Kinetic studies of biogas generated from water hyacinth (<i>Eichhornia crassipes</i>)

Abstract

This research work investigated the operational process of production of biogas by the leaves, stem and their mixtures of the water hyacinth (Eichhornia crassipes), during anaerobic digestion for a period of eight weeks, using locally constructed digesters. Two simplified kinetic models; pseudo first order and pseudo second order were applied to fit the experimental data obtained from the biogas produced. Irrespective of the high correlation coefficients (R2) of the second order kinetic model, the rate of gas production based on validity test fitted well and hence, governed the first order kinetic. Results in This study uncovered the fact that mixed substrate generated gas faster at a rate almost two times more than that of the stems (1: 1.7) and slightly more than the rate for the leaves (1:1.05). The effect of mixed substrate was also shown to favor the leaves than it did the stems. Generally, biogas was successfully obtained from Eichhornia crassipes, in a proportion that competed well with those of similar biomass reported in literature.

Keywords: Kinetic models, biomass, biogas, Water hyacinth, energy