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Bioelectrochemical system treats wastewater and generates biogas

| By Scott Jenkins

The first full-scale installation of a unique bioelectrochemical wastewater-treatment system was recently started up at a California brewery. The system, known as the EcoVolt Reactor, was developed by Cambrian Innovation Inc. (Boston, Mass.; www.cambrianinnovation.com). EcoVolt Reactor is a microbial reactor system that eliminates around 90% of biological oxygen demand (BOD) in wastewater while generating methane from the organic carbon.

The EcoVolt Reactor system works by applying a small electric current to an electrochemical cell containing naturally occurring bacteria and archaea species. The applied current activates metabolic reaction pathways that would not be possible in normal anaerobic microbial respiration. The anaerobic microbes are grown on a fixed film that is designed for enhanced stability, says Justin Buck, co-founder and chief technology officer at Cambrian. The system is related to a microbial fuel cell, Buck explains, but instead of generating a current from the biological redox reactions, a small current is added to stimulate desired anaerobic respiration pathways and products. The current also provides continuous feedback in real time, allowing the system to monitor itself.

bioelectrochemical wastewater-treatment system

The initial EcoVolt Reactor installation treats high-BOD spent brewery water at a California craft beer facility, producing enough biogas to generate 130 kW of renewable electricity and 45,000 therms of heat per year in a combined heat and power (CHP) system. Downstream polishing units (EcoVolt MBRs — aerobic membrane bioreactors) remove the remaining BOD and trace solids, producing clear, reusable water (80,000 gal/d). The EcoVolt system allows the brewery to cut its water footprint by 40% while producing more than 20% of its energy demand.

The EcoVolt Reactors are modular, railcar-sized units that are road-transportable and fully automated, so capacity can be expanded by adding units, Buck says. Cambrian is looking for its first applications in the beer and wine-making space because the wastewater from those processes disrupts municipal water treatment systems and comes with significant expense to producers, Buck says. It may expand to other applications in the future.