Suitability of treated FS using Jatropha curcas on unplanted sand drying beds for agricultural use in Dar es Salaam, Tanzania

Abstract

Abstract The huge amount of water in faecal sludge (FS) has been presented as one of the major faecal sludge management (FSM) challenges and concerns. Jatropha curcas (JC) has been adopted as a dewatering and disinfection solution for FS treatment. However, very little is known about the agricultural suitability of their physical–chemical characteristics, nutrient and pathogen levels. The agricultural suitability of by-products from the unplanted sand drying beds was investigated by assessing the physical–chemical parametric indices, Wilcox diagram and pathogen removal rate. The qualitative method was adopted for both untreated and treated FS samples. A total of 60 samples for dry sludge and 70 samples for both leachates from control and JC chambers were analyzed for three months. Its agricultural suitability was judged by the level of salinity and sodium hazard in leachate and pathogen levels. The results showed that the salinity level of leachate from the JC chamber falls under medium- and low-risk levels. The removal efficiency of Escherichia coli by JC in leachate was from 7 ± 2 × 109 CFU/g to 6 ± 1 × 102 CFU/100 mL. Treating FS with JC is suitable for reducing salinity and sodium hazards in leachate hence favourable for irrigation. Further treatment of dry sludge is required before being used for agriculture.