Biogas Production from Anaerobic Co-digestion of Water Hyacinth (Eichhornia crassipes) and Cow Manure

Abstract

Production of electricity, heat and fuel are important for today’s social and economic growth. Biogas produced by anaerobic co-digestion is an alternative, carbon-neutral, renewable fuel that can be generated from local, low-cost organic materials. Co-digestion of Water Hyacinth (Eichhornia crassipes) and cow manure, was performed with a designed laboratory anaerobic fermentation system at 39°C ± 2°C. Co-digestion was conducted with 100% cow manure as a basis, and cow manure and water hyacinth ratios of 25%:75%:, 50%:50%, and 25%:75% for complete water hyacinth plants, water hyacinth roots and water hyacinth leaves fractions. Biogas production per gram volatile solid for anaerobic digested cow manure was between 134 ml to 355.59 ml. Co-digestion of cow manure and water hyacinth showed the highest average biogas production per gram volatile solids for complete water hyacinth and water hyacinth root mixture ratios of 25% cow manure and 75% of water hyacinth and water hyacinth roots yielding 273.01 ml and 462.63 ml respectively. The least biogas per gram volatile solids produced during co-fermentation was for complete water hyacinth and water hyacinth root with a ratio of 75% cow manure and 25% water hyacinth and water hyacinth root, yielding 163.77 ml and 250.28 ml respectively. Water hyacinth leave mixture at 50% cow manure and 50% water hyacinth leaves had the lowest average biogas production of 172.54 ml per gram volatile solids. The highest biogas production of 283.55 ml per gram volatile solids was achieved for a mixture of 75% cow manure and 25% water hyacinth leaves. The biogas composition without CO2 showed a biogas content for the cow manure between 54 and 65%. The application of co-digestion utilizing cow manure and water hyacinth as a feedstock could help minimize the negative environmental impact of water hyacinth and help to restore biodiversity, water quality and habitat of infested sites.