Electrochemical disinfection of toilet wastewater using wastewater electrolysis cell. (1st April 2016)

• Record Type: Journal Article
• Authors: Huang, Xiao; Qu, Yan; Cid, Clément A.; Finke, Cody; Hoffmann, Michael R.; Lim, Keahying; Jiang, Sunny C.
• Is Part Of: Water research. Volume 92(2016)
• Page Start: 164
• Page End: 172
• Publication Date: 2016-04-01
• Subjects: Electrochemical disinfection -- Toilet wastewater -- Wastewater electrolysis cell -- Microbial pathogens -- Disinfection byproducts -- Solar energy; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2016.01.040
• Languages: English
• ISSNs: 0043-1354

Abstract

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 (HAA5 ) 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-log10 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-log10 reduction of MS2 was observed in toilet wastewater even at the highest [NaClO] dosage (36 mg/L, as Cl2 ) 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 TiO2 anode were negligible under the same electrolytic conditions. The formation of THMs and HAA5 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. Graphical abstract: Highlights: A mobile toilet was developed for toilet wastewater treatment. 5-log10 reductions of bacteria and viruses were achieved within one hour. Reactive chlorine species were the main oxidants responsible for disinfection. The formation of organic disinfection byproducts was investigated. The treated water is safe for toilet flushing and irrigation.