surface area larger than the unit size (18

ft x 8 ft) is required as well as room for the reaction tank,

storage tanks for the feed, permeate, and filter cake,

auxiliary equipment, and access. Grade should be no more

than approximately 1% and must be able to support the

equipment without allowing it to sink or tip. The trailermounted unit can clear small obstructions such as rocks or

other surface irregularities.

The trailer-mounted unit stands less than 8 ft high and can

be placed inside of a building with at least that much

clearance.

3.4.3 Climate Characteristics

The ambient temperature can affect the reaction rate of

chemicals in the reaction tank. Under the normallyencountered range of operating conditions, no major

problems should be experienced. However, perhaps more

9
important is the potential impact of temperatures on flux

rate. Cold temperatures can also cause freezing of the

sodium hydroxide solution (ii that is the alkali selected), the

fecdwater, and the permeate. Mechanical and electrical

problems could also be encountered. If the system is to be

operated in a cold or freezing climate, modifications to the

systems to include heating coils and insulation could

overcome such problems. The unit can also be housed in a

heated structure to prevent cold-related problems.

High temperatures do not hinder treatment with the

technology but may be hazardous to personnel due to the

potential for heat stress disorders and contact with heated

metal parts.

Weather conditions such as rain or high winds do not

immediately damage the technology or prevent its operation.

ln areas where the weather is frequently severe or highly

variable over the planned treatment time, the unit should be

sheltered to prevent damage from continuous exposure to the

elements and to ensure consistent operating conditions and

consistent product water and solids.

3.4.4 Utility Requirements

The EPOC microfiltration process requires a source of 240

volt. 3 phase electricity. During the demonstration, a

portable generator provided the necessary electricity to the

process at this remote site; the power could also be drawn

from a municipal power grid, if available.

Only a few hundred gallons per day of water for equipment

cleaning is required. Water would also be required for

emergency purposes and use in an on-site laboratory.

During the demonstration test, a portable compressor was

used to supply air for a diaphragm pump and pneumatic

valve operation. This requirement could be eliminated by

replacing these air-operated components with electric

counterparts. When treating some wastewaters, the

equipment may need occasional cleaning with hydrochloric

acid; during the demonstration, untreated feedwater (2.3 pH)

was used for this purpose.

3.5 Applicable Wastes for the Technology

The EPOC microfiltration technology may be applicable to

many different types of liquid wastes. To be treated with

the EXXFLOW and EXPRESS technologies, the liquid

waste must have the following characteristics:

I It must be pumpable.

* The contaminants must be in particulate form; the

particles must be large enough to be removed by the

dynamic membrane, or * It must be feasible to precipitate dissolved

contaminants such as metal ions chemically to allow

treatment and removal of the solids. * Separation must provide an advantage; i.e., the

hazardous characteristics of the wastewater must

become concentrated in either the sludge or the

permeate by the process.

Wastes of varying chemical and physical characteristics can

be treated by this technology. The materials of construction

of the mixing tanks, the tubing support textiles, and piping

can be varied to handle wastes which are corrosive. A nonleachable (by TCLP) solid filter cake can be produced

depending on the toxic constituents in the liquid and the

chemical additives used.

Acid mine drainage is only one application for the EPOC

technology. Other applicable wastes may include

contaminated groundwater (dissolved/dispersed metals,fine

silt/clay), industrial or municipal wastewaters containing

solids and/or precipitable inorganic ion contamination (e.g..

metal finishing); industrial process wastewater (e.g., pickle

liquor) for recycle or reuse of the water or solids; and

process sludges for production of a dry filter cake,

particularly where dewatering by other, conventional means

has proven ineffective.

The system is particularly well suited for removal of metals,

which tend to form difficult-to-separate sludges and which

can be precipitated readily with bases. Case studies reported

by the developer (Appendix D) have demonstrated that the

system also can treat organic compounds such as oil, grease,

pesticides, and kerosene where these can be coagulated or

adsorbed on a medium. Other organic pollutants that may

lend themselves to the technology could include textile dyes,

polymer latexes, fermentation broths, etc. The EPOC

technology does not remove volatile organic compounds

from liquids but presumably could be used in conjunction

with another technology to remove or treat the volatile

organic compounds. Evaluation of the system for organic

materials was beyond the scope of the site demonstration test

and at least laboratory testing would be necessary to evaluate

the effectiveness of the technology with any particular waste

stream.

In considering applications for the EPOC technology, the

required quality of the discharge and solids must be

considered, particularly when evaluating the costeffectiveness of alternatives. Microfiltration, as with the

EPOC EXXFLOW, can probably produce a more polished

permeate than obtainable by clarification in either a lagoon

or a clarifier. Dewatering, as with the EXXPRESS, could be

10
very attractive where the sludge is hazardous, particularly

where sludge volume is a significant factor in disposal cost.

3.6 Evironmental Regulatory Impacts

Operation of the EPOC dynamic membrane filtration process

for treatment of liquids containing heavy metals and/or other

contaminants will require compliance with certain Federal,

State and local regulatory standards and guidelines. This

technology may be used at Federal Superfund National

Priorities List (NPL) sites and other sites. Superfund site

regulatory requirements applicable to the use of this

technology are discussed below under Comprehensive

Environmental Response, Compensation, and Liability Act

(CERCLA). Other Federal, State and local environmental

regulations are subsequently discussed in more detail as they

apply to the performance, emissions and residuals of the

technology as evaluated during the demonstration test.

3.6.1 The Comprehensive Environmental

Response, Compensation and Liability Act

(CERCLA)

The Comprehensive Environmental Response, Compensation

and Liability Act (CERCLA) of 1980 as amended by the

Superfund Amendments and Reauthorization Act (SARA) of

1986 provides for Federal funding to respond to releases of

hazardous substances to air, water, and land. Section 121 of

SARA, entitled cleanup standards, states a strong statutory

preference for remedies that are highly reliable and provide

long-term protection. It strongly recommends that remedial

actions use on-site treatment that “...permanently and

significantly reduces the volume, toxicity, a mobility of

hazardous substances.” In addition, general factors which

must be addressed by CERCLA remedial actions are:

# long-term effectiveness and permanence; * short-term effectiveness; * feasibility: and * cost.

The EPOC dynamic membrane microfiltration technology

has been shown to remove >98%of toxic (cadmium, copper

and zinc) metals from the contaminated acid mine drainage

from the demonstration site. The combined EXXFLOW and

EXXPRESS process produced a filter cake which passed the

Toxicity Chamcteristic Leaching Procedure (TCLP). The

chemical precipitating reaction occurring before the filtration

process also raised the pH of the liquid so that the water

exiting the process no longer exhibited the characteristic of

corrosivity.

The removal of the contaminants from the acid mine

drainage to the non-leachable filter cake was performed

rapidly by the process. Because the contaminants are then

separated from the water, this improvement is permanent

The contaminants removed are bound chemically and

physically in the filter cake solids, as evidenced by the

TCLP results.

The EPOC process equipment evaluated during the

demonstration was not designed to remove organic

contamination, and no volatile compounds were expected in

the liquids tested during the demonstration test. The

emissions potential in this situation is very low and is

limited to the potential for dust emissions while transporting

powdered treatment chemicals (e.g., lime). If liquids

containing volatile components were to be treated using this

technology, a pollutioncontrol system could be used to

control emissions, or the volatile contaminants could be

removed first using a different technology (e.g., stripping)

before microfiltration.

In addition to the above general requirements, Section 121

of CERCLA requires that Superfund treatment actions must

meet or exceed “applicable or relevant and appropriate

requirements, criteria, or limitation under any Federal law or

State environmental statute.” Local statutes may also be

relevant and appropriate. These criteria, as related to the

EPOC microfiltration technology, are discussed below.

3.6.2 Other Federal Regulations

The Resource Conservation and Recovery Act (RCRA) is

the primary Federal legislation governing hazardous waste

activities. Subtitle C of RCRA contains requirements for the

generation, transportation, treatment, storage and disposal of

hazardous waste, most of which are also applicable to

CERCLA activities.

The use to which the EPOC microfiltration technology was

put during the demonstration test would not have been

regulated under RCRA, as the acid mine drainage present at

the Iron Mountain does not fit the legal definition of a solid

waste, of which all RCRA hazardous wastes are a subset.

The filter cake produced from the process is a solid waste,

and has the potential for being a hazardous waste. However,

the TCLP results for the demonstmtion showed that the filter

cake produced did not exhibit a hazardous waste

characteristic and would not be a RCRA hazardous waste on

that basis. Many of the potential uses of the EPOC

microfiltration technology would be regulated by RCRA,

either because the feed stream would qualify as a RCRA

hazardous waste (making all effluent streams hazardous

wastes by the derived-from rule), or the filter cake or other

11
effluent could exhibit a characteristic making it a hazardous

waste.

If a hazardous waste is treated or generated during treatment

with the EPOC microfiltration technology, the responsible

party must obtain an EPA generator identification number

and comply with accumulation and storage requirements for

generators under Title 40, Code of Federal Regulations

(CFR) Part 262 or have a RCRA permit or interim status.

A hazardous waste manifest must accompany any off-site

transportation of the hazardous waste, and transport must

comply with Federal Department of Transportation (DOT)

hazardous waste transport regulations. Any TSD facility

receiving the waste must also be permitted and in

compliance with RCRA standards.

The RCRA land disposal restrictions (40 CFR Part 268)

require that certain hazardous wastes receive treatment after

removal from a contaminated site and prior to land disposal,

unless a variance is granted. The microfiltration treatment

may allow for disposal of the liquid effluent from the

process as non-hazardous This will require evaluation on a

case by case basis. The filter cake solids from the

microfiltration process may be restricted from land disposal

and require further treatment prior to disposal. If necessary,

stabilization/solidification may be used to further reduce the

mobility of contaminants in the filter cake to below the

applicable treatment standard limits. Other treatments may

be appropriate depending on the original waste contaminants

and the treatment chemicals used.

3.6.2.1 Clean Water Act

The Clean Water Act regulates discharges to surface water

through the National Pollutant Discharge Elimination System

(NPDES) regulations. These regulations require point-source

discharges of wastewater to meet established permit limits or

water quality standards The EPOC microfiltration process

produces a treated liquid effluent that may be regulated

under the CWA if it is to be discharged either directly or to

a POTW. If the process effluent were discharged to a

surface water body, a NPDFS permit indicating maximum

levels of specific parameters would be required. For

example, the Iron Mountain Mine AMD would probably be

required to meet a pH range of at least 6 to 9.

3.6.2.2 Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) establishes primary

and secondary national drinking water standards. These

standards consist of Maximum Contaminant Levels (MCLs),

MCL goals (MCLGs), and aesthetic standards. MCLs may

be applicable and relevant where either surface or

groundwater may be used for drinking water. Depending on

the disposal options for the treated water from the EPOC

microfiltration process, the process effluent (permeate) may

have to meet strict guidelines for the amounts of some metal

species and water quality parameters.

3.6.2.3 Clean Air Act

The Clean Air Act (CAA) establishes primary and secondary

ambient air quality standards for protection of public health.

and emission limitations for certain hazardous air pollutants.

In most applications no emissions would be expected from

the EPOC process: therefore, the CAA would not be

applicable. In situations where electrical power to the

process equipment may be supplied by fuel-burning

generators, use of these generators may be regulated by the

CAA. However, State and local standards for diesel exhaust.

as well as for nuisance dusts, would be likely to be more

stringent, considering the probable size of such equipment.

3.6.2.4 The Occupational Safety and Health Act

The Occupational Safety and Health Act (OSHA) covers the

safety of employees in the workplace. OSHA regulations

cover the selection and use of engineering controls, safe

work practices and use of personal protective equipment at

hazardous waste sites. OSHA regulations would cover the

use of the EPOC microfiltration technology whether the use

occurs at a hazardous waste site or at an ordinary workplace.

such as a manufacturing facility. OSHA regulations cover

the allowable exposures of workers to chemical hazards,

noise, and thermal and electrical conditions regardless of the

place the work is occurring. OSHA rules require that

training in hazardous waste handling practices be given to all

employees who work on hazardous waste sites.

Specifically. work with the EPOC process would certainly

require protective measures for spills and leaks of acid and

alkali such as the acid mine drainage or the precipitating

bases. Protection against dust could also be necessary.

3.6.3 State And Local Regulations

Meeting Applicable or Relevant and Appropriate

Requirements (ARARs) may require compliance with State

and local law that are more stringent than Federal standards

or that may be the controlling standards in the case of nonCERCLA treatment activities. For use of the EPOC

microfiltration technology, State and local water quality

standards may be the most significant requirements. Water

discharge standards can be set based on the use of the water,

a site risk assessment, and/or currently available treatment

12
options. When the Old No. 8 acid mine drainage was

treated with caustic or lime, effluent concentrations achieved

through the EPOC treatment system of all metals of concern

were below or close to 1 mg/L except for aluminum, and

well below 0.1 mg/L for all heavy metals.

3.7 Manpower Requirements

Although the developer believes that the EPOC

microfiltration system can be operated with a minimum of

oversight, such was not the case during the demonstration

tests, at least for operation of the EXXPRESS dewatering

unit. As noted in this report, considerable effort was required

to adjust cycling and pressure for the EXXPRESS unit and

to remove plugs of filter cake to the point where any usable

information could be generated. During these tests, two

professional staff members were involved almost constantly

in these efforts. This would not be practical in a

remediation or process application, but it is not clear whether

the problems were due to equipment inadequacies,

unanticipated and unexplained characteristics of the sludge,

or a result of the means of precipitating the metals as

hydroxides.

Addition of alkali to precipitate the metals as hydroxides in

the reactor vessel also required more than the expected

attention since overdosing with precipitant produced pH

spikes that were accompanied by elevated aluminum

concentrations in the permeate. A more sophisticated pHcontrolled alkali feed system and improved agitation might

reduce the attention required in this area

3.8 Testing Requirements

It would at first appear that only minimal testing of the feed

wastewater stream would be required to develop appropriate

processing conditions and precipitant addition rates.

However, the difficulties with pH control during the

demonstration, even after laboratory and optimization testing

with the two wastewaters at the site, suggest that additional

information may be needed. For example, it may not be

sufficient to add a calculated amount of alkali to precipitate

the metals. As noted, alkalinity may play a part in the

effectiveness of precipitation. In addition, the physical

character of the precipitate may affect the efficiency of

separation in the EXXFLOW and, particularly, dewatering

in the EXXPRESS. Although the developer indicated that

the particles must be larger than 0.1 um to be removed in

the EXXFLOW and smaller than 1 um so that they do not

plug or blind the EXXPRESS membrane. no tests were

identified or run to determine the actual particle size, other

than laboratory and field shakedown tests of the system.

13
Section 4

Economic Analysis

4.1 Introduction

The primary purpose of this economic analysis is to estimate

costs (excluding profit) for commercial-scale treatment using

the EPOC microfiltration system. With realistic costs and a

knowledge of the basis for their determination, it should be

possible to estimate the economics for operating similarsized systems at other sites utilizing scale-up cost formulas.

Among such scale-up cost formulas availabk in the literature

for chemical process plant equipment is the “six-tenths rule”

[1].

This economic analysis is based on assumptions and costs

provided by EPOC, on results and experiences from this

SITE demonstration, and on best engineering judgement. The

results are presented in sufficient detail so that, if the reader

disagrees with any of the assumptions made. the reader can

draw his/her own conclusions using his/her own

assumptions.

Although the SITE demonstration tested the EXXFLOW

microfiltration system and the EXXPRESS automatic sludge

dewatering system as an integrated unit, the results showed

that the EXXPRESS module was ineffective in dewatering

the concentrate from the EXXFLOW module, and

consequently did not meet the developer’s claims. Therefore.

for purposes of this cost analysis, an alternate dewatering

system was considered for both pilot-scale and full-scale

systems. The consequences of not dewatering the concentrate

were also investigated for the pilot-scale unit to determine

how much of an impact this step would have on costs.

Although the EXXFLOW pilot-scale unit was operated at a

permeate flow rate of 3 gpm during the SITE demonstration,

it was assumed that it could achieve its design permeate

flow rate of 7 gpm. It was also assumed that the

performance of full-scale equipment would be similar to that

demonstrated with the pilot-scale unit.

Certain actual or potential costs were omitted because sitespecific engineering aspects beyond the scope of this SlTE

project would be required. Certain functions are assumed to

be the obligation of the responsible party or site owner and

also were not included in the estimates.

Coat figures provided here are “order-of-magnitude”

estimates, generally +50%/-30%. and are representative of

charges typically assessed to the client by the vendor

exclusive of profit.

4.2 Conclusions

* Dewatering the concentrate from the EXXFLOW

microfiltration unit before disposal decreases costs for the

pilot-scale unit - $33/1ooO L ($125/1000 gal) without

&watering, compared to S27/1ooO L (5103/1000 gal)

with dewatering.

* For the pilot-scale unit, labor, consumables and supplies,

and effluent treatment and disposal costs account for

about 80% of overall cleanup costs. Site preparation. and

startup and fixed costs are the next largest cost

contributors Since they are one-time charges, their effect,

on a percentage basis, could be reduced for longer

duration projects. Annualized equipment costs, utilities,

and residuals disposal from the dwe system

contribute the least.

* Treatment costs for the 190 L/min (50 gpm) full-scale

unit with dewatering ($12/1000 L, $47/1000 gal) are

about half of what they are for the pilot-scale unit thus

demonstrating the cost advantages of scale-up.

* For the full-scale unit, start-up and fixed costs, labor,

consumables and supplies, and effluent treatment and

disposal account for close to 90% of total costs.

Comparing cost percentages to the pilot-scale unit with

14
dewatering, reductions in labor, and effluent treatment

anddisposalcostsaremanthanoffsetbyincreasesin

consumables and supplies. Labor shows the largest

decrease because manpower requirements are not affected

by unit size but rather by the duration of treatment.

Residual disposal costs also double due to scale-up, but

again this is more than offset by reductions in other cost

categories. Site preparation, annualized equipment costs.

and utilities contribute the least.

* Although they were not included here, accounting for

permitting and regulatory activities, analytical

requirements, facility modification, repair and

replacement, and demobilization could significantly

increase costs.

4.3 Issues and Assumptions

This section summarizes the major issues and assumptions

used to evaluate the cost of EPOC's microfiltration system.

In general, assumptions are based on information provided

by EPOC. -

4.3.1 System Design and Performance Factors

As stated earlier, the SITE demonstration used an

EXXFLOW microfiltration module in tandem with an

EXXPRESS automatic sludge dewatering system. Although

thissystemwasdesignedtoproducepermeatcatarattof7

gpm. it was operated at 3 gpm during the SITE

demonstration. Therefore the estimates for both the 7 gpm

pilot-scale and the 50 gpm full-scale units used proportioned

flow rates based on results of this SITE demonstration, as

shown in the table below:

Details of the calculations used to derive these numbers can

be found under the “Effluent Treatment and Disposal” costs

section. For this analysis, it was assumed that performance.

in terms of percent reduction, for all three units was similar

to that tested

Costs for the pilot-scale unit were estimated with and

without dewatering of the concentrate stream. Demonstration

results showed that the filter cake product from the

EXXPRESS unit passed the TCLP test and would be

considered non-hazardous for disposal purposes. Although

the concentrate stream was not specifically tested during the

demonstration, it was assumed that it too would pass the

TCLPtest and could be considered non-hazardous as well.

For the scenario without dewatering, two further cases were

considered. First, it was assumed that the concentrate stream

from the EXXFL0W unit, being non-hazardous, could be

disposed of on-site. For this case, there would either be no

or very little effluent disposal costs. Although this is a very

real possibility at the Iron Mountain Mine Superfund Site, it

would be a rather rare occurrence at other cleanup sites.

Therefore, no costs were included for this case. In a second

case it was assumed that disposal of the concentrate stream

would be required off-site. Since this a more realistic

possibility, this cost was included in this analysis.

The dewatering system selected assumed that solids content

could be increased from 1.2% to 20%. The residual filter

cake produced was again assumed to be non-hazardous and

could be disposed of off-site at a nominal cost.

4.3.2 System Operating Requirements

This analysis assumed that the waste being treated was

similar to that tested during the demonstration. The alkali

chemical used was assumed to be 50% caustic. Flow rates.

the amount of recycle, the type and concentration of

contaminants, the type and amount of alkali used, the type

and size of dewatering equipment used, if any, will all affect

system operation and, consequently, costs.

This analysis assumed a cleanup duration of one year. EPOC

projected that one operator could fulfill all operational duties

in two hours during a normal 8-hr shift. The rest of the time

he/she would be available for other non-EPOC process

related tasks. Since the equipment was assumed to operate

24-hr/day, 3 shifts per day, 7 days per week, for 50 weeks

per year, labor costs were based on 3 operators being

required. EPOC indicated that larger flow units could be

built by essentially adding additional microfiltration modules

without increasing the labor requirements.

4.3.3 Utilization Rates and Maintenance

Schedules

A 90% on-line stream factor was used for costing. Although

this was not demonstrated, EPOC feels that this is realistic

if design and operational modifications were done and

15
sufficient time for shakedown testing were allowed. They

base their contention on prior experience with equipment that

i s installed and that has been operating for several years in

the field. Scheduled maintenance was assumed to be

performed during the regular shift.

4.3.4 Financial Assumptions

Annualized equipment costs are based on a 15-year life, 6%

simple interest rate, and a salvage value of 10% of the

original equipment cost. The time value of money was not

accounted for.

The following is a list of additional assumptions used in this

study:

- Access to the site is readily available.

- Utilities (electricity, water. sewer hookup,

telephone, etc.) are easily accessible.

-Thepermeatestreamwillnotrequire any

further treatment.

- There are no wastewater pretreatment

requirements.

4.4 Basis For Economic Analysis

In order to compare the cost-effectiveness of technologies in

the SITE program, EPA breaks down costs into the 12

categories shown in Tables 4-1 and 4-2 using the

assumptions for each cost factor described in more detail

below.

4.4.1 Site Preparation Costs

The amount of preliminary preparation will depend on the

site and is assumed to be performed by the responsible party

(or site owner). Site preparation responsibilities include site

design and layout, surveys and site logistics, legal searches,

access rights and roads, and preparations for support

facilities, decontamination facilities, utility connections. and

auxiliary buildings. These preparation activities are assumed

to be completed in 500 staff hours. At a labor rate of $50/hr,

this would equal $25,000.

Although these were not considerations for this SITE

demonstration, other significant costs associated with site

preparation may include well drilling, preparation and

development, as well as buying and installing a groundwater

or surface-water pump and associated plumbing, especially

if the equipment will be located a considerable distance

away from the well. Based on experience from previous

SITE demonstrations, the cost to drill, prepare and develop

a well was assumed to be $5,000. It was assumed that only

one well was necessary to provide the required flow rate

regardless of the size of the unit used and that no holding

tank was necessary.

The size of the pump also would depend on the size of the

treatment system assumed. The pilot-scale 7 gpm unit would

probably require a l/4 HP, 10 gpm centrifugal pump, costing

about $l,000, while the full-scale 50 gpm unit would

probably require a 2 HP, 75 gpm centrifugal pump costing

about $3,500, based on the “six-tenths scale-up rule”.

Access roads and other site-specific auxiliary structures

which may be necessary, such as concrete pads or a

building, can be very expensive but are not included here.

Therefore, the total site preparation costs for a pilot-scale or

full-scale unit would be between $30,000 and $35,000 as

shown in Tables 4-l and 4-2.

4.4.3 Permitting and Regulatory Costs

Permitting and regulatory costs are generally the obligation

of the responsible party (or site owner). These costs may

include actual permit costs, system health and safety

monitoring requirements. and the development of monitoring

and analytical protocols. Permitting and regulatory costs can

vary greatly because they are site- and waste-specific. No

permitting costs are included in this analysis: however,

depending on the treatment site. this can be a significant

factor since permitting activities are project dependent.

4.4.3 Equipment Costs

The EPOC Microfiltration System assumed for this

economic analysis includes a reaction tank, the EXXFLOW

microfiltration unit, recirculation pump and associated

plumbing, instrumentation, monitoring and control

equipment. The size of the reaction tank would be dependent

on the size of the EXXFLOW unit and on the alkali used

due to different reaction tunes with different chemicals. It

would also include an alkali feed system with a feedback

control loop to maintain a set pH, a level control, and a

mechanical stirrer, the size of which again would he

dependent on the size of the reaction tank and the alkali

Used.

The cost of rental equipment used in this SITE demonstration such as storage tanks, office trailers, pickup trucks for

transporting supplies, diesel generators, air compressors. and

forklifts are not included.

16
1.

2.

3.

4.

5.

6.

7.

8.

9.

Site Preparation

Pamitting & Regulatory

Equipment(annualized)

Startup& Fixed

Consumable & Supplies

Utilities

Effluent Treatment & Disposal

’ Dewatering System

- Capital (annualized)

-O&M

Total

31,000

-

6,500

25,650

84,000

101,750

3,145

145,365

145,635

l0. Analytical

11. FacilityhWi6&a,Repir&

Replacement

12. Demobilization

7.80

1.63

6.45

21.12

25.59

36.62

-

31,000

-

6,500

25,650

84,000

101,750

3,145

635

zl

67,420

8,600

-

9.45

-.

1.98

7.82

25.60

31.02

0.96

20.55

2.62

-

-

_..

Totals 397,680 100 328,065 100

$/1000 gal 125 103

$/1000 L 3 3 2 7

1.

2

3.

4.

5.

6.

7.

8.

-

17,400

91,350

84,000

690,900

6775

4535

12,400

73,450

90,385

61.780

1.62

8.49

7.81

64.20

0.63

8.40

5.74

17
EPOC estimates the cost of a 7 gpm pilot-scale

microfiltration unit, similar to that used in this SITE

demonstration, to be about $70,000. A full-scale 50 gpm unit

is estimated to cost $187,500. These costs do not appear to

follow the so-called “six-tenths rule”. Hence, the cost for the

full-scale unit appears to be relatively low when compared

to the cost of the pilot-scale unit.

The annualized equipment cost is calculated using the

following equation and financial assumptions discussed

earlier:

i(1 + iy

Capital Recovery = (V - VJ ~~~~-~~~~~~-

(i + ly.-1

where V = the cost of the original equipment

Va = the salvage value of the equipment.

n = the equipment life (15 years),

i = the annual interest rate (6%).

4.4.4 Startup and Fixed Costs

EPOC’s EXXFLOW microfiltration units can be mobile,

such as the 7 gpm pilot-scale unit used in the SITE

demonstration, or fixed, such as the 50 gpm full-scale unit.

Transportation costs are only charged to the client for one

direction of travel and are usually included with mobilization

rather than demobilization costs. Transportation costs are

variable and dependent on site location as well as on

applicable oversize/overweight load permits, which vary

from state to state. For purposes of this cost estimate,

trucking charges will be based on a 40,000 lb, 48 ft long, 8

ft high legal load and will assume that a driver is included.

One tractor/trailer is required for the 7 gpm pilot-scale unit

while the 50 gpm full-scale unit requires three such

tractor/trailers. Assuming that it will cost $ 1.65/mile, a 1,000

mile trip would cost $1,650 for the 7 gpm pilot-scale unit

and $4,950 for the 50 gpm full-scale unit

Assembly consists of unloading the EPOC EXXFLOW

microfiltration system from the trailers, setting up the system

in place, installing instrumentation, hooking up utilities, and

other miscellaneous installation tasks. Assembly costs are

estimated to be $5,000 for the 7 gpm pilot-scale unit and

$l5,000 for the 50 gpm full-scale unit.

EPOC estimates that waste-specific testing of the system

would require 2 weeks prior to the commencement of

treatment. This would involve checking out and

troubleshooting each of the systems individually for the

particular waste to be treated Two workers would be

required for 12 hr/day, 5 day/wk. Start-up costs are assumed

to be limited to labor charges at a rate of $40/hr excluding

travel and per diem. for a total of $9,600.

Working capital is assumed to be based on the amount of

money currently invested in maintaining a one-month

inventory of supplies and consumables. The predominant

item here is assumed to be treatment chemicals, i.e.. 50%

NaOH, at a cost of $30/1000 gal of waste (see Consumables

and Supplies). For the pilot-scale unit, the associated cost

would be $8,l00 (7 gal/min x 60 min/hr x 24 hr/day x 30

days x 0.9 x $0.03/gal) and $58,320 for the full-scale unit.

Insurance and taxes are usually approximately 1% and 2%

to 4% of the equipment capital costs, respectively. The cost

of insurance for a hazardous waste process can be several

times more than this. For purposes of this estimate.

insurance and taxes together are assumed to be 10% of the

annualized equipment capital costs [3].

The cost for health monitoring programs has not been

included here. Depending on the site and the location of the

system, local authorities may impose specific guidelines for

monitoring programs, the stringency and frequency of which

may have a significant impact on project costs.

A contingency cost of 10% of the annualized equipment

capital costs is allowed for any unforeseen or unpredictable

cost conditions, such as strikes, floods, and price variations

[3,4].

The total for start-up and other fixed costs would then be the

sum of all of the sub-categories discussed above. i.e..

$25,650 for the 7 gpm pilot-scale unit and $91,350 for the

50 gpm full-scale unit.

4.4.5 Labor

EPOC assumed that after start-up, system operation would

be automatic, and require only 2 hr/shift of operator attention

to perform routine tasks such as monitoring, routine

maintenance, and documentation activities. They assumed a

labor rate of $40/hr including overhead and administrative

costs. but excluding per diem, travel, and rental car expenses

that might be needed if EPOC personnel were to be used. It

is the developer’s intention to hire and train local people so

that they do not incur these additional expenses. The cost

and time to hire and train local personnel, which may be

substantial, is not included.

The annual cost of labor for both size units is calculated as:

2 hr/shift x 3 shifts/day x 7 days/wk x 50 wk/yr x $40/hr = $84,000.

18
4.4.6 Consumables and Supplies

Consumables required for the operation of the EPOC

microfiltration system are limited to treatment, membrane

forming. and cleaning chemicals. The cost of membraneforming and cleaning chemicals arc inconsequential in

comparison to treatment chemicals.

For purposes of this economic analysis, caustic soda (NaOH)

is assumed to have been used at a dosage rate of 0.15 lb (69

gm) of 50% NaOH per gallon of waste. At $0.20/lb of 50%

NaOH. it would cost about $30/1000 gal of waste treated or

$95,250 for the pilot-scale unit and $680,400 for the fuIl

scale unit. Further cost reductions may be realized if

treatment chemicals are bought in bulk quantities. In that

case, however, provisions for proper storage and handling

must be accounted for.

Based on data from previous operations over a period that

reflects operating conditions similar to those experienced

during the demonstration tests, the costs for spare parts,

including spare microfilters for the EXXFLOW unit,

office/general supplies, pump seals. fuses, valve o-rings, and

diaphragms are estimated at $2,000/yr for the pilot-scale unit

and $6,000/yr for the full-scale unit.

Health and safety gear, which includes hard hats, safety

glasses, repirators and cartridges, protective clothing,

gloves. safety boots, etc., are estimated to cost

$ 1 ,500/person.

4.4.7 Utilities

The electricity required for the EXXFLOW microfiltration

system is estimated by EPOC to be 5.2 kW for the pilotscale unit and 11.2 kW for the fulI-scale unit. Assuming no

monthly charge and a flat rate of $ for electricity,

it would cost 53.145 to operate the pilot-scale unit for a year

and 56.775 to run the full-scale unit, both at a 90% on-line

stream factor.

4.4.8 Effluent Treatment and Disposal

Two process streams are produced by the EXXFLOW

microfiltration system. The permeate is considered to be

essentially free of contaminants and is assumed to meet

standards appropriate for discharge to a POTW or the local

sewer system, at a cost of $0.20/1000 gal. This corresponds

to 3.175 million gallons of treated water discharged per year

for the pilot-scale unit and 22.68 million gallons for the fullscale unit. The associated costs would be $635 for the pilotscale unit and $4,535 for the full-scale unit.

The concentrate is the reduced volume portion of the initial

wastestream with the enriched contaminants that would

require further treatment Based on SITE demonstration test

results with caustic soda, 252 lb of filter cake, of which

12.5%. or 31.5 lb (252 lb x 0.125) is solids, were produced

from the EXXPRESS unit. This corresponded to an inlet

stream of 1.2% solids or 2,625 lb (31.5 lb / 0.012) of

concentrate entering the EXXPRESS unit in 240 min. If the

density is assumed to be 8 lb/gal. this equals 1.37 gpm

(2625 lb/8 lb/gal/240 min). A flow of 1.37 gpm represents

46% of the permeate flow rate of 3 gpm. Therefore, a pilotscale unit operating at a p flow rate of 7 gpm would

generate 3.2 gpm of concentrate, while a full-scale unit

operating at a permeate flow rate of 50 gpm would produce

22.7 gpm of concentrate with 12% solids.

If the concentrate were not dewatered. it could be disposed

of off-site a s non-hazardous waste at a cost of about

$0.l0/gal. This would add an additional $145,000 (3.2

gaVminx60mirJhrx24hr/dayx7&y/wkx50wWyrx

0.9 x $0.l0/gaI) to effluent treatment and disposal costs for

the pilot-scale unit.

Alternatively. a dewatering system would concentrate the

contaminants into a reduced volume filter cake product

(estimated at 20% solids). Water from the dewatering step

could be recycled, thereby minimizing costs for subsequent

transportation and/or ultimate disposal of the filter cake. To

highlight how much of a contribution this dewatering step

would reduce the overall technology cost, the pilot-scale unit

cost estimate includes costs with and without this dewatering

step. The full-scale unit costs were developed including

dewatering.

Plate and frame pressure filtration was assumed to be used

for the &watering step. Components of the system include

filter plates, filter cloth, hydraulic pumps, pneumatic booster

pumps, control panel, connector pipes, and support platform.

Installation, engineering, and contingency costs were added

to the equipment costs. Installation costs were estimated at

35% of the equipment costs, while contingency and

engineering fees were estimated to be 15% of the equipment

and installation costs. Based on vendor quotes, capital costs,

in 1989 dollars, were $33,300 for a 32 gpm system (for the

7 gpm pilot-scale unit), and $118,900 for a 22.7 gpm system

(for the 50 gpm full-scale unit). These costs were corrected

to 1993 dollars using the annual average construction cost

index as published in Engineering News-Record (ENR)

magazine. It was 4615 for 1989 and 5210 for 1993, resulting

in an index ratio of 1.13. Therefore, the indexed capital costs

are $37,600 ($33,300 x 1.13) for the 3.2 gpm system, and

$134,000 ($118,900 x 1.13) for the 22.8 gpm system in 1993

dollars.

19
The annualized capital costs for the dewatering system are

calculated in the same way, using the same assumptions as

for the EXXFLOW system discussed previously. For the 7

gpm pilot-scale unit this is $3,485 and for the 50 gpm fullscale unit, $12,400.

Operating and maintenance costs were based on estimated

electricity usage, maintenance, labor, taxes and insurance.

The electricity usage and costs were based on a usage rate

of 0.5 kWhr/l000 gal and $0.08/kWhr, and lighting and

control energy costs were estimated at $l,000/yr.

Maintenance was approximated at 4% of the capital cost

Taxes and insurance were approximated at 2% of the capital

cost. The labor cost for the plate and frame pressure

filtration system was approximated at $31,200 per man-year

at thirty minutes per cycle per filter press. In 1989 dollars,

the operating and maintenance cost for the 7 gpm pilot-scale

unit is estimated to be $56,000 and $65,000 for the 50 gpm

full-scale unit. The corresponding indexed costs in 1993

dollars are $63,300 and $73,450, respectively.

An ancillary consideration when using a dewatering system

is the additional land area that would be required. It is

estimated that approximately 2,500 f? would be required,

irrespective of the size of the &watering system used. No

costs for this land were included in this estimate.

4.4.9 Residuals/Waste Shipping, Handling and

Transport Costs

Waste disposal includes storage, transportation and treatment

costs and are assumed to be the obligation of the responsible

party (or site owner). The only residuals or solid wastes

generated from this process are the filter cake and

miscellaneous items (e.g.. used modules. protective gear.

etc.).

Since the filter cake generated by the microfiltration system

passed the TCLP test, it is considered to be a non-hazardous

waste that can be Iandfilled at a cost of $0.10/gal, assuming

there is no free liquid. For the pilot-scale unit, a concentrate

flow rate of 3.2 gpm with 1.2% solids caresponds to 0.038

gal/min of solids being dewatered (3.2 gal/min x 0.012). If

the filter cake is 20% solids, then this equals 0.19 gal/min of

filter cake being generated (0.038 gal/min/ 0.2). The yearly

disposal cost for the filter cake would then be $8,600 (0.19

gal/min x 60 min/hr x 24 hr/day x 7 day/wk x 50 wk/yr x

0.9 x $0.10/gal Similarly, for the full-scale unit, yearly

filter cake disposal costs would be $61,780.

If. however. the filter cake is hazardous, disposal costs could

increase substantially.

4.4.10 Analytical Costs

Standard operating procedures do not require planned

sampling and analytical activities. Periodic spot checks may

be executed at EPOC’s discretion to verify that equipment

is performing properly and that cleanup criteria are being

met, but costs incurred for these actions are not assessed to

the client. The client may elect or be required by local

authorities to initiate a sampling and analytical program at

their own expense. Therefore. analytical costs associated

with environmental monitoring have not been included in

this estimate. Specific sampling and monitoring requirements

could contribute significantly to the cost of the project.

4.4.11 Facility Modification, Repair and

Replacement

Since site preparation costs were assumed to be borne by the

responsible party (or site owner), any modification. repair,

or replacement to the site was also assumed to be done by

the responsible party (or site owner).

Maintenance costs consist of labor and materials and will

vary with the nature of the waste and the performance of the

equipment, Maintenance labor has previously been accounted

for under "Labor Costs”. The annual cost of maintenance

materials is assumed to be 3% of equipment capital costs

and includes provisions for design adjustments and

equipment replacement as needed This has already been

accounted for in the consumables and supplies cost category.

4.4.12 Demobilization Costs

Site demobilization will include shutdown of the operation.

final decontamination and removal of equipment, site

cIeanup and restoration, permanent storage costs, and site

security. Any other requirements will vary depending on the

future use of the site and are assumed to be the obligation of

the responsible party. No costs have been included for

demobilization.

4.5 Results

Table 4-l shows the total annual cleanup cost for a 7 gpm

pilot-scale system to be $327,000 ($27/l000 L) with

dewatering and $397,000 ($33/1000 L) without dewatering.

This is a $70.000 savings and clearly shows the advantages

of dewatering the concentrate from the EXXFLOW

microfiltration unit before disposal. Not surprisingly, the

largest cost component without dewatering is effluent

treatment and disposal (37%). followed by consumables and

20
supplies (26%), and labor (21%). With dewatering, the

largest cost component becomes consumables and supplies

(3 1%), followed by labor (27%), and effluent treatment and

disposal (21%). In either case, these three cost categories;

labor, consumables and supplies, and effluent treatment and

disposal, accounted for 75-85% of costs.

The next biggest cost contributors were site preparation (8 to

9.5%), and startup and fixed costs (6.5 to 8%). It should be

remembered that this cost estimate is based on a one year

remediation. Since these are one-time charges, their respective

percentage contribution to costs as well as the overall $/L

cost will go down as the length of the project increases.

Annualized capital equipment costs, and utilities each

contributed less than 2%. Residuals disposal from the

dewatering system accounted for an additional 2.6%.

Considering the fact that effluent treatment and disposal costs

were almost cut in half by dewatering, this is not a significant

contribution.

Table 4-2 shows the total annual cleanup cost for a 50 gpm

full-scale system to be $l,l00,000 ($12.50/1000 L),

including concentrate dewatering. On a $/L basis, this is a

two-fold reduction from the corresponding pilot-scale system

and clearly shows the advantage of large scale operation.

As in the 7 gpm pilot-scale unit with dewatering, the largest

cost component is consumables and supplies (64%). Startup

and fixed costs, effluent treatment and disposal, and labor are

the next largest cost categories, each contributing about 8 to

8.5%. On a percentage basis, startup and fixed costs stayed

about the same compared to the 7 gpm pilot-scale unit with

dewatering. However, effluent treatment and disposal, and

labor were cut by more than half In fact, the cost category

showing the largest reduction is labor, from 26% to 8%. This

is because of the assumption that the same number of people

would be required to operate the system regardless of size.

Only the remediation time seems to affect labor costs. These

four cost components; startup and fixed costs, labor,

consumables and supplies, and effluent treatment and

disposal, accounted for close to 90% of the total.

The cost of residuals disposal increased from about 2.6% for

the pilot-scale unit to 5.74% for the full-scale unit because of

the-increase in equipment size; i.e., processing more waste

produces more filter cake that must be dewatered and

eventually disposed of However, this was more than made up

by the reduction in effluent treatment and disposal costs. Site

preparation, annualized capital equipment costs, and utilities

each contributed 3% or less.

regulatory activities, analytical requirements, facility

modification. repair and replacement, and demobilization.

Accounting for these factors could significantly increase

costs.

4.6 Development of a 700 GPM Microfiltration

System

EPOC has developed a Microfiltration System that is able to

treat 2,700 L/min, (700 gpm) of contaminated groundwater

with a total metal concentration of 5 mg/L at pH 5. This fullscale unit is designed to be operated as a fixed facility. The

vendor has provided the following costs for this system.

Major equipment costs are estimated to be $1,350,000.

Installation costs include transportation, assembly, and

shakedown testing of the individual systems. Installation

costs are estimated to be $50,000. Waste specific equipment

testing is estimated to require 3 workers for 12 hr/day, 5

day/wk, for 3 weeks. It is assumed that system operations

will be automated, requiring only one system operator to run

the unit. It is assumed that a maintenance operator will also

be required for 12 hr/day. Spare parts are estimated to cost

$ 15,000 per year. Assuming that the treatment chemical is

50% NaOH, it is estimated that 250 lb/day of NaOH will be

required. The electricity requirements for this unit is

estimated to be 59.7 kW, 460 V, 3 phase.

The cost of operating this 700 gpm unit to treat contaminated

groundwater with a heavy metal concentration of 5 mg/L at

pH 5 is approximately $2.60/1000 gal (if only the costs

calculated in this report are considered). This is an

approximate estimate based on a total treatment time of 12

months, and using 50% NaOH as the treatment chemical.

The cost is significantly lower than the treatment costs of the

7 and 50 gpm units treating acid mine drainage (total metal

concentration of 3,000 mg/L at pH 2.3) and relates to the size

of the unit and the type of waste being treated.

References

1. Perry, R.H., Chilton, C.H., Chemical Engineer’s

Handbook; Fifth Ed., McGraw-Hill, Inc. New York,

1973, pg. 25-16.

2. Douglas, J.M., Conceptual Design of Chemical Process;

McGraw-Hill, Inc. New York, 1988.

3. Peters, M.S., Timmerhaus, K.D., Plant Design and

Economics for Chemical Engineers; Third Ed.,

McGraw-Hill, Inc. New York, 1980.

This analysis did not include costs for 4 out of the 12

categories, specifically, costs associated with permitting and 4. Garrett, D.E., Chemical Engineering Economics; Van

Nostrand Reinhold New York, 1989.

21
Appendix A

Process Description

A.1 Introduction

The EPOC Microfiltration Process is based upon the ability

of a particulate to be retained by a semi-permeable

membrane. The physical structure of a membrane is very

diverse ranging from solid structures, such as inorganic and

polymeric membranes, to transitory or dynamic membranes

that are temporarily famed. The EPOC Process may be

viewed in three steps:

precipitation of metals by adding alkali

Concentration of the precipitates by the EXXFLOW

microfiltration unit and the production of product

water (permeate).

Separation and dewatering of the EXXFLOW

concentrate in the EXXPRESS unit to produce a

semidry filter cake.

The EPOC microfiltration process is a relativity simple

process design consisting of a few subassemblies which

make up the entire process. These subassemblies are the

reaction tank, the EXXFLOW unit, the EXXPRESS unit, and

the filter cake dewatering system. Each of these

subassemblies is discussed in greater detail in the following

sections.

A.2 The Reaction Tank

The chemical reaction to form particles which are large

enough to be filtered from the liquid waste stream is the first

step in the microfiltration process. Raw water enters the

reaction tank and is treated with the alkali of choice resulting

in the precipitation of the dissolved heavy metals. The

reaction tanks are typically constructed of hard plastics

which are inert to the waste stream and the harsh alkaline

conditions. The reaction tank used for the SITE

demonstration test was fitted with a dry chemical feeder

which controlled the dose rate of powdered alkali (such as

Ca(OH), or MgO). Tanks can also accommodate liquid

alkali (50% NaOH solution) with the dose rate being

controlled by a metering pump. The dose rate of chemical

is set to match the feed rate of the raw water so that the

desired pH is maintained in the reaction tank. The reaction

tank is sct on level control such that the raw feed rate can be

controlled entering the tank. During normal operation, the

reaction tank is under steady state and the level in the

reaction tank is maintained.

The reaction tank is fitted with a mechanical stirrer that

provides agitation to enhance the chemical reaction and

prevent excessive solids from settling in the bottom of the

tank. Different treatment chemicals exhibit different settling

characteristics and, therefore, the stirrer plays an important

role in preventing clumping and caking within the reaction

tang. Stirring also prevents clumping of solid treatment

chemical as it hits the liquid surface in the tank.

Reaction tanks are sired based upon the feed rate of raw

water and the flow rates which the EXXFLOW unit can

accommodate. The size of the reaction tank and the flow

rate of raw water will dictate the residence time for the

chemical reaction. The tank must be sized properly to allow

sufficient residence time for the precipitation of the heavy

metals from solution. For treatment chemicals that have

long reaction time, such as MgO. the tank must be large

enough to provide for a residence time in excess of two

hours. Treatment chemicals such as NaOH react instantly:

consequently, the tank can be much smaller.

A.3 EXXFLOW Unit

The EXXFLOW unit is designed to concentrate the solids in

the waste stream (reject) and produce clean permeate. This

is accomplished thorough crossflow microfiltration. In

crossflow filtration. the flow is directed parallel to the

surface of the membrane. The EXXFLOW crossflow

microfiltration process employs a curtain array of permeable

textile tubes, each about I in. in diameter. Resin manifolds

are cast onto each curtain end to form modules which are

connected to a pump for liquid inlet and to a back pressure

valve at the outlet. Liquid feed to the EXXFLOW unit

22
flows from the bottom of the reaction tank. By introducing

a controlled liquid flow into the tubes and regulating the

outlet pressure, suspended and colloidal matter in the liquid

forms a membrane layer on the internal surface of each tube.

The goal of a crossflow filtration application is not to trap

the components within the pore structure of the membrane.

as in unconventional filtration; rather, the large material is

temporarily retarded on the membrane and is then swept

clean by the crossflow action. Should the quantity or quality

of suspended matter in the feed liquid be insufficient or

inappropriate to form a membrane, a filter aid material is

added to the initial feed to form the membrane. Membranes

or filter layers of widely different characteristics can be

produced by using different pretreatment chemicals or

additives.

After membrane formation, the membrane at the liquid

surface is dynamic, being continually formed and swept

down the length of the tubes by the longitudinal flow of the

chemically-treated feed. This cleaning action prevents

particles from being trapped within the membrane’s matrix

and thus substantially adds to its life. To become treated

product liquid, or permeate, the feed water filters radially

through the membrane layer and out of the textile tube walls

for collection. The solids removed from the permeate

become concentrated and are swept out of the tubes with the

remaining liquid, or concentrate. Figure A-l illustrates the

EXXFLOW operation.

A uniformly high quality permeate is achieved with the

EXXFLOW crossflow microfiltration process. Removal of

virtually all suspended solids down to about 0.1 pm has been

demonstrated in laboratory and field trials. Other

experimental work indicates that the EXXFLOW unit can be

developed to produce a low pressure process that will also

reject high molecular weight dissolved solids.

A3.1 Dynamic Membrane Concept

The dynamic membrane which is formed on the inner wall

of the EXXPLOW tubes is the medium which performs the

separation of the permeate from the reject. Suspended solids

contained in the feed water deposit on the inner surface of

theporoustubesataratcwhichisa~tionofdrcfluid

flow rate and backpressure on the module. The deposit on

the inside of the tube wall is called the dynamic membrane.

During the formation of the dynamic membrane, the flow of

fluid through the tubes exerts a shear force on the deposited

solids that tends to entrain particles back into suspension.

After a short period of time, a steady state equilibrium is

established at which the deposition rate of solids equals the

erosion rate of the dynamic membrane. It is this dynamic

membrane that actually controls the dynamics of the

filtration process. Pores of the dynamic membrane are much

smaller than pores of the tubes. Suspended solids contained

in the feedwater are filtered by the dynamic membrane

rather than the tube itself. The function of the tube is to

support the dynamic membrane without allowing particles to

intrude into the tube matrices. At the same time the tube

must be very porous to minimize resistance to fluid flow.

Physical and chemical properties of the dynamic membrane

are also very important to the process. Like the support

tube, the dynamic membrane must have a low resistance to

the flow of the filtrate. It should be relatively noncohesive

so that particles are easily re-entrained by the flow of fluid

past the membane, thus minimizing membrane thickness.

By adding small quantities of various chemicals, the

characteristics of the dynamic membrane can be changed to

assist in the filtration process.

A3.2 EXXFLOW Attributes

EXXFLOW crossflow microfiltration units are of modular

construction employing a number of manifolded curtains, or

modules. Modules are connected together either in parallel

or in series with each other, or any number of tubes within

a module can be similarly connected.

Two basic configurations of EXXPLOW units are available:

linear, where a number of curtain modules are suspended

with the tubes running parallel to the ground, and spiral,

where the modules are wound in a spiral with the tubes

parallel or perpendicular to the ground. Curtain modules

may also be suspended vertically or supported horizontally.

Other variants permit the curtain to be formed into

cartridges. Selection of the type of configuration depends on

the space requirement and the duty envisaged for the

EXXFLOW unit. Wgure A-2 shows a typical EXXPLOW

spiral filter module.

Ease of cleaning is an important feature of the EXXPLOW

crossflow microfiltration unit that distinguishes it from other

crossflow microfiltration systems. In most cases, cleaning

is simply a matter of momentarily stopping the feed,

resulting in tube collapse which causes the dynamic

membrane material to be dislodged from the tube wall and

flushed out with the reject flow. Depending on the

configuration of the tubular army, other cleaning systems can

be fitted, such as internal ball cleaning, reverse flow

flushing, water or air spray jet, or squeeze roller cleaning.

The EXXFLOW technology is based upon the highly

spedid woven textile tubular array as well as on the

formation and maintenance of dynamic membranes and

cleaning techniques. Currently, the cloth is available in two

basic designs, each of which can be woven in any length and

23
Filtrate

Figure A-l. EXXFLOWFiltration T- and Flexible Tube

Module.

Figure A-2. EXXFLOW Crossflow Microfilter

Figure A-3. EXXPRESS Automatic Sludge Dewatering System

24
in any tube diameter desired for specific applications. The

porosity or permeability can be varied and post weaving

treatments applied to impart specific cloth characteristics.

While polyester yarn is the standard material employed.

other materials can be used to influence results of the

EXXFLGW process depending on the permeate qualities

desired for specific feed liquids.

A.4 EXXPRESS Unit

Suspended solids in the water are concentrated by

recirculation through the EXXFLOW unit and then the slurry

is fed to the EXXPRESS unit. Typical feed to the

EXXPRESS units are dilute slurries that contain between 2

and 5% solids. The EXXPRESS units dewater these streams

by operating a module in a “dead end” mode by closing a

valve at the reject end of the module. Typically. the

EXXPRESS microfiltration unit is hung parallel to the

ground and is traversed by a set of mechanical rollers. As

the concentrated waste stream enters the EXXPRESS

module, solids form a thin membrane layer on the internal

walls of the tubes similar to that of the EXXFLOW unit.

The associated water in the waste stream permeates through

the membrane layer and escapes to the outside of the tubes

as filtrate. When the membrane layer reaches a controlled

thickness, the discharge valve is opened and the exterior of

the module is traversed by mechanical rollers. As the rollers

traverse the module, the cake that has formed on the wall of

the tubes is broken from the surface and flushed from the

module.

Water that permeates through the tube wall during the

dewatering cycle is recycled to the EXXPRESS feed tank or

to the reaction tank. Generally, the water that permeates the

EXXPRESS unit needs to be recycled because the filtration

is not as effective as the EXXFLOW module.

A.4.1 EXXPRESS Operation

The primary objective of the EXXPRESS is to dewater the

concentrated feed entering the unit In normal dead end

filtration. the fluid is pushed through the membrane material

to remove entrained solids. In this mode. the flow is

perpendicular to the surface of the membrane and particles

are retained by becoming entrapped within the matrix of the

membrane. In the EXXPRESS unit, the dewatering occurs

at the tube walls with water flowing radially from the

direction of flow down the tube. The EXXPRESS operates

automatically in two cycles: load, and cake discharge. In the’

load cycle, the discharge valve at the end of the module is

closed and fluid enters the EXXPRESS tubes and fitrate

begins permeating though the tube walls. As the fluid is

discharged though the tube wall, the solids begin to

accumulate on the inside of the tubes. As the solids deposit,

increased pressure is required to force liquid through the

increasing membrane thickness. When the membrane

reaches a controlled thickness, the discharge cycle begins.

The discharge valve is opened and flush water is sent

through the tubes while the mechanical pinch rollers begin

traversing the EXXPRESS module. Since the inner walls

have been coated with solids, the internal tube diameter is

decreased, resulting in higher fluid velocities within the tube.

As the tube rollers traverse the module, the pinching causes

the cake to break from the tube walls and decrease the tube

diameter further, resulting in still higher fluid velocities at

the rollers. This creates a venturi effect which causes the

cake chips to be drawn into the liquid stream and swept

from the EXXPRESS module (Figure A-3). The resulting

fluid that exits the module contains the solid cake chips and

the flush liquid This two phase stream is then pumped to

the dewatering screen to separate the solids from the liquid.

The load and discharge cycles are controlled automatically

by a process controller. It also allows for manual control

of the pinch rollers that traverse the module. The automatic

controller also controls opening and closing of the discharge

valve.

A.5 Sludge Dewatering

Filter cake dewatering occurs through the use of a gravity

dewatering (wedgewire) screen. The dewatering screen has

a grating that is small enough to pass the flush liquid but

retain the solid filter cake chips. Fluid carrying the cake

chips that exit the EXXPRESS unit is pumped directly to the

dewatering screen. Fluid that passes though the grating is

collected in the EXXPRESS feed tank where it can be

recycled to the EXXPRESS for further dewatering. Solids

that are trapped on the screen eventually accumulate and fall

into a drum or storage container for proper disposal.

There are many designs which can accommodate the

dewatering of the sludge. The system described above was

used during the SITE demonstration tests. Modification of

this design may have been able to produce filter cake with

higher solids content The dewatering mechanism should be

designed based upon specific process attributes.

25
Appendix B

Vendor’s Claims

This appendix summarizes the claims made by the

developer, EPOC Water, Inc., regarding the microfiltration

technology under consideration. This appendix was generated

and written solely by EPOC, and the statements presented

herein represent the vendor’s point of view. Publication here

does not represent EPA’s approval or endorsement of the

statements made in this section; EPA’s point of view is

discussed in the body of this report.

B.1 Introduction

The EPOC microfiltration technology treats wastewater or

dilute sludge containing heavy metals to meet stringent

discharge limits. Wastewaters of this type range from

contaminated groundwater containing 1 to 2 mg/L of heavy

metals, through industrial wastewaters containing up to 50

mg/L of heavy metals, to acid mining wastes containing up

to 1,000 mg/L. Typically, the industrial wastewaters will

also contain particulates, oil & grease and organic materials

including solvents and detergents.

The ideal treatment technology has to achieve two functions:

first. produce a treated water suitable for discharge and

second, produce a small volume of concentrate for disposal

or reclamation. The concentrate should be compact so that

it passes the RCRA paint filter test and the toxicity

characteristic leaching procedure (TCLP).

Other important considerations are:

I) operator handling of the waste should be

minimized,

ir the treatment should be cost effective,

(I) the system should be robust and versatile providing

treatment of a wide range of different contaminants

and different concentrations.

B.2 EPOC Microfiltration Technology

The microfiltration technology is a pressure driven

separation process for removing suspended solids.

particulates and heavy metal precipitates. The microfilter

modules utilize a patented flexible woven tube bundle that

has excellent chemical and temperature resistance. The

modules can be operated in EXXFLOW mode, with a crossflow tube velocity, or in dead-end EXXPRESS mode, such

that the system operates as an automatic tubular filter press.

The EXXFLOW mode is used to separate suspended solids

and precipitated heavy metals. The EXPRESS mode is

used to dewater weak sludges or the concentrate from the

EXXFLOW process.

Wastewaters containing dissolved metals are dosed with

chemicals to precipitate the metals. Typical chemicals are

alkalies such as lime, sodium hydroxide (caustic).

magnesium oxide, or sulfides such as sodium sulfide and

carbamates. Generally, heavy metals precipitate as their

hydroxides within the pH range 9-10 and which alkali to use

depends on the waste characteristics and process economics.

Sulfide and carbamate chemistry is applicable in the pH

range 7-10 and often provides for a higher quality treated

Water.

B.2.1 EXXFLOW Microfiltration

The EXXFLOW microfilter is a robust and compact unit

available in size ranges of 5 gpm to 2,000 gpm. The system

consists of a feed tank, recirculation pump, EXXFLOW

modules and control system as shown in Figures B-l and B2. The tubular filter modules are available in various sixes

with 10 sq ft to 150 sq ft of filter area to accommodate

different plant flow rates. The modules are configured in

banks with up to 16 modules per bank.

26
II l-l II

Figure B-l. Typical Vertical Module Configuration.

Figure B-2. EPOC Microfiltration Process Schematic.

27
The feedwater containing the precipitated heavy metals is

pumped into the filter module bank(s). Thetreated Or

filtered water is collected in the module housing and

discharged.In some applications, pH adjustment is needed

prior to discharge. The EXXFLOW modules operate with

the wastewater on the inside of the tubes such that the

suspended and colloidal matter forms a thin dynamic

membrane layer on the internal surface of the tubes. The

liquid flow is maintained by the recirculation pump to

control the thickness of the layer. Tube velocities of 3 fps

to 6fps are typically used. Part of the feed becomes treated

water and the remainder(reject) is recirculated to the feed

tank.

A concentrate bleed stream removes the solids and

precipitated heavy metals from the system to maintain the

recirculation loop at 1to5% w/w solids. The concentrate is

automatically discharged from the unit and transferred to the

solids dewatering unit

Typically the system operation is controlled by a

programmable logic controller (PLC). The microfilter is

fabricated from corrosion resistant materials: polyester cloth,

epoxy end castings and FRP module shells. Operating

parameters are 0°C to 65’c (32 to 1509’) tern- range.

pH 2 to12 and pressures of 20 to 50 psi.

Periodically the modules are cleaned due to the build-up of

impurities at the tube surfaces. The EXXFLOW modules

are backwashed by the backwash pump which draws filtrate

back through the microfilter tubes. Because the tubes are

flexible, they collapse duringthe backwash operation and

break up the impurity layer. Difficult-to-remove foulants are

chemically cleaned with acid, hypochlorite. or alkaline

detergents.

B.2.2 EXXPRESS Automatic Tubular Filter

Press (ATFP)

TheATFP process uses two cyclic operations of solids

loading and cake discharge. In the load cycle, the waste is

pumped into the EXXPRESS tube module with the reject

valve closed. The solids form a thin cake of up to 5mm

(3/16 in) on the inside of the tubes. The filtrate is collected

in the lower compartment and drained out. The

load/dewatering cycle is complete when the pressure inside

the ATFP reaches 50 to 75 psi or the load cycle timer is

finished The cake discharge cycle then commences by

opening the reject valve and traversing the modules with

rollers which disrupt the shape of the tube. This disruption

causes a venturi action which simultaneously and

aggressively causes the filter cake to chip off into the flush

stream and also cleans the filter cloth on each cycle. The

flush water (same as the feed water) is directed to a

wedgewire separating screen. After the cake discharge

cycle, the ATFP starts a new load cycle. The flush water is

recycled to the front of the system. An EXXPRESS process

diagram is shown in Figure B-3.

Figure B-3. EXXPRESS Dewatering Schematic.

28
B . 3 Applications of the EPOC

EXXFLOW/EXXPRESS Technology

The technology has been successfully applied for:

removal of hexavalent chromium from

contaminated groundwater

removal of kerosene from aluminum metal ports

washer

removal of nickel solids from electronic industry

operations grinding

removal of dissolved nickel and zinc from plating

wastes

removal of dissolved ethylene glycol, copper, and

nickel from manufacturing

removal of hexavalent chromium. copper, iron, and

nickel from electroplating

removal of iron and manganese from groundwaters

removal of emulsified oil and iron from oil field

waters

removal of pesticides, arsenic, zinc, and oils from

pesticide manufacturing

removal of lead and other heavy metals from

ceramics wastes

removal of copper particulates from ink wastes

removal of oil & grease and heavy metals from

industrial laundries

removal of lead from battery manufacture

removal of heavy metals from hazardous waste

treatment facility.

B-l provides details of the capability of the

To date, the process has been applied full-scale mainly to

wastewaters containing heavy metals and oil and grease and

to contaminated groundwaters. The technology is ideally

suited as a pretreatment process prior to other technologies

such as activated carbon, air stripping, ion exchange, and

reverse osmosis.

Table B-l. Wastes Compatible with the EPOC System

INDUSIRY TYPE

AcidhiineDraiMge

Eatcry MeMfecmtc

cbanial Mellufecfufc

Ca~tamiaedGmundwucr

Gmuxlweter Gmteining HcxanLnt

a . MdvGc

llhstdlAlm&ia

l&s

oil Field Wastewater

Mcld Plating

Paint pigments

PCStiCidU

wak SludgeJ fnm MMuf~uuIing

COMPGUNDS

Aluninum

AntillKmy

Arsenic

Cdmium

CIlumniutn

cokult

Copper

cyanide

Dyes

inks

ho

KCfOSClE

Lud

Manganese

M=W

Nickel

Gil&GK!UC

Ptitr

Pigments

sc1enium

Silver

VUdillm

waste Oil

B.4 System Advantages

The EXXFLOW/EXXPRESS technology has the following

advantages over existing systems:

*

technology by industry and by contaminant material.

The EXXFLOW/EXXPRESS system is available as truck

and trailer mounted units as well as for permanent

installations.

EPOC usually tests all wastewaters before operation to

determine the optimal chemical dosages and process

parameters.

They provide a combined heavy metal separation

and sludge dewatering system.

The microfilter barrier ensures high quality treated

water.

The microfilter can take high solids and oily

feedwater without pretreatment.

The system is very tolerant to changes in feedwater

concentrations.

Minimal operator attention and handling of sludges.

Proven cost-effective technology on size ranges

from 5gpm to 3 mgd.

Transportable in the smaller size ranges.

29
* Modular construction, allowing phased expansion.

* Adaptable to wastes containing 1 to 10,000 mg/L of

heavy metals.

* Filter cakes are compact and in most cases pass the

TCLP. Wastes can also be further stabilized at the

EXXPRESS treatment stage by the addition of fixative

agents such as silicates, fly ash, and kiln dust.

30
Appendix C

Site Demonstration Results

C. 1 Introduction

In January of 1989, Epoc Water, Inc. (EPOC) of Fresno, CA

submitted a proposal for their microfiltration technology to

the U.S. Environmental Protection Agency’s (EPA)

Superfund Innovative Technology Evaluation (SITE)

Program administered jointly by the office of Research and

Development (ORD) and the Office of Solid Waste and

Emergency Response (OSWER). EPA selected the EPOC

microfiltration technology for demonstration in the SITE

program. Iron Mountain Mine(IMM) in Redding, California

was selected by EPA and EPOC as an appropriate site for

the technology demonstration. The technology was

demonstrated at the IMM site in May and June of 1992.

This appendix briefly describes the IMM site and

summarizes the SITE demonstration activities and the

demonstration test results.

C.2 Site Description

The IMM site is located approximately 9 miles northwest of

Redding, California in Shasta County. Figure C-l is a map

of the site. For more than 100 years, the IMM site was

mined for copper, zinc, iron, silver, gold and pyrite. Mining

activities were discontinued in 1962.

As rainfall and groundwater flow on the exposed surfaces of

the mining areas, sulfuric acid is produced and high

concentrations of aluminum, copper, zinc, cadmium, and iron

are released from the mining deposits. The result is acid

mine drainage (AMD) which has a low pH due to the

sulfuric acid and a high heavy metals content.

Large volumes of AMD flow from the IMM site in several

different streams. The IMM site is the worst AMD problem

in the country at this time, in terms of total volume of AMD

produced and total quantity of heavy metals released. The

flow of AMD from Iron Mountain is controlled through use

of a reservoir, which prevents too much AMD from entering

the Sacramento River. In the past, fish kills and other

problems have occurred due to heavy winter rains and

overflow of the reservoir.

Several acid mine drainage streams exist on the site. Five

major sources account for the majority of the copper, zinc,

cadmium and iron that migrate from the site. These five

sources of AMD are: the Richmond Portal and the Lawson

Portal, which discharge into Boulder Creek; and the Big

Seep, Old No. 8 Mine Seep and the Brick Flat Pit Bypass

discharging into Slickrock Creek. The two streams chosen

for the demonstration were the Richmond Portal and the Old

No. 8 Mine Seep.

C.3 Wastewater Contamination Characteristics

Both the Richmond Portal and the Old No. 8 Mine Seep had

high levels of aluminum and iron. with some arsenic,

cadmium, copper, lead, magnesium, manganese and zinc.

The concentration of iron in the Richmond Portal WY

approximately 20,000 mg/L with a pH of 0.6 and a

conductivity of 195,000 pmhos/cm. The Old No. 8 Seep had

an iron concentration of approximately 2,000 mg/L with a

pH of 2.3 and a conductivity of 8,000 pmhoskm. The

Richmond Portal liquid had a pale green color and both

streams had a characteristic metallic odor.

C.4 Review of SITE Demonstration

The Site Demonstration was divided into three phases: 1)

site preparation, 2) technology demonstration. and 3)

demobilization. These activities and a review of the

technology and equipment performance during these phases

are described below.

31
Figure C- 1.
C.4.1 Site Preparation 0 A heavy duty construction forklift for filter cake

handling and treatment chemical handling,

A level area of approximately 1,000 sq ft was selected near

the flume that contained water from the Old No. 8 Seep.

The test site was located within 50 yd of the location where

the Old No. 8 Seep percolated from the ground. An office

trailerwas brought on site along with a portable toilet. Five

polyethylene storage tanks (capacity of 6000 L or 1,600 gal

each) were brought to the site and leveled in the area

Plywood was used to create a “floor” on which quipment

could be leveled and set up. The plywood also created a

building platform to which equipment such as pumps, tubing

and flow meters could be anchored. To obtain test water, a

gravity syphon was created by connecting a line from the

Old No. 8 flume and the storage tanks. This produced a

continuous source of raw feed during the demonstration test.

C.4.2 Support Equipment

Support equipment for the microfiltration system included

storage tanks for the treated and untreated acid mine

drainage and for clean water, a generator and compressor for

power and compressed air, and a forklift for material

handling. Specific items include:

Five 6000 L (1,600 gal) polyethylene tanks for storage

and volumetric measurement of the feed and treated

water,

- Two platform scales for weighing filter cake and

treatment chemicals,

s An office trailer approximately 20 ft by 8 ft with two

rooms for shelter, storage and the field laboratory,

s A 1600 L (425 gal) polyethylene water wagon/truck

tank for water transport,

I

A 3/4 ton pickup truck for transporting supplies, fresh

water. and for transportation of the Richmond Portal

water to the test site,

* A cellular phone for emergency communications,

laboratory communications, ordering supplies and

scheduling deliveries,

s A 20 kW diesel generator with 3-phase 240 volt 60 hz

capacity to power the process equipment, and singlephase 110 volt service for the support equipment and

the field trailer,

An air compressor with a capacity of 100 scfm for

pump and pneumatic valve operation,

. Several 55 gal drums to contain the filter cake from the

process.

* Transfer pumps for the liquids,

1 A sump pump for collecting water,

I

Analytical equipment for measuring field parameters,

- Piping and flow meters for measuring liquid flow rates

and volumes,

e Several gas cans for transporting gas and diesel to fill

the compressor and generator,

s Extra lumber for constructing pipe and flow meter

supports, and

. Miscellaneous hand tools, including a hammer.

wrenches and screwdrivers.

C.4.2.1 On-Site Support Services

Field sample analyses were performed in a two-room field

trailer. Half of the trailer was used as the laboratory. while

the other half provided air-conditioned shelter for the field

crew as well as storage for supplies and equipment. A

portable computer and printer were used for data processing.

There were no other support buildings or services available

on-site.

A forklift was brought to the site to facilitate the handling of

the sludge filled drums. The forklift was also used to move

pallets of treatment chemicals and the liquid sodium

hydroxide drums.

C.4.2.2 Utilities

Utilities required for the demonstration included water.

electricity, phone service and compressed air. Since no

utility lines were available at the demonstration site, all

utilities were provided through portable means. A 20 kw

diesel generator was used to provide electricity to both the

microfiltration process equipment and the field trailer Three

phase, 240 volt power was supplied to the process

equipment. and single phase. 120 volt power was used for

the trailer and miscellaneous support equipment

Compressed air was provided by a gasoline-powered

compressor with a capacity of 100 scfm.

33
Fuel for both the generator and the compressor, purchased

at a service station in Redding. was brought to the site each

day in gasoline cans using a rented pickup truck. This same

truck, outfitted with a 425 gal tank, was used to transport

non-potable water for equipment decontamination and

process needs to the site from a clean water source located

elsewhere on Iron Mountain. Water was stored in 1,600 gal

tanks at the test site. Potable water for drinking was

purchased in bottles and brought to the site. Reagent-grade

water for cleaning sampling equipment and performing field

blanks was purchased from a laboratory supply house.

Telephone service was provided by a cellular phone rented

for the demonstration. This telephone was required for

ordering supplies, scheduling deliveries, maintaining contact

with the analytical laboratory and home offices and for

emergency communications. The nmote location of the site

made the acquisition of a portable telephone vital to the

safety of the field crew.

C.4.3 Technology Demonstration

This section describes the operational and equipment

problems and health and safety issues associated with the

SITE demonstration.

C.4.3.1 Operational Problems

The SITE team experienced operational problems during the

demonstration. Some of these problems resulted in changes

to the demonstration schedule, duration, and number of test

runs performed. Other problems required decisions to be

made in the field to solve them. These operational problems

and their resolutions are described below:

* The Iron Mountain Mine Site is fairly remote and

reachable only by narrow dirt road. Transportation of

equipment to the site required extra care and planning.

All utilities required on the site had to be supplied

through portable items. Access to the Iron Mountain

Mine site is controlled through several locked gates

along the road; supplies could only be delivered when

a member of the field team carrying a key was present

at the outermost gate to provide access. At least an

hour was required to drive between the nearest sources

of equipment and the site. These access problems

required additional planning and personnel to ensure

needed supplies were on site and to avoid delays.

c The developer required a much longer initial

shakedown period than initially anticipated. Both

mechanical and chemical problems occurred for several

weeks, delaying the commencement of the

demonstration test. Even after testing had begun, some

days of testing had to be aborted due to equipment

problems. T h e demonstration test unit was

continuously modified and changed in the field

throughout testing. The number of test runs to be

performed was reduced significantly after several weeks

in the field had passed and several repeated failures of

the EXXPRESS unit had occurred. All but one of the

runs using Richmond Portal water as the feed were

eliminated.

Samples could not be shipped the same day due to

the long days at the test site. Samples were shipped

the morning following their collection by overnight

courier service.

It was considered unsafe to travel the road from the

Iron Mountain Mine site after dark. This, as well as

the 1 hr travel time to the site or back, cut down the

available time for testing each day.

The startup time for the unit was much longer than

anticipated by the developer, hence, the 8 hr runs

originally planned were decreased to 6 hr in order to be

able to complete the sampling activities. In fact, most

of the demonstration runs lasted about 4 hr. These

changes resulted in modifications to the original

sampling plan.

During one day of the demonstration test, access to the

site was blocked completely due to a truck accident

(not related to this project) and the resulting cleanup on

the road to the site. No testing could be performed on

that day.

Since the demonstration testing period was much longer

than originally planned and the developer’s personnel

had another commitment to fulfill, a three-week-long

hiatus occurred before the testing could be completed

The process unit had to be drained and cleaned each

day to prevent settling, scaling and fouling of the

process equipment. The nightly cleaning may not have

been required if the unit were operated continuously.

C.4.3.2 Equipment Problems

The SITE team experienced many equipment problems

during the demonstration test. These problems resulted in:

(1) repeating the affected demonstration test runs, (2)

eliminating several planned runs, (3) on-site equipment

maintenance and modification, and (4) changes in the

demonstration schedule and duration.

34
The equipment that was brought on site was different

from that originally described in the testing documents.

A source of compressed air to operate a diaphragm

pump was required that had not been planned o r

acquired. During testing in cold temperatures, the

pneumatic pump began to stall as ice accumulated on

th e discharge manifold An air drying mechanism was

installed to prevent freezing of the pump parts.

Several electrical and mechanical problems with the

equipment occurred during shakedown requiring

maintenance, modification of the equipment. and

acquisition of additional and replacement parts.

Electrical problems were most likely due to inclement

weather conditions experienced during shakedown and

testing. The developer had to bring an additional person

to the field to assist with operation and maintenance of

the equipment.

The feed water (Old No. 8) did not react with the

treatment chemicals instantaneously and the mixture did

not behave as anticipated by the developer. Control of

the pH of the treated feed and the permeate required

time for trial and error; on some days samples could

not be collected. Poor control led to inconsistent

permeate output.

Repeated problems with clogging of the EXXPRESS

filter tubes occurred requiring many changes to

operating procedures and equipment configuration.

These problems also resulted in equipment downtime

and aborted runs.

The dewatering screen for the filter cake did not

perform as well as anticipated. More water was

retained in the filter cake than was felt to be

representative of the process operation. Minor

modification of the screen helped but did not eliminate

this problem.

A basket strainer was installed to remove large clumps

of solids before fluid was fed to the EXXFLOW unit.

C.4.3.3 Health and Safety Considerations

In general, health and safety hazards associated with this

demonstration test were physical in nature. The pH of the

Old No. 8 stream was about 2.3 and that of the Richmond

Portal stream was 0.6. These highly acidic liquids presented

a hazard to personnel through splashing on the skin or in the

eyes. Lifting of heavy items and working with and around

the operating equipment were additional physical hazards as

were the hazards associated with tripping or slipping on the

uneven and rocky ground surface.

Heat stress was a major concern during much of the

demonstration activities as temperatures in the area were in

the 80s and 90s during most of the demonstration testing.

The hazard was increased by the need to use protective

clothing that reduced evaporation from the skin and added

additional weight to the personnel. The air conditioned

trailer and the availability of cool potable liquids were very

important in the prevention of heat stress disorders.

Other hazards of the site included: fire and explosion hazard

from the liquid fuel on site for the generators; potential

exposure to sodium hydroxide which is corrosive and

powdered lime which can be a respiratory irritant; insects

and animals prevalent at the site: and exposure to inclement

wcatha (hail,thunderstorms). The remote location of the

site provided the additional hazards associated with driving

along the narrow dirt toads and the unavailability of nearby

assistance in case of emergency.

Personnel were required to wear protective clothing

appropriate to the tasks being performed. Steel-toed boots

were used in all areas on site. Chemical resistant boots were

used during any tasks with potential contact with the low pH

feed liquids. Modified level D protection was used during

sample collection, including hard hat, faceshield, latex inner

gloves and nitrile outer gloves. Sampling and handling of

the Richmond Portal liquid was performed by personnel

wearing splash repellant full-body coveralls and goggles with

a faceshield in addition to the hard hat and gloves. For field

laboratory analyses, goggles, latex or nitrile gloves, and a

splash apron were worn as a minimum. Dust masks were

worn when transferring the 50 lb bags of lime to the feed

hopper. No other respiratory protection was required on this

site because no volatile compounds were present in the

waste liquids.

C.4.3.4 Site Demobilization

The process equipment was drained, decontaminated and

removed from the demonstration site after testing was

completed All of the piping and pumps were disassembled.

Some of this equipment was decontaminated for reuse on

other sites. while materials that were contaminated or

damaged were disposed of. Equipment and tools to be

retained were sent off-site for storage. All of the rental

equipment was returned, including the trailer, generators,

forklift and platform scales. The site was later cleared of

any remaining debris.

The drums of filter cake were to stay on site; they were

transported to another area on Iron Mountain for permanent

storage. Other contaminated materials, including used

personal protective equipment. were placed in drums for offsite disposal. The storage tanks, which had become

35
contaminated and weathered, were cut into pieces and

drummed for off-site disposal. A total of 12 drums was sent

to a hazardous waste landfill.

C.4.3.5 Experimental Design

The objectives of the technology demonstration were to 1)

assess the technology’s ability to remove toxic metals

present in the acid mine drainage (AMD) waters, viz. Old

No. 8 Mine Seep and Richmond Portal,at the IMM site.

with a 90% confidence level, to residual levels claimed by

the developer (see Table C-2), and 2) evaluate the system’s

ability to dewater the metals-bearing sludge resulting from

the separation of precipitated metals and the treated water to

solids concentrations >20% for NaOH treatment and >40%

for lime treatment.

These objectives were achieved through a carefully planned

and executed sampling, analysis and monitoring plan, but

with changes which were implemented in the field as a

result of process and operational modifications made by the

developer either just prin to the start of the demonstration.

during the testing, or as a result of some operational

problems encountered.

The EPOC microfiltration technology was tested on two

AMD streams. the Old No. 8 and Richmond Portal. It is

known from conventional metals precipitating processes that

for a given wastewater sm consisting of an array of

metals at different but more or less steady concentrations,

there exists an optimum pH for a given precipitating agent

at which an optimum residual metals concentration in water

is realized. These optimum pHs and required reaction times

for the treatment of Old No. 8 and Richmond Portal with

lime. caustic and magnesium oxide were established through

beaker tests by EPOC at its Fresno, CA facility prior to the

start of the demonstration. Therefore, the only parameter

that was to be varied to evaluate the technology was the

selection of precipitating agent(s). The demonstration runs

conductedonthetwoAMDstreamsaredescribedinterms

of the precipitating chemical(s) and the actual flow rates, run

time and volume treated, and are presented in Table C- 1.

In order to achieve the demonstration objectives, solid and

water samples were collected from the EPOC microfiltration

system and were analyzed for a number of critical and noncritical parameters. These parameters had been further

categorized as process or analytical and as off-site laboratory

or field determined. Metals (i.e., Al, As, Cd,Cr, Cu, Fe, Pb,

Mn, MO, Ni, and Zn), pH and total solids of the water

samples and the metals, pH and moisture content of the filter

cake solids were considered critical analytical parameters,

and the flow rates and total volumes of the water streams

andthemassratear\dtotalmassofthcsolidssbeamswere

considered critical process parameters. Non-critical

measurements that were also performed included total

dissolved solids, acidity or alkalinity, sulfate, temperature

and conductivity, turbidity and dissolved oxygen of the water

samples and density and toxicity characteristic leaching

procedure (TCLP) for metals in the filter cake solids. In

addition, electrical consumption and system pressure were

also monitored. EPA-approved sampling, analytical. quality

assurance, and quality control (QA/QC) procedures were

followed to obtain reliable data. The Technology Evaluation

Report provides and/or summarizes all results.

C.4.3.6 Review of Treatment Results

This section summarizes the results of both critical and noncritical measurements for the demonstration of the EPOC

microfiltration technology and evaluates the technology’s

effectiveness in treating the acid mine drainage streams

contaminated with heavy metals.

Summary of Results for Critical Parameters

The SITE Demonstration test was conducted at the Iron

Mountain Mine Superfund Site, in Redding, CA. This site

is contaminated with several water sources that are laden

with heavy metals. Two water sources were tested during

the demonstration; which are known as Old No. 8 Mine

Seep (ON8) and Richmond Portal Seep (RP). Both acid

mine drainage streams are contaminated with high ppm

levels of iron, aluminum, copper, and zinc. Several other

metals were present at much lower levels but were still

considered critical in the evaluation of this technology.

Test runs were made using three treatment chemicals on

water collected from the Old No. 8 seep and a combination

of two chemicals was evaluated on water from the

Richmond Portal Seep. Test runs averaged about 4 hr in

length during which samples were collected of the raw feed,

permeate, and filter cake. Samples were composited for

each of the parameters based upon a weighted average of the

flow rate and production rate of filter cake. Several grab

samples were also obtained during each run. Samples were

analyzed primarily for metals to determine removal

efficiencies and the fate of the heavy metals. Results for the

treated effluent (permeate) are summarized in Table C-2.

The first series of tests were performed in duplicate on water

obtained from the Old No. 8 seep with 50% sodium

hydroxide as the precipitating agent Average feed

concentrations of aluminum, copper, iron and zinc were

approximately 700, 170, 2000 and 60 mg/L (ppm).

respectively. Results for the permeate composite samples

36
R
for both tests indicated that all metals were reduced to levels

less than the claimed 1.0 mg/L or 0.1 mg/L objectives with

the exception of aluminum, Results for aluminum in the

composite samples for the first and second test were 61 and

12 mg/L respectively; iron concentrations in the composite

samples of the permeate were 0.27 mg/L and 0.15 mg/L;

below the developer’s claim of 1 mg/L. Although aluminum

was not reduced below the vendor claim of 1 mg/L,

reductions of 91% and 98% were observed in the two test

runs. The high residual aluminum was probably caused by

the difficulty encountered in controlling the pH in the

reaction tank. The improved reduction in the second run can

be attributed to the process operators becoming more

familiar with pH control and operational characteristics

requiredtotreatthiswater.

Similar results were observed in the succeeding tests with

the Old No. 8 Mine Seep and lime, magnesium oxide, and

the mixture of magnesium oxide and caustic, with some

notable exceptions. These results are also presented in Table

C-2. SpecificalIy, reduction of aluminum to <l mg/L was

achieved with the magnesium oxide and the mixture of

magnesium oxide and caustic, but not with lime. Iron was

reduced further below the 1.0 mg/L objective, to about 0.1

mg/L, with lime, magnesium oxide, or magnesium

oxide/caustic. And. while lead remained below the

objective, 1.0 mg/L, in all tests, the removal appears to be

less complete with magnesium oxide than with caustic or

lime. Similarly, manganese removal was less complete with

the magnesium oxide, Because of the low concentrations of

several of the metals in the feed water, it is not possible to

discern differences in removals of these metals with the

different bases.

All tests with the Old No. 8 Mine Seep were carried out at

a flow rate of about 3.0 gpm, (see Table C-l) and

discharged permeate at essentially the same rate throughout

the approximate 4 hr of treatment, within the limits

encountered due to forced interruptions and other factors.

The original plan was to use a flow rate of approximately 7

gpm. but operational problems made this rate unachievable

with this wastewater.

Table C-2 also indicates the elevated pH values observed in

the permeates from all the tests. It is unknown whether more

precise pH control would have affected permeate quality,

sludge production, or sludge quality. Another question that

remains unanswered is whether the permeate would have

precipitated additional solid if it were re-neutralized to a pH

of 4.0 for discharge.

When a mixture of magnesium oxide and caustic was used

to precipitate the metals from the Richmond Portal AMD,

high removals of all heavy metals and aluminum were

observed whik iron and manganese failed to meet the

developer’s claims of 1 .0 mg/L and 0.1 mg/L. respectively.

Nevertheless, with an initial concentration of 20,600 mg/L

iron, 2140 mg/L aluminum, and 399 mg/L copper. the

precipitation and microfiltration were very effective in

removing metals. The raw feed flow rate for this single test

was approximately 1 gpm and permeate flow rates were

slightly higher, about 1.25 gpm. Permeate pH was <9.0.

In addition to affecting the residual metal content in the

permeate, the choice of base also affected the solids content

in the sludge and. consequently, in the filter cake. This also

affected the efficiency and operational effectiveness of the

EXXPRESS microfiltration unit. The sludge from the caustic

treatment was clearly more fluid than that from either lime

or magnesium oxide, presented greater operating difficulties

in the EXXPRESS, and resulted in significantly lower solids

content in the resulting filter cakes. None of the filter cakes,

regardless of base used. achieved the claimed minimum

solids content, 20% with caustic and 40% with lime (or

magnesium oxide). In addition, the calcium sulfate

coprecipitated with other metals when using time appears to

add further operational difficulties to sludge dewatering in

the EXXPRESS. It remains the developer’s opinion that the

EXXPRESS system could be optimized to overcome these

difficulties and achieve the objectives.

In addition to lower-than-expected solids content in all filter

cakes from the EXXPRESS, the total mass of solids

recovered from all tests were significantly lower than

anticipated by calculating the theoretical solids available and

comparing to the weights and solids content of the filter

cakes as recovered. Visual examination of the system

indicated that significant volumes of solids were retained in

the system, both settled in the reaction vessel and dispersed

in the liquid retained in the system.

A compilation of the data for the several tests is presented

in Table C-3 and more detailed information on the filter

cake yields is summarized in Table C-4.

38
3
Table C-4. Filter Cake Output from EPOC EXXPRESS.
Appendix D

Case Studies

The information contained in the following case studies was provided by EPOC Water, Inc. and has not been subjected to

EPA’s QA/QC program nor reviewed by EPA for accuracy.

41
D.1 Bench Scale Treatability Testing

EPOC Testing Facility, Fresno, CA

This case study presents the treatability testing performed by

EPOC and SAIC in May of 1990 using water from the Iron

Mountain Mine site. The purpose of this treatability testing

was to confirm the treatability of the Iron Mountain

wastewaters using the EPOC system and to determine the

operating conditions, treatment chemicals, and target

reductions for use of the technology.

D.l.l Beaker Tests

The first phase of the treatability testing involved beaker

tests to determine which precipitating agents would be

appropriate to precipitate the metallic constituents of the

waste. This test was performed using beakers and filtration

of the resulting slurry through a vacuum filtration apparatus

using a 0.45 um membrane filter. Based on the historical

water characterization data of the waste streams, lime

(calcium hydroxide) and caustic (sodium hydroxide) were

chosen and tested as precipitating agents.

D.1.2 Single-Tube Treatability Tests

After the beak tests, treatability tests were conducted using

single-tube EXXPLOW and EXXPRESS units. Each unit

used was 2.5 cm (1 in.) in diameter and 1 meter long.

EPOC chose to use only lime as a precipitating agent during

these tests.

The tests were conducted by treating the wastewater from

both the Old No. 8 seep and the Richmond Portal by

precipitating with lime and heating the slurry using the two

bench-scale process units. Sampling and analysis of the

feed. permeate and filter cake from these units was

performed for the units on both of the streams. The

analytical results are summarized in Table D-l. Overall, the

results show the applicability of the technology to the acid

mine drainage; a reduction of four orders of magnitude of

some of the toxic metals was produced by the bench-scale

technology.

Table D-1 . Treatability Test Results
D.2 Hazardous Waste Reduction

FMC Corporation, Fresno, California

This case study presents the use of a combination

EXXFLOW/EXXPRESS system to remove pesticides, heavy

metals and oils from a rinse liquid produced by the FMC

Corporation. The system is in use for recycling of the water

and for hazardous waste volume reduction.

D.2.1 Facility Operations

An EXXFLOW/EXXPRESS combination system is used.

The waste stream, at 10 to 15 gpm. is adjusted to pH 11

prior to entering the EXXFLOW microfilter. Because of the

higher pH, the hazardous materials become less soluble and

are precipitated. The EXXFLOW microfilter concentrates

the hazardous constituents to twenty times the original

concentration and removes the oil emulsions present in the

waste. The concentrate stream is directed to the

EXXPRESS unit where it is dewatered to 45% solids by the

automatic tubular press. The liquid removed from the cake

by the press is recycled to the EXXFLOW feed. The

EXXFLOW recoveres 99% of the water. The filtrate is

polished with a small activated carbon adsorption unit prior

to reuse by the plant

D.2.3 System Performance

Twenty to 50 gal/day of filter cake is produced from this

unit. as compared to the 10 to 15 gal/min of influent

Ninety-nine percent or better of all of the hazardous

constituents are removed by the system, as shown in Table

D-2. The system has been in use since 1989.

Table D-2. Removals of Hazardous Constituents

D.2.3 Costs

The capital cost for this technology application was

approximately $175,000; installation costs were $12,000.

The volume reduction as well as the production of a semidry product significantly reduces the disposal costs for the

operation. The ability to reuse the water in the plant

provides an additional cost savings. Epoc estimates that a

cost savings of $1.5 million per year is being achieved

versus disposal of the liquids as hazardous waste. As

hazardous liquids become more difficult to dispose of due to

new regulations, and the cost of water increases, the use of

this technology could provide substantial savings over the

long term.

43
D.3 Groundwater Remediation

Talley Corporation Newbury Park, CA

ThiccuestudydescribesrheuseofacombinedEIOCFlDW

andExxPREsSunittobratwn-grollndwatclat

an abandoned manufacturing plant._ The groundwater was

deu3minedtoa3ntainhexavakntchfomiumatSOOto6OO

ppb and elevated levels of trichloroethylene. Fifty gpm of

groundwaterwasftnnaiybeingpumpedandtreatedwithan

ion exchange system for removal of the chromium, while air

stripping was used to remove the trichloroethylene. EPOC

estimates that substituting the EXXFUIWAXXPRESS unit

for the ion exchange significantly reduced the operating

costs. The EPOC system was installed in January of 1991.

See Figure D-l for a process schematic.

D.3.2System Performance and Costs

ThcEXXFLOWtreataiwate~containslessrhan 10 ppb of

total chromium, well within the regulatory limit of 50 ppb.

No information on reliability is available for this system.

The cost for the equipment was approximately $150,000 and

installation costs were $12,000. The operating costs for this

treatmealtsystemafeestimaMatsO25per1OOOgalfor

electrical power (12 HP at 460 VAC) and $0.02 per gal for

chemical consumption. Labor and maintenance costs were

notreparteaEPOCe&imab%daattheprojectedpayback

time for their unit over the ion exchange is less than twelve

months.

D.3.1 Facility Operations

A single stage chemical reactor is used to precipitate the

hexavalent chromium. The precipitate3 are then removed

from the w using the EXXFLOW microfilter. The

EXXPRESStubularfilte~pressisthenusedtodewaterthe

EXXFLOW reject so that kss than 1 lb/day is produced

while returning the liquids to the EXXFLOW feed. The

permeatefromtheEXXFLOWisthentreatedbytheexisting

airstripper for removal of the trichlorethylene. The

ueaunentsystanisintiockedwiththeglwndwaterpumps.

thcaifstripperandachfomiumi3nalyzcrfortbetreated

water.

Figure D-1 Talley Corporation Process Schematic

44
D.4 Zero Discharge of Ceramics Waste

Duncan Enterprises, Fresno, CA

This ceramics factory produces a waste stream containing up

to 2 gm/l of lead and other heavy metals and 23% w/w

suspended solids including ceramics fines, clays, paint

pigments, and binders. Since the cost of disposing of this

material was becoming prohibitive, recycling was

investigated. The solids and metals were being removed

through a rotary vacuum filter using diatomaceous earth

(DE) as a filter aid.The DE added nearly 50% to the waste

volume and precluded recycling of the solids.

D.4.1 Facility Operation

An EXXPRESS Automatic Tubular Press was used first in

the treatment train to dewater the high solids waste. The

filtrate from the EXXPRESS unit is treated to lower the pH

and precipitate the remaining heavy metal constituents. The

metal precipitates are removed from the liquid in an

EXXFLOW microfilter having a 20 gpm capacity. The

EXXFLOW produces a filtrate of high enough quality to be

recycled in the plant.

The concentrate from the microfilter is added to the feed for

the EXXPRESS unit. The filter cake from the EXXPRESS,

containing 50% solids, is dried and vitrified for reuse as

ceramic frit. AU waste in the unit is recycled so that no

disposal is required.

D.4.3 System Performance

The final filtrate water quality is compared with the raw feed

in Table D-3.

Table D-3. Concentration Comparison

D.4.3 Costs

Epoc estimates that the unit saves over $500,000/year

compared to disposal costs. The EXXFLOW/EXXPRESS

unit has been in operation since May of 1990.

45
D.5 Industrial Waste Water

Commercial Aluminum Cookware, Toledo, OH

This case study presents the use of a combined EXXFLOW

and EXXPRESS microfiltration system to remove machine

oil. kerosene and particulates from process washwater. The

waste stream comes from a water wash and rinse removing

oil and dirt from aluminum cookware prior to a deionized

rinse and hard anodizing. The water contains up to 150

mg/L of oil and grease.

D.5.1 System Operation

EXXFLOW microfiltration was chosen to treat the

wastewater to recycle quality. An inert powdered absorbent

is added to the water, binding to the oil and grease and

allowing them to be removed by the microfilter. The

microfilter also removes metal fines and other particulates

present in the waste stream. Up to 40 gpm of wash water are

treated by the system. The solids from the EXXFLOW filter

are concentrated further in an EXXPRESS tubular filter

press. The resultant filter cake has 30 to 40% w/w of solids.

D.5.2 System Performance

Use of the EXXFLOW process removes the metal fines,

measured at 10 to 50 mg/L, to below detectable levels. The

oil and grease content of the water is reduced from 150

mg/L to less than 5 mg/L. Since 5 mg/L is the discharge

limit for oil and grease for the stream, treatment with the

EXXPRESS unit would allow discharge of the effluent to

the sewer system. However, the water quality of the effluent

is also acceptable for reuse in the processwasher and 99%

of the water is now recycled in this manner.

D.5.3 Costs

While no detail cost data are available for this case study,

EPOC estimates that the 40 gpm system as installed returned

its total cost within the first three months of operation. as

compared to off-site disposal of the contaminated water.

D.5.4 Reliability

This system was installed in July of 1990 and continues to

be in operation. No other reliability information is available.

46

*U.S. DPRIMTW OFFICE: 1995-653-484