ABSTRACT
Hight birth rate in developing countries generates huge amounts of faecal sludge to treat at a given time. In sub-Saharan Africa, it is estimated that 95% of households are not connected to a sewerage system for excreta disposal, and faecal sludge treatment of plants is almost absent, thus the necessity of developing cost-effective technologies to contain their harmful effect. In response to this preoccupation, pilot scale experiments combining drying beds with maturation ponds were conducted in Yaounde (Cameroon) for the treatment of faecal sludge. Raw faecal sludge was applied once a week at a load of 200â kg DM/m2/yr. on a 1 m2 section drying bed planted with Echinochloa pyramidalis plant for dehydration. The leachate obtained was subsequently polished in two shallow maturation ponds (50â cm depth) in series, following a varying hydraulic retention time (HRT) of 4, 7, and 10 days. Results showed the set-up to be effective at 10 days HRT in reducing significantly (p < 0.05) nutrient and organic pollutants as well as faecal coliforms in the final effluent compared to 4 and 7 days. However, suspended solids removal remained inefficient due to high algal biomass. The performance of the system enabled the treatment to meet the requirements of the Cameroonian guidelines for discharge and reuse in non-restricted agriculture. These results constitute advancement towards a comprehensive treatment of faecal sludge with the perspective of reuse of the effluent. Validation of this treatment scheme at full scale is ongoing for its adoption and implementation in the Cameroon national sanitation strategy.
Subject(s)
Ponds , Sewage , Cameroon , Plants , Feces , Waste Disposal, Fluid/methodsABSTRACT
The removal of pathogens in irrigation water is of great importance in developing countries. Indeed, wastewater generally reused for agriculture in countries such as Cameroon is associated with health and environmental concerns. Recent studies have shown a strong disinfectant action of the natural coagulant from the seeds of Moringa oleifera. These findings have raised the question whether or not they can be used to polish effluents from natural systems treating faecal sludge. This paper deals with trials carried out to investigate the effect of these extracts in reducing faecal indicators from initially treated faecal sludge leachate. Bacteriological and physico-chemical parameters were used to determine the optimum conditions and assess treatment efficacy. Settling time of 3 h at a concentration of extracts between 267 and 333â mg/L permitted to reduce Escherichia coli and faecal coliforms from 4.85 to 3.92 ulog (86.74%) and from 5.75 to 4.87 ulog (86.39%) respectively with 1 ulog equal to 90%. For the same settling time and at a concentration of 333â mg/L, faecal streptococci were removed from 6.40 to 5.67 ulog (81.33%). This level of removal suggests that this natural coagulant cannot be used alone for disinfection of heavily loaded effluent. Further investigations are therefore still needed to fulfil the Cameroon and WHO guidelines for safe reuse in agriculture.