Energy efficient portable air cathode electrochlorinator for point-of-use disinfection of toilet wastewater

Zhihui Ma; Haitao Wang; Qixing Zhou; Bolong Liang; Mingmei Li; Pengfei Wang; Sihui Zhan

doi:10.1016/j.jhazmat.2023.130793

Energy efficient portable air cathode electrochlorinator for point-of-use disinfection of toilet wastewater

J Hazard Mater. 2023 Apr 15:448:130793. doi: 10.1016/j.jhazmat.2023.130793. Epub 2023 Jan 13.

Authors

Zhihui Ma¹, Haitao Wang², Qixing Zhou¹, Bolong Liang³, Mingmei Li⁴, Pengfei Wang⁵, Sihui Zhan⁶

Affiliations

¹ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, 300350 Tianjin, China; Carbon Neutrality Interdisciplinary Science Center, Nankai University, 300350 Tianjin, China.
² MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, 300350 Tianjin, China. Electronic address: envwang@nankai.edu.cn.
³ College of Ecology and Environment, Hebei University, Baoding 071002, China.
⁴ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, 300350 Tianjin, China.
⁵ Tianjin Key Laboratory of Clean Energy and Pollution Control, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin 300401, China.
⁶ MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, 300350 Tianjin, China. Electronic address: sihuizhan@nankai.edu.cn.

PMID: 36731314
DOI: 10.1016/j.jhazmat.2023.130793

Abstract

Active chlorine is the most widely used disinfectant for water disinfection as well as surface sterilization. Here, we report an air cathode electrochlorinator for point-of-use disinfection of toilet wastewater. The air cathode dominated by a four-electron pathway to reduce O₂ to OH^- was more suitable for chlorine synthesis than through a two-electron pathway to H₂O₂, which could reduce chlorine back to chloride ions. The minimum driving potential of the air cathode electrochlorinator was as low as 0.94 V, which made it possible to be directly powered by a piece of commercial mini photovoltaic solar panel without electronic converter. Under the cell voltage of 2 V, the Faraday current efficiency was 82.0 % and the electrical energy required to produce 1 kg active chlorine was estimated to be only 1.75 kWh. The normalized energy consumption to disinfect simulated toilet wastewater with a pathogen concentration of 10⁷ CFU/mL was estimated to be 7.2 W h/m³. Moreover, the material cost for fabrication of the electrochlorinator was estimated to be less than $ 0.62. These features guarantee the air cathode electrochlorinator of high potential for point-of-use disinfection of toilet wastewater.

Keywords: Active chlorine; Air cathode; Electrochlorinator; Toilet wastewater; Water disinfection.