Low Temperature Domestic Wastewater Treatment in a Microbial Electrolysis Cell with 1 m² Anodes: Towards System Scale‐Up

Abstract

The potential benefits of applying microbial electrolysis cell (MEC) technology to wastewater treatment are clear and profound. Previous pilot studies have demonstrated a 'proof of concept' with domestic waste at ambient temperatures, but have not yet treated waste to required discharge standards, and have not reached energy neutrality. In addition, these reactors have been many orders of magnitude smaller than would be needed for full scale wastewater treatment plants. Scale-up affects many of the parameters that underpin performance; understanding its impact will be vital to further progress. Modifying a previously tested cassette-style design, we reduced the internal resistance, and increased the module size by a factor of 16, constructing an MEC with six 1 m 2 anodes. This created an anodic surface area to volume ratio of 34 m 2 m -3 . The system was operated at a hydraulic retention time of 5 hours on settled domestic wastewater for 217 days, producing more current than a scaled-down reactor, which was run in parallel. The large MEC produced 0.8 L of 93% pure H 2 d -1 at ambient winter temperatures (11.4 + 2.5°C). Chemical oxygen demand (COD) removal averaged 63.5% with an average effluent quality of 124.7 mg COD L -1 , achieving the European Urban Wastewater Treatment Directive (1991) consent.

Microbial Fuel Cells 2018

“…To solve the fouling of an ion-exchange membrane, some research groups have focused on modifying the membrane by a treatment with polymer compounds, such as poly (sodium 4-styrene sulfonate) (PSS)/poly(diallyldimethylammonium chloride) (PDADMAC) [34]. An ultra-low voltage customized DC-DC booster circuit [37] and maximum power point tracking (MPPT) [38] may provide an affordable voltage and current for self-sustained electrodialysis applications. Although further studies will be needed in the future, these results may provide a basis for techniques to isolate acetate from actual fermentation end products and culture broth from bioelectrochemical systems.…”

“…The bacteria act as a biocatalyst in microbiological fuel cells [6]; therefore, coal (carbon cloth, carbon brush) is most often used as the anode material [6,35], while carbon materials and metal electrodes perform the role of cathodes. In addition, new electrode materials or catalysts are currently being sought to act as cathodes [36][37][38][39].…”

Applications of Emerging Bioelectrochemical Technologies in Agricultural Systems: A Current Review

“…The matching between fermentation and electrohydrogenesis rates is the key to further improvement in the system performance, which can be achieved through specially designed feeding strategies or novel stepwise processes [76]. Although long-term pilot studies of MECs have been conducted, larger-scale MECs have not been built up yet, mainly due to economic concerns from the expensive costs of electrodes and external energy inputs [87][88][89]. In practice, relatively more inexpensive renewable power sources for H 2 production in MECs could be wind, geothermal and hydropower, etc.…”

Bioelectrochemical Systems for Energy Valorization of Waste Streams

“…In Ref. [4], a similar cassette electrode design but at two different scales: 0.6 m 2 and 1 m 2 anodes. It ran using settled domestic wastewater (347 mgCOD•L −1 ), at a real treatment site at ambient temperatures (8.6-15.6°C) for 217 days, with a HRT of 5 h. By decreasing the spacing of the cassettes and increasing the HRT from the Heidrich study, the COD removal was on average 63.5%, and the effluent reached European Urban Wastewater Treatment Directive discharge standards [73].…”

“…Although the ability of certain bacteria to generate electrical current was first described more than 100 years ago [2], it was not until the beginning of the present century that this phenomenon started to draw real interest form scientists and engineers. During the last 15 years, the progress made in the fields of bioelectrochemistry and BES has allowed to take the leap from the laboratory to the pilot scale [3,4] so that commercial development seems to be at hand.…”