Evaluation of the Biogas Productivity Potential of Fish Waste: A Lab Scale Batch Study

Purpose: The biogas productivity potential of fish waste (FW) was evaluated. Methods: Batch trials were carried out in 1.3 L glass digesters kept in a temperature controlled chambers at 36.5˚C. The first order kinetic model and the modified Gompertz model were evaluated for biogas production. The Chen and Hashimoto model was used to determine the critical hydraulic retention time (HRT Critical) for FW under mesophilic conditions. The feasibility of co-digestion of FW with animal manure was studied. Results: The biogas and methane potential of FW was found to be 757 and 554 mL/g VS, respectively. The methane content in the biogas produced from FW was found to be 73% and VS removal was found to be 77%. There was smaller difference between measured and predicted biogas production when using the modified Gompertz model (16.5%) than using first order kinetic model (31%). The time period for 80%-90% of biogas production (T80-90) from FW was calculated to be 50.3-53.5 days. Similarly, the HRT Critical for FW was calculated to be 13 days under mesophilic conditions. The methane production from swine manure (SM) and cow manure (CM) digesters could be enhanced by 13%-115% and 17%-152% by mixing 10%-90% of FW with SM and CM, respectively. Conclusions: The FW was found to be highly potential substrate for anaerobic digestion for biogas production. The modified Gompertz model could be more appropriate in describing anaerobic digestion process of FW. It could be promising for co-digestion of FW with animal manure.