Decentralised Composting
The existing physical plan and socio-economical situation of many cities in low and middle-income countries strongly favours the implementation of decentralised systems. Decentralised composting systems are less technology dependent. Low cost, locally available materials and simple technology can be used.
- decomp database
a collection of small and medium scale composting sites all over the world - Lessons learned
on technical, financial, organisational and institutional aspects of decentralised composting - Market demand analysis and sales marketing
- Economic valuation of decentralised approaches versus centralised systems
- Co-composting of faecal sludge and municipal organic waste
Lessons leaned on technical, financial, organisational and institutional aspects of decentralised composting
Publications
The book
Decentralised Composting for Cities of Low- and Middle-Income Countries
- A User's Manual describes approaches and methods of composting on
neighbourhood level in small-and middle-scale plants. It considers issues of
waste collection, composting technologies, management systems, occupational
health concerns, product quality, marketing and end-user demands.
The
reader is led step by step through the planning, implementing and operational
stages of a decentralised composting scheme.
A joint publication by Waste Concern and Sandec
English-Version, low resolution [pdf, 4.2 MB]
English-Version, high resolution [pdf, 9.8 MB]
Hindi-Version [pdf, 9.1. MB]
French-Version, low resolution [pdf, 3.8 MB]
French-Version, high resolution [pdf, 11.8 MB]
The book Sustainable Composting [pdf] presents the findings
from the DFID-funded research project 'Promoting Compost as a Business for the
Urban Poor' in the form of guidelines developed from case studies. The
guidelines are helpful for planning and managing compost projects for creating
sustainable employment for the urban
poor.
Case Study Analysis
Dhaka, Bangladesh
A neigbourhood collection and
composting scheme in Mirpur which is using manual labour and a passive aerated
windrow
technique
India
In 6 cities of Southern India composting
schemes were documented and assessed. Lessons learned on the key technical,
institutional, organisational, financial and social aspects were summarised and
documented in a brief pamphlet for municipal managers [pdf, 586 KB]. Details of the
individual cases documented are available as factsheets [pdf].
Asmara, Eritrea
A collaborative research project
assessed the major organic waste generators and drafted potential treatment
options by composting for the city of Asmara. Benefits and risks of the use of Organic Matter from Asmara
Landfill in Agriculture [pdf 1.4 MB].
Indonesia
The research project was conducted in
collaboration with Yayasan Dian Desa in Yogyakarta. Main focus of the pilot
project initiated was on small-scale decentralised composting operated by a community-based primary
waste collection service [pdf]. The objectives of the project were to encourage
low-income urban communities to manage their own waste collection, to integrate
resource recovery and recycling into their collection scheme, and also to gain
experience with such systems for replication in other communities.
Market demand for compost
Experience has shown that numerous waste composting projects have failed in the past as little attention had been paid to compost market demand analysis. Market demand studies were conducted together with partner institutions in Tanzania, Pakistan, and Vietnam. The overall goal was to understand the barriers to compost sales and advocate improved market demand research before initiating composting schemes.
The result of these studies is the book Marketing Compost - A Guide for Compost Producers in Low and Middle-Income Countries [pdf]. This guide describes a marketing approach to composting, and is intended to help compost producers run more viable initiatives by unlocking the value of their product. The handbook does not cover everything there is to know about marketing, but starts from basics and introduces the key principles and techniques. These include understanding the ‘marketing environment’, identifying appropriate target customer groups, and developing and promoting products to suit the market.
The study Marketing Compost in Nepal [pdf] contains a marketing study for two compost producers in Nepal. The survey was done according to Sandec's Marketing Handbook and gives an overview of the market environment in Nepal, estimates the market demand of compost and makes suggestions on how to promote the product.
Economic valuation of decentralised versus centralised systems
Decentralised composting units on backyard, neighbourhood or
community level significantly reduce the waste amount that needs further
handling by the responsible entity. Therefore, small-scale composting units
treating municipal solid waste have a positive influence on the total
expenditures for urban solid waste management (SWM). For a municipal authority
responsible for solid waste management, recycling organic matter can reduce:
- costs of transport,
- costs of the disposal facilities, by prolonging the sites life span and also by reducing the environmental impact of disposal sites as the organics are largely to blame for the polluting leachate and methane problems. In addition to these direct financial savings, spill over effects such as economic savings due to employment generation, poverty alleviation, raising of waste awareness with the population, less use of foreign exchange for fertilisers, reduced resource exploitation, and an improved environmental management may result.
Co-composting of faecal sludge and municipal organic waste
Pre-treated faecal sludge (e.g. solids removed from settling/thickening tanks, sedimentation ponds or drying beds) is composted together with organic solid waste. Temperatures in the heaps should reach 55-60°C and inactivate the pathogens. The produced compost constitutes a very good soil conditioner.
When to use?
Co-composting is a very interesting
option when agricultural reuse of fecal sludge and solid waste is desired. Solid
waste needs to be available in sufficient quantity and quality (sorting).
Advantages
Allows producing a good and pathogen
free soil conditioner in relatively short time (resource recovery)
Disadvantages
Contaminants in solid waste may
reduce compost quality.
Design
It is important that the mixture of solid
waste and faecal sludge are optimal for composting. A moisture content of 50-60%
and a C:N ratio of 30-35 should be guaranteed. Good aeration by frequent turning
of the heaps is required to maintain thermophilic conditions. The composting
process is generally completed after 6 weeks to 2 months.