Kinetics of Methane Production from Co-digestion of Agricultural Wastes
Abstract
Anaerobic digestion (AD) is widely used for treatment of organic waste for biogas production. Co-digestion of agricultural wastes with various substrate combinations is one of the ways to increase and stabilize biogas yield. The influence of co-substrates on kinetics of methane production in anaerobic fermentation of pig and manure slurry was studied by performing a series of laboratory experiments using food waste, biowaste and winemaking waste as co-substrates. Experiments were performed in the laboratory reactors of Hohenheim biogas testing system in batch mode at the temperature of 37C. Methane production rate was used to evaluate co-digestion of agricultural slurry. Research results showed that co-substrates gave significant effect to methane production kinetics. The kinetic parameters of methane production i.e. potential yield of methane (P), maximum methane yield rate (Rm) and duration of lag-phase (?) were analyzed using modified Gompertz equation. Technical time to produce 95% of potential methane yield was investigated and efficient period of anaerobic digestion was calculated. The potential production of methane was reached in lag-phase duration (?) of about 10-15 days. Maximal methane production rate was reduced 2-3 times in co-digestion than in mono-digestion of pig and cattle manure during anaerobic digestion for 35 days.
