Development of an Electrochemical Process for Blackwater Disinfection in a Freestanding, Additive-Free Toilet

Abstract

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. coli–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.