Small-Scale Sludge Treatment System for Daeum Mien – Kandal Province: A GRET Sanitation Project in Cambodia

The French NGO GRET, established in 1976, has a mission of fair international development, through designing and implementing field projects, providing expertise, conducting research, and running information and exchange networks for development issues, and currently works in 27 countries. As part of this mission, GRET professionals have taken on various water and sanitation projects in developing countries, including, since 1988, in the Kingdom of Cambodia. Water and sanitation are one of the most pressing issues facing people in rural Cambodia. Of particular difficulty for sanitation advocates in Cambodia is the old habit of open defecation, with the result of exposing human excreta to the environment. This leads to water and soil contamination and to widespread disease outbreaks. The UN estimated that, in 2008, only 23% of rural residents and 82% of urban residents had access to improved sanitation, which means the country still has a long way to go to achieving ‘sanitation for all’. For these residents that do have improved sanitation though, a new problem arises. With the exception of households connected to a sewerage system, the other forms of improved sanitation (pit toilets, pour-flush latrines leading to pits or septic tanks, flush toilets leading to septic tanks) all create sludge – the concentrated solid result of the accumulation and compression of several years of blackwater entering the pit/tank. Failure to regularly remove this accumulated sludge (which is the norm in Cambodia), results in a loss of efficiency of the pit/tank and, therefore, causes further groundwater pollution than would otherwise be the case. Prior to this project, business for private desludgers was relatively minor, with no sludge treatment plants and correspondingly high prices, given the current standard of living. The 7 private desludging operations established in the city were simply disposing of the highly potent sludge onto farmers’ fields, often charging a fee from the farmer for this disposal. This was not a sustainable option, as untreated sludge is dangerous to both human health and the environment due to its high pathogen levels. Recognizing this issue and opportunity, the French NGO GRET began a small-scale sludge treatment plant project, as part of their larger PACEPAC sanitation programme in Cambodia. Choosing a farmer’s field site called Daeum Mien on the rural outskirts of Phnom Penh, the project used an innovative new, small-footprint and low cost design for a sludge treatment plant that would fully process the sludge into useable compost.

This teaching case is available here.

Published by Sustainable Sanitation Alliance.