Feasibility Study of Biogas Production from Water Hyacinth : A Case of Lake Chivero – Harare, Zimbabwe

摘要

Water hyacinth is considered as a noxious weed in many parts of the world as it grows very fast and depletes nutrient and oxygen rapidly from water bodies, adversely affecting flora and fauna. There have been instances of complete blockage of waterways by water hyacinth making fishing and recreation very difficult. This paper investigated the possibility of producing biogas from Water Hyacinth (WH) taking Lake Chivero as a case study. It also focused on comparing the biogas output from dry and fresh water hyacinth. The wet mass of WH in Lake Chivero was found to be 197 400 tons/yr and the dry mass was 23 688 tons/yr. Experimental analysis gave a Water Hyacinth Total Solids of 10% and a Volatile Solids of 89.13%. Laboratory experiments showed that 1kg of WH yields 12.1 liters of biogas and a potential yield of 1681.08m3/day which in turn yields 573 248.28 m3/yr. The potential biogas obtainable would benefit 934 households and has an electrical generation potential of 87.56kW.The digester volume required was computed to be 10 419.90 m3.