Accelerating the Commercial Implementation of Electromethanogenic Reactors

Addressing the urgent global challenges of sustainable energy production and responsible water management is critical to achieving long-term environmental and economic resilience. The United Nations Environment Programme (2023) highlights the pivotal role of resource recovery and wastewater treatment in advancing Sustainable Development Goals 6 (clean water and sanitation) and 7 (affordable and clean energy). Biogas technologies that extract chemical energy from organic-rich wastewaters—originating from domestic, industrial, and agricultural sources—represent a promising avenue for sustainable development.

However, traditional anaerobic digestion (AD) systems are often economically and technically unsuitable for small and medium enterprises (SMEs), limiting broader adoption. In contrast, electromethanogenic reactors offer a next-generation solution: scalable, decentralised systems that couple wastewater treatment with direct methane production through bioelectrochemical processes. Accelerating their commercial deployment can empower businesses to participate in the circular economy—transforming waste into energy, reducing operational costs, and contributing to climate action—especially in sectors currently underserved by conventional biogas technologies.

The aim of this research was to accelerate the commercialisation and implementation of electromethanogenic reactor technology, by addressing some of the key challenges associated with this as yet underutilised technology.

Scale demonstration- A pilot scale EMR of 4000 L capacity was designed, built and operated at a brewery, treating real brewery wastewater. Stable hydraulic retention times and organic loading rates of 2.3 days and 6.75 kg tCOD/m3/d were achieved, which verified that the technology could be commercially viable where AD is not and offered insights into the mode of operation of larger systems. The outcomes of this work resulted in the sale of a commercial scale (53,000 L) system.

Process control, biosensing and automation- By observing and utilising electrode module current to activate a pump, an automated biosensor based system was created which exhibited stable operation over 74 days. With further development, this could form part of a commercial automated control system leveraging the electrode modules of EMRs to reduce operator burden and OPEX, improving commercial viability.

Exploiting the microorganisms- Identifying the enriched microorganisms in microbial communities can indicate which microbes are playing a key role in EMRs. This information was used to suggest candidates for bioaugmentation which will improve performance and stability, reduce startup times and enable inoculation of EMRs without reliance on conventional methods of manure or digestate.

Techno-economic Positioning- After determining the extent of the performance improvement observed in EMR over AD treating energy crops, a techno-economic analysis was carried out to identify the most attractive commercial applications of the technology. New build systems were identified as an attractive financial investment as well as offering a reduced footprint, with a reduction in payback time up to 33% from 6 to 4 years.

Overall, this thesis demonstrates that EMRs are a viable wastewater treatment and energy recovery technology, which has previously been underappreciated in practice. The learnings of this thesis have been implemented on commercial systems at breweries, dairy farms and AD sites and laid the groundwork for biosensor led operation of those systems. Still, the technology needs to be developed further and this thesis lays the groundwork for this process by unlocking industry support.