Optimisation of whey permeate anaerobic digestion at different inoculum to substrate ratios and initial pH values under mesophilic conditions

Azkarahman, A. R., Cysneiros, D., Chatzifragkou, A. ORCID: https://orcid.org/0000-0002-9255-7871 and Karatzas, K.-A. G. (2025) Optimisation of whey permeate anaerobic digestion at different inoculum to substrate ratios and initial pH values under mesophilic conditions. International journal of sustainable energy, 44 (1). 2505444. ISSN 1478-646X doi: 10.1080/14786451.2025.2505444

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.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/123302
Identification Number/DOI	10.1080/14786451.2025.2505444
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Microbial Sciences Research Group
Publisher	Taylor and Francis
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