Electrochemical oxidation disinfects urban stormwater: Major disinfection mechanisms and longevity tests

Wenjun Feng; Ana Deletic; Zhouyou Wang; Xiwang Zhang; Thomas Gengenbach; David T McCarthy

doi:10.1016/j.scitotenv.2018.07.307

Electrochemical oxidation disinfects urban stormwater: Major disinfection mechanisms and longevity tests

Sci Total Environ. 2019 Jan 1:646:1440-1447. doi: 10.1016/j.scitotenv.2018.07.307. Epub 2018 Jul 23.

Authors

Wenjun Feng¹, Ana Deletic², Zhouyou Wang³, Xiwang Zhang³, Thomas Gengenbach⁴, David T McCarthy⁵

Affiliations

¹ Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Infrastructure Research Institute, Department of Civil Engineering, Monash University, VIC 3800, Australia.
² Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Infrastructure Research Institute, Department of Civil Engineering, Monash University, VIC 3800, Australia; University of New South Wales, Sydney, NSW 2052, Australia.
³ Department of Chemical Engineering, Monash University, VIC 3800, Australia.
⁴ Commonwealth Scientific and Industrial Research Organisation (CSIRO), VIC 3168, Australia.
⁵ Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Infrastructure Research Institute, Department of Civil Engineering, Monash University, VIC 3800, Australia. Electronic address: david.mccarthy@monash.edu.

PMID: 30235629
DOI: 10.1016/j.scitotenv.2018.07.307

Abstract

Although electrochemical oxidation (ECO) has shown excellent potential for disinfecting wastewater and surface waters, its application on urban stormwater has been rarely tested. In order to improve stormwater ECO design, this paper explores the major inactivation processes using Boron Doped Diamond (BDD) and titanium Dimensional Stable Anodes (DSA). Both BDD and DSA showed comparable disinfection rates. The mechanism study suggested that BDD relied on hydroxyl radical and the presence of chloride ions, while DSA disinfected stormwater mainly via the production of free‑chlorine. A deterioration study carried out at a catchment in Melbourne, showed a steady performance for BDD and revealed that DSA's performance degraded with time, likely linked to the high operational voltage required for specific chemistry of stormwater. Scanning Electron Microscopes and an Energy Dispersive X-ray Detector tests confirmed elemental losses occurred on the DSA surface, together with an aluminium/silicon coating layer potentially sourced from the stormwater clayish sediments. Furthermore, disinfection by-products in electrochemical disinfected stormwater using either BDD or DSA were at least one order of magnitude lower than the Australia Drinking Water Guidelines limits. The mechanism and long-term study demonstrated that careful anode selection is required as some anodes will deteriorate in stormwater matrices faster than others.

Keywords: Bacteria; E. coli; ECO; Human health risks; Stormwater harvesting.