Degradation of contaminants of emerging concern by UV/H2O2 for water reuse: Kinetics, mechanisms, and cytotoxicity analysis

Abstract

Advanced oxidation using UV and hydrogen peroxide (UV/H 2 O 2) has been widely applied to degrade contaminants of emerging concern (CECs) in wastewater for water reuse. This study investigated the degradation kinetics of mixed CECs by UV/H 2 O 2 under variable H 2 O 2 doses, including bisphenol A, estrone, diclofenac, ibuprofen, and triclosan. Reverse osmosis (RO) treated water samples from Orange County Water District's Groundwater Replenishment System (GWRS) potable reuse project were collected on different dates and utilized as reaction matrices with spiked additions of chemicals (CECs and H 2 O 2) to assess the application of UV/H 2 O 2. Possible degradation pathways of selected CECs were proposed based on high resolution mass spectrometry identification of transformation products (TPs). Toxicity assessments included cytotoxicity, aryl hydrocarbon receptor-binding activity, and estrogen receptor-binding activity, in order to evaluate potential environmental impacts resulting from CEC degradation by UV/H 2 O 2. Cytotoxicity and estrogenic activity were significantly reduced during the degradation of mixed CECs in Milli-Q water by UV/H 2 O 2 with high UV fluence (3200 mJ cm À2). However, in GWRS RO-treated water samples collected in April 2017, the cytotoxicity and estrogen activity of spiked CEC-mixture after UV/H 2 O 2 treatment were not significantly eliminated; this might be due to the high concentration of target CEC and their TPs, which was possibly affected by the varied quality of the secondary treatment influent at this facility such as sewer-shed and wastewater discharges. This study aimed to provide insight on the impacts of post-UV/H 2 O 2 CECs and TPs on human and ecological health at cellular level.

Degradation of trimethoprim by sulfate radical-based advanced oxidation processes: kinetics, mechanisms, and effects of natural water matrices

“…Advanced oxidation technology (AOPs) with • OH and as the main active substance is a promising treatment technology that improves the biodegradability of wastewater through oxidation or directly degrades organic pollutants through mineralization (Hou et al 2018 ; Huang et al 2020 ; Ji et al 2018 ). • OH is a strong oxidant, which has a high redox potential ( E 0 = 1.89~2.72 V vs. NHE).…”

UV/H2O2 degradation of diclofenac in a photocatalytic fuel cell

“…The degradation of DCF has been repeatedly studied in the past and the degradation fragments have been identified by liquid chromatography and other techniques [26][27][28][29][30][31][32][33][34][35]. What is of interest in our case is the fact that DCF is photolyzed under UV irradiation even in the absence of any catalyst.…”

“…The absorbance maximum was reached after 30 min of irradiation and then a progressive decrease of absorbance was detected over the whole spectral range of measurement. Based on literature results, the dominant chemical structure transformations of DCF during photolysis are illustrated by [26][27][28][29][30][31]34,36]. Apparently, chlorine and carboxylic group extraction makes the first degradation steps.…”

“…This drug is recalcitrant and very harmful to the environment [23][24][25]. It is not then a surprise that its degradation by various procedures has been extensively studied [26][27][28][29][30][31][32][33][34][35]. This is why DCF was chosen as a model water contaminant to perform the present measurements.…”

“…Fig.3[26][27][28][29][30][31]34,36]. Apparently, chlorine and carboxylic group extraction makes the first degradation steps.…”