Bio-Electrochemical Systems for Ethanol Wastewater Treatment

Ethanol production for use as biofuel, which will grow to 166 billion liters worldwide by 2020, produces 3-5 liters of waste for every liter of ethanol. This waste contains significant amounts of stillage that is high in both total suspended solids (TSS) and chemical oxygen demand (COD), requiring significant processing for remediation. Current treatment options such as aerobic and anaerobic digestion are not viable due to their poor economic and performance measures. In the project, IntAct Laboratories proposes a completely novel approach to ethanol stillage treatment based on microbial fuel cell (MFCs) processes. MFCs are an attractive candidate for treating the soluble (liquid) portion of stillage because they operate optimally at diffused wastewater ranges, thus precluding the need for costly dewatering or concentration steps, and produce small amounts of electricity, thus creating an energy-efficient combined process. The objectives for this project are a proof of concept to demonstrate ability to treat the soluble stillage fraction in a simple MFC, evaluation of the use of pure cultures in MFCs for ethanol waste treatment, and creation of a preliminary design of an MFC process to be incorporated into a bioethanol facility, including economic analysis and comparison to alternative treatment options. Proof of concept for treatment of ethanol stillage by MFC technology could provide a completely new way to optimize the ethanol value-chain and surrounding infrastructure and lead to significant decreases in waste production. Experimental and modeling results will be used to create a preliminary design for an MFC-based ethanol treatment system that can lead to small-scale field implementation during Phase II R&D. Due to the high water demand for biofuel production and limited treatment technologies, IntAct anticipates that such a system, if proven, will be in high demand as worldwide capacity and production increases significantly in the coming years. An MFC treatment technology for stillage waste would have applications in conventional and advanced (cellulosic) ethanol production plans as well as other biofuel production plants that generate biomass-derived waste streams.