Anaerobic digestion (AD) is widely used to stabilise organic wastes and recover renewable energy as biogas, supporting the conversion of biosolids and other organic resources into useful products. However, conventional AD is constrained by thermodynamically limited syntrophic reactions, volatile fatty acid accumulation, long retention times and the carbon dioxide content of raw biogas. As an alternative, microbial electrolysis cells (MECs) offer complementary bioelectrochemical pathways in which exoelectrogenic microorganisms oxidise organic substrates and transfer electrons to an anode. Applied potential can then support hydrogen production or cathodic carbon dioxide reduction to methane. However, standalone MECs face limitations including low volumetric productivity, carbon loss and electrode cost.

The PRIME trial will evaluate an integrated AD-MEC wastewater treatment process at Severn Trent’s Resource Recovery and Innovation Centre (R2IC). The system uses sustainable electrodes manufactured from recycled carbon fibre and is designed to exploit interactions between methanogenesis, electrochemical reactions and direct or indirect interspecies electron transfer. The trial will assess treatment performance, process stability, energy balance and in situ biogas upgrading across representative operating conditions, while establishing the downstream treatment required to achieve target effluent quality. PRIME will determine whether coupling AD and MEC processes can improve resource recovery and generate methane and hydrogen fuel streams at a meaningful scale.