Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment  

作　　者：Gabriela Scheibel Cassol Chii Shang Juan Li Li Ling Xin Yang Ran Yin 

机构地区：[1]Department of Civil and Environmental Engineering,The Hong Kong University of Science and Technology,Hong Kong 999066,China [2]School of Environmental Science and Engineering,Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Journal of Environmental Sciences》2022年第7期119-128,共10页环境科学学报（英文版）

基　　金：supported by the Hong Kong Innovation and Technology Fund (No. GHP/010/18GD);the National Natural Science Foundation of China (No. 21876210);the Hong Kong Research Grants Council (No. T21-604/19-R);partially supported by a fellowship award from the Research Grants Council of the Hong Kong Special Administrative Region, China (No. HKUST PDFS2021-6S05)。

摘　　要：Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control.Pre-oxidation by chlorine dioxide(ClO_(2))followed by coagulation-flocculation-sedimentation and advanced oxidation processes(AOPs)is one of the promising solutions.However,the chlorite(ClO_(2)^(-))formed from the ClO_(2) preoxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate.ClO_(2)^(–)negatively affects the post-UV/chlorine process due to its strong radical scavenging effect,and it also enhances the formation of chlorate(ClO_(3)^(–)).In this study,dosing micromolar-level ferrous iron(Fe(II))into aluminum-based coagulants was proposed to eliminate the ClO_(2)^(–)generated from ClO_(2) pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO_(3)^(–)reduction.Results showed that the addition of 52.1-μmol/L FeSO_(4) effectively eliminated the ClO_(2)^(-)generated from the pre-oxidation using 1.0 mg/L(14.8μmol/L)of ClO 2.Reduction of ClO_(2)^(-)increased the degradation rate constant of a model micropollutant(carbamazepine)by 55.0%in the post-UV/chlorine process.The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO^(-)·and ClO_(2)·by Fe(II)addition.Moreover,Fe(II)addition also decreased the ClO_(3)^(–)formation by 53.8%in the UV/chlorine process and its impact on the formation of chloroorganic 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.

关 键 词：Chlorine dioxide(ClO_(2)) Advanced oxidation process Ferrous iron MICROPOLLUTANTS Disinfection byproducts(DBPs) 

分 类 号：TU991.2[建筑科学—市政工程]