Enhancement of bio-methane production by lignocellulose substrates

Abstract

In this study, water hyacinth, sweet sorghum bagasse and amaranth stems were used in a pig manure matrix to produce biogas with a high methane content. The anaerobic digestion was monitored over a period of 40 days, after which the biogas production significantly decreased. Samples were taken of the gas and the leachate every 5 days to monitor the production of gas and to evaluate the formation of volatile fatty acids in the leachate. The pH of the leachate was monitored using a pH meter and the cell growth in the leachate was monitored using ultraviolet spectrometry. The biogas composition was determined using gas chromatography and the volatile fatty acids in the leachate was quantified using HPLC. It was found that the addition of lignocellulose to a pig manure matrix resulted in a significant increase in the methane content and a decrease in the carbon dioxide content of the biogas. The leachate contained high amounts of volatile fatty acids such as acetic acid, lactic acid, succinic acids and butyric acid. The research showed that co-digestion in an anaerobic digester can be used to manipulate the composition of both the produced biogas and the leachate obtained after digestion