Generation of biogas from segregates of municipal solid wastes in Jos, Nigeria

Abstract

A study was carried out to explore the amount of biogas that could be produced using segregated portions of municipal solid wastes (food residue, leaves, paper and a mixture of the three segregates) in Jos city, Nigeria, as substrates. The segregates were mixed with water and cow dung as inoculums, in the ratio of 3:3:1 and subjected to anaerobic digestion using a laboratory-biogas generation system set at 37oC for a period of 25 days. The initial and final pH values of the substrates were recorded. The amount of biogas generated was measured by the method of downward displacement of water from a measuring cylinder. Total plate and methanogenic bacterial counts were taken prior to, during and after fermentation respectively. The bacteria associated with the wastes were cultured on nutrient agar and modified methanogenic agar medium, enumerated, isolated and then characterized using standard bacteriological techniques. Microbial succession during the fermentation process of biogas production was determined. The results show that all the substrates demonstrated potentials for biogas production with leaves generating the highest volume of biogas. The volumes generated by each segregate were 996cm3, 52cm3, 36cm3 and 24cm3 for leaves, food residue, mixture of segregates and paper respectively. The microorganisms isolated include
Staphylococcus aureus, Streptococcus spp, Escherichia coli, Clostridium spp, Methanococcus spp and Methanobacterium spp. The results on the microbial succession study indicate that Streptococcus spp, Clostridium
spp, Escherichia coli, Methanobacterium spp and Methanococcus spp were the most active organisms involved in the biodigestion/biogas generation process. It can be concluded from the study that municipal solid wastes are a potential energy source for biogas generation that could be optimized at industrial scales.