Department Sanitation, Water and Solid Waste for Development
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
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.
Decentralised Composting - Assessment of Viability through Combined Material Flow Analysis and Cost Accounting [pdf]
Decentralised Composting in Developing Countries - Financial and Technical Evaluation in the Case of Asmara City [pdf]
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.