title: Two-stage anaerobic digestion process for complete inactivation of enteric bacterial pathogens in human night soil.
abstract: Anaerobic digestion offers a good alternative for human waste treatment. However, the fate of enteric bacterial pathogens present in human night soil (HNS) remains a major concern for hygienic safety of the process. A two-stage anaerobic digestion process, consisting of separate acidogenic and methanogenic digesters, was designed and its efficacy in the inactivation of Salmonella typhi was compared to a single-stage digestion process. In a single-stage digestion, complete pathogen inactivation was achieved only in the digesters with high levels of volatile fatty acids (VFA approximately equal to 18,000 mg/l) and acidic pH (approximately equal to 6.0). These digesters, however, showed drastic reduction in methane yield. In the two-stage digestion process, S. typhi was completely inactivated in the acidogenic digester and the methanogenic digester was free from the pathogen even after receiving a daily dose of the pathogen. The process also achieved complete inactivation of other enteric pathogens, viz., Shigella dysenteriae and Vibrio cholerae. The two-stage process was efficient in biogas generation from HNS. Thus, the two-stage process ensures complete hygienic safety in anaerobic digestion of human night soil.
authors.affiliation: Department of Internal Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, IL 60201, USA. dkunte@enh.org
authors.forename: D P
authors.initials: DP
authors.lastname: Kunte
authors.forename: T Y
authors.initials: TY
authors.lastname: Yeole
authors.forename: D R
authors.initials: DR
authors.lastname: Ranade
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism* / Q000502:physiology; D019149:Bioreactors; D004755:Enterobacteriaceae / Q000502:physiology*; D005160:Facility Design and Construction; D005232:Fatty Acids, Volatile / Q000494:pharmacology; D006262:Health; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D012499:Sanitation; D012988:Soil Microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology
chemical_list: D005232:Fatty Acids, Volatile; D008697:Methane