Abstract/Summary

The use of whey permeate as anaerobic digestion (AD) feedstock presents a potential challenge for methane (CH4) production due to its acidity and high carbon content. This study investigated the optimal parameters of whey permeate AD by incorporating CH4 yield with CH4 equivalent of produced volatile fatty acids (VFAs) over volatile solid degradation to determine the mass balance of the system. Batch AD experiments were conducted at various inoculum-substrate ratios (ISRs), initial pH levels, and mesophilic temperatures. Results demonstrated that ISR influences VFA profiles regardless of the variation in temperatures and pH, with the exception at ISR 2. Mass balance analysis showed that the highest yield (1441.42 ± 43.78 NLCH4kgVS−1 degraded) was achieved in reactors operated at ISR 2, initial pH of 7.5, at 30°C. The results confirmed a dynamic effect of ISR and temperature throughout whey permeate AD. Finally, response surface methodology was employed to understand operational optimisation based on mass balance data.