Quantification and characterization of faecal sludge from a tropical urban area: the case study of Douala, Cameroon

Abstract

Faecal sludge (FS) management is a challenging problem in low-income countries where the majority of the urban population relies on on-site sanitation systems. The design of treatment plants relies on accurate knowledge on FS quantities and characteristics. Due to the lack of information on the quality and quantity of FS in the Cameroonian context, this study aims at evaluating the quantity and the quality of FS produced at the city scale by mechanical trucks at the dumping site of “Bois des singes” in Douala. Quantification was done through enumeration of emptying trucks and emptying truck capacities during one-week period while in the laboratory, analyses of composite samples were performed by the determination of physico-chemical, bacteriological and parasitological parameters in samples according to the standard protocols. Results on the quantification of FS in the city of Douala revealed that the weekly volume of faecal sludge dumped in natural environment at “Bois de singe” is estimated at about 2,890 m³ with an average of 50 discharges per day by mechanical emptying trucks. Concerning the characterization of FS samples, FS exhibited high strength because of its higher concentration of organic, bacterial and helminth eggs loads. Therefore, there is need for proper health and environmental protection measures to prevent threats due to dumping of untreated faecal sludge into the environment after on-site sanitation technologies emptying by the construction of a treatment plant.

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Keywords: Faecal sludge management, treatment plant, FS quantification, FS characterization, tropical urban area, Cameroon