Development of an electrochemical process for blackwater disinfection in a freestanding, additive-free toilet

By Katelyn Sellgren, Christopher Gregory, Michael Hunt, Akshay Raut, Brian Hawkins, CB Parker, Ethan Klem, Jeffrey Piascik, Brian Stoner

Electrochemical disinfection has gained interest as an alternative to conventional wastewater treatment because of its high effectiveness and environmental compatibility. Two and a half billion people currently live without improved sanitation facilities. Our research efforts are focused on developing and implementing a freestanding, additive-free toilet system that treats and recycles blackwater on site. In this study, we sought to apply electrochemical disinfection to blackwater. We compared commercially available boron-doped diamond (BDD) and mixed metal oxide (MMO) electrodes for disinfection efficiency in E. coliā€“inoculated model wastewater. The MMO electrodes were found to be more efficient and thus selected for further study with blackwater. The energy required for disinfection by the MMO electrodes increased with the conductivity of the medium, decreased with increased temperature, and was independent of the applied voltage. Fecal contamination considerably increased the energy required for blackwater disinfection compared to model wastewater, demonstrating the need for testing in effluents representing the conditions of the final application.

Bibliography

Sellgren, K., Gregory, C., Hunt, M., Raut, A., Hawkins, B., Parker, C. B., ... Stoner, B. (2017). Development of an electrochemical process for blackwater disinfection in a freestanding, additive-free toilet. (RTI Press Publication No. RR-0031-1704). Research Triangle Park, NC: RTI Press. DOI: 10.3768/rtipress.2017.rr.0031.1704

Authors

Katelyn SellgrenKatelyn L. Sellgren, PhD, is a chemical engineer in the Engineered Materials, Devices and Systems Division at RTI.

Christopher GregoryChristopher W. Gregory, MSEE, was an electron engineer in the Electronics and Applied Physics Division at RTI (now the Engineered Materials, Devices and Systems Division) at the time of data collection. He is currently a research engineer at Micross Components.

Michael HuntMichael I. Hunt, BS, was an electrical engineer in the Electronics and Applied Physics Division (now the Engineered Materials, Devices and Systems Division) at RTI at the time of data collection. He is currently an electronic hardware maintenance engineer with the Northrop Grumman Corporation.

Akshay RautAkshay S. Raut, PhD, was a postdoctoral associate at Duke University in Durham, NC, at the time of data collection. He is now a process technology engineer at the Intel Corporation.

Brian HawkinsBrian T. Hawkins, PhD, is a research biologist in the Engineered Materials, Devices and Systems Division at RTI.

CB ParkerCharles B. Parker, PhD, is the director of the nanomaterials and thin films laboratory at Duke University in Durham, NC.

Ethan KlemEthan J. D. Klem, PhD, is a research scientist in the Engineered Materials, Devices and Systems Division at RTI.

Jeffrey PiascikJeffrey R. Piascik, PhD, is a senior research electron engineer in the Engineered Materials, Devices and Systems Division at RTI.

Brian StonerBrian R. Stoner, PhD, is an RTI Distinguished Fellow in materials and electronic technologies.

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