Activity pattern of bacteria in biodigester based on gas production and burning hour analyses

Abstract

Pollution around the world continues to grow and hence there is a growing interest in devising efficient and cost effective waste management. Biogas technology has in recent times viewed as a very good source of sustainable waste management. The present study was undertaken to investigate the role of different types of mesophilic, thermophilic and anaerobic bacteria in the bio digester responsible for biogas production. The activity pattern of bacteria in the bio digester based on gas production and the burning hour analyses of the biogas were also estimated in the study. Six samples of slurry from two biodigesters; one installed at University livestock farm and other at buffalo farm in the College of Veterinary and Animal Sciences, Mannuthy were collected using a pump in to UV sterilised polythene bag and subjected to microbial analysis. The activity pattern of microorganisms in the biodigester at the buffalo farm was studied based on the gas production pattern (Sasse, 1988). When the mean total viable count were examined (Mortan, 2001) from top to bottom of biodigester it was observed that aerobic mesophilic counts decreased and anaerobic mesophilic counts increased towards bottom. While both aerobic and anaerobic thermophilic bacterial count increased towards the bottom of the biodigester. Methanogenic bacteria constituting the thermophilc organisms were found to be actively growing at the bottom of biodigester. The burning hour analysis of biogas from one of the biodigester (at the buffalo farm) was also carried out (Sasse, 1988). Burning hour analysis showed that a volume of 0.1074 m3 methane rich biogas could produce a blue flame for an hour. The study illustrates the importance of biogas technology, besides supplying energy and manure, provides an excellent opportunity for mitigation of greenhouse gas emission and reducing global warming through substituting firewood for cooking. Keywords: biogas, biodigester, activity pattern, burning hour