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Published April 1, 2016 | Supplemental Material + Published
Journal Article Open

Electrochemical disinfection of toilet wastewater using wastewater electrolysis cell

Abstract

The paucity of proper sanitation facilities has contributed to the spread of waterborne diseases in many developing countries. The primary goal of this study was to demonstrate the feasibility of using a wastewater electrolysis cell (WEC) for toilet wastewater disinfection. The treated wastewater was designed to reuse for toilet flushing and agricultural irrigation. Laboratory-scale electrochemical (EC) disinfection experiments were performed to investigate the disinfection efficiency of the WEC with four seeded microorganisms (Escherichia coli, Enterococcus, recombinant adenovirus serotype 5, and bacteriophage MS2). In addition, the formation of organic disinfection byproducts (DBPs) trihalomethanes (THMs) and haloacetic acids (HAA_5) at the end of the EC treatment was also investigated. The results showed that at an applied cell voltage of +4 V, the WEC achieved 5-log_(10) reductions of all four seeded microorganisms in real toilet wastewater within 60 min. In contrast, chemical chlorination (CC) disinfection using hypochlorite [NaClO] was only effective for the inactivation of bacteria. Due to the rapid formation of chloramines, less than 0.5-log_(10) reduction of MS2 was observed in toilet wastewater even at the highest [NaClO] dosage (36 mg/L, as Cl_2) over a 1 h reaction. Experiments using laboratory model waters showed that free reactive chlorine generated in situ during EC disinfection process was the main disinfectant responsible for the inactivation of microorganisms. However, the production of hydroxyl radicals [ OH], and other reactive oxygen species by the active bismuth-doped TiO_2 anode were negligible under the same electrolytic conditions. The formation of THMs and HAA_5 were found to increase with higher applied cell voltage. Based on the energy consumption estimates, the WEC system can be operated using solar energy stored in a DC battery as the sole power source.

Additional Information

© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) Received 30 August 2015; Received in revised form 8 January 2016; Accepted 19 January 2016; Available online 21 January 2016. This work was supported by the Bill and Melinda Gates Foundation OPP 1069500 and OPP 1111246. Graduate Fellowship support to X. Huang and K. Lim was provided by the U.S. National Science Foundation Partnerships for International Research and Education (OISE-1243543).

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August 22, 2023
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