The Bio-methane Potential of the Water Hyacinth (Eichhorniacrassipes)

Abstract

The maintenance of waterways by local municipalities and irrigation authority has been made difficult due to the presences and nature of Eichhorniacrassipes, commonly known as water hyacinth. The water hyacinth is a very aggressive invader that forms copious mats, covering the entire surface of waterways. It causes oxygen depletion resulting fish kill. This plant species has no known direct food value to wildlife and is considered a pest species. In its drive for green economic development, its potential energy contribution within a slurry mixture via biomethanization should be explored. Biomethanization has become an increasing interest in many industrialized societies for the socio-economic benefits of being able to utilize organic waste to produce an environmentally friendly biogas which reduces carbon emissions to the environment burned. Also, the effluent can be used as fertilizers and raw materials for composting. Utilization of water hyacinth in this manner will certainly aid in the reduction of pollution in local waterways hence this study seeks to compare the anaerobic digestion of manure and water hyacinth, and determine the water hyacinth-manure mix ratio for optimum gas production. In this research, fresh water hyacinth was collected and chopped up into small pieces. A series of experiments using the biodigesters was conducted, where each biodigester was fed with chopped water hyacinth and mixed with various combinations of manure (100%, 75%, 50%, 25% and 0%) and 250ml of water, for five different fermentation slurries. Biomethanation was carried out in triplicates with a retention time six (6) weeks (42 days) in the mesophilic temperature range. The study showed that there was no statistical difference in the methanization of manure and water hyacinth. Further, the 25% water hyacinth and 75% manure (25%W.H-75%M) mix ratio produced the highest volumes of biogas that was significantly different from all other slurry mixtures. This implies that water hyacinth can be used to enhance biogas production.