Experimental and Kinetics Studies for Biogas Production Using Water Hyacinth (Eichhornia crassipes [Mart.] Solms) and Sugar Mill Effluent

The present study investigated the kinetics of biogas production by co-digestion of Eichhornia crassipes supplemented with sugar mill effluent. The influence of digester temperature (30 and 40 degrees C) on biogas production during the anaerobic digestion of mixed substrates was evaluated. Experimental values obtained in 15 days batch study revealed that the digester incubated at 40 degrees C produced higher biogas production (6771 mL) than the digester incubated at 30 degrees C (6325 mL). For digester incubated at 40 degrees C, value of kinetic constants i.e. mu(m) (biogas production potential), lambda (lag phase) and P (cumulative biogas production) were 0.21 day(-1), 8.89 days and 6862.60 mL, respectively, while values of mu(m,)lambda and P for other digester (incubated at 30 degrees C) were 0.20 day(-1), 9.47 days and 6426.47 mL, respectively. Modified Gompertz plot showed significant coefficient of determination (0.99) for co-digestion process at both temperatures. Digester incubated at 40 degrees C was found with maximum drop in pH (6.4), chemical oxygen demand (488.89 mg L-1), total solids (21.49%), total kjeldahl nitrogen (0.82%), total organic carbon (14.19%) and volatile solids (16.53%) on 15th day of hydraulic retention time. Analysis of co-substrate by Fourier transform infrared spectroscopy further confirmed the presence of organic compounds responsible for biogas production. These results proved that biogas production can be enhanced in co-digestion process at 40 degrees C with simultaneous treatment of industrial effluent. The present study will be useful for the integrated management of biomass and industrial waste for energy recovery.