Photo-electrochemical oxidation flow system for stormwater herbicides removal: Operational conditions and energy consumption analysis

Zhaozhi Zheng; Kefeng Zhang; Cui Ying Toe; Rose Amal; Ana Deletic

doi:10.1016/j.scitotenv.2023.166375

Photo-electrochemical oxidation flow system for stormwater herbicides removal: Operational conditions and energy consumption analysis

Sci Total Environ. 2023 Nov 10:898:166375. doi: 10.1016/j.scitotenv.2023.166375. Epub 2023 Aug 19.

Authors

Zhaozhi Zheng¹, Kefeng Zhang², Cui Ying Toe³, Rose Amal⁴, Ana Deletic⁵

Affiliations

¹ School of Civil and Environmental Engineering, University of New South Wales, Kensington, NSW 2052, Australia. Electronic address: zhaozhi.zheng@unsw.edu.au.
² School of Civil and Environmental Engineering, University of New South Wales, Kensington, NSW 2052, Australia.
³ School of Chemical Engineering, University of New South Wales, NSW 2052, Australia; School of Engineering, University of Newcastle, Callaghan, NSW 2308, Australia.
⁴ School of Chemical Engineering, University of New South Wales, NSW 2052, Australia.
⁵ School of Civil and Environmental Engineering, University of New South Wales, Kensington, NSW 2052, Australia; School of Civil and Environmental Engineering, Engineering Faculty, Queensland University of Technology, Queensland 4001, Australia.

PMID: 37598967
DOI: 10.1016/j.scitotenv.2023.166375

Abstract

Photoelectrochemical oxidation (PECO) is a promising advanced technology for treating micropollutants in stormwater. However, it is important to understand its operation prior to practical validation. In this study, we introduced a flow PECO system designed to evaluate its potential for full-scale applications in herbicides degradation, providing valuable insights for future large-scale implementations. The PECO flow reactor demonstrated the ability to treat a larger volume of stormwater (675 mL, approximately 10 times more than previous batch experiments) with effective removal rates of 92 % for diuron and 22 % for atrazine over 6 h of operation at 2 V. To address the large volume issue in stormwater treatment, a multiple module parallel application design is being considered to increase the treatment capacity of the PECO flow reactor. During the flow reactor operations, flow rate was found to have a notable impact on removal performance, particularly for diuron. At a flow rate of 610 mL min^-1, approximately 90 % removal of diuron was achieved, while at 29 mL min^-1, the removal efficiency decreased to 60 %. While light intensity had minimal effect on diuron degradation (all settings achieved over 90 % removal), it enhanced atrazine degradation from 9 % to 31 % with an increase in intensity from 63 mW cm^-2 to 144 mW cm^-2. Remarkably, the PECO flow system exhibited excellent removal performance (>90 % removal) for diuron even at extremely high initial pollutant concentrations (240 μg L^-1), demonstrating its capacity to handle varying contaminant loads in stormwater. Energy consumption analysis revealed that flow rate as the primary factor influenced the specific energy consumption rate. Higher flow rate (e.g., 610 mL min^-1) were preferable in flow reactor due to its well-balanced performance between removal and energy consumption. These findings confirm that the PECO flow system offers an efficient and promising approach for stormwater treatment applications.

Keywords: Energy consumption; Herbicides removal; Operational conditions; PECO; Stormwater treatment.