Survival of pathogens in dried faecal sludge (Uganda)

High generation of faecal sludge has poured more attention on its reuse as a soil conditioner. However, because of the high level of pathogens in it, there is the need for treatment before land application. Composting has been regarded as the most feasible method in reducing pathogen concentrations in faecal sludge and monitoring the concentration of pathogens during the composting process is necessary to ascertain its efficiency. This study evaluated the survival of E. coli and Salmonella spp in the compost from three treatment plants by quantifying their concentration before and after the treatment process. The concentration of bacteria was quantified using culture method. The results were then compared to those obtained using quantitative real-time PCR (qPCR). Results from culture method and qPCR were not significantly different and the three composting plants were generally not efficient in reducing the concentration of E. coli and Salmonella spp to the recommended level. Hence, composts from these plants would not be suitable in agriculture. Although temperature was monitored within the recommended range, the compost materials might not have been exposed to the required time-temperature condition due to lack of turning during the thermophilic stage. Salmonella also showed better survival than E. coli in different conditions, suggesting that E. coil may not be a reliable indicator for Salmonella.