Methane fermentation of water hyacinth: effect of retention time and temperature

Abstract

The influence of retention times of 10, 20, 30 and 40 days on the semi-continuous anaerobic digestion of water hyacinth was tested at the laboratory level. Biogas was successfully produced using 50 and 30 g total solids/l slurries at retention times of 30 and 40 days. The retention time of 40 days proved to be much better than shorter retention times in terms of total gas produced, methane percentage and degree of decomposition of organic matter. The effect of incubation temperatures of 25, 37, 45°C and the variable temperature range of 32 to 42°C on the semicontinuous digestion of water hyacinth was also tested in the laboratory. Biogas could be successfully produced at all temperatures tested except at 45°C. At 37°C and at the variable temperature range of 32 to 42°C gas production was very rapid. Digestion at 25°C was more efficient and gas release was slower. Digestion at 45°C was very erratic.