Comparison of anaerobic digestion of various food and non-food wastes: impact of inoculum source on biogas production

This study investigated how the inoculum source and type of organic waste influence biogas production, removal of various pollutants, and chemical parameters under thermophilic conditions at 55 °C. The three inoculum sources evaluated were horse manure (HM), cattle manure (CM), and municipal sewage sludge. The study evaluated the biochemical methane potential (BMP) of several substrates including food waste (FW), orange peel (OP), coffee grounds (CG), duckweed (Lemna gibba) (DW), and seagrass (SG). The results indicated differences in biogas production depending on the inoculum used. With horse manure, the highest yield was obtained by DW, producing 4549.87 ml of biogas per gram of total volatile solids (TVS). Using DW with CM had a maximum production of 7423.05 ml/g of TVS, while using anaerobic sludge as inoculum consistently produced the least biogas with all substrates. The study also evaluated the removal efficiency of various parameters including COD, TS, TVS, NH4+ and TKN. Finally, the estimated kinetic parameters for the biogas production potential and rates were discussed using the first order model and the modified Gompertz model, and found that the modified Gompertz plot had a higher correlation than the first-order model with the maximum plot to simulate the biogas accumulation production.