The effect of anaerobic digestion on the survival of Salmonella and coliform bacteria

Abstract

The decline in viable number of Salmonella spp and coliform bacteria was investigated in laboratory based anaerobic and aerobic digestion of cow dung. The results indicated that the unheated anaerobic digestion had a greater reduction in the viable number of Salmonella spp and coliform
bacteria 1.05 x 104 cells/ml and 1.26 x 104 cells/ml respectively than the aerobic digestion 4.50 x 106 and 1.58 x 106 cells/ml respectively. The anaerobic and aerobic digestions were found to be temperature dependent. Decrease in temperature from 31±1 to 26±1oC resulted in increase in viable cell count in the digesters. The final pH was found to be 8.10 in the unheated anaerobic digestion. The reduction of Salmonella spp to 1.05 x 104cells/ml showed that anaerobic digestion can help in combating the spread of pathogenic organisms at livestock production sites, abattoirs, meat processing units and farm lands.

Keywords: Salmonella spp, coliform bacteria, cow dung, anaerobic and aerobic digestion