Methane Production by Anaerobic Digestion of Water Hyacinth (eichhornia Crassipes)

Water hyacinth (Eichhornia crassipes) is an aquatic biomass species that exhibits prolific growth in many s s o f h e world (1). It has been suggested as a strong candidate for production of methane because of high biomass yield potential (2). Several studies have been carried out which establish that methane can be produced from water hyacinth under anaerobic digestion conditions (3-6). Both batch and semicontinuous digestion experiments were performed. The highest apparent gas yields reported were obtained in the batch mode of operation over long detention times (4), but the yields were based on wet hyacinth containing unspecified amounts of water and ash. Some of t h e data in the literature on gas yield and production rate are difficult to interpret because they a r e experimentally observed values and are not reduced to standard conditions. The energy recovery efficiencies in the product gas a re also not available because the energy contents of the feed were not determined. The work described in this paper w a s initiated to develop more quantitative data in terms of t h e physical and chemical characteristics of water hyacinth.