CCET guideline series on intermediate municipal solid waste treatment technologies

Product(Non-Waste)

Composting
Prevention
Preparing for re-use
Recycling

Waste

Recovery
DisposalTechnologicalaspects
Financialaspects
Governancecapability

Public awareness& cooperationof residents
Socialconditions

August 2020

Institutional
aspects

CCET guideline series on intermediate municipal solid waste treatment technologies:

Composting
Authors

Copyright

Kosuke Kawai (National Institute for Environmental© United Nations Environment Programme, 2020

Studies, NIES), Chen Liu (Institute for Global

This publication may be reproduced in whole or in part

Environmental Strategies, IGES), and Premakumara

and in any form for educational or non-proﬁt purposes

Jagath Dickella Gamaralalage (IGES)

without special permission from the copyright holder,provided acknowledgement of the source is made.

Project Coordination of CCET Guideline series

The United Nations Environment Programme would

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

appreciate receiving a copy of any publication that uses

Keith Alverson (UNEP IETC), Shunichi Honda (UNEP

this publication as a source.

IETC), Misato Dilley (UNEP IETC)
No use of this publication may be made for resale or forPeer Reviewers

any other commercial purpose whatsoever without prior

Members of the Japan Society of Material Cycles andpermission in writing the United Nations Environment

Waste Management (JSMCWM): Kiyohiko Nakasaki

Programme.

(Tokyo Institute of Technology), Kazunori Iwabuchi(Hokkaido University), and Tooru Matou (Kyoto

Disclaimer

University)

The designations employed and the presentation of thematerial in this publication do not imply the expression

Other external reviewers: Soumya Chaturvedula (ICLEI –of any opinion whatsoever on the part of the United

Local Governments for Sustainability South Asia), Ritu

Nations Environment Programme concerning the legal

Thakur (ICLEI – Local Governments for Sustainability

status of any country, territory, city or area or of its

South Asia), Achu Sekhar (ICLEI – Local Governments

authorities, or concerning delimitation of its frontiersfor Sustainability South Asia), Anurudda Karunarathna

or boundaries. Moreover, the views expressed do not(University of Peradeniya), and Thilini Rajapakshanecessarily represent the decision or the stated policy(University of Peradeniya)of the United Nations Environment Programme, nordoes citing of trade names or commercial processes

Acknowledgment

constitute endorsement.

This guideline was prepared by the IGES Centre
Collaborating

Environmental

The International Environmental Technology Centre

Technologies (CCET) in cooperation with the UNEP

with

UNEP

on

works with developing countries to implement

IETC and the Japan Society of Material Cycles andsustainable solutions to environmental challenges, with

Waste Management (JSMCWM) with financial support

focus on holistic waste management.

from the Government of Japan. The authors and project
team would like to thank all involved for their valuable
contributions in making this guideline a reality.

CCET guideline series on intermediate municipal
solid waste treatment technologies:

Composting

August 2020

Contents
List of Abbreviationsii

About this Composting Guidelineiii

1. Introduction

1

1.1 Objectives of composting1

1.2 Benefits of composting1

1.3 Opportunities and challenges for cities in developing countries4

2. Pre-conditions for Sustainable Composting5

2.1 Social conditions

7

2.2 Public awareness and cooperation of residents

9

2.3 Institutional aspects

11

2.4 Governance capacity

12

2.5 Financial aspects

13

2.6 Technological aspects

14

3. Main Technology and Composting Processes

17

3.1 Waste suitable for composting17

3.2 Types of composting systems

19

3.3 Fermentation

21

3.4 Mechanical separation

21

3.5 Deodorising

22

4. Case Studies

23

4.1 Surabaya City, Indonesia

23

4.2 Kuliyapitiya Urban Council, Sri Lanka

26

4.3 Hanoi City, Vietnam

31

4.4 Nagai City, Japan33

5. Conclusion and Recommendations

36

References

37

About the CCET Guideline series

CCET guideline series on intermediate municipal solid waste treatment technologies

CompostingiList of Abbreviations

ii

BOD

Biochemical Oxygen Demand

GHGs

Greenhouse Gases

JICA

Japan International Cooperation Agency

JOCVs

Japan Overseas Cooperation Volunteers

KITA

Kitakyushu International Techno-cooperative Association

KUC

Kuliyapitiya Urban Council

MSW

Municipal Solid Waste

NSWMSC

National Solid Waste Management Support Center

NVQ

National Vocational Training

PKK

Pemberdayaan Dan Kesejahteraan Keluarga (Family Welfare Movement)

RTs

Rukun Tetangga (Neighbourhood Units)

URENCOUrban Environment Company

VOCs

Volatile Organic Compounds

CCET guideline series on intermediate municipal solid waste treatment technologies

CompostingAbout this Composting Guideline
Target audience & purpose ofthis guideline
This guideline focuses on the introduction ofcomposting projects based on source separationof organic waste and aerobic fermentation
at plants for Municipal Solid Waste (MSW)
management in the cities of developing Asia.1
The guideline aims to assist decision-makers andpolicy-makers at the local level, who have limited
or no technical background on composting, toevaluate the feasibility of introducing composting
projects as an appropriate strategic option forimproving waste management. This guideline will:(1) provide a holistic understanding about
composting systems including bothadvantages and disadvantages, as well as
requirements about the technical and nontechnical aspects of planning sustainable
composting projects, andshould be prevented and minimised at all points ofthe food supply chain, with inedible or expired foodreused for animal feed (Teigiserova et al., 2020).
Several options, including composting, Anaerobic
Digestion (AD), incineration, and landfilling, areavailable to manage organic waste such as foodwaste, trimmed trees, swine faeces, and sewage
sludge. Composting, generally categorised asrecycling, can be the most preferred technology
option for organic waste management to reduce
environmental impacts and move forward toward
the creation of a sustainable society.
Composting is just one potential element out ofmany in a functioning MSW system. Composting
plants alone cannot solve existing waste problems,and decisions on selecting composting as an
appropriate technology should be made on thebasis of an integrated MSW management planin the respective city or country.

(2) propose key evaluation criteria and a precheck flow to objectively determine andevaluate criteria when considering the potential
of introducing composting projects.

Prevention
Preparing for re-use

Composting

Position of compostingin the waste hierarchy
The introduction of composting should go along
the waste hierarchy (Fig.1) for the management ofwaste with priority placed on prevention, followedby reuse, recycling, recovery, and disposal (Pireset al., 2019). The excess generation of edible foodRecycling
Recovery
DisposalFig. 1 Waste hierarchy for sustainable waste
management (Source: EU Waste Framework Directive 2)

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/

CCET guideline series on intermediate municipal solid waste treatment technologies

Compostingiii

Approach and structure of this guideline
This guideline was prepared primarily based on areview of the expertise and practical experiencesof composting projects in Japan and other Asian
countries, in addition to available literature. It
emphasises the importance of source separation
as well as compost demand to assess thefeasibility of introducing successful sustainable
composting projects, and consists of four mainparts. The first part, “Introduction”, includes basic
information about the objectives and benefits ofcomposting. The second section, “Pre-conditionsfor Sustainable Composting”, describes the
key evaluation criteria needed when planning acomposting project and provides a pre-check
framework for sustainable composting. The
key evaluation criteria include technical, as well
as non-technical aspects, i.e. social conditions,public awareness and cooperation of residents,
institutional aspects, governance capability andfinancial aspects. The third part, “Main Technology
and Composting Processes”, briefly explains
the types of waste suitable for composting,decentralised and centralised systems, andthe main technical processes of composting.
The fourth section, “Case Studies”, highlights
actual cases on composting projects fromboth developed and developing countries, andprovides helpful lessons including a project thatwas unsuccessful. This guideline concludes withthe authors’ recommendations on composting
projects.
In this guideline, the terms composting,composting system, and composting project are
separately defined. Composting refers to a seriesof technical processes from acceptance of the
raw materials to the production of compost. A
composting system encompasses to a broader
scope, including source separation, collectionof organic waste and utilisation of compost, in
addition to plant processes. A composting projectiv

CCET guideline series on intermediate municipal solid waste treatment technologies

Compostingrefers to a series of tasks involved in planningcomposting systems, constructing and operating
composting plants, securing demand for compost,
and other related points.
In addition, this guideline does not address biodrying technology, in which waste is simply dried
biologically and eventually disposed of or used ascover soil on landfill sites.

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

1. Introduction

1

Introduction

1.1 Objectives of composting
The role of compost, organic fertiliser derived fromwaste, has been overshadowed by the excessive
use of pesticides and chemical fertilisers inagricultural practices. The lack of compost usedin farm fields and the dependence on chemicalfertilisers have had a number of negative impacts,
such as deteriorating soil conditions, deficient orexcess nutrients, insect outbreaks, and solidified
soil, to name a few. However, organic waste
generated in daily life can help recover soil
fertility if it is used to produce compost.
The Food and Agriculture Organization of theUnited Nations (2011) has reported that roughly
one-third of the food produced around the world
is lost or wasted, a figure that is almost equivalent
to a staggering 1.3 billion tonnes per year. Foodwaste makes up a significant part of MSW (Kawai
et al., 2016) and contains a substantial amountof moisture. Untreated MSW in developing
countries is mainly disposed in uncontrolled
landfills or dumping sites and has been provento be a source of methane (CH4) gas due to thedecomposition of food waste in an anaerobic
state. Moreover, the direct disposal of organic
waste in landfill sites results in the generation of
putrid odours in surrounding areas and leachaterich in concentrations of Biochemical Oxygen
Demand (BOD).
Organic waste, and food waste in particular, isa biogenic material and decomposes naturally.
When organic waste is treated properly insteadof dumped in landfill sites, fewer greenhousegases are generated, and various environmental
problems that result from improper disposal,
such as odours, vermin, compromised water
quality, fires and smoke, and pollution fromvehicles transporting waste to landfill sites, can bealleviated. Composting, a biodegradation processthat transforms organic matter into water, carbon

dioxide, energy, and composted matter (Bagchi,
2004, Intergovernmental Panel on Climate Change,2006), has been adopted throughout the world
over the years as a technology that can stabiliseorganic residues (Diaz et al., 2007). Compost,
the product of organic waste composting, canact as a partial substitute for chemical fertilisers(Nakakubo et al., 2012).
Compost is an effective soil conditioner. The longer
farmers utilise chemical fertilisers, the worse thesoil quality of farmland becomes. Compost can beused to recover soil conditions that are crucial toensuring sustainable agricultural practices.
Composting aims to:(1) treat organic waste such as food waste,garden waste, livestock excreta, and othertypes of waste in aerobic or anaerobic statesand deactivate causative bacteria, viruses,
and weed seeds through the heat of microbial
fermentation, and(2) produce organic fertilisers that physically
improve soil conditions and act as a partial
substitute for nutrients such as nitrogen,phosphorus, and potassium contained inchemical fertilisers, upon which modern
agriculture fully depends.

1.2 Benefits of composting
Composting has two notable benefits: reducing
negative environmental impacts from improper
waste management and improving soil conditions.
However, composting can also have several
disadvantages if composting systems do not
operate effectively. Similarly, some requirements
must be met to introduce composting as apotential practice in terms of technology, theenvironment, Greenhouse Gas (GHG) emissions,
resources and society as a whole (Table 1).

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting1

1. Introduction

Table 1 Main advantages, disadvantages and requirements of composting

Advantage

Disadvantage

Requirement

Composting can be practiced
in almost any region, with the
exception of extremely cold
regions. Local aerobacter,actinomycetes and fungus
play a primary role in the
degradation of organic
waste and the production ofcompost. Composting requires
simpler equipment than othertreatment technologies suchas incineration. Compostingalso can apply at different
scales, from household or
decentralised efforts to largescale centralised facilities.

Improper fermentation in ananaerobic state slow down
the process, lower the qualityof compost, and cause
unpleasant odours. Poorlyperforming equipment forremoving contaminants suchas plastics and glass leads to aserious downturn in demand forcompost.

Adequate processes must be
installed to remove as many
contaminants as possible fromthe product mechanically and/or manually, such as plastic,
paper, glass and metals. Source
separation is necessary to avoid
contamination. Moisture content,
temperature, oxygen supply,
pH, C/N ratio, particle size, anddegree of compaction should bemaintained within the appropriate
range during the aerobic
fermentation process.

The treatment of organic
waste at composting plants
helps mitigate or eliminate
negative environmental
impacts in and around landfill
sites such as odours, vermin,
fires and others.

Composting can also generate
odours if the plant is not welldesigned and processes do not
operate properly or efficiently. A
mixture of ammonia, hydrogensulphide, methyl mercaptan, andacetaldehyde causes odours.
Flies and insects can breed inand around composting plants.
The inappropriate disposal ofcontaminants and residues
removed from the compostingprocess may adversely impact
the environment.

Operators should take measures
to deodorise odours at composting
plants. Temperatures during thefermentation process should be
more than 50-55°C to destroy fly
eggs and larvae. Double-entry
doors can prevent adult flies fromentering the plants.

CH4 gas emissions fromlandfill sites can be reduced.
The fermentation process
is conducted in an aerobic
state and emits significantly
less CH4 gas than landfilling.
Composting can reduce theneed for chemical fertiliser,
which is associated with large
GHG emissions.

A certain amount of CH4 andnitrous oxide (N2O) gases are
generated during the aerobic
fermentation process. According
to the 2006 IPCC Guidelines
for National Greenhouse Gas
Inventories, the emission factorsof CH4 and N2O are 10 kg-CH4/twaste and 0.6 kg-N2O/t-waste,
respectively, by dry basis.

Composting requires regularturning and aeration to maintainaerobic conditions in thefermentation process and avoid
GHG emissions.

Composting at decentralised
levels can reducetransportation and operationalcosts. It is less expensive
Economic
to construct and operate
implications composting plants thanincineration plants. Compost
can enhance the local
agriculture, food, and tourist
industries.

Operators must secure land forcomposting plants as well as
access roads. The more serious
operators are about controllingodours, the more costly it will
be to invest in and maintaindeodorising processes.

The local government andstakeholders should recognise theadditional benefits of producing
soil conditioners other than waste
management. A budget should besecured for maintenance, as wellas to cover costs for construction
and operation. Grants or loans mayhelp local governments launchcomposting projects.

Compost can improve soil
conditions biologically,physically and chemically andResource
contribute to the realisation ofperspective sustainable agriculture.

Compost derived from organic
waste may not contain an
adequate supply of nutrients or
be fully substituted for chemicalfertilisers. Some nutrients must
be chemically added.

Local farmers must gain a better
understanding of the effectivenessof compost for farmland andbe motivated to use it. Local
governments and residents
should be aware of the various
applications of compost forroadside trees, gardening, etc.

Residents in urban areas are
not likely to participate in
the separation of food waste
at source due to a lack ofawareness and motivation.
Finding suitable locations toconstruct composting plants is achallenge.

All stakeholders should be awareof the effectiveness of compost
and be motivated to participate
in composting projects. New
legal systems may be required tostrengthen and reinforce projects.
Composting projects should be
beneficial for all stakeholders
including waste generators,
municipalities and farmers.

Technology

Environment

GHG
emissionsSocialaspects,other2

Source separation anddecentralised composting
projects at the community
level can help develop andenhance social networks,
community participation
and awareness on local
environmental issues.

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting1. Introduction

1.2.1 Reducing negative environmental impacts
from improper waste management
Composting can reduce negative environmental
impacts from inappropriate waste management
at open dumping or landfill sites. Many
developing countries rely fully on open dumping or
uncontrolled landfilling in their MSW management
practices because it is less expensive to constructand operate sites. However, the direct disposalof untreated organic waste in open dumping
or landfill sites has indisputable environmental
impacts at both the local and global levels.
Improper disposal of organic waste in open
dumping or landfilling results in the generation of
GHG emissions and leachate high in BOD, which
pollute ground water and rivers if not treated.
Such improper landfilling of MSW also results inbreakouts of fires, odours and vermin at disposalsites. MSW should be properly treated before it islandfilled to avoid serious environmental impacts.
Composting is one of the best options available
to reduce the amount of organic waste being
directly transported to dumping sites.
1.2.2 Improving soil conditions
Years must pass for soil to form as it is affected byclimate, geography, and biology. Soil is a mixtureof organic and inorganic components composedof rocks, stones, clay, sand, volcanic ash, andanimal and plant residues. Soil contains particles
of various sizes, and has a cellular structure ofmoisture and air. Soil can be divided into threephases: solid, liquid and gas (Fig. 2). When in asolid phase, soil physically supports roots andadjusts the supply of nutrients. In a liquid phase,
it supplies water and nutrients to roots. Soil in agaseous phase supplies oxygen to roots. Thebalance of the three phases greatly affects crop
growth, and soil with a solid phase consistency ofaround 40% is considered suitable for cultivation.
Soil would have an extremely hard consistency if
it were higher than 50% in a solid phase; at 30%,
the consistency would be too soft (Japan Soil
Association, 2014).

Soil with a higher proportion of clay has greater
capacity to retain water but lower capacity todrain water. On the other hand, soil with a larger
proportion of sand has greater capacity fordrainage but lower capacity to retain water. Soilsuitable for farming has the capacity to retainand drain water, retain nutrients and ventilate. To
ensure that soil possesses this capacity, it shouldhave an aggregated structure with a moderate
mixture of clay and sand, and with “humus” as its
key element.
Organic substances are continuously suppliedand degraded in soil. Some organic substances
do not completely degrade but remain in the soil
in a complex composition and structure, known
as humus. Humus enhances the soil’s capacity
to retain and drain water, preserve nutrients,
ventilate, and act as a pH buffer. Humus also
contains growth hormones such as auxin andcytokinin, which promote plant growth and resultin an increased volume of roots. Compost canpartly replace chemical fertilisers in terms ofsupplying nitrogen, phosphorus, and potassium.
More importantly, compost derived from foodwaste can be a source of humus, which cannot
be produced artificially (Hermann et al., 2011) but
demonstrates the various advantages mentioned
above and contributes to the formation of asustainable soil management and food recycling
system.

Gaseous
phase

Solid
phase

Liquidphase

Fig. 2 Three phases of soil
Soil with a solid phase consistency of around 40% issuitable for cultivation. The proportion of soil ingaseous and liquid phases changes in line with dry
conditions.

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting3

1. Introduction

Box 1 Historical production and use of compost in Japan
Iwata et al. (2001) offers a historical perspective
on agriculture and the use of organic fertilisers inJapan. In the Edo period (1603-1868), the main
fertilisers used in agriculture were composed ofyoung buds and leaves from broad-leaf trees,
wild grass, barnyard manure, and human waste.
Farmers at that time used these types of fertilisers
because they did not have the means of purchasing
expensive fertilisers such as dried sardines, oilcake, and soybean cake. Human urine and faeces
were carefully collected to produce fertiliser, with
farmers carting agricultural products to urban
areas in the morning and returning to rural areas in
the evening with human waste. This material cycle
between urban and rural areas continued until the
Meiji era (1868-1912). However, due to an increasein the population of urban areas during the Taishoera (1912-1926), there was an excess supply ofhuman waste, which resulted in a breakdown of
the material cycle between urban and rural areas.
Although farmers mainly utilised the organic
fertilisers they produced themselves with leaves,trees, and manure, some started to purchase oil
cake, dried sardines and chemical fertilisers.
According to Fujita (1993), in the ten years
following the end of World War II, the number ofcomposting plants for MSW in Japan increased
to 30 where European technologies such as theDano system (Dziejowski et al., 2002) were applied.
However, these European composting technologies
were not suitable for MSW in Japan with its higher

1.3 Opportunities and challenges
for cities in developing
countries
In recent years, the amount of waste has
increased dramatically, especially in urban areas,
due to population growth, urbanisation andlifestyle changes in Southeast Asia and otherdeveloping countries. As a result, the importanceof intermediate treatment facilities, such ascomposting plants, is on the rise to reducethe volume of waste as pressure increases on
the existing capacity of final disposal sites.
Centralised composting can be successfully
applied to the cities or areas that meet all or mostof the following:

4

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting

moisture content, since the technologies had
been developed for waste in Europe that had alower moisture content. At some plants in Japan,
paper waste, such as newspapers, were mixed into
food waste to reduce moisture content. Almost
all composting plants had disappeared by the1970s, and incineration became the predominant
waste management technology used to manage
MSW in Japan. Composting underwent a revivalin the 1980s with an increase in the numberof composting plants to treat sewage sludge,
livestock manure, and agricultural waste. However,as of 2018, MSW delivered to composting plants
accounted for only 0.5% of the total. Currently,
there are about 100 centralised composting plantsfor MSW located throughout Japan.
Japan’s long history of using compost on
farmland supplied nutrients to the soil, such as
nitrogen, potassium, phosphorus and humus
which encouraged microorganisms to flourish in
the soil, created a sound balance between waterdrainage and retention, and acted as a chemical
buffer. Japanese composting practices have been
established on the principles of source separationof organic waste. Recently, a limited quantity of
MSW is being managed at composting plants, butwaste generators, who are required to be involvedin composting projects, are actively separatingorganic waste at source and discharging it in orderto supply high-quality raw material for composting.

(1) Cities or areas that seek alternative treatment
systems to replace landfilling(2) Cities or areas that can separately collectquality raw materials for composting(3) Cities or areas that can secure enough demandfor compost(4) Cities or areas that can secure an adequate
budget to operate composting plants for long
periods of time(5) Cities or areas that have adequate manpower
and institutional arrangements to develop andimplement sustainable composting projects

2. Pre-conditions for Sustainable Composting2

Pre-conditions for
Sustainable Composting

Various conditions must be in place to ensure thata composting project is introduced successfully.
Based on guides for decision-makers (Rand etal., 2000, Kamuk, 2013, Mutz et al., 2017), key
evaluation criteria can be verified from six
perspectives: social conditions, public awarenessand cooperation of residents, institutional
aspects, governance capability, financial aspects
and technological aspects. Following the six
perspectives together with relative key evaluation
criteria for each, a modified pre-check flow (Fig.
3) can be used as a guide at the beginning of
the planning stage. The key evaluation criteria andpre-check flow are presented to assist decisionmakers and policy-makers in taking a closer lookat whether local governments are able to prepare
the conditions required for composting projects.
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, it is not yet suitable to introduce
composting projects. It is strongly
recommended that the evaluation besuspended or that the situation be re-evaluatedafter improvements are made;(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
not met, caution should be exercised
as composting projects can be risky toimplement.

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting5

6

CompostingFig. 3 Pre-check flow to be conducted at the beginning of the planning stage

CCET guideline series on intermediate municipal solid waste treatment technologies

in cases where advisable key criteria are not met, consider it risky to implement

Moisture content
can be maintained
within an
appropriate range
during the aerobic
fermentation
process.

Appropriate
methods for the
separate collection
and transportationof organic waste
can be established.

Technical aspects

Advisable key criteria

Market strategies
for compost are
carefully
developed at theplanning stage.

Local governments
have the capacity
to estimate andsecure a budget forcomposting
projects.

Financial aspects

in cases where strongly advisable key criteria are not met, consider improving the situation
through support measures or alternative proposals

All local
governmentofﬁcers involved incomposting
projects aredeveloping theircapacity forcomposting, as wellas the entire waste
management
system.

The heads of local
governments aretaking the initiativein composting
projects.

Governance capability

Strongly advisable key criteria

Local residents
residing nearcomposting plants
are not adversely
affected bycomposting
projects.

The administrative
body is stable andsustainable.

Appropriate sites
can be secured forthe construction ofcomposting plants.

Institutional aspects

in cases where mandatory key criteria are not met, suspend the evaluation or re-evaluate after
improvements are madeCompost should
be utilised forfarming by project
operators todemonstrate its
effectiveness andsafety.

Residents arecontinuously being
encouraged toseparate organic
waste.

Cooperation and understanding of residents

Mandatory key criteria

Other stakeholders
are involved incomposting
projects from theplanning stage.

Local farmers areclosely involved incomposting
projects from theplanning stage.

There is adequate
demand forcompost.

Social conditions
Feasibility
study andbusinessplanning
for full
implementation

2. Pre-conditions for Sustainable Composting2. Pre-conditions for Sustainable CompostingBox 2 Stages of composting projects
As a composting project progresses, the types andnumbers of stakeholders, geographical boundaries,
and composting technologies may change.
Progress can be divided into three stages: planningstage, setup and operating stage, and upgrading
stage (Tasaki et al., 2016). Each stage may takemonths or years, depending on the local situation.
Planning stage
In the planning stage, the local government
assesses the level of interest in local areas andstarts to develop plans for the type of composting
system and technology that will be used, amount ofwaste to be collected as a raw material, number andcapacity of trucks to collect waste for composting,capacity of composting sites, initial and operationalcosts, quality and quantity of compost produced
annually, and local demand for compost, andconsiders other relevant issues for inclusion in theplan. If a composting project is established basedon source separation of organic waste, a feasibility
study on source separation can be included in thisstage. Feasibility studies on source separation
should start on a small scale before expanding thetarget area of the composting project.
Setup and operating stage
In this stage, the local government has completed

its assessment and developed plans for thefeasibility of a composting project, and compostinghas been positioned as one solution for reducing
environmental impacts. Next, the local government
should secure a budget to design, construct andoperate the composting facility. Generally, a local
government enters into a contract with a privatecompany to design and construct a composting
facility. Some local governments operate thefacility with their own staff, while others use private
contractors.
Waste suitable for composting is collected andtransported to a composting plant. The produced
compost is distributed to users such as local
farmers and residents.
Upgrading stage
Composting moves away from its singular focus
on waste management, and shifts to an emphasison enhancing local agricultural businesses. Local
farmers find better ways of cultivating vegetables
on farmlands using compost derived from organic
waste to improve the quality of crops, which
are then sold at local markets and used at local
restaurants. As a result of this improved quality,
markets and local restaurants can attract morecustomers, which leads to the establishment of arecycling loop for the food supply chain.

2.1 Social conditions
Mandatory key criteria
There is adequate demand for compost.
Securing adequate demand for compost products
is a pre-requisite for the successful operationof composting plants. However, it is difficult toensure an adequate level of demand for compost
in high population density areas due to the lack offarmland. Composting plants should be designed
to be situated in places that are located nearareas with substantial tracts of farmland. If
this is not possible, composting operators mustsecure demand for compost products connectingwith existing fertiliser companies or creating new
business networks. Then, a balance among theamount of waste to be treated, compost supplied,and compost delivered should be carefully
estimated and verified at the planning stage.
Typically, one kilogram of compost per square
meter is distributed annually to farmlands. In otherwords, if 10,000 tonnes of compost is produced
annually, a minimum of 10,000,000 m2 or 1,000 haof farmland must be secured so that all produced
compost will be used. Composting plants should
be located near an area with considerable
farmland to ensure the routine distribution ofcompost, while also taking into account the factthat a certain percentage of farmers are not willing

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2. Pre-conditions for Sustainable Composting

to use compost. Plants should also be equippedwith storage units for compost since demandvaries seasonally and compost can be distributed
to farmlands only two or three times a year. In
addition to farmers, some residents may requirecompost for home gardening (Fig. 4) and cities cangive preferential use of city waste-based compost
in municipal gardens and parks and government
premises.

Fig. 4 Compost packed
in a 5-kg plastic bag for
distribution to residents inOsaki Town, Japan

Strongly advisable key criteria
Local farmers are closely involved in composting projects from the planning stage.
Compost users are an absolutely essential
part of composting projects. Without theirunderstanding or support, local governments andother stakeholders will never be able to launch
successful composting projects. Local farmers,
arguably the most vital users of compost, should
be involved in the process from its inception.
Compost can be used as a substitute for somenutrients that are present in chemical fertilisers,
reducing their use and improving soil conditions.

Farmers can use organic fertilisers such ascompost derived from organic waste to maintainquality soil conditions. They should be engaged
in composting projects from the planning stage
to ensure that their opinions are reflected inplans as primary users of compost. Without theparticipation of local farmers who use compost
regularly, producers will face challenges in sellingcompost in local areas or may need to find demandfurther afield.

Advisable key criteria
Other stakeholders are involved in composting projects from the planning stage.
In addition to local farmers, local governments
should encourage the involvement of key
stakeholders from the planning stage, suchas community group leaders, women’s
unions, agricultural cooperatives, commercial
associations, restaurants, hotels, vegetableretailers, and households. Community groupleaders and women’s unions can encourage
residents to participate in separation at sourceand dispose of organic waste appropriately.
In addition, households who have an interest,
willingness and space for family farming or
gardening can make household or backyard

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Composting

compost using their separated organic waste
at source. Agricultural cooperatives can act as
focal points for distributing compost to local
farmers. Commercial associations can support
the processing and distribution of agricultural
products grown with compost. Restaurants, hotels
and vegetable retailers as waste generators canprovide information on the quantity and quality oforganic waste generated regularly, which is helpful
in making decisions on designing the capacity ofcomposting plants. The approval and supportof waste generators is essential in assuring thatcomposting projects are sustainable.

2. Pre-conditions for Sustainable Composting

2.2 Public awareness and cooperation of residents
Mandatory key criteria
Residents are continuously being encouraged to separate organic waste.

Residents are the primary generators of MSW.
When local governments design a composting
system combined with the separation of organic
waste at source, residents play an importantrole in supplying this waste as raw materials forcomposting.

proportion of waste generators who separateorganic waste as a percentage of the total numberof waste generators. Proper separation rate refers
to a parameter that describes how accurately theorganic waste is separated. Proper discharge rate
is a parameter demonstrating that mixed waste
is discharged appropriately by those who do notseparate waste in order to avoid contaminating
the waste that has been properly separated byresidents as organic waste. These three key
parameters have an impact on the quantityand quality of the waste separately collected
as organic waste, and should be a target for
improving the quality and securing an adequate
quantity of raw materials.

Good source separation determines whether acomposting project succeeds or fails. Three key
parameters can be used as an indication ofprogress on source separation: participation rate,
proper separation rate and proper discharge rate
as shown in Fig. 5 (Kawai et al., 2017). Participation
rate, the most important parameter, refers to theParticipation
rate

Properseparation
rate

There are several possible measures that can be put
into place to increase the participation rate. Local
governments need to create opportunities andconditions that minimise difficulties for residents
when separating organic waste. To do so, thelocal government must frequently communicate
with waste generators and identify existing
problems with source separation and collection.
The key point here is that residents should becontinuously encouraged so they are motivated
to separate waste for proper composting. Fig. 6
illustrates how behavioural psychology works

Properdischarge
rate

Fig. 5 Three key parameters for source
separation of organic waste
Separation

Phase 2

Evaluation offeasibility

Motivation to separate
Evaluation of
cost benefits

Evaluation ofsocial norms

Phase 1

Awareness ofeffectiveness

Mature interest insource separation
Awareness of
responsibility

Awareness ofenvironmental risk

Fig. 6 Structure of behavioural psychology on source separation

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Composting92. Pre-conditions for Sustainable Composting

when applied to source separation. In phase 1,
residents develop a mature interest in source
separation by becoming aware of risks to theenvironment caused by human activities, their
responsibility in reducing environmental impacts,
and the effectiveness of source separation (e.g.
establishing recycling loops or food supply chains,
Fig. 7). In addition, residents can be motivated
to separate food waste by evaluating whether
source separation is appropriate as it may require
additional work, time and costs, the need to involvefamily or neighbours in source separation, andwhether instructions and equipment for source
separation have been sufficiently prepared by
local governments. Purchasing vegetables grownwith compost at local markets (Fig. 8, 9) may help
waste generators, that is, vegetable consumers,

recognise how their involvement in separatingorganic waste at source contributes to agricultural
practices and keep them motivated to continue
collaborating with composting projects.
National and local governments have an option
to set up new legal systems to promote source
separation; for example, waste will not becollected if it is not separated properly, or waste
generators will be fined if they do not separate
waste appropriately. Legal systems can help
promote and improve source separation, but the
groundwork should be carefully laid. Strict systems
may inconvenience waste generators in their daily
lives, while permissive systems may result in aloss of effectiveness for proper source separation.

Consumption

Source separation

Food products
Food waste
Processing & Delivery
Collection & Transport

Agricultural products

Composting

Agriculture
CompostFig. 7 Recycling loop of food supply chain based on source separation

Fig. 8 Vegetables grown with compost in
Motegi Town, Japan

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CompostingFig. 9 Vegetables grown with compost in Ikeda
Town, Japan2. Pre-conditions for Sustainable Composting

Advisable key criteria
Compost should be utilised for farming by project operators to demonstrate its
effectiveness and safety.

The effectiveness and safety of compost forfarming may be unknown when a project islaunched. Target users may have a negative
impression of compost derived from waste, suchas that it causes odours or contains unsuitablewaste like plastic, glass, or metals. Because ofthis, residents and other waste generators may
lose sight of the objective of separating organic
waste at source, and farmers may be hesitant
to use compost. To enhance the cooperation
and understanding of both waste generatorsand compost users, it is advisable for project
operators to prepare test farmland plots
where compost can be utilised for farming todemonstrate its effectiveness and safety (Fig.

10). This demonstration should be positioned sothat it promotes public awareness on composting.

Fig. 10 Test farmland in Osaki Town, Japan

2.3 Institutional aspects
Mandatory key criteria
Appropriate sites can be secured for the construction of composting plants.

Securing a construction site is a fundamental
element of satisfying requirements and achieving
the goals of composting plans. Sites are subject
to various laws and regulations, such as urban
planning and building standard laws, and thus, it isimportant to design plans from a comprehensive

perspective. The stability and reliability of thelocal government are also an important partof this criterion. The most important point inconstructing composting plants is the ability tosecure a site where consent from local residents
in surrounding areas can be obtained.

Strongly advisable key criteria
The administrative body is stable and sustainable.
Since MSW is managed as a public service andcomposting plants should be in operation for
decades, the stability of the administrative body isa key point for the sustainability of a composting
project from an institutional perspective.

Whether composting plants are operated
by local governments or private companies,
local governments must take the initiative on
composting projects. If a private company thathas managed and operated a composting plant

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2. Pre-conditions for Sustainable Composting

withdraws, local governments must immediately
find an alternative contractor to operate the plantand secure destinations for waste that cannot becomposted until operations can be restarted at
the plant.

Strongly advisable key criteria
Local residents residing near composting plants are not adversely affected bycomposting projects.

The operation of composting plants may poseissues for nearby residents due to the highvolume of traffic for transporting waste, odours,
and vermin or insects from composting plants.
In line with regulations during construction andoperation phases, the operators of composting
plants should pay special attention to residents
in surrounding areas to ensure that these plants

do not have an adverse effect on their daily lives
and environment.
Composting plants can play a positive role indeveloping neighbourhoods, for example, by
allocating sections for residents who do nothave space to grow their own crops by using thecompost produced at the plant.

2.4 Governance capacity
Mandatory key criteria
The heads of local governments are taking the initiative in composting projects.

The introduction of composting projects is
influenced by political trends and strongly
impacted by the will of those in power in local
governments. The head of the local government,such as the city mayor, must have a positive
attitude towards the construction and operationof composting plants. The roles of related
departments of the local governments must be
clarified initially, with officers in charge appointed
by the head of the local government.

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CCET guideline series on intermediate municipal solid waste treatment technologies

Composting

After the election of the head of a local government,
the new leader often pivots on policies that havebeen implemented under the former head. However,the new leader should not interrupt ongoing waste
management plans, for example, by changing
personnel, if that was not part of promises madeduring the election. Waste management systems
are developed based on careful communication
between various stakeholders including residents
and farmers as well as local governments.

2. Pre-conditions for Sustainable Composting

Strongly advisable key criteria
All local government officers involved in composting projects are developing theircapacity for composting, as well as the entire waste management system.

Local governments should formulate specificplans to establish composting projects that take
into account a variety of considerations, including
future owners or operators of composting plants,
amount of waste collected as raw materials fromsources, number and capacity of trucks to collectwaste for composting, capacity of composting
plants, type of composting technology, life cycle
costs including initial and operational costs forcomposting, quality and quantity of compost
produced annually, and local demand for compost.
Feasibility studies on source separation can be
included at the planning stage if composting

projects will be established based on source
separation by waste generators. A feasibility
study on source separation should be initiated ona small scale before the project area is expanded.
To proceed with these steps, all local government
officers in charge should develop their capacity
on composting as well as waste management
systems prior to the start of a project. External
support can be sourced through the involvementof outside experts and consultants, as needed. The
department of the local government in charge ofcomposting should maintain its level of capacity
even if personnel are reshuffled.

2.5 Financial aspects
Mandatory key criteria
Local governments have the capacity to estimate and secure a budget for composting
projects.

Local governments should estimate budgets toconstruct, operate, and maintain composting
plants while they are in service once a decision
has been made to move forward with acomposting project. To estimate the budgetthat will be needed for a composting project,
local governments can request external experts
and consultants to provide technical support,
if necessary. If contractors own and operate
plants, the local government should estimate thetipping fee per tonne of waste to be paid to thecontractors. It is preferred for the government toallocate land to private operators for constructing
composting plants since searching for land canprove to be a highly challenging task for private

operators. Where applicable, local governments
should also consult with national governments orinternational donor agencies to negotiate terms
for grants or loans to construct the plants. Local
governments also need to secure a budget for thecollection and transport of waste. Items needed
to collect separated waste, such as collection
containers, should be adequately prepared by
local governments to help residents easily disposeof waste. A budget for disseminating informationand public awareness should also be available at
all times to encourage residents, especially people
moving from other areas, to take part in source
separation for composting.

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2. Pre-conditions for Sustainable Composting

Advisable key criteria
Market strategies for compost are carefully developed at the planning stage.
An adequate demand for compost is importantfor composting projects in terms of the balance
between raw materials and compost. In addition
to the quality of compost, demand is also dictatedby the selling price of compost and transportation
fees. Appropriate prices for compost should beanalysed taking the price of chemical fertilisersand different types of compost into account.

The project operators should discuss the priceof compost with local farmers in advance anddevelop marketing strategies in the initial stageof planning. An alternative use of compost is inparks and to improve streetscapes. In the eventthat demand for compost falls, it is advisable toassess and estimate latent demand for compost
in sectors other than agriculture.

2.6 Technological aspects
Mandatory key criteria
Appropriate methods for the separate collection and transportation of organic waste
can be established.

contaminants. The separation of the organic
components of MSW at source is an important
process because it reduces non-organic content
in the waste collected as organic waste (Cerda etal., 2018, Hargreaves et al., 2008). The separate
collection of organic waste is an essential elementin supplying better raw materials to produce highquality compost.

The raw materials for composting should notcontain contaminants such as non-biodegradable
and hazardous waste, as they have a negative
effect on the final quality of compost. The initial
inclusion of non-organic components such as
plastic and glass in waste collected as organic
waste determine the impurity content at the end of
the composting process (Cerda et al., 2018). Plastic
waste contained in compost is not biodegradable
but eventually decomposes into smaller pieces
under the influence of sunlight, although it
remains in the soil as microplastics for millennia.
If organic waste is separated well at source andmunicipalities successfully collect only wastethat is suitable for composting, it will not benecessary to utilise a series of well-equippedmechanical processes to separate and remove

There are several options for the separate
collection and transport of organic waste (Table
2, Fig. 11), and the most suitable option should be
adopted based on the local situation and detailed
feasibility studies on the collection of organic
waste for composting. Plastic waste is one of
the greatest challenges facing the world. Bioplastic bags may have two types; the petroleum-

Table 2 Options for the separate collection and transportation of organic waste based on theexperiences in Japan

14

Packaging for collection
and transportation

Location

Type of truck

Frequency

Time

Plastic bag
Paper bag
Plastic container

CurbsideCollection point

FlatbedCompactor

Designated day
Every dayMorning
Afternoon
Evening

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting2. Pre-conditions for Sustainable Composting

based plastic which can be biodegraded, and theplastic bag which is (partly) composed of biogenic
materials. As of now, there are various types of
bio-plastic bags and it is still doubtful whether any
bio-plastic bags can be fully degraded in the soil.
Plastic bags can be used as packaging for organic
waste if the plastic bags are surely removed atcomposting plants by mechanically or manually.

Fig. 11 Paper bags forcollecting organic waste in
Ikeda Town, Japan

Plastic containers are placed in each community
to collect organic waste from households
in the community (Fig. 12, 13). All households
participating in the separate collection of organic
waste discharge organic waste in the sharedcontainers. Any contamination in the containers
can be recognised at first sight. Plastic containers
are reused after cleaning inside.

Fig. 12 Placing organic waste
into containers at a collection
point in Nagai City, Japan

Fig. 13 Flatbed truck fortransportation of food waste
in Nagai City, Japan

Strongly advisable key criteria
Moisture content can be maintained within an appropriate range during the aerobic
fermentation process.

The moisture content of the compost mixture
is an important factor as it provides a medium
for transporting dissolved nutrients required
for the metabolic and physiological activities
of microorganisms (Kumar et al., 2010). To
activate aerobic bacteria, the moisture content of
the feedstock should be kept above 40%, while ahigher moisture content prevents air from blowing
into the feedstock. Food waste has a high moisture
content of around 70% to 80%. To maintain aerobic

conditions, it is necessary to reduce the moisture
content by adding organic additives such as
sawdust (Fig. 14) or rice husk (Fig. 15) at the initialstage of the aerobic fermentation process. Dry
leaves (Fig. 16), grass (Fig. 17) and tree trimmings
can also be used to adjust moisture content.
Kaneko et al. (1986) reported that a moisture
content of 50% to 60% at a constant temperature
with adequate aeration maximises respiratory
activity.

Fig. 14 Sawdust stored at a composting plantin Motegi Town, Japan

Fig. 15 Rice husk used to adjust moisture content
at a composting plant in Nagai City, Japan

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Composting15

2. Pre-conditions for Sustainable CompostingFig. 16 Dry leaves stored at a composting
plant in Motegi Town, Japan

Fig. 17 Grass stored at a composting plant inOsaki Town, JapanBox 3 Key actions needed for successful composting projects
A review of existing composting projects helps
in identifying key actions that can lead to thedevelopment and implementation of successful
composting projects (Table 3). Some key actions
may have a significant impact on further

development, while others may not be effective atall, depending on the local situation. Actions do notneed to be followed in the order presented in thetable, but can be reviewed and implemented as thesituation demands.

Table 3 Types and characteristics of composting projects
Types of actions

16

ExamplesPlanning

Clarification of objectives, preparation of action plans

Involvement of key persons

Involvement of local chief executive, community leaders and farmers

Cooperation with stakeholders

Cooperation with business associations, agricultural associations,
women’s associations

Allocation of personnel

Designation of departments and officers in charge

Collection of information

Interviews with experts on composting technology and agriculture

Study of select cases

Visits to sites and interviews with key persons

Review of case studies

Study on the feasibility of separating organic waste at source in themodel area, verification of the effectiveness of compost on agriculture

Organisation of explanatory
meetings

Arrangement of periodic briefings for residents and other stakeholders

Implementation of public
relations campaigns

Distribution of information on composting projects in local magazines,
websites, SNS, and personal communications

Organisation of lectures byexperts

Arrangement of scientific lectures by professionals to residents

Confirmation of local positions

Submission of questionnaires to residents involved in source
separation

Branding

Requests for copy, logo and mascots for composting projects

Authentication

Certification of the quality of compost and agricultural products basedon standards

Evaluation

Presentation of awards to residents and communities who havecollaborated in the composting project, evaluation of improvements inrecycling rates and value for money

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting3. Main Technology and Composting Processes

3

Main Technology and Composting
Processes

3.1 Waste suitable for composting
Organic waste that can decompose biologicallyis suitable for composting. Below are examples oforganic waste that can be used as raw materials
for composting:a) Food waste such as residue from cooking
preparation and leftovers after meals (Fig. 18)b ) Leaves and trimmed trees

Fig. 19 Food waste unsuitable for compostingcollected from households in Hanoi City, Vietnamc ) Rice and wheat strawd) Cattle and swine faecese ) Night soil and sewage sludgef ) Vegetable and fruit wastes coming from freshor public markets
Note that c ), d ) and e ) may not be categorised
as MSW but may be managed independently insome countries.

Fig. 18 Food waste suitable for compostingcollected from households in Hanoi City, Vietnam
Seashells, eggshells, shrimp shells, chicken bones,
pork bones, beef bones, coconut shells and fruit
seeds are not suitable for composting due to thedifficulty in degradation (Fig. 19), although thesewastes are often categorised as food waste. These
wastes should preferably be removed from the raw

materials for composting if facilities do not havethe proper processes to remove them. Also, wastewith high salt and pungent components should be
minimised because this renders bacteria inactive
during the composting fermentation process.
Waste that does not biologically decompose,such as plastics, metals, glass, oil, cigarettebutts, gum, diapers, and other such items, is notsuitable for composting since it may interferewith the composting process. Paper waste isoften categorised as unsuitable for compostingeven though paper is biodegradable. The aerobic
fermentation process for composting generally
takes from ten days to three months (Elango etal., 2009), but a much longer period is required for
paper to decompose. Farmers tend to avoid using
low-quality compost containing pieces of nonbiodegradable waste, such as plastics and glass.
Hazardous and harmful waste, such as medicines,
dry batteries, spray cans, pesticides, mercury
thermometers, and other items, should not bemixed in raw materials for composting since
mixing hazardous waste has an adverse effect on
the quality of compost (McDougall et al., 2001),
and eventually threatens the health of people who
ingest the crops harvested on farmland wherecompost was used.

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3. Main Technology and Composting Processes

The use of cattle and swine faeces and sewage
sludge requires careful attention to be paid tothe proximate and chemical composition. Milkcows ingest copious amounts of water andfaeces contain higher moisture content. On theother hand, the faeces of cows used for meat
have a much lower moisture content, while pig
faeces generally contain a significant amountof moisture. Bedding for cows and pigs such as
rice straw, rice husk and sawdust is an excellent
mixture used for reducing the moisture content offaeces. Residual components of herbicides in feedcrops may remain in faeces and cause growth
problems for crops when compost derived fromcattle and swine faeces is used on farmlands.
Sewage sludge is the organic and inorganic
residue produced during wastewater treatment,
and contains substantial quantities of nitrogenand phosphorus in combination with high levels oforganic constituents (Arthurson, 2008). However,
the heavy metal content in sewage sludge has
been a major limitation for compost derived fromsewage sludge (Amir et al., 2005). Appropriate
guidelines and standards to handle faeces andsewage sludge should be prepared to assurecompost quality.

Box 4 Recycling rates in the food supply chain
According to FAO (2019), approximately 30%of the food produced globally is either lost or
wasted annually. This is happened at different
stages of the food supply chain, including food
manufactures, wholesalers, retailers, service
industries and households. Considering its
negative impacts towards food-security, economic
lost and environmental pollution, reduction offood loss and waste has identified as a firstpriority according to the waste hierarchy and 3Rs.
Redirecting of edible food to be reused, such asanimal feed and recycling food waste are also
important before dispose them in the landfills. A

larger amount of less-contaminated food waste
can be collected from food manufacturers thanfrom actors further down the food chain (Fig. 20).
Recycling rates for food waste generated by food
wholesalers, retailers, and food-service industries
as well as households tend to be lower becauseof less efficient collection practices and higher
contamination rates. Note that contamination here
does not refer to hazardous materials, but to waste
unsuitable for composting such as paper, plastic,
glass, metals, and other items. Households are a
primary focus for tackling MSW issues as they are
the main sources of food waste for composting.

High

Low

Recycling rate

Food manufacturers

Food wholesalers

Food-service industries

Households
Low

Contamination rate

Food retailers

High

Fig. 20 Recycling and contamination rate of food waste generated
by actors along the food supply chain

18

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Composting3. Main Technology and Composting Processes

3.2 Types of composting systems
In developing countries and in major cities inparticular, MSW generation is on the rise as
populations grow, and local governments arebeing confronted with the challenge of how
to manage this increased waste. As waste
generators are responsible for reducing waste asmuch as they can, one solution for reducing MSW
generation is household-based and communitybased composting. The more households actively
separate organic waste from other waste andcompost organic waste themselves, the less
MSW municipalities need to collect and manage.
If households cannot secure adequate space forcomposting at home or in communities, local
governments may choose to concentrate andmanage MSW at composting plants rather thantransport organic waste to landfill sites. Since itis difficult to completely remove contaminants
such as pieces of plastic and glass from compost,
this guideline strongly recommends that organic
waste be separated at source as much as possible
before collection and transportation.

Fig. 21 Baskets for household composting in
Surabaya City, Indonesia

Fig. 22 Plastic barrel for community-based
composting in Surabaya City, Indonesia

3.2.1 Household- and community-based
composting (decentralised composting)Households and communities can produce
compost on their own from organic waste, if
adequate space is available in their houses andcommunities to set up containers, and if organic
waste is separated well at source. Household andcommunity-based composting, also known as adecentralised composting system, is technicallyeasier to manage. Various types of containers
are used for composting at the household andcommunity level, such as plastic baskets (Fig.
21), clay pots, cardboard, and iron or plastic
barrels (Fig. 22), and well-ventilated containers
are recommended. Lining the inside of thebaskets with cardboard can help keep moisture
content stable (Fig. 23). The waste in baskets andcontainers should be mixed regularly to maintainaerobic conditions.
Odour is the most critical environmental issue forhousehold- and community-based composting.
Odour occurs in anaerobic conditions caused

Fig. 23 Cardboard-lined basket in Surabaya
City, Indonesia
by excessive moisture during the fermentation
process. Moisture content, one of the mostimportant parameters, should be monitored
and maintained at around 60% for aerobic
fermentation to be successful. The moisture
content of food waste is generally around 80%, butfood waste with higher moisture content, such as
leftover watermelon, should not be included as araw material. Squeezing or straining out moisturefrom food waste before disposing of it in baskets
and containers can prevent excessive moisture,stop anaerobic decay, discourage odour and

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3. Main Technology and Composting Processes

deter insects. Sandwiching dry soil between layersof food waste has a positive effect in absorbing
odours and repelling insects, as well as removing
moisture.
When community-based composting is introduced,
the local government should carefully select andsecure spaces where containers can be set up forfermentation based on consensual agreementwith the community. An appropriate number ofcontainers should be set up based on the numberof households supplying organic waste. Comparedwith household-based composting, containers
used for community-based composting should beequipped with ventilation and drainage functions
since a larger amount of organic waste will beplaced in these containers which may become
anaerobic due to the higher moisture content.
A case study on household- and community-based
composting in Surabaya, Indonesia is described in
4.1.
3.2.2 Centralised composting
If local governments have confirmed that they cansufficiently gain the cooperation of local waste
generators in separating organic waste, they may

Raw materials
Food residue
LeavesRice straw
Wheat straw
Trimmed branches
Sewage sludge
SeptageLivestock excreta

opt for centralised composting. Although the typeand number of processes at composting plants
depend on the quality of raw materials, composting
usually includes the following processes: adjusting
moisture content, fermentation, and mechanicalseparation, in addition to the separate collectionof raw materials at source. Fig. 24 illustrates the
typical flow of the composting process. Plasticbags are removed in the initial process if they areused to collect and transport raw materials. Since
raw materials for composting generally have ahigh moisture content, sawdust and rice husk areoften added to absorb and adjust the moisture
content. Next, raw materials are biologicallydecomposed in the fermentation process throughaerobic fermentation, the more common typeof fermentation. In addition to vapour, CO2, CH4,
and N2O gases are generated as a result of
the decomposition of organic waste. After thefermentation process, contaminants such as
metals, glass and plastic are removed, and finallycompost is produced. Composting plants mustalso be equipped with a deodorising process if
residents are in the vicinity. The main processes ofcentralised composting (fermentation, mechanicalseparation and deodorising) follow below.

CO2 , CH4 , N2O

Rice husk

Mechanicalseparation

Sawdust

H2O

Adjustment ofmoisture content

Aerobic
fermentation

Mechanicalseparation

Contamination
MetalsContamination
Plastic

Fig. 24 Typical flow of the composting processes

20

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Composting

Glass
Plastic

Compost3. Main Technology and Composting Processes

3.3 Fermentation
Fermentation is divided into two types: aerobic
treatment and anaerobic treatment. Anaerobic
treatment refers to the process in which anaerobic
bacteria decompose and stabilise organic
components in the absence of air. Anaerobic
treatment requires a longer period of timethat can last up to ten months to complete thefermentation process due to the slow anaerobic
reaction. Aerobic treatment refers to the process
in which aerobic bacteria decompose and stabiliseorganic components in an air-rich environment(Fig. 25, 26). This treatment requires that a certain
concentration of oxygen be maintained by feeding
air into the mixture through stirring and mechanicalventilation. Aerobic treatment produces compost
in a shorter period of time. This guideline focuseson aerobic fermentation because of the simpler
technology involved and the higher potential for
installing and operating composting plants indeveloping countries.

Fig. 25 Primary aerobic fermentation process
in Osaki Town, Japan

Fig. 26 Secondary aerobic fermentation
process in Osaki Town, JapanThe effectiveness of the fermentation process
is influenced by factors such as temperature,oxygen supply, moisture content, pH, C/N ratio,
particle size, and degree of compaction (Onwosi
et al., 2017). These factors can be maintained andimproved by mixing organic waste (Getahun et al.,2012) and supplying moisture when necessary.
Blowing or drawing air into the bottom of the
mixture is also an effective way to supply oxygenand enhance aerobic fermentation. If the moisture
content is too high, it is impossible to feed air
into the waste, which results in an anaerobic
state. During the fermentation process, organic
components are reduced to about 50% due tobiological decomposition, and the moisture
content in the raw materials also decreases
due to the evaporation of moisture caused byfermentation heat.

3.4 Mechanical separation
In addition to fermentation, centralised composting
facilities require another important process calledmechanical separation. Mechanical separation isused to remove contaminants from the mixture
both before and after the fermentation process(Fig. 27). The level of mechanical separationinfluences the quality of compost. Several
methods of mechanical separation are necessary
to completely remove contaminants, even if
organic waste is collected separately from otherwaste.

Fig. 27 Mechanical separation after thefermentation process in Nagai City, Japan

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3. Main Technology and Composting Processes

3.4.1 Sieving
Sieving is the process of physically removing
larger particles using screens before or after
fermentation. Biodegradable components
become smaller during the fermentation
process. After the fermentation process, thesieving process can physically separate nonbiodegradable components from compost. Dueto the high moisture content of compost justafter primary fermentation, and the various typesof non-biodegradable waste such as plastic films
and textiles contained in the mixture, screens may
become blocked. Screens can be put through aseries of movements to avoid blockages: up-anddown, back-and-forth, circular, and trommel (Fig.
28).

Fig. 28 Trommel to remove contaminants after
the fermentation process in Ikeda Town, Japan

3.4.2 Ferrous metal separation
Ferrous metals (Fe) can be sorted with magnets
that attract Fe from composting streams. Thiscan be carried out, for example, with an overband
magnetic separator or a magnetic drum (Fig. 29).

3.4.3 Electromagnetic separation
Non-ferrous metals can be sorted by using
the eddy current separators. An eddy current
is induced by a series of rare earth magnetic or
ceramic rotors at the head of a conveyor thatspins at high speed independently of the conveyor.
This process induces temporary magnetic forcesin non-magnetic metals of the same polarity as
the rotor, repelling the metals and then separatingthem from feedstock.

3.5 Deodorising
Odours must be deodorised in composting
plants if they are located around residential
areas. However, it is difficult to eliminate odours
completely, which are much stronger when
compost is acidic, in comparison to when it is ina neutral or alkaline state (Sundberg et al., 2013).
Ammonia, Amines, dimethyl sulfide, acetic acidand Volatile Organic Compounds (VOCs) are keycauses of odours (Mao et al., 2006; Maulini-Duranet al., 2014; Scaglia et al., 2011). Biofilters suchas soil (Fig. 30) and compost itself are methods
generally employed in composting facilities totreat and reduce odours. An important strategy
for reducing odours from compost is to rapidly
pass through the initial low-pH phase. This canbe accomplished through a combination of highaeration rates that provide oxygen, and additives
such as recycled compost (Sundberg et al., 2013).

Fig. 30 Soil for deodorising in Nagai City,
Japan
Fig. 29 Magnetically separated metals in
Hanoi City, Vietnam

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4

Case Studies

4.1 Surabaya City, Indonesia
Surabaya, the second largest city in eastern Java
with a population of three million people, serves
as an important commercial and industrial capitalof the province. This city of three million people
generates over 1,500 metric tonnes of MSW a
day in the following sectors: residential (68%),
markets (16%), commercial/industrial (11%),streets and open spaces (5%), with organic wastecomprising more than 50% of the composition of
MSW (Gilby et al., 2017). The city has succeededin reducing the amount of MSW generated bymore than 20% over a three-year period (20052007) by promoting composting practices withthe establishment of composting centres and the
distribution of thousands of composting baskets
to residents, introduction of waste separation andreduction activities at households, communitymanaged waste collection, and the organisationof community clean-up campaigns and waste
recycling activities with local NGOs, the private
sector (formal and informal) and media (Maeda,2009). Surabaya’s achievement exemplifies how
a city can reduce a large amount of waste in ashort period of time with a limited budget by
first targeting organic waste and establishinga composting-based integrated sustainablewaste management system (Maeda, 2009:
Premakumara et al., 2011).
Before the establishment of Surabaya’s solid
waste management model of composting, MSW
was mainly landfilled. The waste issue in Surabaya
peaked in October 2001 with the closure of the
only final disposal site belonging to Surabaya City
at Keputih, creating havoc as waste destined forthis site lined the streets around the city.
In 2004, the Kitakyushu International Technocooperative Association (KITA) in Kitakyushu Cityand Pusdakota, a local NGO in Surabaya, worked
together to design a pilot project in Kampong

Rungkut Lor, a low-income neighbourhood locatedadjacent to the largest industrial area in the city.
After six months of trial and error, an efficientcomposting method known as the Takakura
Method (named after a composting expert from
Kitakyushu) was developed based on a traditional
windrow composting method and adopted at
Pusdakota’s composting centre. The Takakura
Method uses fermentation microorganisms as
seed compost, which were originally cultured
from local fermented foods, such as soy sauce,yoghurt, and fermented beans (tempe and tape inIndonesian), fruits and vegetable peels, rice bran
and rice husks. The most remarkable feature of
the Takakura Method is its speed; it takes only one
to two weeks to decompose a large portion of theorganic compounds, in contrast to the windrow orother methods that usually take more than threemonths. Therefore, the Pusdakota composting
centre started producing quality compost in large
quantities (1.4 metric tonnes/day) from organic
waste separated at source collected from thecommunity.
Surabaya City scaled up the project by adopting thesame composting method at existing composting
centres, establishing new centres, and distributing
thousands of composting baskets to residents. As
a result, the city operated 13 composting centres(Fig. 31) with a capacity of about 40 tonnes a day
in total, to process a large amount of organic waste
collected from vegetable markets and street/park
maintenance activities and has distributed 19,000
baskets (Fig. 32) to households for free.
The city purchased the baskets from Pusdakota
and outsourced the distribution of baskets
to PKK (Pemberdayaan Dan Kesejahteraan
Keluarga, a women’s group) and other NGOs,
taking advantage of their grassroots access tocommunities. These NGOs have set up a networkof community environmental leaders called
environmental cadres, who teach residents how

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4. Case Studies

to produce compost from kitchen waste using
the baskets, as well as what environmental andhealth impacts can be expected by keeping the
kitchen environment garbage-free. Environmental
cadres then follow-up by monitoring the usage ofthe baskets to troubleshoot common problems.
Many households followed suit, which changed
the mindset of residents and discouraged people

from dumping waste on streets and in streams,
and as a result, created greener and cleaner
communities. Pusdakota also started functioning
as a community waste station with the separate
collection of organic and inorganic waste, including
recyclables, thus encouraging waste segregation
at source.

Fig. 31 Composting centre

Fig. 32 Takakura composting basket

As reported by Maeda (2009), the promotion ofcomposting has a multiplying effect of more thandouble in terms of waste reduction—40 tonnes a
day by 13 composting centres, 40 tonnes a day
by 40,000 households, and 120 tonnes a day byusing and recycling other dry waste (waste banks
and manufacturing handicrafts from plastic
waste). Moreover, Surabaya spends just one totwo percent of its total solid waste management
expenditure to achieve these results, including
the operation and maintenance of 13 composting
centres, distribution of composting baskets,
supporting the activities of PKK, NGOs andenvironmental cadres, and organising the Green24

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and Clean Campaign. All of these activities
amounted to only IDR 1.5-2 billion (USD 150,000200,000) annually from 2006 to 2008. Other cities
are encouraged to adopt a similar strategy basedon the following five steps (Maeda, 2009).
Step 1 Waste reduction target setting andinstitutional setup
First, local governments should set waste
reduction targets with the mayor’s support. A
lead department should be designated, which isoften the solid waste management department,
and co-ordination should be developed with otherrelated departments, including park management,

4. Case Studies

environmental management and city planningdepartments.
Step 2 Set up market-waste composting centres
A local government can immediately start a
composting project by setting up a composting
centre and processing the organic waste fromvegetable markets that would otherwise betransported to and disposed of at final disposalsites. A composting project requires space anda building for the composting centre, a shredder
for cutting the waste into pieces and technicaltraining for staff. The project can be launchedon a small scale, such as by processing one
tonne of compost a day on a trial run and using
the produced compost at city parks, and thengradually scaling up the project after confirming
effects.
Step 3 Identify community partners anddistribute compost baskets
It is advisable to identify partner communities orschools where strong leadership or community
bonds already exist rather than targeting the entire
city from the very outset of the project. Developing
a network of community environmental leaders
who teach residents how to use compostingbaskets and monitor progress is also an effective
approach, as exemplified in Surabaya’s case.
The active involvement of PKK, which works
closely with the city government and co-ordinateswith other NGOs and environmental cadres, isanother advantage that other Indonesian cities
can emulate as PKK is present in every city.
Composting baskets can be distributed for free as
waste reduction impacts will be larger than actual
distribution costs in a few years.
Step 4 Set up community-based composting
centres
Supporting local partners in establishingcommunity composting centres through theprovision of capital, buildings and equipment isan effective approach to encourage community
participation in solid waste management. Anotheroption is to provide shredders and technicaltraining for existing community material recovery
facilities. The city government may need to act

as the buyer of the produced compost or assist
in marketing the compost to farmers to support
operations, especially at the beginning stage. City
governments can also encourage community
participation by first setting up composting centres
for market waste, gradually accepting household
waste and then handing over operations to thecommunity.
Step 5 Organise community clean-up campaigns
Organising a community clean-up campaign andallowing communities to compete with one otheris an effective approach to encourage community
participation. Co-organising the campaign withprivate companies and media groups is an
excellent strategy to mobilise resources, widely
publicise the campaign and encourage further
participation by communities.
There are several critical elements that can befound in Surabaya’s success.
1. Social conditions: There were no new sites
available to be used as a landfill in Surabaya
due to a scarcity of public land. People
noticed the hygienic effects of keeping the
kitchen environment garbage-free, which
would otherwise rot and attract flies andcockroaches, and consequently may have an
undesirable impact on the health of family
members. Residents understood that thepractice of composting was one way to solve
this problem.
2. Technological aspects: An efficient householdcomposting method, known as the Takakura
Method, was developed to produce quality
compost. Composting centres provided followup support.
3. Institutional aspects: Surabaya City has beendeveloping various activities to carry out waste
management as an administrative measure.
Step-by-step development was added inproportion to the progress of improving waste
management such as the introduction ofcomposting, updating the compost centre,
upgrading the resource separation and

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4. Case Studies

recycling centre, allocating and maintaining abudget for waste management improvement,
publicising the city planning master plan,setting up waste reduction targets, anddeveloping an award system, among others.
4. Governance capability: The city has apositive attitude towards composting anddemonstrates leadership in all activities as
explained above. Meanwhile, in collaboration
with NGOs, private companies, and the media,
Surabaya organised a community cleanup campaign called the Green and Clean
Campaign. The number of participating
communities (Rukun Tetangga, RTs) involvedin the campaign increased from 325 in 2005,
the first year of the programme, to 1,797 by
2008, which is about 20% of all RTs in the city.
5. Financial aspects: Surabaya has distributed
19,000 compost baskets for free over the
past five years and procured baskets from
Pusdakota for approximately IDR 100,000(USD 10) per unit. Assuming the distribution
cost, including the promotional andeducational activities carried out by NGOsand environmental cadres, was also IDR
100,000 (USD 10) per basket, then the total
expenditure by the city for the five-year period
was IDR 3.8 billion (USD 380,000). On the other
hand, assuming each basket helps reduce
one kilogram of organic waste a day, then
19,000 baskets can reduce 19 tonnes a day,which is roughly 6,900 tonnes a year. As thecost for solid waste management in Surabaya
is about IDR 230,000 (USD 23) per tonne ofwaste, the cost saved from waste reduction
can be approximated at IDR 1.6 billion (USD
160,000 = 6,900t x USD 23/t) a year. Based on
this assumption, the city can recoup its initialinvestment in 2.5 years and maintain waste
reduction effects.
In addition, as the actual total amount of
reduced waste is much larger than the
combined compost production capacity atcomposting centres and households, it isinferred that both the promotion of household-

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based composting and the separate collectionof organic waste function as ways to encourage
residents to further reduce other types of
dry waste. Therefore, the free distribution of
thousands of composting baskets helps tooffset any associated costs in a few years andis an activity that can be recommended forother cities to follow suit.
6. Public awareness and cooperation ofresidents: Generally, residents had threeincentives to practice household composting.
First, most people enjoy using the selfproduced compost for plants and gardens.
Second, they noticed that rotting waste in
kitchens could have an undesirable effecton the health of family members. And third,
residents can generate extra income for theirhouseholds by selling compost and plants
or vegetables grown using it. For example,
Pusdakota purchases the compost producedby basket users at IDR 700 (USD 0.07) per
kilogram, which enables a household to receive
an income of IDR 4,200 (USD 0.42) a month byproducing one kilogram of organic waste a day
as about 20 percent of the input ends up in the
final product .
However, waste-to-energy incineration has recently
become a focus in Indonesia’s national waste
management strategy. Under Presidential Decree
No.18 of 2016, seven Indonesian cities (Jakarta,
Tangerang, Bandung, Semarang, Surakarta,
Surabaya, Makassar) have been nominated as
eligible for support in developing WtE incineration
projects. However, since WtE plants requirea minimum of 1,000 tonnes of MSW a day tooperate at peak efficiency, Surabaya is facing newchallenges in sustaining its composting system
as waste is diverted elsewhere.

4.2 Kuliyapitiya Urban Council,
Sri Lanka
With the establishment of the National Solid Waste
Management Support Center (NSWMSC) and theinception of the PILISARU Programme (a national

4. Case Studies

program launched by the Ministry of Environmental
and Natural Resources), Kuliyapitiya Urban
Council (KUC) put forward a proposal to establish
an integrated solid waste management systemin the city. This integrated approach solved
many issues in managing waste, including
the construction of a composting facility to
manage biodegradable waste, recycling centre
for resource recovery, semi-engineered landfill
for the disposal of residual waste and a low-costwastewater treatment system for sewage as wellas leachate management. Today, the Kuliyapitiya
integrated waste management facility has enabled
Kuliyapitiya to thrive as it recovers resources from
MSW (Karunarathna, 2020).
Change from collection and disposal practices toan integrated MSW management approachWith a population of 6,554, KUC is the second
largest township in Kurunegala District, North
Western Province of Sri Lanka. Until the rightleadership appeared in 2009, and in the absenceof basic infrastructure for MSW treatment or
disposal, Kuliyapitiya Urban Council was nodifferent from any other small local authority
in that it delivered substandard MSW services

to the public while placing the ultimate burden
on environment. The Kuliyapitiya Urban Council
struggled to manage the city’s large quantities ofwaste generated from households, commercial
enterprises and public places.
Until 2008, all waste was openly disposed on
barren land at one corner of the city (Fig. 33). As
the mountains of disposed waste grew higher,
workers burned it to secure enough space forthe next day. The smoke from burning waste
created an unpleasant environment and posed
significant health risks for residents. KUC faced
enormous pressure to close the dumping site andshift operations to a remote location. However,finding a place to dump the waste was almost an
impossible task as land resources within the city
limits were scarce.
Environmental Preservation Centre of KUC
The establishment of NSWMSC in 2007 andthe inception of the PILISARU Programme in2008 created opportunities for local authorities,
including the Kuliyapitiya Urban Council, to look formuch needed technical and financial assistance.
The KUC put forward a proposal to establish

Before 2009

From 2009 to date

Before 2009

From 2009 to dateFig. 33 Kuliyapitiya waste disposal facility before improvement in 2008 and after setting up theEnvironmental Preservation Centre in 2009 (Karunarathna, 2020)

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4. Case Studies

an “Environment Preservation Centre” (Fig. 33),
an integrated waste treatment and disposal
facility, on the same land that had been used asa dumpsite for many years to help reduce theamount of waste sent for final disposal. Planners
proposed an integrated waste treatment anddisposal facility that would include a small biogas
unit for highly problematic and spoiled waste,
a composting facility for biodegradable waste,a facility to sort and recover recyclable wastefrom non-biodegradable waste and a small semiengineered landfill facility for the disposal ofresidual waste.
The composting facility was one of the first fullscale windrow composting systems capable ofhandling up to 10 metric tonnes of biodegradable
waste. Once the composting facility commenced
operation in 2009, the biggest challenge was tosort mixed MSW received through the conventional
collection system. Five to six workers were
employed full-time to sort incoming waste. Dueto the high cost of this extra labour, issues withworker’s hygiene and the inefficiency of the entire
system, KUC spent more than expected at the
beginning of the project, requiring them to develop
short- and long-term measures to implement asource-segregated waste collection system forthe entire city.
Implementation of source-segregatedwaste collection
From the start, the most challenging task facing
the urban council was to encourage the public tobecome involved in segregating waste. In 2009,
the Bell collection system was introduced in one
ward as a pilot project. Bell collection is a system
where a collection vehicle for biodegradable waste
plays a unique tune to announce its approach
to households so residents can directly unload
household garbage bins into the collection
vehicle (Fig. 34). A collection worker on the vehicle
inspects the waste to make sure it is completely
segregated. In cases where waste had not been
separated properly, residents received a warningand the waste was not accepted. In general, the28

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residents in the city cooperated with this sourcesegregation collection system since collection
was conducted on a regular basis. The support andencouragement from higher authorities helped
workers effectively implement the collection ofwaste separated at source. With this system toseparate waste at source, the composting facility
did not require as many workers on a full-timebasis. The positive steps taken by KUC wererecognised, and the PILISARU project donated askid steer loader to aid composting operations.

Fig. 34 Source-segregated collection by the
Bell collection system (Karunarathna, 2020)

With the success of this pilot project, KUC
expanded the scheme to two other wards in 2010.
Residents were informed of the new collection
scheme through community meetings, posters,
and notices in residential areas, and formalawareness campaigns were organised in schools
and public/private sector institutions. In 2014,
reusable bags were distributed to households toaid in the separation of biodegradable and nonbiodegradable waste. By 2016, KUC started to
implement source-segregated waste disposal
and collection in the entire city. Once the entire
KUC residential community had adjusted to thisdisposal and collection scheme, KUC developed
strategies targeting populations migrating to thecity for work, trade, shopping and other purposes.
The KUC’s decision to obtain help from experts
such as NSWMSC and Japan Overseas
Cooperation Volunteers (JOCVs) significantly
helped in the implementation of this scheme.
Since 2009, KUC has been a destination for JOCVs

4. Case Studies

to work with communities in introducing soundwaste management practices, source-segregatedwaste disposal, and recycling.
Windrow composting of biodegradable waste
Workers for the Environmental Preservation
Centre were hired from nearby communities andplaced in permanent cadre. There are nine workers
engaged in daily operations, with one worker
placed at the compost sales outlet and anotherworker trained to operate the skid steer loader.
The overall management of the site is handled bya trained supervisor who is also responsible forrecord keeping.
First, waste is bought to the facility by six waste
collection tractors and unloaded on a concrete
floor. Waste is thoroughly inspected, and any
remaining non-biodegradable waste is removed
manually. The biodegradable waste feedstock is
loaded into a wooden frame using the loader andgradually piled up to a maximum height of 2m.
The initial pile height is about 2m; however, the piledecreases in height to 1.5m or less within few days
(one week maximum) due to rapid degradationand compaction (Fig. 35).
The first windrowing of the new pile is carried out
after two weeks, with piles windrowed weekly
after that period. Although heavy waste during
the windrowing process is handled entirely by theloader, a worker spreads and uniformly compacts
the waste in piles. Water is added to the mixture
during the windrowing process, especially while
the composting pile is undergoing maturation
after 10 weeks of initial decomposition.
Leachate from the waste piles is diverted to atreatment plant through a concrete drain system.
Leachate is minimal during dry spells, which allows
even outdoor concrete floors to be used to pile
fresh waste. However, operations are restricted toindoor spaces during the rainy season, when an
excessive amount of leachate is generated. The
leachate treatment facility is a locally designed
coconut coir brush-based system that mimics

Fig. 35 Piling up composting feedstockusing wooden frame and skid steer loader(Karunarathna, 2020)
attached growth biological treatment. The
leachate treatment system also receives partiallydigested sewage collected from households andinstitutions. The wastewater treatment system
has been designed for optimal operation whenboth types of wastewater are treated together.
Treated wastewater is reused at the composting
plant whenever watering is required during thewindrowing process.
Matured compost is sieved using a trommel
screen with a standard size specified by the Sri
Lankan government. Residue collected after
backend sieving and a portion of the matured
compost are mixed with incoming fresh waste tocontrol moisture and increase bulkiness. However,a small portion of residue, plastic particles andinert waste is disposed at the semi-engineered
landfill site.
Compost products and quality assurance
The most challenging task in the compost
production process is to maintain the steady

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4. Case Studies

and appropriate quality of the final product. The
incoming waste includes a substantial amountof fine inert contaminants at source as well as
during handling at the composting facility. Waste
from both public spaces and private institutions
contain a significant amount of soil and sandwhich eventually end up in the produced compost.
With the exception of a higher amount of sand, theproduced compost satisfies all quality standards
for use as agricultural compost. Compost quality
testing (moisture, sand ratio, pH, EC, N, P, K, Mg,
OC, C/N ratio) is regularly carried out at least once
every six months by sending compost samples
to government approved laboratories. The resultsof this independent quality testing (Fig. 36) aremade available to buyers, which guarantees
product quality. This practice has built confidence
in buyers and helped to maintain a steady demandfor compost.

Fig. 36 A sample compost quality test report(Karunarathna, 2020)

Environmental, economic and social benefits
The KUC maintains all financial records from theEnvironmental Preservation Centre to ensure thata full financial audit can be conducted at the endof each year and to demonstrate the financial
sustainability of the centre. About 100 metrictonnes of compost is produced annually. The
total operational cost of processing biodegradable
waste at the composting facility is LKR 2,289(USD 13.5) per metric tonne; however, a greater
portion of this cost is recovered through thesale of compost, and the absolute operational

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expenditure is only LKR 289 (USD 1.7) per metrictonne.
A financial analysis shows that a good composting
system can recover much of its expenditure
on waste disposal through compost sales.
Accounting for the social and environmental
benefits of composting, it is imperative thatthe overall benefits of the composting scheme
are far and above those of conventional open
dumping. The composting facility has achieved
KUC’s main target of reducing the volume ofwaste in the landfill. Capitalising on the successof the Environment Preservation Centre, KUC’s
long-term vision is to make Kuliyapitiya a zerowaste city. The strategy to achieve this vision is bypromoting recycling and encouraging householdbased composting to reduce the burden on thecentralised composting facility.
At present, KUC has been able to considerably
reduce the amount of waste disposed at the semiengineered landfill site. Estimates show that thecomposting facility receives 4.9 tonnes/day of
biodegradable waste. Out of a total 2.1 tonnes/
day of non-biodegradable waste, about 1.79
tonnes/day is recovered at the material recovery
facility as recyclables and only 0.32 tonnes/day
is disposed at the semi-engineered landfill site.
The remaining waste is either disposed onsite ascompost produced from households or recycled
through informal recyclers.
The composting facility has created job
opportunities in nine neighbouring villages. The
unique human resource management system atthe centre with flexible work hours and overtime
enables the KUC to attract young and educatedworkers from neighbouring villages and allows thefacility to operate continuously even on weekends
and public holidays. All workers are supplied withpersonal protection gear to protect them fromcontaminants. Moreover, all staff must undergo
professional training to receive their National
Vocational Qualification (NVQ level 2). At least
once a year, KUC conducts health check-ups for
all workers.

4. Case Studies

The composting facility is well managed, keeping
fly and odour issues to a minimum, which benefits
communities located nearby. At present, KUC has
completely banned the burning of waste at thedisposal site as well as in the city.

Residents perceive the positive changes inthe system and support KUC in its mission tomaintain the sanitary conditions of the city andfinal disposal site. In return, residents are provided
with a well-organised and regular waste collection
system.

Key outcomes and lessons learnt
The KUC case demonstrates the results that canbe gained from the successful implementation of
a composting system and associated facilities tofind a solution to waste management issues in asmall city. The key achievement in this case is
the shift from a “collect and dump” scenario to
one in which resources are recovered through theestablishment of an integrated waste treatment
and disposal facility where resources in urban
waste can be recovered and recycled.
First and foremost, the key to success was thecommitment of KUC’s leadership in finding a longlasting solution to its waste issue. Leadershipmade crucial decisions at the right time to change
from conventional waste management practices
to an integrated waste management approach.
As a small local authority with limited financial
resources and technical expertise to move forward,
KUC opted to look for outside opportunities andresources.
The collaborative financial and technical support
from the national government through NSWMSC
and the PILISARU Programme assured thesteady progress and full implementation of KUC’s
waste management action plan. Once financial
and technical support were guaranteed, KUC
implemented source-segregated waste collectionthat could be achieved within three years. Steadycollaboration with NSWMSC and the PILISARU
project helped the council to secure continuous
support for expansion and to launch supportiveawareness activities.
Benefits are shared among all stakeholders and theworkforce, in particular. Workers are encouraged
and rewarded with a sense of ownership of thecentre and are motivated to contribute more.

4.3 Hanoi City, Vietnam
With financial support from the Spanish
government, the Hanoi Urban Environment
Company (Hanoi URENCO) constructed acomposting plant in Cau Dien that started
operation in 2002 to produce compost from MSW(Fig. 37). To enhance composting activities, asource separation and collection project wasestablished with technical support from the Japan
International Cooperation Agency (JICA) throughits “Implementation support for the 3R initiativeof Hanoi city for cyclical society” programmeover three years from 2006 (Japan International
Cooperation Agency et al., 2009; Taniguchi et al.,2011). In this project, organic (biodegradable)
and inorganic (non-biodegradable) waste wasseparated by residents in four model areas, andthe organic waste was collected and transported
separately to the composting plant. According to
guidelines designed by the Hanoi city government,
biodegradable food and garden waste werecategorised as organic waste, with other waste(including non-biodegradable food waste suchas seashells, chicken bones, and coconut shells)
categorised as inorganic waste. Items such as
paper, textiles, and wood are generally categorised

Fig. 37 Aerobic fermentation at a composting
plant in Hanoi City, Vietnam

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4. Case Studies

as organic, but they are regarded as inorganic in
Hanoi because of the lengthy time required forbiodegradation.
The source separation and collection project was
implemented in Phan Chu Trinh in the Hoan Kiem
District and Nguyen Du in the Hai Ba Trung District.
This area represented about 0.2% of the morethan seven million residents of Hanoi (General
Statistics Office of Vietnam, 2015). All households,
as well as business entities such as offices, shops,
restaurants, and hotels, are obligated to separateorganic and inorganic waste and discharge eachtype of waste into designated containers.
Various methods were adopted to publicly
disseminate information on the source
separation and collection project and how toappropriately separate organic and inorganic
waste during the JICA project in order toencourage households to become involved in
the process. Guidebooks on source separation
were distributed to all households and waste
collectors for Hanoi URENCO in the model area.
Waste collectors were trained as instructors
on source separation to provide guidance toresidents. A number of informational meetings
were held for residential group leaders andhousehold members. Information on source
separation was disseminated through local radio
stations and community message boards. Local
TV programmes collaborated to popularise thepractice of separating waste at source in Hanoi.
In the model areas in Hanoi, organic and inorganic
waste could be discharged into designated waste
collection containers from 18:00 to 20:30 everyday. Some waste generators used dust bins, andothers used plastic bags to dispose of waste.
In either case, organic waste was disposed intogreen containers and inorganic waste into orange
ones (Fig. 38). Both types of containers were set
up side-by-side every day on the main streets by
Hanoi URENCO workers before the beginning of
the drop-off period.
The project continued in two of the model areas

32

CCET guideline series on intermediate municipal solid waste treatment technologies

CompostingFig. 38 Containers for organic waste (green) andinorganic waste (orange) in Hanoi City, Vietnam
after the project finished in 2009. However,progress has not been monitored by any of theparticipating agencies since the completion of the
JICA project.
Kawai et. al. (2017) proposed three key parameters(participation rate, proper separation rate andproper discharge rate) for behaviour related tosource separation of household organic waste,
and monitored the progress of the programme
based on the physical composition of household
waste sampled from 558 households in the model
programme areas of Hanoi in August 2014. The
results showed that 13.8% of 558 households
separated organic waste, and 33.0% of households
improperly discharged mixed (unseparated) waste.
About 41.5% of the waste (by weight) collected asorganic waste was contaminated by inorganic
waste, and one-third of the waste disposed of asorganic waste by waste generators was inorganic
waste.
Currently, although Hanoi URENCO does notseparately collect organic waste, it collects mixed
waste, all of which is transported to the landfillsite. No containers for the separate collection oforganic and inorganic waste are placed on thestreets in Hanoi. It seems that Hanoi URENCO
experienced a continuous downturn in demandfor compost and, as a result, reduced the amountof compost produced. In the end, they ceasedtransporting waste collected as organic waste to
the composting plant. It is crucial that continuous
demand be secured for compost to ensure4. Case Studies

sustainability. The low quality of the raw materials
for composting negatively affected the qualityof compost because pieces of plastic and glass
could not be removed. Most farmers are reluctant
to use poor-quality compost even if it costs lessthan chemical fertilisers.

4.4 Nagai City, Japan
Nagai City is located in Yamagata Prefecture, witha population of 27,000. Local farmers in Nagai
City recognised that the condition of soil on theirfarmlands was deteriorating due to the longterm use of chemical fertilisers. They determinedthat organic fertilisers needed to be used on
farmland to improve soil conditions, and thatfood waste generated in the kitchens in theirown homes could be used as the raw material fororganic fertilisers. The city government of Nagai
supported the establishment of environmentallyfriendly agriculture based on proposals by
its residents. Food waste mixed with othercombustible waste, which had been disposed ofat the local incineration plant, is now collectedfrom approximately 5,000 households in Nagai to
produce organic fertiliser at the composting plant(capacity of nine tonnes per day of food waste)using rice husk and cattle faeces. The composting
system reduces combustible waste by 30%
and annually produces 400 tonnes of organic
fertiliser. All the compost produced is distributed
to local farms to grow crops, which are sold andconsumed locally. This guideline shows the stepsof how this composting system was establishedin Nagai (Tasaki et al., 2016), which may be helpful
for other local governments that are considering
the development of composting systems.
Following a suggestion from the mayor of Nagai
City, who encouraged the public participation of
local communities, a committee composed ofresidents was established to discuss the next
master plan of the city. A working group on
agriculture was launched under the committee topromote the local farming industry. By investigating
examples in other areas, the committee foundways to produce compost derived from food waste
for use as organic fertiliser. The working groupon agriculture compiled its recommendations
on promoting the development of a composting
system through the collection of food wastefrom households and the use of the compost
produced on farms. The mayor adopted theserecommendations as part of a new master planon the future of agriculture.
The residents who were involved as membersof the working group on agriculture establisheda study team on organic agriculture and invited
farmers, members of the chamber of commerce,
and members of the women’s union to takepart. The study team negotiated with the mayor
and successfully received financial support for
their study to achieve the recommendations
made for the new master plan. The members of
the study team on organic agriculture started
to investigate how to collect food waste fromhouseholds, different types of composting, waysof utilising compost and other activities related tosustainable waste management. They compiled
and submitted a final report on food waste
composting to the mayor.
Based on the results of the investigation, the study
team independently analysed the feasibility offood waste composting. A member of the study
team asked the women’s union to collaborate withthe feasibility study, and 30 households started
to separate food waste at their homes. Anothermember of the study team who owned a restaurant
separated food waste for composting on a trial
basis. Collection bins for food waste were set up
in two areas, and food waste was disposed of in
the bins twice a week. The separated food waste
was collected by the study team and transported
to a composting depot at a local cattle farm,where food waste was mixed with cattle faeces
and fermented aerobically. The farmers who weremembers of the study team utilised the compost
for agriculture and grow vegetables, which were
distributed to the households who had cooperated
in separating food waste. The feasibility study
lasted for two years with municipal subsidies

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting33

4. Case Studies

offered to purchase necessities and rent a truck
to collect food waste.
The study team introduced their activities online,
and people interested in this initiative visited thefood waste composting site in Nagai. The mayor
ordered the farm policy planning division of Nagai
City to expand activities on food waste compostingin the city. Other related divisions provided
and shared necessary data and implemented
public awareness activities to introduce these
activities. A promotion team was established incollaboration with related divisions of the Nagai
city government.
Nagai City officially initiated a feasibility study
on the separation and collection of food waste
in model areas in partnership with the study
team on organic agriculture. The farm policy
planning division acquired a budget, and thestudy team carried out the feasibility study. Since
the feasibility study required an increase in thenumber of cooperating households, the networkof the women’s union collaborated with the study
team to increase cooperation with 100 households
in the residential area. Through a process of trial
and error, they concluded that buckets (Fig. 39,40) were the best option for keeping food waste
at home and bringing it to collection bins based
feedback from users. The farm policy planning
division of Nagai City recognised the residents’high level of interest on food waste composting
and finally decided to implement composting on afull scale following a feasibility study in the modelarea.
Together with the study team on organic
agriculture, Nagai City embarked on an initiative toformulate a project plan to construct and operate
the composting plant and encourage organic
farming using compost. Good practices on foodwaste composting in other areas of Japan were
investigated, in which the importance of demandfor compost was emphasised. These goodpractices also suggested that it was important
to demonstrate to users the advantages ofusing compost. Based on this investigation, the34

CCET guideline series on intermediate municipal solid waste treatment technologies

Compostingcity decided to collect food waste from central
residential areas only. This is because households
in rural areas in Nagai City managed food waste
on their own and because transporting food wastefrom rural areas was inefficient.
Based on the composting plan, Nagai City
constructed a composting plant with a subsidy
from the Ministry of Agriculture, Forestry and
Fisheries (Fig. 41). The composting plant used
cattle faeces from livestock farmers and riceFig. 39 Discharging food waste using a bucket
at a collection point

Fig. 40 Food waste discharged into acollection container

Fig. 41 Composting plant in Nagai City, Japan

4. Case Studies

husk from rice farmers to mix with food waste.
The proportion of food waste, cattle faeces, andrice husk changed and improved through trial anderror. Officers from the environmental divisionof the city government visited areas where foodwaste was constantly being separated andcollected together with members of the study
team on organic agriculture to promote andmonitor the activity in the early days. The study
team members carefully explained that source
separation of food waste was necessary to createa sound environment for the future and asked local
people for their cooperation in separating foodwaste at home. The members of the study teamon organic agriculture were committed to utilising
the compost produced at the composting plant.
The study team on organic agriculture faceda challenge in determining how to increase
the number of farmers utilising compost. As asolution, a guideline on cultivation methods using
the compost was developed, and a system tocertify crops produced according to the guideline
was established, with a certification office set
up in the farm policy planning division of the city
government. In this system, special labels areattached to farm products to indicate their status
as certified products (Fig. 42). The members of thestudy team on organic agriculture held meetings
for farmers and residents to explain about the
food waste composting and certification system.
The study team also endeavoured to increase thenumber of shops and restaurants using certified
farm products in cooperation with the network of
the local chamber of commerce (Fig. 43).

about the effects of food waste compostingon school lunches and called for residents totake further steps to separate food waste athome. Nagai City and the study team on organic
agriculture were commended by the prefectural
government for expanding the local production offarm products for local consumption.

Fig. 42 Label for certified products

Fig. 43 Sales of vegetables grown withcompost at a local market

Nagai City had instituted a policy to consume
local farm crops by promoting its use in school
lunches. The farm policy planning division of
the city government negotiated with the boardof education on the use of certified rice andvegetables for school lunches in the city. Farmers
who supplied certified farm crops for school
lunches increased their use of the produced
compost, which resulted in increased demand
for the compost. The city government launched apublic awareness campaign informing residents

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting35

5. Conclusion and Recommendations

5

Conclusion and Recommendations

Composting aims to treat organic waste
biologically and to produce compost, an organic
fertiliser, that improves soil conditions chemically,
biologically and physically. Composting helps
reduce the volume of MSW disposed in landfill
sites in developing countries and dramaticallyreduces environmental impacts by producing
the compost that users need. Composting also
reduces methane emissions from landfills andlowers carbon footprint. In addition, household
and community-based composting can
specifically bring social and economic benefits
to the users.
Composting projects are strongly recommended
for cities or areas that seek alternative treatment
systems to replace landfilling. The city or area
should be able to separately collect quality raw
materials for composting, secure enough demandfor compost, and safeguard an adequate budget
to operate composting plants for decades. The
city or area should also have a sufficient level ofmanpower and institutional capacity to ensurethat composting projects are sustainable.

36

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting

Compost should not contain contaminants, suchas non-biodegradable or hazardous waste, as
they can negatively impact quality. This guideline
asserts that the separate collection of organic
waste is an essential element in supplying
quality raw materials for composting to produce
high-quality compost. There are several options
available to residents for the separate collection
and transport of organic waste. The mostsuitable option should be adopted based on
local situations and detailed feasibility studies toensure that only high-quality waste is collected.
A composting system needs users, such as
local farmers, who should be included fromthe very start of the planning stage to ensurethat their opinions are reflected in the system.
Without the involvement of local farmers who use
compost regularly, composting systems will not
be successful in accomplishing the goals of thelocal government to reduce the amount of waste
disposed of in landfills and streamline waste
management.

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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 designinga 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.

CCET guideline series on intermediate municipal solid waste treatment technologies

Composting39

United Nations Avenue, Gigiri
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