Production of biologically safe digested manure for land application by a full-scale biogas plant with heat-inactivation

Abstract

Inactivation of indigenous indicator micro-organisms such as faecal coliforms, coliphages, and faecal streptococci was investigated in a full-scale biogas plant that mainly digested cow manure. The biogas plant consisted principally of a feed reservoir, fermentation tank (37 °C), heat-inactivation process (70 °C), and five reservoirs for the heat-inactivated, digested manure that was used by a local livestock farmer as liquid fertilizer. Although all the indicators tended to exhibit stepwise decreases with each stage of treatment, coliphages were found to be more capable of surviving than faecal coliforms and faecal streptococci under mesophilic anaerobic conditions as well as high temperature conditions (heat-inactivation at 70 °C). Liquid fertilizer produced at the biogas plant had faecal coliform densities less than the stipulations of the US EPA 40 CFR 503 Class A limits. Heat-inactivation tests indicated that although coliphages exhibited more tolerance than other bacterial indicators between 37 and 70 °C, they were more sensitive to continuous temperature increase than faecal coliforms and faecal streptococci.

Keywords

biogas plant livestock waste indicator micro-organisms liquid fertilizer heat-inactivation wmr 1349—6

Get full access to this article

View all access options for this article.

References

APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) ( 1989): Standard Methods for the Examination of Water and Wastewater , 17th edition., APHA, AWWA, WEF, Washington DC, USA.

Bendixen, H.J. & Ammendruo, A. (1992) Veterinary Research, Monitoring and Consulting on Establishment and Operation of Joint Biogas Plants, Safeguards Against Pathogens in Biogas Plant. Ministry of Agriculture, Danish Veterinary Service, Fredriksberg, Denmark.

Berg, G. & Berman, D. (1980) Destruction by anaerobic mesophilic and thermophilic digestion of viruses and indicator bacteria indigenous to domestic sludges . Applied and Environmental Microbiology, 39, 361-368.

Carrington, E.G. , Pike, E.B. , Auty, D. & Morris, R. (1991) Destruction of fecal bacteria, enteroviruses and ova of parasites in wastewater sludge by aerobic thermophilic and anaerobic mesophilic digestion. Water Science and Technology, 24, 377-380.

Ketratanakul, A. & Ohgaki, S. (1989) Indigenous coliphages and RNA F+-specific coliphages associated with suspended solids in the activated sludge process. Water Science and Technology, 21, 73-78.

Kurita, K. , Nakagawa, S. , Ono, M. , Ishida, T. & Ishiwata, T. (2003) Operating outline of Betsukai resources circulation experimental facility, Monthly Report of Civil Engineering Research Institute of Hokkaido, No. 603, pp. 10-19 (in Japanese).

Russell, A.D. (1982) The Destruction of Bacterial Spores. Academic Press, London, UK.

Scanlan, P. , Santha, H. & Fronek, S. (2004): Advanced anaerobic digestion for Class A pathogen removal. In: Proc. of the 10th World Congress on Anaerobic Digestion (AD2004), vol. 1, pp. 466-471, 29 August-2 September, Montreal, Canada. IWA Publishing, London, UK.

Uemura, S. , Takahashi, T. , Takaishi, A. , Machdar, I. , Ohashi, A. & Harada, H. (2002) Removal of indigenous coliphages and fecal coliforms by a novel sewage treatment system consisting UASB and DHS units. Water Science and Technology, 46, 303-309.

10.

US EPA (US Environmental Protection Agency) ( 1999) Environmental Regulation and Technology, Control of Pathogens and Vector Attraction in Sewage Sludge, EPA/625/R-92-013,. US EPA, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, Ohio, USA.