Pathogens control benefit of some manure-based biogas plants in Thailand
Pratin Kullavanijaya (a*), Angsuma Suwongpho (a), Wilawan Sintuprapa (b)

a) Pilot Plant Development and Training Institute, King Mongkut^s University of Technology Thonburi, Bangkok 10150, Thailand
b) Department of Biotechnology, Faculty of Agro-industry, Kasetsart University, Bangkok 10900, Thailand
*pratin.kul[at]kmutt.ac.th

Abstract

The hygienic aspect is a primary expectancy of biogas technology promotion in Thailand. A major controlling strategy is limiting the widespread ability of pathogens bearing significantly in animal manures through anaerobic digestion. This study explored the persistence and inactivation of some selected pathogenic bacteria, Escherichia coli (E. coli) and Salmonella spp., in samples collected from 16 biogas plants employing differently configurations of a balloon digester (BD), anaerobic fixed-dome (AFD), anaerobic covered lagoon (ACL), and a hybrid system combining a channel digester and UASB (C-UASB). These plants operated for the treatment of swine, dairy cattle, and chicken manure. The effects of operating conditions and sub-unit combination on persistence and inactivation of E. coli and Salmonella spp. were investigated. The obtained results demonstrated the importance of the operational conditions on E. coli and Salmonella spp. reduction. The different kinds of manure, type of digester^s configuration, and stage of digestion also promoted the variations in numbers of each pathogen. Household biogas plants, BD and AFD, seemed to encourage more instability by the organic and hydraulic overloaded, causing significantly higher contamination of pathogens in the effluent. Better management and longer retention of ACL and C-UASB promoted more reduction efficiency of E. coli and Salmonella spp. The digestate drying bed was an integral unit that needed about 1-3 days for the non-detection of indicated microbes. This finding confirmed a beneficial accreditation of manure-based biogas plants in the inactivation of pathogens while simultaneously promoting organic waste stabilization, energy production, and the benefits of hygienic control.

Keywords: Biogas plant, E. coli, Pathogens, Salmonella spp., Survival

Topic: Waste and environmental management