Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

In this research, three faecal sludge sanitizing methodslactic acid fermentation, urea treatment and lime treatmentwere studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m(3) of faecal sludge was estimated to be Euro32 for lactic acid fermentation, Euro20 for urea treatment and Euro12 for hydrated lime treatment.