Performance of thermal pretreatment and mesophilic fermentation system on pathogen inactivation and biogas production of faecal sludge: Initial laboratory results

The performance of thermal pretreatment of faecal sludge and biogas production of continuous stirred tank reactor (TPCSTR) system on faecal sludge was evaluated in the laboratory of the University of Science and Technology Beijing, China. First, the effectiveness of thermal pretreatment on the inactivation of pathogens and the relationship between complete inactivation time and TS were researched. Second, the effect of sludge retention time (SRT) on the TPCSTR performance of faecal sludge was investigated. Results demonstrated that the time it took for the complete inactivation of pathogens (i.e., faecal coliform, salmonella spp., faecal streptococcus) was 60, 60, 80, 80, 100, 100, and 100 min for the TS faecal sludge concentrations of 1%, 2%, 4%, 6%, 8%, 10%, and 12%, respectively. The experiments showed that the TPCSTR process was stable and efficient to inactivate pathogens under the operation conditions (i.e., TS = 8%, agitation speed = 120 rpm, and temperature = 37 ± 1 °C). The highest biogas production of faecal sludge was 453.21 L kg −1 [TS] day −1 at SRT of 25 days.