Performance evaluation of the UV activated chlorite process on trimethoprim: Degradation efficiency, energy consumption and disinfection by-products formation. (June 2023)

• Record Type: Journal Article
• Authors: Ye, Wen-Kai; Tian, Fu-Xiang; Chen, Chen; Ye, Jing; Liu, Fu-wen; Wang, Bo; Hu, Xiao-Jun; Xu, Bin
• Is Part Of: Chemosphere. Volume 327(2023)
• Publication Date: 2023-06
• Subjects: Trimethoprim (TMP) -- UV/chlorite -- Reactive chlorine species (RCS) -- Electrical energy per order (EE/O) -- Disinfection by-products (DBPs); Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2023.138540
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: As the primary inorganic by-product species of ClO2, chlorite is believed to have negative toxicological effects on human health and therefrom greatly limits the wide application of ClO2 in water treatment. The synergistic trimethoprim (TMP) removal concerning degradation efficiency, energy consumption and disinfection by-products (DBPs) formation in the UV activated chlorite process accompanied by the simultaneously elimination of chlorite was comprehensively evaluated. UV/chlorite integrated process removed TMP far more rapidly than UV (1.52%) or chlorite (3.20%) alone due to the endogenous radicals (Cl, ClO and OH), the contributing proportions of which were 31.96%, 19.20% and 44.12%. The second-order rate constants of TMP reaction with Cl, ClO and OH were determined to be 1.75 × 10 10, 1.30 × 10 9 and 8.66 × 10 9 M −1 s −1 . The effects of main water parameters including chlorite dosage, UV intensity, pH as well as water matrixes (nature organic matter, Cl − and HCO3 − ) were examined. kobs obeyed the order as UV/Cl2 >UV/H2 O2 ≈UV/chlorite>UV, and the cost ranking via electrical energy per order (EE/O, kWh m −3 order −1 ) parameter was UV/chlorite (3.7034) > UV/H2 O2 (1.1625) >UV/Cl2 (0.1631). The operational scenarios can be optimized to achieve the maximum removal efficiencies and the minimum energy costs. The destruction mechanisms of TMP were proposed by LC-ESI-MS analysis. The overall weighted toxicity in subsequent disinfection was assessed as UV/Cl2 >UV/chlorite > UV, the values of which in post-chlorination were 6.2947, 2.5806 and 1.6267, respectively. Owing to the vital roles of reactive chlorine species (RCS), UV/chlorite displayed far higher TMP degradation efficiency than UV, and concurrently presented much less toxicity than UV/Cl2 . In an effort to determine the viability of the promising combination technology, this study was devoted to reduce and reuse chlorite and synchronously realize the contaminants degradation efficiently. Graphical abstract: Image 1 Highlights: The efficiency/cost/toxicity tradeoff for TMP removal by UV/chlorite was comprehensively evaluated. The roles and reactivities of relating radicals as .OH, Cl and ClO were distinguished. Effects of chlorite dosages, UV intensity, pH and water matrixes on kobs and EE/O were explored. The UV/chlorite destruction mechanisms of TMP were proposed by LC-ESI-MS analysis. UV/chlorite displayed much less toxicity than UV/Cl2 due to the less reactivity of ClO. in system.