Experimental and kinetic study of biogas production of fish processing industry in anaerobic digestion as future renewable energy resources

Biogas is a renewable energy which can be used as an alternative source to replace fossil fuels. Recently, the use of energy has become an important issue because the oil sources and natural gas are depleting. Utilization of waste to produce biogas can reduce the consumption of commercial energy sources such as kerosene as well as the use of firewood. Tilapia fish fillet industry generates large proportion of liquid fish wastes that can be digested anaerobically. The aim of this research was to study the biogas potential of different pH value and quantity of inoculum added. A first order kinetic model and the modified Gompertz model were also used to predict biogas production. Optimum pH for biogas production is pH 7; value of addition 10%, 20%, and 30% inoculum is 217.25 ml/gram, 228.02 ml/gram, and 370.76 ml/gram. Optimum inoculum for biogas production is 30% (v/v) on every pH 5.7, and 9.0 is 373.60 ml/gram; 370.76 ml/gram; and 274.8 ml/gram. The effective time for biogas production on pH 7 with 30% inoculum because of time to produce faster than other variable, base of Gompertz equation with λ value is 17.28.