Effect of disinfection on the photoreactivity of effluent organic matter and photodegradation of organic contaminants. (1st July 2022)

• Record Type: Journal Article
• Authors: Wan, Dong; Wang, Jie; Chen, Tong; Xiang, Weiming; Selvinsimpson, Steplinpaulselvin; Chen, Yong
• Is Part Of: Water research. Volume 219(2022)
• Publication Date: 2022-07-01
• Subjects: Dissolved organic matter -- Laser flash photolysis -- Reactive species -- Chlorine disinfection -- UV254 disinfection -- Ozone disinfection; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118552
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: The RS generation from DOM before and after disinfection was studied using ESR spectrometry. The three disinfection processes promoted the photoproduction of OH. The k obs of DEET increased by 26−361% in DOM solutions after disinfection. The interaction between diphenhydramine and 3 EfOM* after disinfection was studied by LFP. The quenching rate constant of 3 DOM* by diphenhydramine increased by ∼41% after chlorination. Abstract: Chlorine, UV254, and ozone are three typical processes commonly used for wastewater disinfection, which could change the photoreactivity of dissolved organic matter (DOM) in effluents of wastewater treatment plants (WWTPs). The photoinduced reactive species (RS) from DOM, primarily including the excited triplet state of DOM ( 3 DOM*), singlet oxygen ( 1 O2 ), and hydroxyl radical ( OH), play important roles in the attenuation of contaminants. However, the effect of disinfection processes on the photosensitized degradation of contaminants is poorly understood. This paper presents the first evidence that 3 DOM*, 1 O2, and OH interaction with three typical contaminants (diphenhydramine, cimetidine, and N, N -diethyl- m -toluamide (DEET)) was largely impacted by DOM after disinfection. The results of electron spin resonance (ESR) spectrometry and laser flash photolysis (LFP) experiments demonstrated that the chlorination increased the formation rate of 3 DOM* and 1 O2, while UV254 irradiation and ozonation decreased the formation rate of these RS. All these three disinfection processes promoted the photoproduction of OH and increased the photodegradation rate constants ( k obs ) of DEET by 26−361%. The k obs of diphenhydramine, cimetidine, and DEET correlated positively with the formation rate of 3 DOM*, 1 O2, and OH, respectively. The bimolecular reaction rate constant of 3 DOM* with diphenhydramine increased by ∼41% after chlorination. These findings suggest that disinfection processes altered the photogeneration of RS from DOM, which significantly impacts the fate of trace pollutants in aquatic environments. Graphical abstract: Image, graphical abstract