Challenging conventional temperature ranges in anaerobic digestion: intermediate (45 °C) as general optimum with feedstock-dependent performance differences from mesophilic (35 °C) and thermophilic (55 °C) conditions

Pincam, Tararag, Liu, Yong-Qiang, Short, Michael, Guo, Bing, Sadhukhan, Jhuma and Bywater, Angela (2025) Challenging conventional temperature ranges in anaerobic digestion: intermediate (45 °C) as general optimum with feedstock-dependent performance differences from mesophilic (35 °C) and thermophilic (55 °C) conditions. Bioresource Technology, 441, 1-12, [133609]. (doi:10.1016/j.biortech.2025.133609).

Abstract

This study challenges the conventional view that anaerobic digestion (AD) performs optimally only under mesophilic and thermophilic conditions by systematically evaluating AD at an intermediate temperature of 45 °C, using two energy crop-based feedstocks with varying digestibility. The results showed that, for readily biodegradable feedstock, digestion at 45 °C yielded the highest methane production and exhibited superior process stability. For lignocellulose-rich feedstock, similar methane yields were produced across three temperatures but generated more viscous digestate than readily biodegradable feedstock, especially at lower temperatures. Feedstock composition strongly influenced system resilience and volatile fatty acid accumulation, with readily degradable feedstock displaying greater sensitivity to temperature changes. Overall, the findings demonstrate that temperature effect on AD is feedstock-dependent and that 45 °C represents a general optimum, providing enhanced energy efficiency, process stability and favourable rheological characteristics. These insights offer practical guidance for optimising full-scale AD systems through feedstock-specific temperature control strategies.

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Contributors

Author: Yong-Qiang Liu

Author: Angela Bywater

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