CCET guideline series on intermediate municipal solid waste treatment technologies

Product(Non-Waste)

Mechanical-BiologicalTreatment
Prevention
Preparing for re-use
Recycling

Waste

RecoveryTechnologicalaspects

DisposalFinancialaspects
Governancecapability

Public awareness& cooperationof residents
Socialconditions

October 2020

Institutional
aspects

CCET guideline series on intermediate municipal solid waste treatment technologies:

Mechanical-Biological Treatment (MBT)
Authors

Copyright

Tomonori Ishigaki (National Institute for Environmental© United Nations Environment Programme, 2020

Studies, NIES), Chen Liu (Institute for Global Environmental

This publication may be reproduced in whole or in part

Strategies, IGES)

and in any form for educational or non-proﬁt purposes
without special permission from the copyright holder,

Project Coordination of CCET Guideline series

provided acknowledgement of the source is made.

Premakumara Jagath Dickella Gamaralalage (IGES),The United Nations Environment Programme would

Kazunobu Onogawa (IGES), Yasuhiko Hotta (IGES),

appreciate receiving a copy of any publication that uses

Miwa Tatsuno (IGES), Miki Inoue (IGES), Shunichi Honda

this publication as a source.

(United Nations Environment Programme International
Environmental Technology Centre, UNEP IETC), andNo use of this publication may be made for resale or

Keith Alverson (UNEP IETC)

for any other commercial purpose whatsoever without
prior permission in writing from the United Nations

Peer Reviewers

Environment Programme.

Members of the Japan Society of Material Cycles andWaste Management (JSMCWM): Toshihiko Matsuto

Disclaimer(Hokkaido University), Mikio Kawasaki (Center for

The designations employed and the presentation of theEnvironmental Science in Saitama), Chart Chiemchaisrimaterial in this publication do not imply the expression(Kasetsart University), Dong-Hoon Lee (University ofof any opinion whatsoever on the part of the United

Seoul), and Toru Nishiyama (IGES)

Nations Environment Programme concerning the legal
status of any country, territory, city or area or of its

Acknowledgment

authorities, or concerning delimitation of its frontiersThis guideline was prepared by the IGES Centre

or boundaries. Moreover, the views expressed do not

Collaborating with UNEP on Environmental Technologies

necessarily represent the decision or the stated policy(CCET) in cooperation with the UNEP IETC and the Japanof the United Nations Environment Programme, norSociety of Material Cycles and Waste Management

does citing of trade names or commercial processes(JSMCWM) with financial support from the Government

constitute endorsement.

of Japan. The authors and project team would like tothank all involved for their valuable contributions in

The International Environmental Technology Centre

making this guideline a reality.

works with developing countries to implement
sustainable solutions to environmental challenges, withfocus on holistic waste management.

CCET guideline series on intermediate municipal
solid waste treatment technologies:

Mechanical-Biological Treatment (MBT)

October 2020

Contents
List of Abbreviationsii

About this Mechanical-Biological Treatment Guidelineiii

1. Introduction

1

1.1 Definition of mechanical-biological treatment (MBT)

1

1.2 Historical background and main features of MBT

2

1.3 Opportunities and challenges for cities in developing Asian countries4

2. Pre-conditions for Sustainable MBT (RDF/SRF)

6

2.1 Social conditions

8

2.2 Public awareness and cooperation of residents

10

2.3 Institutional aspects

10

2.4 Governance capability

11

2.5 Financial aspects

12

2.6 Technological aspects

13

3. Main Technology

14

3.1 General technical requirements

14

3.2 Typical MBT processes in developing Asian countries

16

4. Sustainability and Related Global Issues

19

4.1 GHGs and climate change

19

4.2 SDGs

19

5. MBT Practices

20

5.1 Phitsanulok, Thailand

20

5.2 Nashik, India

22

5.3 Rayong, Thailand

25

5.4 Mitoyo, Japan

27

References

29

About the CCET Guideline series

30

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)i

List of Abbreviations

ii

BOO

Build-Own-Operate

CLO

Compost-like Output

GHGs

Greenhouse Gases

GIZ

German Society for International Cooperation

GTZ

German Technical Cooperation Agency

MBT

Mechanical-Biological Treatment

MSW

Municipal Solid Waste

NIMBY

Not In My Backyard

PFI

Private Finance Initiative

RDF

Refuse Derived Fuel

SDGs

Sustainable Development Goals

SRF

Solid Recovered Fuel

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)About this Mechanical-BiologicalTreatment Guideline
Target audience & purpose ofthis guideline
This guideline focuses on Mechanical-BiologicalTreatment (MBT) technology for Municipal
Solid Waste (MSW), mainly household waste
and commercial waste, in urban areas of Asiandeveloping countries.1 The guideline aims toassist decision-makers and policymakers at thenational and city levels and other stakeholders,such as energy plants, as well as manufacturingindustries that are seeking sources of alternative
fuel, to evaluate the feasibility of introducing MBT
technology as an appropriate strategic option forimproving waste management. This guideline will:(1) provide a holistic understanding about MBT
technology including both advantages anddisadvantages, as well as information about
the technical and non-technical aspects ofplanning a sustainable MBT facility, and(2) propose key evaluation criteria and a precheck flow in the decision-making process
to objectively determine and evaluate criteria
when considering the potential of introducing
MBT technology.

Position of MBT in the waste hierarchy
The introduction of MBT technology should follow
the waste hierarchy ( Fig. 1). In this scenario,
priority is placed on prevention to reduce waste
generation, followed by re-use and recycling.
Evaluating the waste stream and identifying
additional potential for reducing, reusing, andrecycling waste are also a critical part of theMSW decision-making process. MBT projects

can be categorised as a type of complementary
technology for the recovery of energy and for theuse of materials in chemical or additional energy
processes from remaining non-recyclable MSW.
For this reason, measures for MBT technology
should not compete with waste reduction, reuse
and material recycling measures.
Furthermore, MBT technology is just one
potential element out of many in a functioning
MSW system. It alone cannot solve existing waste
problems, and decisions on selecting MBT as an
appropriate technology should be made on thebasis of an integrated MSW management plan in
the respective city or country.

Product(Non-Waste)

Waste

Prevention
Preparing for re-use
Recycling

MBT

Recovery
DisposalFig. 1 Waste hierarchy for sustainable waste
management (Source: EU Waste Framework Directive2)

Approach and structure of this guideline
This MBT guideline consists of five mainparts: Chapter 1, “Introduction”, provides basic
information about the concept of MBT technology
and its history, advantages and challenges.
Chapter 2, “Pre-conditions for Sustainable MBT”,

1

The terms “developed and developing countries” in the CCET Guidelines are used to define economies as classified by the World Bank in its
World Development Indicators report published in 2016. The term “developed countries” refers to high-income countries and regions, while
the term “developing countries” encompasses low-income, lower middle income, and upper middle income countries and regions.

2

EU Waste Framework Directive (Directive 2008/98/EC on waste): https://ec.europa.eu/environment/waste/framework/

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Mechanical-Biological Treatment (MBT)iii

describes the key evaluation criteria needed whenplanning an MBT facility and provides a pre-check
framework for sustainable MBT facilities. The
key evaluation criteria include technical, as well
as non-technical facets, i.e. social conditions,public awareness and cooperation of residents,
institutional aspects, governance capability andfinancial aspects. Chapter 3, “Main Technology”,
explains the key technologies used in processes
at MBT facilities. Chapter 4, “Sustainability and
Related Global Issues”, covers the SDGs, GHGs,
and issues that impact the world, and Chapter 5,“MBT Practices”, features actual examples fromboth developed and developing countries.

Message for the busy reader
Busy readers can look over Chapter 1 to quickly
gain a general overview of MBT technology. For
readers considering the potential of introducing
MBT technology, please use Fig. 5 on page 7 asa guide to check conditions that must be in placeat the beginning of the planning stage. Details on
the technology involved in MBT can be found in
Chapter 3.

iv

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)1. Introduction

1

Introduction

1.1 Definition of mechanicalbiological treatment (MBT)
Mechanical-Biological Treatment (MBT) is apretreatment method used before landfilling to
reduce the amount of waste to be disposed.3
MBT literally means the combination of
mechanical crushing and sorting processes andbiological treatment (e.g. aerobic and anaerobic
decomposition) (Fig. 2). The advantage of MBT interms of appropriate waste management is thatit can be applied to mixed domestic solid waste
without systematic segregation. An MBT facility
can incorporate a number of different processes
in a variety of combinations for a wide range of
purposes.4 An advantage in terms of resources isthat MBT can be used to produce Refuse Derived
Fuel (RDF) or Solid Recovered Fuel (SRF)5 andrecover recyclable resources, such as metals,
through the sorting process.6 Biogas can also
be recovered through anaerobic digestion. In
addition to digestate which is generated from theanaerobic digestion process, a stable organic end
product known as Compost-like Output (CLO)7 is
also generated from the aerobic process. Bothdigestate and CLO can potentially be used as asource of organic matter on land or to restore
landfill caps and can also be repurposed as
construction materials, such as backfillingmaterials or aggregates. SRF is a fuel produced
from non-hazardous waste in compliance with
the European standard EN 15359 and also withthe developing standard in ISO (TC300). RDF isa collective term referring calorific wastes thatis potentially used as fuel without the relevantinternational official definition. However, there

Mixed waste input

Recyclables(metals, paper, plastic, etc.)(Aerobic decomposition)

CLO

Mechanical treatment

RDF/SRF

Biological treatment(Anaerobic decomposition)(crushing, shredding, sorting, separation, etc.)(aerobic decomposition, anaerobic decomposition,
bio-drying, etc.)

Biogas and digestate

Remaining waste to landfill

Fig. 2 Typical flow chart of the main processes of MBT

3

Barbara Zeschmar-Lahl, Johannes Jager, Ketel Ketelsen (2000) Mechanisch-biologische Abfallbehandlung in Europa, Blackwell
Wissenschafts-Verlag, Berlin. ISBN: 978-3826332616

4

Stephanie, Thiel and Karl Joachim, Thomé-Kozmiensk (2010) Mechanical-Biological Pre-Treatment of Waste – Hope and Reality
https://www.iswa.org/uploads/tx_iswaknowledgebase/Thiel.pdf

5

The category of RDF is defined as the combustible fraction of waste produced by mechanical treatment in the European Waste Catalogue(EWC). To avoid confusion, the abbreviation SRF is used to refer to solid fuels produced by MBT.

6

Department for Environment, Food & Rural Affairs, UK, (2013) Mechanical Biological Treatment of Municipal Solid Waste

7

CLO is also sometimes referred to as “stabilised bio-waste” or a soil conditioner; it is not the same as compost derived from source
segregated waste or “soil improvers” that have a lower level of contamination and a wider range of end uses.

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)

1

1. Introduction

is a few domestic standrad or rules about RDF,
and the definition of SRF in ISO is still under theprocess as of 2020. Therefore we keep the both
description as SRF/RDF in this guideline. In theparticular practices, the actual name of the fuel as
it is called has been described.

1.2 Historical background andmain features of MBT
MBT was originally introduced as a way to
pretreat waste before landfilling.8 Major drivers
behind the development of MBT technology
include regulatory restrictions on the quality of
waste to be landfilled,9 the search for reasonable
pretreatment technology before landfilling, andincreased costs of landfill disposal. The first
MBT facilities were developed with the aim of
reducing the environmental impact of landfilling
residual waste in Europe.10 Residual waste is a
mixture of waste that is not suited for recycling, ishighly diverse in composition and properties,11 anddoes not fall under a particular category in source
separation schemes. Therefore, the applicationof MBT for mixed municipal waste is seen as aprospect in developing urban regions in Asia andplaces the capability of improving recycling rates
and extending the service life of landfills directly
into the hands of local authorities.
Furthermore, MBT processes are less energy-

intensive than other waste treatment processes
and can conserve energy as well as reduce thevolume of waste.12, 13 In addition, the process of
mechanical separation and biological treatment
need not rely on advanced technology or highend machines.14 The use of localised technology,
including reverse innovation,15 is recommended
to ensure that MBT processes can be adjusted
to local waste properties.16 The technology to be
introduced must be attractive to local governments
or other stakeholders that are facing budgetary or
financial constraints in enforcing policy measures
for improving waste management.
Moreover, MBT systems can form an integral
part of a region’s waste treatment infrastructure
by complementing other waste management
technologies17 to achieve several different aims,
including reducing the volume of waste to belandfilled while simultaneously improving theperformance of recycling (other than RDF) andrecovering biodegradable waste. The typicalobjectives of MBT include:• Reducing the amount of waste to be landfilled• Diverting non-biodegradable and biodegradable

MSW destined for landfills through themechanical sorting of MSW into materials forrecycling and/or into solid fuels such as RDF
or SRF for energy recovery

8

Barbara Zeschmar-Lahl, Johannes Jager, Ketel Ketelsen (2000) Mechanisch-biologische Abfallbehandlung in Europa, Blackwell
Wissenschafts-Verlag, Berlin. ISBN: 978-3826332616

9

The Council of the European Union (1999) Council Directive 1999/31/EC on the Landfill of Waste, Official Journal of the European
Communities, L182,16/07/1999, pp1-19

10 Joern Heerenklage, Rainer Stegmann (1995) Overview of mechanical–biological pretreatment of residual MSW, Proceedings Sardinia 1995,
fifth international landfill symposium, pp 913–925
11 Eunomia Research & Consulting (2002) Ecomomic Analysis of options for managing biodegradable municipal waste, Final Report to theEuropean Commission https://ec.europa.eu/environment/waste/compost/pdf/econanalysis_finalreport.pdf
12 Eunomia Research & Consulting (2002) Ecomomic Analysis of options for managing biodegradable municipal waste, Final Report to theEuropean Commission https://ec.europa.eu/environment/waste/compost/pdf/econanalysis_finalreport.pdf
13 Kardono, Agung Riyadi, Widiatmini Sih Winanɵ, Wahyu Purwanta, Annex1-3 Technology factsheets waste sector, Mechanical-biologicaltreatment (MBT), Indonesia Technology Needs Assessment for Climate Change Mitigation 201214 Klaus Fricke, Heike Santen, Rainer Wallmann (2005) Comparison of selected aerobic and anaerobic procedures for MSW treatment. Waste
Management 25, 799–810
15 Reverse innovation, also referred to as “trickle-up innovation”, is a technology or practice first developed or used in the developing world
before spreading to the industrialised world.
16 Maria Chiara Di Lonardo, Francesco Lombardi, Renato Gavasci (2012) Characterization of MBT plants input and outputs: a review: Reviewsin Environmental Science and Bio/Technology, 11, 4, 353-363
17 Matthias Kuehle-Weidemeier (2015) Waste to Energy and Re-sources, More Sustainability by Mechanical Biological Treatment (MBT) http://
giecdn.blob.core.windows.net/fileuploads/file/kuehle-weidemeier_mbt1.pdf

2

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)1. Introduction• Diverting biodegradable MSW sent tolandfills by reducing the dry mass of
biodegradable municipal waste or reducing
the biodegradability of municipal waste prior
to landfill• Stabilising waste into CLO for use on land
• Converting waste into a combustible biogas• Drying materials to produce a high-calorific,
organically-rich fraction for use as RDF/SRF

The main advantages, disadvantages andrequirements of MBT from different perspectives
are summarised in Table 1.

for energy recovery

Table 1 Main advantages, disadvantages and requirements of MBT

Waste

Technology

Advantage

Disadvantage

Requirement*

1. Reduced volume of waste
destined for landfills

1. Poor quality of dry
recyclables separated out
during the MBT process

1. Management of debris suchas rejected solid fuels or
CLO

1. High feasibility of use incombination with existing
technology

1. Unsuitable for bulky
waste, liquid waste andnight soil

1. Essential to adapt drying
and separation processes
for waste in Asia with highmoisture levels, as well as
for waste that is organic

2. Advanced technology or
high-end machines not
required

2. Need for initial wastesorting process to remove
foreign objects and improve
efficiency

3. Suitable for moist MSW withanaerobic digestion or biodrying before separation
1. Intensive, low-energy method 1. RDF/SRF consumption
depends on fuel price and
2. Savings in fuel costs forindustrial situation
users of RDF/SRF
Economic
implications

3. Potential use of CLO as soil
conditioners or back fillingmaterials
3. Can be adapted to markets
for recyclables, RDF/SRF,
CLO and biogas

2. Essential to consider thelimited pool of industrial
consumers of RDF/SRF
in Asian markets, risk ofoverstock of rejected RDF/
SRF or increase in volume
of waste for disposal

1. Crucial to secure multiple
sales channels for RDF/SRF
2. Profits expected from salesof valuable metals and
CLO for income rather thantreatment costs. In contrast,
the cost for disposal ofdebris should be taken into
account even though it has
potential for use as CLO.

3. Fewer benefits in using
CLO
Public health

Environment

GHG
emissions

1. Less infectious and toxic
than dumpsites

1. Waste not effectively
sanitised compared tothermal treatment orcomposting

1. Important to regulate andscreen feedstock for nonhazardous waste

1. Less environmental
pollution from landfills

1. Projections for noise,
vibration, dust and waste
volume1. Important to regulate andscreen feedstock for nonhazardous waste

2. Efficient for resourceand energy recovery
and conserving natural
resources such as soils,
metals and fuels
1. Lower GHG emissions in
the overall process of waste
management

2. Potential emissions ofatmospheric pollutants by
RDF/SRF consumers
1. Increased emissions of
nitrous compounds fromlandfills as a result of low
C/N debris

1. Life cycle assessments
recommended* Does not include common issues in other waste management facilities that need to be considered, such as plant/facility siting,traffic, air emissions, dust/odours, bio-aerosols, flies, noise, litter, waste resources, design principles, public concerns, etc.
(Source: author)

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Mechanical-Biological Treatment (MBT)3

1. Introduction

1.3 Opportunities andchallenges for cities indeveloping Asian countries
Several attempts have been made to transfer
MBT technology to developing countries in Asia18
and South America.19 However, these efforts havemostly failed to adapt the technology to local
conditions and results have been limited. In recent
years, especially in Southeast Asia where urban
development has been remarkable, the focus ofattention has been redirected to the introductionof MBT as a technology to cope with the increasein waste volume as well as the promotion of 3R(reduce, reuse and recycle) policies.20, 21
MBT is recommended for:(1) Cities that are becoming more urbanised
and need to develop integrated waste
management, but do not have a stablefinancial base or external/internal support,
and/or have poor source separation practices

RDF/SRF, such as the existence of a cement
industry, remaining capacity at a lignite power
plant or WtE plant, or heat demand at a paper
manufacturer in the wood industry
MBT may be attractive to (Fig. 3):(1) A local authority that wants to maximise
landfill space and is continuing to manage
waste by direct disposal, and/or is looking fora cost-effective pretreatment method before
landfilling(2) A waste management company or local
authority that wants to leverage economic
incentives from waste management andrecycling(3) An industry that is aiming to save on fuel costs,
or to expand the utilisation of recyclable
materials(4) A central government that is aiming to expand
the utilisation of renewable energy(2) Cities with an industrial base that can use

Waste to Resource Industry

Local Authority

 that wants to enhance regional resource efficiency
 that is looking for cost-effective pretreatment
methods before landfilling that must maximise landfill capacity

 that wants to expand the economic incentives
from waste management and recycling

Industrial User

Central Government
 that wants to expand theuse of renewable energy that is shifting to acircular economy

 that wants to save fuel costs, or to expand thepossible uses of recyclable materials

Fig. 3 Users that can benefit from MBT
18 Tomonori Ishigaki, Ssatoru Ochiai, Masato Yamada, Dong-Hung Lee, Jae-Ram Park, Komsilp Wangyao (2016) Applicability of MBT in Middle
Scale and Small Scale Municipality in Asia, The 9th Inter-continental Landfill Research Symposium, pp.100-101.
19 Alberto Bezama, Pablo Aguayo, Odorico Konrad, Rodrigo Navia, Karl E Lorber (2007) Investigations on mechanical biological treatment ofwaste in South America: towards more sustainable MSW management strategies. Waste Management, 27, 228–237
20 Nemanja Stanisavljevic, Paul H Brunner (2014) Combination of material flow analysis and substance flow analysis: A powerful approach fordecision support in waste management, Waste Management & Research, 32, 8, 733-744
21 International Solid Waste Association Task Force (2014) Globalization and Waste Management
https://www.iswa.org/index.php?eID=tx_iswaknowledgebase_download&documentUid=3818

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Mechanical-Biological Treatment (MBT)1. Introduction

However, the characteristics of MSW in developing
countries in Asia differ from that in developed
countries due to differences in consumption levels
and lifestyles. This means that the reasoning
behind the demand for MBT technology also varies.
For European Countries those were forced to
introduce the pretreatment of MSW in accordancewith EU directive,22 the main role of MBT facilities
is to stabilise organic waste and recover valuable
recyclable materials. For developing countries,
where at least 50% of MSW contains organic
waste,23 the amount of recyclables present in
waste is much lower as these materials are
separated out by the informal recycling sector.24
In this context, the demand for MBT facilities
in Asia is primarily for the treatment of organic
waste and utilisation of byproducts (such as RDF,
SRF, biogas and CLO), while the separation ofrecyclables has a limited overall effect. Althougha variety of treatment and mechanical separation
options are available,25 the use of this output as
byproducts must be optimised in order to identify
outlets for the variety of materials and fuels
derived from the MBT process.
The key to sustainable MBT is securing a market
for RDF/SRF. Because of the limited numberof industrial furnaces in developing countries
compared to developed countries, potential
consumers must be found in wide areas (intercity or inter-province) for a broad range ofapplications. Competition with other RDF/SRF
manufacturers and other alternative fuels canfind these manufacturers struggling to meet high-quality requirements from consumers, for example,
setting a calorific value of 5,000 kcal/kg,26, 27 which
is close to that of coal. In some cases, efforts are
made to slightly improve sorting efficiency to raise
the quality of RDF/SRF to match market needs.
Meanwhile, there are cases where waste only
undergoes biological treatment with little sorting
to reduce the volume of landfilled waste.
Waste such as food waste or inedible partsof fruits or vegetables in Southeast Asia has
high levels of moisture and organic matter.28
The introduction of such waste into the MBT
process may result in poor crushing and sorting
efficiency. Therefore, the moisture content ofwaste must be lowered before the start of the
MBT process. Solar drying is possible under someconditions,29 but other problems exist, including
odours, scattering of garbage and vulnerabilities
to sudden precipitation. Endogenous heat during
the biological process must be applied prior to
the use of heat, such as a bio-drying process inwhich organic matter is decomposed and driedby generated heat using a biological reaction.30
Waste heat is sometimes used for drying RDF/
SRF, but this type of valuable, high-quality energy
is better used as high-density energy flux.
Above all, the choice of introducing MBT
technology depends on the size of the city,
industrial concentration, and the feasibility of
improving the transportation environment, whichshould be reviewed in line with the growth of thecity and the region as a whole.

22 The Council of the European Union (1999) Council Directive 1999/31/EC on the Landfill of Waste, Official Journal of the European
Communities, L182,16/07/1999, pp1-19
23 World Bank (2018) What a Waste Global Database, https://datacatalog.worldbank.org/dataset/what-waste-global-database
24 Agamuthu Pariatamby (2017) Chapter 3 Waste Management, In Asia Waste Management Outlook, UN Environment Programme
25 Stephanie, Thiel and Karl Joachim, Thomé-Kozmiensk (2010) Mechanical-Biological Pre-Treatment of Waste – Hope and Reality
https://www.iswa.org/uploads/tx_iswaknowledgebase/Thiel.pdf
26 Jidapa Nithikul, Obulisamy Parthiba Karthikeyan, Chettiyappan Visvanathan (2011) Reject management from a mechanical biologicaltreatment plant in Bangkok, Thailand, Resources, Conservation & Recycling, 55, 417–422
27 Satoru Ochiai, Tomonori Ishigaki, Komsilp Wangyao, Masato Yamada (2014) Adaptability of Mechanical Biological Treatment in TropicalAsia, A Case Study in Thailand, 25th Annual Conference of Japan Society of Material Cycles and Waste Management, pp.625-626
28 Ashok V Shekdar (2009) Sustainable solid waste management: An integrated approach for Asian countries, Waste Management, 29, 14381448
29 André Guimarães Ferreira, Lindomar Matias Gonçalves, Cristiana Brasil Maia (2014) Solar drying of a solid waste from steel wire industry.
Applied Thermal Engineering, 73, 104–110.
30 Costas Velis, Philip John Longhurst, Gillian H. Drew, Richard Smith, Simon James Trent Pollard (2009) Biodrying for mechanical-biologicaltreatment of wastes: a review of process science and engineering, Bioresource Technology 100, 11, 2747–61.

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Mechanical-Biological Treatment (MBT)5

2. Pre-conditions for Sustainable MBT (RDF/SRF)

2

Pre-conditions for Sustainable
MBT (RDF/SRF)

Before making a political decision to select MBT as
an appropriate waste treatment technology for theoverall waste management system, it is necessary
to have a comprehensive understanding andevaluate the situation from various perspectives
in order to ensure that MBT is implemented in asustainable manner. There have been numerous
examples where “proven” technologies indeveloped countries have failed in developing
countries because sufficient attention was not
paid to “soft” strategic aspects, namely, political,
institutional, social, financial, economic andtechnical elements.31, 32 Although each MBT facility
requires a site-specific approach, it is possible toidentify a few key generic factors.
In this guideline, key evaluation criteria can beverified from six perspectives–social conditions,public awareness and cooperation of residents,
institutional aspects, governance capability,
financial aspects and technical aspects (Fig. 4).
Following the six perspectives together withrelative key evaluation criteria for each, a modified
pre-check flow (Fig. 5) can be used as a guideat the beginning of the planning stage. The key
evaluation criteria and pre-check flow are presented
to assist decision-makers and policymakers intaking a closer look at whether local conditions
are suitable for MBT technology and developing atransparent assessment of what technology best
fits with these conditions. This does not, however,replace the need for a professional assessment
on feasibility when planning a MBT project. Only
after confirming its probability for success shoulda project move on to the next step, which is a moredetailed feasibility study and implementation planfor introducing appropriate technology before theactual construction of a MBT facility, as shown in
Fig. 4.

Key evaluation criteria are divided into threegroups: (1) mandatory key criteria ( in pink ), (2)strongly advisable key criteria ( in yellow ), and (3)advisable key criteria ( in green ). Arrows should be
followed to proceed to the next step in cases where
evaluation criteria are met. If criteria have not beenmet, the following actions are recommended:(1) in cases where mandatory key criteria
are not met, MBT is not yet suitable. It isstrongly recommended that the evaluation besuspended or that the situation be re-evaluatedafter improvements are made;Key aspects to check at
the planning stage whenselecting appropriate technology

Social conditions
Public awareness andcooperation of residents

Institutional aspects

Financial aspects

Governance capability

Technological aspects

Feasibility study andbusiness planning for introducing
appropriate technology

Fig. 4 Key aspects to check at the planningstage when selecting appropriate technology(Source: author)

31 International Solid Waste Association Task Force (2014) Globalization and Waste Management
https://www.iswa.org/index.php?eID=tx_iswaknowledgebase_download&documentUid=3818
32 Kai Münnich, Gunnar Ziehmann, Klaus Fricke (2002) Biological pre-treatment of municipal solid waste in low income countries, Proceedingsof International Symposium on Environmental Pollution Control and Waste Management, p.293-303.

6

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)Hazardous andinfectious waste
must be separated
from MSW tominimise theimpact on thequality of
RDF/SRF.

MBT is positioned
in upper level plans(comprehensive
plans, regional
development
strategies, etc.).

Positive
attitudes frame
commitments to
reduce waste
management
costs.
Revenue can beensured throughthe sale of
RDF/SRF based oncontracts andagreements with
consumers on
RDF/SRFconditions.

Financial aspects

Governance capability

Localisedtechnology,
including reverse
innovation, isavailable.

Basic data andtechnology must be
available tominimise moisture
content andhazardous waste.

Technical aspects

Fig. 5 Pre-check flow to be conducted at the beginning of the planning stage whendeveloping MBT projects
in cases where strongly advisable key criteria are not met, consider improving the situation
through support measures or alternative proposals
in cases where advisable key criteria are not met, consider it risky to implement

Strongly advisable key criteria

Advisable key criteria

in cases where mandatory key criteria are not met, suspend the evaluation or re-evaluate after
improvements are madeA site where an
MBT facility can bebuilt is available.

Schemes topromote theutilisation of
RDF/SRF are inplace.

Institutional aspects

Cooperation and understanding of residents

Mandatory key criteria

There is a strongsocial need to
introduce MBT due
to the necessity to
prolong the service
life of disposalsites and promote
policies on the useof renewableenergy.

An appropriate
system for MSW
collection andtransport should bein place to secure
MSW sources for
RDF/SRF and ﬁnal
disposal for CLOs.

There is a strong
market demand for
RDF/SRF.

Social conditions
Feasibility
study andbusinessplanning
for full
implementation

2. Pre-conditions for Sustainable MBT (RDF/SRF)(Source: author)

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Mechanical-Biological Treatment (MBT)7

2. Pre-conditions for Sustainable MBT (RDF/SRF)(2) in cases where strongly advisable key criteria
are not met, support measures should
be introduced, or alternative proposals
considered;(3) in cases where advisable key criteria are notmet, caution should be exercised as MBT canbe risky to implement.
In addition, considering that the main purposeof MBT in developing countries in Asia is theseparation of a fraction of RDF/SRF and that the“CCET guideline series on intermediate municipal
solid waste treatment technologies: Composting”
and “CCET guideline series on intermediate
municipal solid waste treatment technologies:
Waste-to-Energy Incineration” have been designed
as part of the same series, this guideline mainly
focuses on RDF/SRF, and the related issues ofcomposting and anaerobic digestion technology
are not addressed here in detail.

2.1 Social conditions
2.1.1 Secure users of RDF/SRF

Mandatory key criteria
There is a strong market demand for RDF/SRF.
The local region should possess a strong industrial
background to ensure the continuous and stableutilisation of RDF/SRF. Sustainable operation
can only be achieved with industrial furnaces,
waste incinerators, or RDF/SRF power plants.
For example, cement kilns that are located withina profitable distance would be potential users of
RDF/SRF.33, 34 Lignite power plants are also someof the biggest users of RDF/SRF in Europe andcould have similar potential in Asia.35 Pulp andpaper manufacturers also require alternative fuelfor their boilers.
Contracts between RDF/SRF providers (MBT
owner/operator) and users are mainly based on thequality of RDF/SRF and the market price of fossil

fuels. On top of that, a key factor for the successful
distribution of RDF/SRF is a relationship of mutual
trust with local consumers. Industrial RDF/SRF
users generally require a stable supply of fuel interms of quality and quantity. If there are no issues
with waste collection and transportation systems,
RDF/SRF production will be stable in terms of theamount produced. RDF/SRF is not strong in termsof cost competitiveness,36 and therefore, should be
consumed as close as possible to the local region.
RDF/SRF must prove that it can offer consumers
the level of quality they require. The application ofregional or international standards may be needed
to ensure the quality of RDF/SRF.
In order to increase the marketability of RDF/

33 ECOFYS (2016) Market opportunities for use of alternative fuels in cement plants across the EU
http://www.titan.rs/public/uploaded_files/ecofysreport_wastetoenergy_2016-07-08.pdf
34 Costas A Velis, Philip John Longhurst, Gillian H. Drew, Richard D Smith, Simon James Trent Pollard (2010) Production and quality
assurance of solid recovered fuels using mechanical-biological treatment (MBT) of waste: a comprehensive assessment. Critical Reviews inEnvironmental Science and Technology 40, 12, 979–1105
35 Thomas Glorius (2009) SRF in a CHP-plant in Germany ERFO Conference om Solid Recovered Fuels (SRF) – A sustainable option for Spain
36 Jan Theulen (2013) Standardization as a help to facilitate SRF acceptance and use, Experience of the European Cement Industry
http://www.eu-projects.de/Portals/11/08_Theulen_ERFO.pdf

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SRF, legislation promoting the use of recycledmaterials, e.g. green procurement, can be applied
to increase the use of RDF/SRF, although it canhave an adverse effect on a large segment ofbusinesses and industries in the region. A Feedin Tariff on renewable energy use is also aneffective measure to promote the use of RDF/SRF
which contains renewable fractions.

2.1.2 Secure feedstock for RDF/SRF

Strongly advisable key criteria
An appropriate system for MSW collection and transport should be in place to secure
MSW sources for RDF/SRF and final disposal for CLOs.

In general, MBT can be applied to any population
size because its treatment capacity can be
flexibly expanded by changing the machinery
used. In terms of the efficiency of mass treatment,
MBT is recommended for small- to middlescale municipalities (e.g. population of less than
100,000). However, it is essential to secure a certain
quantity and quality of MSW. Future changes incomposition as a result of the implementationof policies such as reducing plastic, for example,
should be taken into consideration because it canaffect the stable production and quality of RDF/
SRF. For example, existing formal and informal
schemes for recycling paper and plastic affect thequality of RDF/SRF.

2.1.3 Social needs

Advisable key criteria
There is a strong social need to introduce MBT due to the necessity to prolong theservice life of disposal sites and promote policies on the use of renewable energy.

It is necessary to identify the needs of the society
for introducing MBT, such as requirements toprolong the service life of disposal sites, which
include both illegal waste disposal areas andlandfills, as well as to promote policies on the use ofrenewable energy and so on. It is essential to cometo an agreement on constructing MBT facilities,

as well as other waste management facilities.
If all segments of society are willing to expand
landfill capacity, they will proactively support theconstruction of MBT facilities. Alternatively, if
there are any objections against WtE incineration,for example, there may be passive or no support
for the implementation of MBT.

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2. Pre-conditions for Sustainable MBT (RDF/SRF)

2.2 Public awareness and cooperation of residents
Mandatory key criteria
Hazardous and infectious waste must be separated from MSW to minimise the impact
on the quality of RDF/SRF.

To avoid the loss of RDF/SRF value throughcontamination with hazardous compounds, it
is essential that people cooperate to remove
waste containing hazardous substances. Toxic

chemicals as well as infectious waste must be
carefully separated from domestic waste that will
be sent to MBT facilities.37, 38

2.3 Institutional aspects
Strongly advisable key criteria
Schemes to promote the utilisation of RDF/SRF are in place.
Commonly accepted and universal quality
standards for RDF/SRF should be put in placethrough agreements based on common testing
methods. Standards on quality will lower the barrier
for potential RDF/SRF users and will expand themarket. Although there may be quality standards
in Europe39, Japan40 or the United States41 that

may be of reference, it is recommended thatcountry-based or regional-based standards beestablished based on local conditions. Global
standards are currently being developed by theInternational Organization for Standardization(ISO) and will be published at a later date.42

Strongly advisable key criteria
A site where an MBT facility can be built is available.
Securing a construction site is a fundamental
part of satisfying requirements and achieving
the goals of MBT plans. Sites are also subject
to various laws and restrictions, such as urban

planning and building standards, so it is importantto advance plans from a comprehensive
perspective.

37 Kardono, Agung Riyadi, Widiatmini Sih Winanɵ, Wahyu Purwanta (2012) Annex1-3 Technology factsheets waste sector, Mechanicalbiological treatment (MBT), In Indonesia Technology Needs Assessment for Climate Change Mitigation 201238 Vera Susanne Rotter, Thomas Kost, Joerg Winkler, Bernd Bilitewski (2004) Material flow analysis of RDF-production processes, Waste
Management, 24, 1005–1021
39 CEN, EN15359 (2011) Solid Recovered Fuels―Specifications and Classes. Brussels, CEN
40 JIS Z 7311 (2010) Refuse derived paper and plastics densified fuel.
41 ASTM E856-83(2004) Standard Definitions of Terms and Abbreviations Relating to Physical and Chemical Characteristics of Refuse Derived
Fuel
42 Rieko Kubota Development of SRF standard in ISO TC300, Knowledge sharing seminar on RDF production, utilization, standardization
seminar

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2.4 Governance capability
Mandatory key criteria
Positive attitudes frame commitments to reduce waste management costs.

The introduction of MBT projects is influenced bypolitical needs in local governments. The headof the local government must have a positive
and open attitude towards the construction andoperation of MBT facilities. The roles of related
departments in local governments must be
clarified initially, with officers in charge appointed
by the head of the local government.
Meanwhile, MBT is often regarded as a traditional
type of technology for treating mixed MSW in apractical and reasonable way in cases where
the level of technology and economic scale areless mature in terms of incineration or othertypes of technology used for mass treatment.43
MBT is recommended for municipalities thatcannot afford to introduce high-cost treatment

technology, such as incineration. Therefore, it
is important to confirm the cost-effectiveness of
implementing MBT to reduce municipal budgets
for waste management.44, 45 MBT should always beassessed against its impacts, such as reductionsin the amount of waste sent to the landfill,energy produced, revenue, and other benefits.
These relevant targets and indicators shall beclearly shown and shared in advance before theproject is implemented, irrespective of whether
the facility is operated by the public or private
sector. Local governments should maintain theright to advise private contractors (i.e. special
purpose companies, SPC), in order to maximise
the effectiveness of the project as demonstrated
by indicators, as well as the monetary value of the
project.

Strongly advisable key criteria
MBT is positioned in upper level plans (comprehensive plans, regional development
strategies, etc.).

MBT should be formally/legally recognised inupper level plans such as comprehensive plans,regional development strategies, and otherrelevant plans. Specific master plans or policy
initiatives will be also effective in realising its

implementation. When MBT is positioned in suchplans, facility design, construction and operation,
as well as actions to educate the public, will move
forward smoothly.

43 International Solid Waste Association Task Force (2014) Globalization and Waste Management
https://www.iswa.org/index.php?eID=tx_iswaknowledgebase_download&documentUid=3818
44 Kardono, Agung Riyadi, Widiatmini Sih Winanɵ, Wahyu Purwanta (2012) Annex1-3 Technology factsheets waste sector, Mechanicalbiological treatment (MBT), In Indonesia Technology Needs Assessment for Climate Change Mitigation 201245 Satoru Ochiai, Tomonori Ishigaki, Masato Yamada (2015) Comparison of Mechanical Biological Treatment Operations Based on Cost andBenefit in Asia, 2nd 3R International Scientific Conference on Material Cycles and Waste Management, pp.210-213

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2. Pre-conditions for Sustainable MBT (RDF/SRF)

2.5 Financial aspects
Mandatory key criteria
Revenue can be ensured through the sale of RDF/SRF based on contracts andagreements with consumers on RDF/SRF conditions.

MBT involves a wide range of costs depending on
the complexity of the technology, especially when
considering the biological process to be adopted
and the degree of mechanisation and automation
to be employed. MBT systems are also particularly
sensitive to markets for recycled materials, RDF/
SRF and CLO that are produced by different
processes because tradability and marketability
are strongly affected by fossil fuel conditions.46
Partnerships between MBT operators andpotential users of outputs should be establishedat the earliest opportunity and care should betaken to ensure facilities can deliver materials of
sufficient quality for the required market (DEFRA,
2013). In particular, unsold RDF/SRF will become aburden for MBT operators if they must be stored at
the facility, an indication that it must be disposedof in landfill sites. Securing RDF/SRF consumers
is essential not only for the successful operationof MBT facilities, but also for sustainable waste
management in the region. SRF can be used ina wide variety of industries for heat and power

generation, such as industrial furnaces andboilers, as well as in municipal facilities, such as
SRF power plants and district heating and cooling
services.47 There should be no expectations thatthe sale of RDF/SRF will result in strong profits
because sales can be highly unstable depending
on contract and market conditions. In this way,these profits should not be considered as a major
form of revenue in budget estimations, although
it may account for some income.
In addition, as with other MSW technology, thecosts of MBT projects (capital and operating
costs) must be secured. Subsidies or loans must
be prepared from the local government’s own
budget to cover the costs for operation (e.g.
maintenance of equipment, fuel, electricity, tipping
fees, etc.), and reliable investors must be involved.
Tipping fees are normally taken into consideration
when the disposal of debris is outsourced. MBT
processes and landfill management are notalways handled by the same sections.

46 ECOFYS (2016) Market opportunities for use of alternative fuels in cement plants across the EU
http://www.titan.rs/public/uploaded_files/ecofysreport_wastetoenergy_2016-07-08.pdf
47 Eleni Iacovidou, John Hahladakis, Innes Deans, Costas Velis, Phil Purnell (2018) Technical properties of biomass and solid recovered fuel(SRF) co-fired with coal: Impact on multi-dimensional resource recovery value, Waste Management, 73, 535-545

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2.6 Technological aspects
Mandatory key criteria
Basic data and technology must be available to minimise moisture content andhazardous waste.

MBT is suitable for mixed domestic waste andresidual waste that does not fall under othercategories in source separation schemes.
Even though MBT is suitable for treating mixed
domestic waste, the high moisture content is atechnical barrier to proper treatment in termsof efficient mechanical separation.48 The biodrying process is efficient in removing moisture,ensuring that the waste can be sorted, which
increases the quality of RDF/SRF. The removalof food waste in advance will also increase theefficiency of the separation process and result in
the production of high-quality RDF/SRF.49 Since
domestic waste in the tropical climate of Asia has
a higher moisture content than that in European

countries,50 it is essential to dry MSW before itis physically separated, although the input ofenergy for heating should be prevented as muchas possible in order to reduce additional operating
costs. Industrial waste, which is mainly composedof paper, plastics and wood, can also be used for
MBT, although these wastes are more suitable asrecyclables. Hazardous waste should not be mixed
in with waste, as hazardous compounds, including
toxic, infectious, or explosive matter in materials,
may affect the quality of RDF/SRF. Bulky waste,liquid waste and night soil are also not suitablefor MBT. Specific waste to be avoided for MBT
shall be decided by local laws and regulations andthrough contracts with RDF/SRF consumers.

Strongly advisable key criteria
Localised technology, including reverse innovation, is available.
As mentioned above, the process for mechanicalseparation and biological treatment does notneed to rely on advanced technology or highend machines. The use of localised technology,

including reverse innovation, is recommended toensure that MBT can be adapted to local waste
properties.

48 Kardono, Agung Riyadi, Widiatmini Sih Winanɵ, Wahyu Purwanta (2012) Annex1-3 Technology factsheets waste sector, Mechanicalbiological treatment (MBT), In Indonesia Technology Needs Assessment for Climate Change Mitigation 2012
49 Maria Chiara Di Lonardo, Francesco Lombardi, Renato Gavasci (2012) Characterization of MBT plants input and outputs: a review: Reviewsin Environmental Science and Bio/Technology, 11, 4, 353-363
50 Ashok V Shekdar (2009) Sustainable solid waste management: An integrated approach for Asian countries, Waste Management, 29, 14381448

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3. Main Technology

3

Main Technology

3.1 General technical requirements
MBT is a comprehensive system that combines
two processes: a mechanical process (waste
preparation and separation) and biological
M: Mechanical (Physical) Processprocess (aerobic or anaerobic waste
decomposition, and bio-drying). The mechanicaland biological processes can be arranged ineither order, with mechanical treatment preceding
biological treatment or vice versa (Fig. 6).
Refuse Derived Fuel

B: Biological Process
Aerobic
degradation

Bio-drying

DebrisAnaerobic
digestion

Resource Recovery

Biogas (energy)

Fig. 6 Brief outline of MBT system

3.1.1 Waste preparation
MSW must be prepared before biological treatment
or materials are sorted, such as removal, shredding,and crushing. Initial waste preparation may take theform of the simple removal of unsuitable objects,
such as mattresses, carpets or other bulky wastes,
which may cause problems with processing
equipment downstream. Additional mechanicalwaste preparation techniques may be used toprepare the materials for subsequent separation
stages. The objective of these techniques may
be to split open refuse bags, thereby liberating
the materials inside, to shred and homogenise
the waste into smaller particle sizes suitable fora variety of separation processes, or to perform
subsequent biological treatment depending on
the MBT process employed (DEFRA, 2013). A
summary of the different techniques used for
waste preparation is provided in Table 2.

Table 2 Waste preparation techniques
Technique14

Principle function

Key concerns

Hammer millMaterial significantly reduced in sizeby swinging steel hammers.

Wear on hammers. Pulverising and ‘loss’of glass/aggregates.
Excludes pressurised containers.

ShredderRotation of knives or hooks at slow
speeds with high torque. The shearing
action tears or cuts most materials.

Potential for large, rigid objects tophysically damage the shredder.
Excludes pressurised containers.

Bag splitter

Relatively gentle shredder used to
split plastic bags whilst leaving the
majority of the waste intact.

No reduction in size of waste.
Potential for large, rigid objects to damage
the splitter.

Manual separation

Separation of plastics, contaminants andoversized materials from waste by hand.

Ethics of roles, health and safety issues.

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3.1.2 Waste separation
Separation technologies exploit the varying
properties of different materials in the waste.
This includes the size and shape of different
objects, density, weight, magnetism, and electricalproperties (DEFRA, 2007). Sorting the waste
allows the MBT process to separate different
materials that are suitable for different end uses

and sequential processes, including material
recycling, biological treatment, energy recovery
through the production of RDF/SRF, and landfill.
A variety of different techniques can be employed,
and most MBT facilities use a series of several
different techniques in combination to achieve
specific end use requirements for different
materials. A summary of the different options for
waste separation is shown in Table 3.

Table 3 Waste separation techniques
Separation technique

Separation property

Target material

Key concerns
Air containment andcleaning

Trommels and screens

Size

Oversized paper, plastic
Small organics, glass,fine fractions

Magnetic separation

Magnetic properties

Ferrous metals

Proven technique

Eddy current separation

Electrical conductivity

Non-ferrous metals

Proven technique

Air classification

WeightLight plastics, paper
Heavy stones, glass

Air cleaning

Ballistic separation

Density and elasticity

Light plastics, paper
Heavy stones, glass

Rates of throughput

Optical separation

Diffraction

Specific plastic polymers

Rates of throughput

Vibrating screen

Size and density

Plastic film, paper, sheets,
sand and stones

Mesh size,
accelerated vibration,
rates of throughput

3.1.3 Biological treatment
The biological processes used in MBT include
aerobic decomposition, aerobic bio-drying,
and anaerobic digestion. There are a variety ofdifferent biological treatment techniques used
in MBT facilities (DEFRA, 2013). The aerobic
decomposition process is similar to composting
though the product quality is not always
comparable. This process aims to maximise thedecomposition of degradable organic matterin domestic waste. Therefore, aeration rates orfrequency of turning is optimised for microbes inthe decomposition process.

The addition of moisture or growth of microbial
cells will lower the quality of RDF/SRF, although thequality of CLO may improve. In contrast, aerobic
bio-drying aims to maximise the evaporation ofmoisture in domestic waste.51 Since the main heatsource is also biological decomposition, aerationand turning processes are also performed.
However, microbial growth must be controlled
because it acts as a moisture sink and impedes
drying. These bacterial cells, also known as heatscavengers, consume heat and inhibit efficientevaporation.
Anaerobic digestion is a familiar process used in

51 Costas Velis, Philip John Longhurst, Gillian H. Drew, Richard Smith, Simon James Trent Pollard (2009) Biodrying for mechanical-biologicaltreatment of wastes: a review of process science and engineering, Bioresource Technology 100, 11, 2747–61.

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3. Main Technology

the management of livestock manure or septage in
Asian countries.52, 53 The isolated use of anaerobic
digestion often fails due to the low rate ofproduction of biogas because of a lack of organic
matter for anaerobic microbes. It is recommended
that the anaerobic digestion process in MBT belinked with other organic sources to produce a
feasible amount of biogas. Table 4 below outlines
the key categories of biological treatment. In someprocesses, all the residual MSW is biologicallytreated to produce stabilised output for disposal
to landfills where no sorting is required.

Table 4 Biological treatment options
Options

Key concerns

1

Aerobic decomposition: Open piles or in-vessel reactors, which are generally used for sludge,night soil, bio-waste or segregated organic-rich fractions

2

Aerobic bio-drying: Optimised for reducing moisture in waste

3

Anaerobic digestion: Generally used for sludge, night soil, bio-waste, or segregated organic-richfractions

3.2 Typical MBT processes indeveloping Asian countries
The mechanical process in MBT is not a single
process but a sequence of processes that use
several technologies. In developing countries
in Asia, the main purpose of the mechanicalprocess is to separate fractions for RDF/
SRF. Appropriate technology must be selectedaccording to the physical properties of waste
to maximise the quality of RDF/SRF. This,
however, does not require advanced technology
to be used, and a combination of locally available
separation techniques can be examined before
implementation.
The anaerobic degradation process is almost
the same as anaerobic digestion (see the “CCET
guideline series on intermediate municipal
solid waste treatment technologies: Anaerobic
Digestion”). However, anaerobic digestion is
unsuitable for unit processes in mixed domestic
waste in Asia due to the low putrescible fractionin the dry base. To enable the successful
implementation of anaerobic digestion,
continuous and stable biogas emissions are
required. If stakeholders are resolute in their
willingness to use biogas and there is a social
and industrial basis to do so, the mechanicalseparation process must be performed prior toanaerobic digestion (Fig. 7-a). Otherwise, since
the residue from this process contains a certain
amount of organics and moisture, it will betechnically and practically difficult for waste to betreated with MBT in terms of RDF/SRF production,
and additional processes may be required forpost-treatment. Another option for the anaerobic
digestion process is to utilise external anaerobic
digestion facilities for treating suitable waste, orto be designed for treating suitable waste such asorganic sludge, agricultural waste, green waste
and others (Fig. 7-b).
The aerobic degradation process requires theintroduction of air for microbes; however, a highaeration rate, such as is used in the composting

52 International Atomic Energy Agency (2008) Guidelines for Sustainable Manure Management in Asian Livestock Production Systems
https://www-pub.iaea.org/MTCD/Publications/PDF/TE_1582_web.pdf
53 Tiffany Joan Sotelo, Hiroyasu Satoh, Takashi Mino (2019) Assessing Wastewater Management in the Developing Countries of Southeast
Asia: Underlining Flexibility in Appropriateness, Journal of Water and Environment Technology, 17, 5, 287–301

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process, is not appropriate for MBT, although
the bio-drying process is favourable for energy,material recovery and cost efficiency in MBT
for mixed waste in tropical countries. The
basic technology used in bio-drying is similar tothat used in composting, although bio-drying
is not optimised for biodegradation.54 Biodrying maximises the evaporation of moisture
in waste by using the heat generated throughbiodegradation. The biggest advantage of biodrying is its ability to help increase separation
efficiency before the mechanical process (Fig. 7-c).
Open-air pile, windrow or other locally developed
technology in the open air are more suitable thanin-vessel reactors from the perspective of cost
and technological feasibility, although practices
in developed countries may demonstrate a levelof effectiveness with in-vessel bioprocesses orbioreactors in waste decomposition.55, 56

In addition, the efficiency of reducing the volume
of waste and producing RDF/SRF is determinedby the order of the mechanical and biologicalprocesses. In considering the high moisture
content of domestic waste in developing countries
in Asia, biological treatment is often performed
prior to mechanical separation in order to increase
separation efficiency. It is for this reason that thebiological process in this region focuses more on
drying than decomposition or digestion.
Also, final waste that is not suitable for RDF/SRF
due to size, contamination or moisture is generally
disposed of in final landfills. While it is regarded as
CLO, its utilisation in the environment as backfillingmaterial should be carefully controlled to avoid
becoming a source of pollution.57, 58 RDF/SRF is
recommended for use in closed areas, such as forcover materials in waste landfills.

54 Costas Velis, Philip John Longhurst, Gillian H. Drew, Richard Smith, Simon James Trent Pollard (2009) Biodrying for mechanical-biologicaltreatment of wastes: a review of process science and engineering, Bioresource Technology 100, 11, 2747–61.
55 Costas Velis, Philip John Longhurst, Gillian H. Drew, Richard Smith, Simon James Trent Pollard (2009) Biodrying for mechanical-biologicaltreatment of wastes: a review of process science and engineering, Bioresource Technology 100, 11, 2747–61.
56 Kardono, Agung Riyadi, Widiatmini Sih Winanɵ, Wahyu Purwanta (2012) Annex1-3 Technology factsheets waste sector, Mechanicalbiological treatment (MBT), In Indonesia Technology Needs Assessment for Climate Change Mitigation 2012
57 Maria Chiara Di Lonardo, Francesco Lombardi, Renato Gavasci (2012) Characterization of MBT plants input and outputs: a review: Reviewsin Environmental Science and Bio/Technology, 11, 4, 353-363
58 Agency for Environmental Protection and Technical Services (2006) Effetti dell’impiego di frazione organica stabilizzata in attivita` diripristino ambientale Report 65/2006

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3. Main Technology

Mixed
MSW

Mechanical separation(pneumatic, vibration,
particle size, magnetic, etc.)

Organics

Anaerobic digestion

BiogasEnergy user

Calorific
fraction

Additional treatment

DebrisLandfill

Fuel(SRF, RDF)

Energy user

Resources(metals)

Recycler( a) Anaerobic digestion in the MBT system

SludgeAnaerobic digestion
Agro-debris

BiogasEnergy user

DebrisLandfill

Organics
Mixed
MSW

Mechanical separation(pneumatic, vibration,
particle size, magnetic, etc.)

Calorific
fraction
Resources(metals)

Additional treatment

Fuel(SRF, RDF)

Energy user

Recycler( b) Mechanically separated organic fraction treated in an external anaerobic digestion process

Mixed
MSW

Preliminary mechanicalseparation

Resources(metals)

Dry
waste

Secondary mechanicalseparation

Biodegradables

Composting

Inert waste

Fuel(fluff SRF)

Energy user

Landfill
Construction

Landfill

Recycler( c) Bio-drying process adopted in the MBT system
Fig. 7 Typical flow of materials and technology in MBT

Mixed
MSW

18

Bio-drying(in-vessel, open pile)

Mechanical separation(pneumatic, vibration,
particle size, magnetic, etc.)

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)

Mixed

Preliminary mechanical

Dry
waste
Bio-

Secondary mechanicalseparation

Fuel(SRF, RDF)

Energy user

Resources(metals)

Recycler

DebrisLandfill

Fuel(fluff RDF)

Energy user

Landfill

4. Sustainability and Related Global Issues

4

Sustainability and Related
Global Issues

4.1 GHGs and climate change
MBT can reduce the direct emission ofGreenhouse Gases (GHG) through waste
treatment in comparison with direct disposal,
thermal treatment, or biological treatment(generally, emissions from MBT < emissions
from disposal site < emissions from incineration).
Indirect GHG emissions can also be reduced by( i ) maintaining low consumption levels for energy,
fuel and chemicals in energy-driven operations,(ii) substituting emissions from the utilisationof fossil fuels with SRF depending on biogenic

carbon content, and(iii) reducing methane emissions from disposalsites by reducing the degradable carbon in waste.
In addition, the reduction of degradable organics
in waste sent to landfills also reduces landfillrelated environmental pollution. MBT debris has
a low C/N ratio, and its effect on the behaviourof substance conversion in landfills is not known.

4.2 SDGs
The main contributions of MBT to the SDGs isshown in Table 5.

Table 5 Main contributions of MBT to the SDGs
Contribution to SDGs

Overall“Achieve the environmentally sound management of chemicals and all wastes
throughout their life cycle, in accordance with agreed international frameworks,
and significantly reduce their release to air, water and soil in order to minimise
their adverse impacts on human health and the environment” (12.4)“Substantially reduce waste generation through prevention, reduction, recycling
and reuse” (12.5)

Production of RDF/SRF as fuelfor power and heat generation“Increase substantially the share of renewable energy in the global energy mix”
(7.2)

Recovery of recyclable materials(metals)“Improve progressively through 2030 global resource efficiency” (8.4)

Utilisation of CLO for
construction“Achieve the sustainable management and efficient use of natural resources”(12.2)

Reduction of GHG emissions in
the waste management system“Improve human/institutional capacity on climate change mitigation” (13.3)

Reduction of landfill-related
environmental pollution“Reduce the adverse environmental impact of cities, including by paying special
attention to waste management” (11.6)“Significantly reduce the release of waste to air, water and soil in order tominimise their adverse impacts on human health/environment” (12.4)

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)19

5. MBT Practices

5

MBT Practices

5.1 Phitsanulok, Thailand
Brief introduction and key points
An MBT facility was introduced in Phitsanulok(Fig. 8) to treat mixed MSW. It featured a uniquesystem that worked in combination with a nationalflagship cement company to produce RDF thatwas mostly transported to a cement kiln ownedby the company. The MBT facility is now closed
but had helped reduce the volume of waste
sent to landfills in this region and reduced themunicipality’s budget for waste management.
Historical background
MBT was implemented to overcome the issue ofa lack of waste disposal capacity in the region.
The MBT system (FABER-AMBRA) was initially
implemented with technical support from theGerman Technical Cooperation Agency (GTZ) in
2000. After construction, the facility was operated
by the local subsidiary of a cement company
under a contract with the municipality. From the
beginning of the project, solid fuels produced
from this process were planned for use in cementkilns, indicating a strong co-dependency on thecompany’s own situation, which also ultimately
became the reason for its closure.

Mixed domestic waste collected from the urban
district in Phitsanulok City and the surrounding
municipalities was treated at the facility, which
received 100 tonnes/day on average. The
collected MSW comprised organic waste (foodand plants, 40.3%), plastics (41.7%), inorganics(8.2%) and other types of waste (9.8%) in a drybased evaluation. The average initial moisture
content was 52.9%.
The facility was operated efficiently for more than
15 years in terms of waste treatment. In contrast,
the cement company was not always satisfied
with the situation because of the low quality of
RDF due to contamination from high moisture

20

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)

organics and waste containing chloride, which
was not directly loaded into the kiln but was refinedon the treatment line at the cement company.
This additional process generated unusable
residue up to 20-30% of RDF, which was rejected
and returned to the municipality. A secondary
reason for the company’s dissatisfaction with thesituation was transportation. The distance from
the MBT facility to the cement kiln was about 350
km. This distance combined with the limited route(highway) posed a problem in relation to accidents
and disasters. In the end, the cement company
terminated its contract with the municipality andshifted to another RDF produced in a facility that
could transport it faster.
Implementation and enablers(a) Social conditions
Since the MBT facility was operated by thesubsidiary of the cement company, the cementkiln was secured as a stable RDF customer. RDF
was provided free to the cement company undera concession agreement for waste treatment.
When the lower heating value of RDF exceeded
21 MJ/kg, the cement company received a refundof about THB 100 (approximately USD 3.2)/kg.
Even though there had been limited success inmarketing RDF because of its low quality, there wasno need to seek a new user under this scheme. For
the cement company, it was essential to procure
alternative fuels, an issue that was solved by thisconcession agreement.

With a population of about 70,000 in an area of 18
km2, Phitsanulok is not such a large city. However,there were objections from residents near thelandfills because such sites had always been
located in provincial areas. They felt that this was
unfair and complained, which strongly motivatedthe local government to maximise the capacity ofan existing landfill in this area. The MBT facility
was located at an existing landfill site, allowing it tobe more favourably accepted by the surrounding5. MBT Practices

residents as a solution to landfill-related problems.
The utilisation of RDF was also consistent with thenational goal of promoting renewable energy witha target to increase energy production from waste
in 2035 by 10 times the figure recorded in 2014.
(b) Public awareness and cooperation ofresidents

Residents were well-informed about theimportance and necessity of avoiding
contaminating domestic waste with hazardous
waste in order to maintain RDF quality. Residents
in the urban area of Phitsanulok City cooperated byseparating hazardous waste as this type of waste
has not been found in successive composition
analyses.
(c) Institutional aspects
The cement company demonstrated internal
quality requirements for RDF of more than 0.3
of bulk density, a lower heating value of morethan 18.8 MJ/kg, and less than 0.8% of chlorine
content. The cement company itself was able toadjust the final quality of alternative fuel with theaddition of other types of waste, such as tires orplastics separated at source.

Since this MBT facility was constructed onremaining land at the existing landfill site, there
were no barriers to securing a site for constructing
and operating the facility. The MBT process was
initially introduced as a positive way to addresssocial objections to the construction and operationof the landfill site.
(d) Governance capability
Costs are always higher when a waste
management system with MBT is comparedwith a simple disposal scheme. German Society
for International Cooperation (GIZ), the funding
agency for the introduction of the MBT facility,
initially estimated that additional capital andoperation costs would be EUR 5.1/Mg of waste
and EUR 5.7/Mg of waste, respectively. A costbenefit analysis revealed that the advantages(value) of RDF would be two to seven times higher
than the operation cost for RDF production. On
the other hand, this estimation does not include

the capital cost of MBT or the cost of residue
treatment. The value of RDF must be efficiently
assessed in terms of the return on investment inorder to generate a profit.
Phitsanulok City has a “zero landfill policy” in
MSW management, which was also developed
through technical support from GIZ. This policy
was based on the concept of the 3Rs (Reduce,
Reuse, and Recycle) that was also set out in anational agenda by the Government of Thailand,and covers public participation and technological
implementation to reduce the amount of waste
sent to the landfill. Public participation was
promoted through a programme on communitybased solid waste management, which greatly
enhanced public awareness and cooperation in
public waste management services. MBT wasa key technology used to cover the reduction ofwaste to be landfilled.
(e) Financial aspects
Even though parts of the facility were constructedwith support from an international development
scheme with GIZ, most of the facility was
installed and updated by a local cement company.
Therefore, the operating scheme was considered
to be close to a Private Finance Initiative (PFI)
scheme. In this scheme, the procurement of abudget, design and construction of the facility
were initially implemented by the public sector withinternational funds, after which the responsibility
for operation was transferred to the private sector.
(f ) Technological aspects
The entire MBT process in this facility consisted ofseveral phases. At first, MSW was de-bagged andhomogenised with a rotating drum. Homogenised
MSW was piled on a pallet plate and maintained
for several months (MBT windrow) for the purposeof bio-drying. The waste was configured in a shapewith a dimension of 50 m (w) x 170 m ( l ) x 4.0
m (h). Apparent density was estimated to be 625
kg/m3. During that period, passive aeration was
also naturally promoted to stabilise the waste.
Convective air flow was performed due to thetemperature difference between the waste layer
and the ambient air. A ventilation pipe was installed

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Mechanical-Biological Treatment (MBT)21

Resources
Recycler(metals)
5. MBT Practices

at the centre of the waste pile to increase Dry
gas
waste
exchange. The penetration of air into the waste
layer promoted the increased activity of the aerobic
Preliminary mechanical
BioMixed responsible
microbes
for the decompositionofseparation
degradables
MSW
solid waste. Generally, this process of bio-drying
took around nine to eleven months.
Inert waste
Resources(metals)

Next, the stabilised waste was transferred to
Recyclersolid fuel. Thea separation facility to produce
separation processes consisted of a trommel,
disc screen, pneumatic separation, and magnetic
separation. Components of the waste which were
not suitable for use in solid fuel were partly utilised

Mixed
MSW

(pneumatic, vibration,
particle size, magnetic, etc.)

Dry
waste

MSW

separation

Biodegradables

Fig. 8 MBT practices in Phitsanulok, Thailand
Resources(metals)

Landfill
Composting of SRF was estimated to be 30%
The production
Constructionof the initial amount of fresh
waste, but 20-30% of
SRF was rejected by the cement kilns and returned
Landfill
for landfilling. Even taking this into consideration,
the amount of waste only comprised 15% of
the initial amount of fresh waste. Operations
were sometimes temporarily suspended due
to customer-specific conditions, culminating in
the cancellation of the contract with the cementcompany.

Mechanical separation

Bio-drying(in-vessel, open pile)

Preliminary
mechanical
Mixed area at
Bio-drying
MBT facility
in Phitsanulok

asSecondarya covermechanicallayer for the bio-drying pile but were
Fuel
Energymostlyseparation
disposed as debris(fluff
at thelandfillsite. user
SRF)

Inert waste

Fuel(SRF, RDF)

Energy user

Resources(metals)

Recycler

DebrisLandfill

Fuel(fluff RDF)

Energy user

Secondary mechanicalseparation

RDF producedin Phitsanulok
Composting

Landfill
Construction

Landfill

Recycler

5.2 Nashik, India
Brief introduction and key points
The MBT system in Nashik (Fig. 9) is used to treat
mixed municipal waste. It was not an organised
system at first, but a mechanical process that had
been introduced to produce RDF in order to treat
the large amount of unsellable waste fractions
Organic(also known as compost rejects). The produced
fractioncompost is used for agriculture, and RDF is used
Mixedindustries.
in localRDF
Mechanical separation
MSW

Historical backgroundResources
With more than a million people, Nashik(metals)
is awell-known holy city for Hindus in the stateof Maharashtra. Waste generation is among
the lowest in India at 0.22 kg/capita/day due
to ineffective collection and the active (butinformal) use of organics as fertiliser in the local
horticulture industry. Although the composting
facility for municipally collected waste had beenin operation before the introduction of MBT, theefficiency
of compost production
due toComposting
Farmers
Fertiliserwas low
the preliminary recovery of organics. The amountof produced
was estimated at 3-5% of
RDF powercompost
plant
input waste, and compost rejects accounted for
60%. Therefore, a mechanical separation process
Recyclerto produce RDF was introduced to reduce theRejects

22

CCET guideline series on intermediate municipalMixed
solid waste treatment technologies

Mechanical-Biological Treatment (MBT) MSW

Landfill5. MBT Practices

volume of compost rejects which would instead
be disposed of at the landfill site.
The MBT facility was fully updated in 2016 undera 30-year concession contract with a privatecompany. Mixed domestic waste treated in thissequential system amounts to 500 tonnes/
day. RDF is traded in fluff form although it had
been previously pelletised, and is then used inindustries and power plants in the region. In India,
coal power plants are the second largest sourceof generated power. Adding to public awarenesson environmental problems caused by the use ofcoal, changing regulations, coal shortages, soaring
coal prices and frequent plant shutdowns havealso increased the need for alternative sourcesof solid fuels. Therefore, RDF is expected to be apotential solution for stabilising the coal crisis in
the country.
Implementation and enablers(a) Social conditions
RDF produced in this facility is currently utilised
in regional industries, such as cement kilns andpower generation plants, but its trading situationis unstable. Even though MBT operations andRDF production fluctuate, it is essential to securea stable customer base to ensure sustainable
operations. Potential customers for RDF include
the manufacturing industry and power generation
plants.

Nashik is an important city involved in an
infrastructure development project known as
the Golden Triangle Project, which also involves
the cities of Mumbai and Pune. This project haspromoted the growth, expansion and developmentof the social, economic and industrial situationin Nashik. In addition, improvements to thetransportation network has increased accessibility
to the Navi Mumbai Special Economic Zone thatis permitted to generate power in captive power
plants. The industrial utilisation of RDF in this area
points to the potential of a large market. Recent
worldwide objections against coal power plants,
however, could act as a force to advance the useof RDF in the country. The Nashik thermal power
station located 10 km away from central Nashik isalso a coal power plant with a capacity of 630 MW.
This is one candidate that may become a regionalcustomer for RDF in the near future.
Forecasts on population growth, industrial
development, and enhancement of the propercollection of municipal waste is compelling
Nashik City to institute an integrated solid waste
management system. In order to maximise
landfill capacity, the MBT process is expected toplay an important role together with the effective
introduction of the formal source separation of
hazardous and organic wastes.
(b) Public awareness and cooperation ofresidents

Although the Maharashtra state has documented
the rules and guidelines for the source separationof hazardous MSW such as old medications,paints, fluorescent tubes, spray cans, fertilisersand pesticide containers, batteries, and shoepolish, contamination still often occurs. The
handling of contaminated RDF is a secondary
problem requiring further dissemination of
information and improved public awareness toaddress this situation. Both RDF and compost
consumers are anxious about the potential forcontaminating MSW. Since residents have also
realised the importance of avoiding contaminating
waste to promote the utilisation of compost andalternative fuel, their cooperation will be essential
in an efficient scheme involving the collection of
separated hazardous waste by the municipality.
(c) Institutional aspects
The national government (Central Public Healthand Environmental Engineering Organisation,
Ministry of Housing and Urban Affairs) has
released a guideline for the use of RDF in various
industries in India, including quality standards for
its utilisation in Waste-to-Energy plants and thecement industry. RDF is categorised into threegrades by its intended use, size, contents of ash,moisture, chlorine, sulfur, and lower heating value.
The highest grade RDF, which is used for direct
co-processing in cement kilns, requires less than
10% of ash, 10% of moisture and 0.5% of chlorine,
and a lower heating value that is higher than 18.8

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Mechanical-Biological Treatment (MBT)23

5. MBT Practices

MJ/kg, for example. This guideline does not have
any legal force nor a formal certification system,
but customers may have a certain reliance on RDF.
The MBT facility is located in a waste management
complex which includes a sanitary landfill andincinerators used for purposes other than for
MBT. It is located close to the city border in anarea that has not been developed for residences
or businesses, even though it is only 10 km
away from the city centre. Although there havebeen no strong objections from residents about
safety to date, this facility is located behind theancient religious ruins of Pandav Leni Caves,and care should be taken to protect the regional
environment in terms of odour, noise, fumes, waste
projections and sanitation to prevent complaints
from the tourism industry.
(d) Governance capability
Forecasts on population growth in Nashik provide
strong motivation for the development of costefficient waste management. Problems withearlier systems stemmed from the low tradabilityof low-quality compost and RDF because of thelack of a stable customer base. A new concession
scheme with a private company will increase thevalue of both CLO as compost and RDF and is
expected to improve the cost-benefit balance.

Upgrading the aging composting plant to an MBT
facility has been outlined in Nashik’s 2011 solid
waste management plan. This is also mentioned
in governmental rules on solid waste managementin 2016 and is regarded as an important process
for reducing landfilled waste, increasing CLO
quality, and producing alternative fuel nationwide.
(e) Financial aspects
A thirty-year design, finance, build, operate andtransfer (DFBOT) contract was awarded to a local
Pune-based joint venture of an Indian and French
conglomerate. This public-private partnership
was launched to introduce an integrated waste
management model that included improvements
to waste collection, dissemination of informationand practices on source separation, improved
landfill management and repairing and upgrading

24

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)machinery in the existing MBT facility. In termsof the RDF price, a governmental committee
suggested that the price be expressed as a fixedprice according to the heating value for usage incement industries. The recommended price was
INR 0.4/1,000 kcal (approximately USD 1.34/
MJ). For example, when the RDF meets quality
standards for the highest-grade category (18.8
MJ/kg), the price will be INR 1,800/tonne of RDF(approximately USD 25.2/tonne).
(f) Technological aspects
The preliminary mechanical separation process
was mainly divided into three categories: drywaste (< 100 mm of particles), biodegradable
waste (20-100 mm), and inert waste (> 20 mm).
Dry waste, including wood, paper, textiles, andjute, was processed to produce RDF. Waste wasput through the process of drying, size reduction,
sieving, and homogenisation, and then finally
shredded to produce fluff. This fluff RDF was thenfurther processed to produce pellets or briquettes
as per customer requirements. The RDF was
utilised in the surrounding industries and power
plants as boiler fuel. After the facility was updated,several problems were discovered with regard tooperation, resulting in a capacity to produce about
20 tonnes/day of RDF. However, the city plans toincrease capacity to 80-100 tonnes/day due tostrong demand from customers.

Biodegradable waste and fine fractions fromthe preliminary mechanical separation process,comprised of 40% domestic waste, were treatedwith windrow composting. Similar to othercomposting plants in India, the produced compost
yield was very low (10%) and generated a portionof rejected fractions because of contaminationfrom plastics or other unsuitable materials forcompost. There were also frequent stoppages
due to mechanical problems. The calorific valueof rejected fractions was about 12,000 kJ/kg,
and therefore, it was expected to be utilised asmaterial to produce RDF. Unless used, this rejectedcompost needed to be disposed into landfills
together with inert waste. In this case, the effects
on waste reduction were not as high as expected
in terms of maximising landfill capacity.

Secondary mechanicalDry
5. MBT Practices separation
waste
Mixed
MSW

Mixed
MSW

Preliminary mechanicalseparation

Biodegradables

Composting

Resources(metals)
Preliminary mechanicalseparation
Recycler

Dry
Inert
waste
waste

Secondary mechanicalLandfillseparation

Biodegradables

Composting

Resources(metals)

Inert waste

Fuel(fluff SRF)

Energy user

Landfill
Construction
Fuel(fluff RDF)

Energy user

Landfill
Construction

Landfill

Recycler

Fig. 9 MBT practices in Nashik, India

Mechanical separation

Bio-drying
Mixed
5.3
Rayong, Thailand(in-vessel, open pile)
MSW

Fuel
(SRF, RDF)

Energy user

Resources

Recycler

Historical(pneumatic,
vibration,background (metals)
particle size, magnetic, etc.)

Rayong Province is an industrial, agriculturaland tourism hub in eastern Thailand. Population,
DebrisLandfill
economic and industrial development has led
to a significant increase in the amount of MSW
Farmers
Fertiliser(over Composting
1,000 tonnes/day). Previously,
each
local
authority in Rayong managed MSW in their own
areas.
Inpower
2007,plant
about 68 local authorities signed
RDF
an agreement to install an integrated solid waste
management
facility called “Rayong Waste-toRecycler
Energy”, developed along the policy of the Ministrymechanical
FuelRayong
ofSecondary
Interior
andmanaged by theProvince
Energyuser
separation(fluff RDF)
Administrative Organization (Rayong PAO). This
Landfillfocuses on reducing
Landfill
project
waste at source.
Composting
Transfer stations are provided
for local authorities
Constructionthat are located far from this integrated WtE
Landfill
facility. However, the various local authorities inRayong are required to pay about THB 400 (USD
12.7) as treatment fees.

Brief introduction and key points
The MBT facility in Rayong, Thailand (Fig. 10) is
part of an integrated waste management system
Organic
from Rayong’s Waste-to-Energy centre underafractioncontract between Rayong Province and a public
Mixed producing and supplying power. About
company
RDF
Mechanical separation
MSW
500 tonnes/day of mixed domestic waste was
Resourcesdelivered to the mechanical separation process(metals)
first, with 30% converted to SRF with a calorificDryvalue around 14,000-17,000 kJ/kg. Previously,
waste
Rejects
SRF was sent to cement kilns, but has recently
Mixed
BioMixed
beenutilised inPreliminary
a private mechanical
SRFMSWpower plant. Small
separation
degradables
MSW
size waste accounted for 45% of the input waste
sent to the composting production
Resources line. Although
Inert waste(metals)these two segments of the mechanical andbiological processes were Recycler
operated by different
companies, an MBT system is considered toinclude a sequential process for waste treatment.
The recyclable fraction from the mechanicalThis project was planned for implementation in
Return of large timber and twigs
Paper
SRF
separation process is about 5% of input waste andthree phases. In the first phase(budgetofmillTHB
is sold to private recyclers. Any remaining debris
115 million or USD 3.67 million), the facility’s
Bio-drying
Resources treatment plant
Mixed
is sent to the landfill whichis also a part of theinfrastructure
and a wastewater
Recycler
Mechanicalseparation(metals)(in-vessel)
MSW
province’s integrated waste management system.
were constructed in an area for sanitary landfill

Mixed
MSW

Organic
fraction

Composting

RDF

RDF power plant

Mechanical separation

Resources(metals)

DebrisLandfill

Fertiliser

Farmers

Recycler

Rejects
Mixed
MSW

Landfill

Fig. 10 MBT practices in Rayong, Thailand

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)25

5. MBT Practices(10,800 m2). The second phase (budget of THB
185 million or USD 5.90 million) was used forconstruction and to upgrade the mechanicalseparation process in the facility. A second
sanitary landfill (19,200 m2) was also constructedin this phase. In the third phase (budget of THB
322 million or USD 10.28 million), a composting
facility was constructed and the landfill area wasextended.
Another important aspect of this project is thecooperative relationship between Rayong PAO
and the Global Power Synergy Company Limited(GPSC) to construct the MSW power plant. This
project consists of two parts: RDF production
and a power plant with the capacity to treat 500
tonnes/day of MSW to produce about 6 to 9 MWof power to sell to the grid.
Implementation and enablers(a) Social conditions
The Rayong Waste-to-Energy plant is situatedin an isolated location in Tambon Nam Khok,
Mueang Rayong district with an area of 0.68
km2. The separation and composting processes
were designed to operate under a closed system.
The landfill is also operated with an engineered
surface covering system. These practices have led
to fewer complaints about odour from residents.
Discharged effluent from the wastewater
treatment facility is also reused in the area,
preventing contamination of the environment
from the release of polluted water.
(b) Public awareness and cooperation ofresidents

The Rayong Waste-to-Energy plant receives MSW
from most municipalities in Rayong and has
had to deal with “Not In My Backyard” (NIMBY)
sentiments from the residents in each municipality.
Engaging the community and involving the local
business sector under the strong leadership of
the governing body has raised environmental
awareness and fostered a willingness to solve
the waste problem with support and cooperationfrom NGOs and the public sector. Because of thework put in to address the NIMBY issue, the plant
was accepted by the residents, who supported

26

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)

the direction promoted by the province.
(c) Institutional aspects
In general, budgeting proposals for system
maintenance (or any additional requirements)
must undergo a long and detailed process that is
not in line with how the project is managed in reality.
Fortunately, the Rayong Waste-to-Energy plant
was completely managed by Rayong Renewable
Energy Ltd. (RY) under a 25-year contract with
Rayong PAO. This, coupled with cooperation with
the GPSC, allows the Rayong Waste-to-Energy
plant to be managed by two private companies,
simplifying the management of the budget andoperation of the facility when maintenance will be
required in the future.
(d) Governance capability
Since the Rayong Waste-to-Energy plant ismanaged by the private sector, Rayong PAO has
been able to address the issue of recruiting an
operator to manage the plant in the long term.
Together with that, the tipping fee which iscollected by the local authority will be discounted
as a result of the guarantee to provide MSW to thepower plant.
(e) Financial aspects
Rayong PAO entered into a 25-year contract with
RY to operate the centre and was able to reducethe budget for recruiting a new operator in thelong term. Moreover, the fact that waste can be
managed centrally has reduced operating costs
for local authorities in the province, while Rayong
PAO has been able to decrease tipping fees for
local authorities if they are able to guarantee thecontinuous delivery of MSW to the plant. A budget
for constructing a new landfill is not required
because the volume of MSW is being reduced
through incineration. GPSC also benefits fromselling electricity to the grid.
(f ) Technological aspects
Integrated solid waste management has been
incorporated into several phases because thefacility was under construction. The facility has
been in operation since 2018, with 500 tonnes/
day of mixed MSW delivered to the mechanical5. MBT Practices

Dry
waste

separation facility. Recyclable materials (5%of Mixed
total MSW) Preliminary
are separated
out at the startof
mechanical
Bioseparation
degradables
MSW
the separation process. Small particles (about
45% of total MSW) pass througha sieve and are
Resources
Inert waste(metals)delivered to the composting facility. The remaining
large-sized MSW is shredded
and incombustible
Recyclermaterials (about 20% of total MSW), such as
ceramic PVC or metal, are separated and thendisposed of at the landfill site. About 30% of total
MSW is RDF, which will be used at the power plantto generate 6 to 9 MW of electricity to be delivered
to the grid.

5.4 Mitoyo, Japan

Organic
fraction

Brief introduction and key points
Mixed
RDF
Mechanical separation
MitoyoMSW City has adopted a unique system for
municipal waste treatment in Japan (Fig. 11), a
country that normally employs the use of Resourcesmass(metals)
burn incineration systems. Municipal waste
collected as residual combustible waste (withaRejects
daily average of 31.5 tonnes/day)
is
mixed
with
Mixed
MSW
wood twigs to increase permeability.
A processof in-vessel bio-drying with air circulation andmoisture control is used to treat this mixed waste.
Six vessels (6 meters wide, 5 meters high and 35
meters long) have been installed in the facility,each with an average bio-drying duration of 17

Secondary mechanicalseparation

Bio-drying(in-vessel)

In-vessel biodegradation process

Energy user

RDF power plant

Historical background
Recycler
MitoyoCity was formed in 2006 with the merger ofseven towns. It currently has a population of about
63,000. At that time, an incinerator built in 1986
(capacity of 62 tonnes/day x 2 incinerators) was
Landfillused to treat waste, but the term of use for theland on which it had been built expired in March
2013, leading to its closure. The landfill reached full
capacity in 2009 and has since been outsourced.

Between 2010 and 2011, Mitoyo City issued a

Return of large timber and twigs

Mixed
MSW

Fuel

(fluff RDF)
days. The dried waste is thentransferred to themechanical separation process
Landfill which divides
Compostingup SRF components (plastics
and paper), large
Construction
timber and wood twigs, and fine fragmented
Landfill
fractions. Large timber and twigs are then returnedto the bio-drying process. SRF fractions are further
processed by removing polyvinyl chloride (PVC),
which should be avoided for industrial boilers.
The product is processed over an average of 13.3
tonnes/day and then sold as feedstock to a solid
fuel production company. After SRF is produced,
it is utilised in paper mills that are a dominantindustry in the region. Stable consumption of
SRF is a key factor for success in MBT in thismunicipality. This case is worth considering as an
Composting
Farmers
Fertiliser
alternative technology to incinerationin the eventthat a user for SRF has been identified.

Mechanical separation

SRF

Paper millResources(metals)

Recycler

DebrisLandfill

SRF produced at Mitoyo

Fig. 11 MBT practices in Mitoyo, Japan

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)27

5. MBT Practices

public offering to decide on the type of waste
disposal method that would be introduced, arriving
at a decision on the use of the system describedabove soon after. Subsequently, demonstration
projects were carried out between 2011 and 2014,
and in fiscal 2015 and 2016, Mitoyo City received
a subsidy from the Ministry of the Environment.
The plant, which actually started operation in April
2017, has been commissioned to Eco-Master, withtechnology and technical components provided by
Shinwasangyo Co., Ltd. under a BOO (Build-OwnOperate) initiative. The plant was constructed at a
cost of JPY 1.6 billion (including land costs), with
JPY 300 million in subsidies. The city has a 20year contract with the company, and treatment
costs are set at JPY 24.8/kg (not includingcollection costs).
Implementation and enablers(a) Social conditions
The reason that this type of system could be
introduced to Mitoyo City is because of thepresence of manufacturers nearby that mixed
about 10% of solid fuel (SRF) with coal to produce
paper.
(b) Public awareness and cooperation ofresidents

Residents had an easier time accepting thissystem because there were no changes to theexisting separation and collection methods used
for incineration treatment.
Odour is generally an issue in bioprocessing
systems. However, this system adopts theeffective method of a biofilter mechanism inwhich exhaust gas is passed through a layer ofwood chips as a way to deodorise the exhaust gas
discharged from the bio-drying process. Before
exhaust gas is deodorised, it has a strong odour.
However, exhaust gas discharged through the filter
smells like natural wood, which has eliminated foulodours from garbage around the factory.
(c) Institutional aspects
After the receipt of proposals from businesses
with the proprietary technology needed to operate

28

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)and manage this system, Mitoyo City implemented
demonstration projects in cooperation with
universities and research institutes. The city
was able to move forward with the introductionof a nationally-authorised treatment method
by applying for and being approved as a projectsubsidised by the Ministry of the Environment.
(d) Governance capability
In 2015, Mitoyo City reviewed its basic plan on thedisposal of MSW. Recognising that all waste is a
resource, the city established a basic philosophy
to “build a sustainable community where resources
circulate” to promote reuse, recycling and resource
recovery as much as possible. Mitoyo City
also instituted a basic policy on controlling thegeneration and emission of waste in a three-way
style of cooperation involving residents, businesses
and the government, with the aim of promoting
the development of a recycling-oriented society
and preventing global warming. This plan clearlyspecified that tunnel composting would be used
as a part of the city’s waste treatment practices.
Essential to the success of this plan was the strong
leadership of the government and partnerships
between the public and private sectors.
(e) Financial aspects
The costs of constructing an incinerator with anequivalent treatment capacity are estimated at
JPY 4 to 5 billion, an indication that the method
employed by Mitoyo City has greatly reduced
waste treatment costs for the city.

With the application of a BOO initiative, the city
was only required to pay for treatment costs but
was not responsible for construction costs.
(f) Technological aspects
This method was originally developed in Europe
for composting. In some cases, it may be
unavoidable for plastic to be mixed into compost,
so it is significant that this method can be used as
an alternative technology to incineration that does
not target the production of compost.

References
Archer E., Klein A., Whiting K. (2005) Mechanical-BiologicalTreatment: A Guide for Decision Makers, Processes,
Policies, and Markets, Juniper Consultancy Services
Ltd.
DEFRA (Department for Environment, Food & Rural Affairs,
UK)(2013) Mechanical Biological Treatment ofMunicipal Solid Waste
Kanning K. and Ketelsen K. (2013) MBT-Best technology
for treatment of moist MSW: AD and bio-drying prior
to energy recovery, Waste-to-Resources 2013 V
International Symposium MBT and MRF, 328-342
Ketelsen K. and Nelles M. (2015) Status and new trends /perspectives of MBT in Germany, Waste-to-Resources
2015 VI International Symposium MBT and MRF, 65186
Kritjaroen, T. (2011) Understanding Urban Governancein the context of Public-Private Partnerships: A
Case Study of Solid-Waste Management in Rayong
Municipality, Thailand, Federal Governance, 8, 3, 69-92
r3 Environmental Technology Limited (2004) Composting of
Mechanically Segregated Fractions of Municipal Solid
Waste - A Review. http://ssu.ac.ir/cms/fileadmin/
user_upload/Daneshkadaha/dbehdasht/markaz_
tahghighat_olom_va_fanavarihaye_zist_mohiti/e_book/pasmand/Composting_of_Mechanically.PDF
Ranaweera, R.M.R.P. and Tränkler, J. (2001) “Pre-Treatment
Prior to Final Disposal - A Case Study For Thailand”
Proceedings Sardinia 2001, Eighth International
Waste Management and Landfill Symposium, Pula,
Cagliari, Italy, III pp.187-196
Velis C.A., Longhurst P.J., Drew G.H., Smith R., Pollard
S.J.T. (2009) Biodrying for mechanical-biologicaltreatment of wastes: A review of process science andengineering, Bioresource Technology, 100, 11, 27472761

CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)29

About the CCET Guideline series
CCET in partnership with the United
Nations Environment Programme (UNEP)- International Environmental Technology
Centre (IETC) and the Ministry of Environment,
Japan (MOEJ) provides technical assistanceto national, sub-national and local
governments in developing countries on
the development and implementation ofwaste management strategies. During theimplementation of CCET activities, it was
found that the issue of waste management
is more complex in developing countries,
characterised by dramatic urbanisation thathas led to an increase in volume and types
of waste (including dangerous chemicals
and metals, such as mercury, lead, etc.),
but with a lack of capacity to sustainably
perform proper waste management,
including legislation and policies for realistic
long-term planning, limited collection and alack of proper disposal, scavenging issues,poor funding, low public awareness, andother issues. Furthermore, a significant
number of inappropriate technologies andequipment has been introduced due toinsufficient knowledge on sustainable waste
management practices. There is an urgent
need to provide accurate information toassist policy-makers and practitioners so thatthey have a clear and holistic view of all waste
management technologies.
The CCET guideline is a series consisting of
key technology options that act as pieces ofa puzzle to identify an optimal technology mix
for addressing the unique challenges facedby governments. It is commonly acceptedthat there are no universally right or wrong
answers to what technology is appropriate
for any one region. Rather, solutions need to
be developed locally and tailored specificallyto local needs and conditions. Citizens andstakeholders need to be involved in designing

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CCET guideline series on intermediate municipal solid waste treatment technologies

Mechanical-Biological Treatment (MBT)

a diverse set of services which, in turn, needs
to be delivered at affordable costs. As withthe pieces of a puzzle that form a clear picture
when connected, the CCET guideline series
offers knowledge-based support for thedevelopment of strategies and action plans.
The main purpose of this guideline series is
to assist policy-makers and practitioners at
the national and municipal levels in selecting
appropriate waste management technologies
and executing related policies to improve
waste management. CCET is focusing
on fundamental intermediate treatment
technologies, including Composting,
Mechanical-Biological Treatment (MBT),
Anaerobic Digestion (AD), and Waste-toEnergy (Incineration).
This guideline series:(1) is a user-friendly, knowledge-oriented
product that provides clear, concise andcomprehensive points, which makes
it easy to identify optimal options at a
glance;(2) has been developed from a “resource
perspective” rather than a “waste
treatment perspective” based on theconcepts of the 3Rs, waste hierarchy andcircular economy;(3) addresses both the physical (technical)
elements of collection, disposal andrecycling as well as the “soft” aspectsof governance, public awareness andparticipation, and institutional andfinancial aspects to encourage social
engagement; and(4) is supported by good practices.

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