This project will demonstrate and validate a distributed treatment system for domestic wastewater that integrates newly developed and highly complementary microbial fuel cell (MFC) and biofilter (BF) technologies. Specific objectives include:

• Integrate the MFC and BF technologies in an operator friendly configuration.

• Demonstrate the production of high-quality re-usable water that meets U.S. Environmental Protection Agency (USEPA) Guidelines for Water Reuse.
• Demonstrate a reduction in energy consumption relative to conventional aerobic wastewater treatment technology.

• Demonstrate a reduction in residuals (sludge) compared to aerobic bioreactors.

• Compare the cost and performance of the MFC/BF system to conventional treatment systems used for water reuse such as ultrafiltration/reverse osmosis.

• Generate life cycle cost data to confirm a payback period of less than 10 years.

This domestic wastewater treatment and reuse technology is comprised of an MFC followed by a BF. The MFC uses exoelectrogenic bacteria on a graphite anode to oxidize organics to carbon dioxide in combination with a carbon cathode that does not contain precious metals and reduces oxygen to water. The MFC treats wastewater organics down to a chemical oxygen demand (COD) of ~150 mg/L and generates electricity at low voltage. Voltage boost converters are used to increase the voltage for a variety of uses. The residual COD is polished in the BF that is comprised of two granular activated carbon contactors. One of the contactors is on-line at a time and treats residual organics via adsorption and biodegradation. After a period of about 6 hours the contactor is taken off-line, drained, and regenerated by the air that is drawn into the contactor. The other contactor is placed on-line. The effluent from the BF is optionally treated using filtration and disinfection to yield water for a variety of non-potable reuse applications.

A distributed MFC-BF technology can provide an energy efficient solution for wastewater treatment and increased water reuse capacity, enhancing the sustainability of Department of Defense (DoD) installations. With respect to water security and sustainability, the MFC-BF system represents a new capability for meeting net water reduction goals for the DoD. Better resource management leads to more resilient and better prepared installations. With respect to energy and economic savings, the system will be evaluated to assess total impacts through holistic life cycle analyses that consider not just the process and local water savings but also the offsets to wastewater treatment, water production, and water conveyance at the installation level. (Project Completion - 2022)

Kim, K.Y., R. Rossi, J. Regan, and B.E. Logan. 2020. Enumeration of Exoelectrogens in Microbial Fuel Cell Effluents Fed Acetate or Wastewater Substrates. Biochemical Engineering Journal, 165:107816. doi.org/10.1016/j.bej.2020.107816.

Logan, B.E., E. Zikmund, W. Yang, R. Rossi, K.-Y. Kim, P.E. Saikaly, and F. Zhang. 2018. Impact of Ohmic Resistance on Measured Electrode Potentials and Maximum Power Production in Microbial Fuel Cells. Environmental Science & Technology, 52(15):8977–8985. doi.org/10.1021/acs.est.8b02055.

Logan, B.E., R. Rossi, A. Ragab, and P.E. Saikaly. 2019. Electroactive Microorganisms in Bioelectrochemical Systems. Nature Reviews Microbiology, 17(5):307–319.

doi.org/10.1038/s41579-019-0173-x.

Myung, J., W. Yang, P.E. Saikaly, and B.E. Logan. 2018. Copper Current Collectors Reduce Long-Term Fouling of Air Cathodes in Microbial Fuel Cells. Environmental Science: Water Research & Technology, 4:513–519. doi.org/10.1039/c7ew00518k.

Rossi, R., W. Yang, E. Zikmund, D. Pant, and B.E. Logan. 2018. In Situ Biofilm Removal from Air Cathodes in Microbial Fuel Cells Treating Domestic Wastewater. Bioresource Technology, 265:200−206. doi.org/10.1016/j.biortech.2018.06.008.

Rossi, R., B.P. Cario, C. Santoro, W. Yang, P.E. Saikaly, and B.E. Logan. 2019. Evaluation of Electrode and Solution Area-Based Resistances Enables Quantitative Comparisons of Factors Impacting Microbial Fuel Cell Performance. Environmental Science & Technology, 53(7):3977–3986. doi.org/10.1021/acs.est.8b06004.

Rossi, R., D. Jones, J. Myung, E. Zikmund, W. Yang, Y. Alvarez, D. Pant, P.J. Evans, M.A. Page, D.M. Cropek, and B.E. Logan. 2019. Evaluating a Multi-Panel Air Cathode through Electrochemical and Biotic Tests. Water Resources, 148:51–59.

doi.org/10.1016/j.watres.2018.10.022.

Rossi, R., P.J. Evans, and B.E. Logan. 2019. Impact of Flow Recirculation and Anode Dimensions on Performance of a Large Scale Microbial Fuel Cell. Journal of Power Sources, 412:294–300. doi.org/10.1016/j.jpowsour.2018.11.054.

Rossi, R., X. Wang, W. Yang, and B.E. Logan. 2019. Impact of Cleaning Procedures on Restoring Cathode Performance for Microbial Fuel Cells Treating Domestic Wastewater. Bioresource Technology, 290:121759. doi.org/10.1016/j.biortech.2019.121759.

Rossi, R. and B.E. Logan. 2020. Impact of External Resistance Acclimation on Charge Transfer and Diffusion Resistance in Bench-Scale Microbial Fuel Cells. Bioresource Technology, 318:123921. doi.org/10.1016/j.biortech.2020.123921.

Rossi, R. and B.E. Logan. 2020. Unraveling the Contributions of Internal Resistance Components in Two-Chamber Microbial Fuel Cells Using the Electrode Potential Slope Analysis. Electrochimica Acta, 348:136291. doi.org/10.1016/j.electacta.2020.136291.

Rossi, R., D.M. Hall, X. Wang, J.M. Regan, and B.E. Logan. 2020. Quantifying the Factors Limiting Performance and Rates in Microbial Fuel Cells Using the Electrode Potential Slope Analysis Combined with Electrical Impedance Spectroscopy. Electrochimica Acta, 348:136330. doi.org/10.1016/j.electacta.2020.136330.

Rossi, R., D. Pant, and B.E. Logan. 2020. Chronoamperometry and Linear Sweep Voltammetry Reveals the Adverse Impact of High Carbonate Buffer Concentrations on Anode Performance in Microbial Fuel Cells. Journal of Power Sources, 476:228715. doi.org/10.1016/j.jpowsour.2020.228715.

Rossi, R., X. Wang, and B.E. Logan. 2020. High Performance Flow Through Microbial Fuel Cells with Anion Exchange Membrane. Journal of Power Sources, 475:228633. doi.org/10.1016/j.jpowsour.2020.228633.

Rossi, R., G. Baek, P.E. Saikaly, and B.E. Logan. 2021. Continuous Flow Microbial Flow Cell with Anion Exchange Membrane for Treating Low Conductivity and Poorly Buffered Wastewaters. ACS Sustainable Chemistry & Engineering, 9(7):2946-2954. doi.org/10.1021/acssuschemeng.0c09144.

Yang, W., R. Rossi, Y. Tian, K.-Y. Kim, and B.E. Logan. 2018. Mitigating External and Internal Cathode Fouling Using a Polymer Bonded Separator in Microbial Fuel Cells. Bioresource Technology, 249:1080-1084. doi.org/10.1016/j.biortech.2017.10.109.