Pilot scale microbial fuel cells using air cathodes for producing electricity while treating wastewater

Ruggero Rossi; Andy Y Hur; Martin A Page; Amalia O'Brien Thomas; Joseph J Butkiewicz; David W Jones; Gahyun Baek; Pascal E Saikaly; Donald M Cropek; Bruce E Logan

doi:10.1016/j.watres.2022.118208

Pilot scale microbial fuel cells using air cathodes for producing electricity while treating wastewater

Water Res. 2022 May 15:215:118208. doi: 10.1016/j.watres.2022.118208. Epub 2022 Feb 17.

Authors

Affiliations

¹ Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
² U.S. Army Corps of Engineers, Engineer Research and Development Center, Construction Engineering Research Laboratory, Champaign, IL 61822, USA.
³ U.S. Army Corps of Engineers, Engineer Research and Development Center, Construction Engineering Research Laboratory, Champaign, IL 61822, USA. Electronic address: martin.a.page@usace.army.mil.
⁴ Tobyhanna Army Depot, Tobyhanna, PA 18466, USA.
⁵ Environmental Science and Engineering Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Kingdom of Saudi Arabia.
⁶ Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA. Electronic address: blogan@psu.edu.

PMID: 35255425
DOI: 10.1016/j.watres.2022.118208

Abstract

Microbial fuel cells (MFCs) can generate electrical energy from the oxidation of the organic matter, but they must be demonstrated at large scales, treat real wastewaters, and show the required performance needed at a site to provide a path forward for this technology. Previous pilot-scale studies of MFC technology have relied on systems with aerated catholytes, which limited energy recovery due to the energy consumed by pumping air into the catholyte. In the present study, we developed, deployed, and tested an 850 L (1400 L total liquid volume) air-cathode MFC treating domestic-type wastewater at a centralized wastewater treatment facility. The wastewater was processed over a hydraulic retention time (HRT) of 12 h through a sequence of 17 brush anode modules (11 m² total projected anode area) and 16 cathode modules, each constructed using two air-cathodes (0.6 m² each, total cathode area of 20 m²) with the air side facing each other to allow passive air flow. The MFC effluent was further treated in a biofilter (BF) to decrease the organic matter content. The field test was conducted for over six months to fully characterize the electrochemical and wastewater treatment performance. Wastewater quality as well as electrical energy production were routinely monitored. The power produced over six months by the MFC averaged 0.46 ± 0.35 W (0.043 W m^-2 normalized to the cross-sectional area of an anode) at a current of 1.54 ± 0.90 A with a coulombic efficiency of 9%. Approximately 49 ± 15 % of the chemical oxygen demand (COD) was removed in the MFC alone as well as a large amount of the biochemical oxygen demand (BOD₅) (70%) and total suspended solid (TSS) (48%). In the combined MFC/BF process, up to 91 ± 6 % of the COD and 91 % of the BOD₅ were removed as well as certain bacteria (E. coli, 98.9%; fecal coliforms, 99.1%). The average effluent concentration of nitrate was 1.6 ± 2.4 mg L^-1, nitrite was 0.17 ± 0.24 mg L^-1 and ammonia was 0.4 ± 1.0 mg L^-1. The pilot scale reactor presented here is the largest air-cathode MFC ever tested, generating electrical power while treating wastewater.

Keywords: Biofiltration (BF); Energy from waste; Microbial fuel cell (MFC); Wastewater.

MeSH terms

Bioelectric Energy Sources* / microbiology
Electricity
Electrodes
Escherichia coli
Wastewater / microbiology

Substances

Waste Water