Ensiling of fish industry waste for biogas production: A lab scale evaluation of biochemical methane potential (BMP) and kinetics

Fish waste (FW) obtained from a fish processor was ensiled for biogas production. The FW silages were prepared by mixing FW with bread waste (BW) and brewery grain waste (BGW), and the quality of the prepared silages were evaluated. The biogas potentials of BW, BGW, three different types of FW, and FW silages were measured. A first-order kinetic model and the modified Gompertz model were also used to predict methane yield. The biogas and methane yield for FW silages after 96 days was calculated to be 671–763 mL/g VS and 441–482 mL/g VS, respectively. There were smaller differences between measured and predicted methane yield for FW silages when using a modified Gompertz model (1.1–4.3%) than when using a first-order kinetic model (22.5–32.4%). The critical HRTs and technical digestion times (T80–90) for the FW silages were calculated to be 21.0–23.8 days and 40.5–52.8 days, respectively.

► Fish waste (FW) was ensiled by mixing with bread waste (BW) and brewery grain waste (BGW).
► The mixture of FW and BW produced good quality silages than the mixture of FW and BGW.
► The methane potential for FW silage was calculated in the range of 441–482 mL/g VS added.
► The modified Gompertz model better predicted the methane yield than the first-order kinetic model.
► A hydraulic retention time >41–53 days is suggested for continuous digestion of FW silages.