Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control.Pre-oxidation by chlorine dioxide(ClO2)fol-lowed by coagulation-flocculation-sedimentation and advanced oxidation processes(AOPs)is one of the promising solutions.However,the chlorite(ClO2-)formed from the ClO2 pre-oxidation stage cannot be removed by the conventional coagulation process using alu-minum sulfate.ClO2-negatively affects the post-UV/chlorine process due to its strong rad-ical scavenging effect,and it also enhances the formation of chlorate(ClO3-).In this study,dosing micromolar-level ferrous iron(Fe(Ⅱ))into aluminum-based coagulants was proposed to eliminate the ClO2-generated from ClO2 pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO3-reduction.Results showed that the addition of 52.1-pmol/L FeSO4 effectively eliminated the ClO2-generated from the pre-oxidation using 1.0 mg/L(14.8μmol/L)of ClO2.Reduction of ClO2-increased the degradation rate constant of a model micropollutant(carbamazepine)by 55.0％in the post-UV/chlorine process.The en-hanced degradation was verified to be attributed to the increased steady-state concentra-tions of HO·and ClO by Fe(Ⅱ)addition.Moreover,Fe(Ⅱ)addition also decreased the ClO3 formation by 53.8％in the UV/chlorine process and its impact on the formation of chloro-organic byproducts was rather minor.The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(Ⅱ)in coagulation in an advanced drinking water treatment train.

Gabriela Scheibel Cassol;Chii Shang;Juan Li;Li Ling;Xin Yang;Ran Yin

Department of Civil and Environmental Engineering,The Hong Kong University of Science and Technology,Hong Kong 999066,China;School of Environmental Science and Engineering,Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology,Sun Yat-sen University,Guangzhou 510275,China

环境科学学报（英文版）

[1]Gabriela Scheibel Cassol;Chii Shang;Juan Li;Li Ling;Xin Yang;Ran Yin-.Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants,chlorite and chlorate during advanced water treatment)[J].环境科学学报（英文版）,2022(07):119-128

micropollutant,micromolar,coagulants

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