Table of Contents
Microbial fuel cells for brewery wastewater treatment - efficiency requirements and treatment performance - Development of scenario-based benchmarks involving conventional wastewater treatment plants
S. Brunschweiger, L. Hörner, T. Hofmann and K. Glas
Water management and waste disposal are significant cost factors in the brewing industry, thus prompting breweries to install in-house wastewater treatment plants to reduce discharge costs. Conventional biological wastewater treatment consists of anaerobic processes or aerobic processes or a combination of anaerobic and aerobic processes to pre-treat the wastewater prior to direct or indirect discharge. Microbial fuel cells (MFCs), which can simultaneously degrade organic compounds in wastewater and generate electricity, have the potential to be used in combination with current wastewater treatment technologies. The energy efficiency and wastewater treatment performance required for MFCs to be effective in the treatment of brewery wastewater has not yet been quantified. To evaluate the application possibilities of MFCs in real-life situations, wastewater treatment plants in two breweries were examined for direct and indirect discharge. The plants were divided into sections and sub-sections to distinguish dif erent treatment stages. Based on the data obtained from this examination, benchmarks for MFCs were determined for different application scenarios and feasible energy recoveries were calculated. From an energy perspective, the energy-intensive aerobic process (scenario 1A and 1B) is the most realistic to replace because of its negative energy balance, thus making MFCs an attractive option if self-sufficient treatment is provided. An overall energy efficiency of at least 18 % for direct discharge (scenario 2B) or 23 % for indirect discharge (scenario 2A) is required for MFCs to achieve an energy gain that is comparable to the energy gain in the anaerobic stage. Based on an energy perspective, a realistically achievable efficiency of 4.5 % (scenario 4B) is sufficient to replace the complete biological wastewater treatment in the case of direct discharge with several stacked MFCs. In terms of the required treatment performance, MFCs could achieve the chemical oxygen demand removal benchmarks for all the scenarios evaluated in this study, even if a longer hydraulic retention time (HRT) is currently required. Due to the compactness, stackability and direct power generation ability of MFCs, they could be very attractive for small breweries as a replacement for the aerobic stage or as a pre-treatment before aerobic treatment to reduce energy costs.
Descriptors: microbial fuel cell, brewery wastewater treatment, energy efficiency
BrewingScience, 74 (January February), pp. 27-38
