Quantification and characterisation of faecal sludge from on-site sanitation systems prior the design of a treatment plant in Bangangte, West Region of Cameroon

Abstract

Poor access to basic sanitation is a global concern, but alarmingly prevalent in low-and middle- income countries. In peri-urban areas, access to sanitation is provided mainly through the use of on-site sanitation systems. Unfortunately, the lack of emptying services as well as treatment plants for faecal sludge hamper the access to sustainable sanitation. The design of such treatment plants requires the mastering of the faecal sludge production and quality from sanitation systems. The present work therefore aims at evaluating the quantity and quality of faecal sludge in the city of Bangangte, West Cameroon, with a view to design and build a treatment plant for this waste. Through a survey of 1350 households as well as public services, on-site existing systems for faecal sludge management were identified, the production of sludge estimated using current estimation methodologies and the sludge quality determined. Five types of on-site systems for faecal sludge containment and treatment were identified: pit latrines (78%), septic tanks (18%), hand-flush toilets (3%), VIP latrines (1%). Faecal sludge production was estimated at 13,659 m3using specific production methodology, 8081 m3 based on the characteristics of the sanitation facilities and 9697 m3 based on the demand for mechanical emptying. An average of 10,479 ± 2870 m3 from the three estimates was proposed in order to minimise the limitations of individual estimation methodologies and avoid the over or under sizing of treatment plants using these estimates. The characterization of the sludge produced exhibited high variability of the sludge quality. The sludge COD/BOD5 and TS/COD ratios confirm the suitability of the sludge produced in the municipality of Bangangte for biological treatments.