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Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment.
J Environ Sci (China). 2022 Jul; 117:119-128.JE

Abstract

Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control. Pre-oxidation by chlorine dioxide (ClO2) followed 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 aluminum sulfate. ClO2- negatively affects the post-UV/chlorine process due to its strong radical 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-µmol/L FeSO4 effectively eliminated the ClO2- generated from the pre-oxidation using 1.0 mg/L (14.8 µmol/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 enhanced degradation was verified to be attributed to the increased steady-state concentrations 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.

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Publisher Full Text (DOI)

Authors+Show Affiliations

Cassol GS
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong 999066, China.
Shang C
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong 999066, China.
Li J
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong 999066, China. Electronic address: lj_hit1@163.com.
Ling L
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong 999066, China.
Yang X
School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China.
Yin R
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong 999066, China. Electronic address: ryin@connect.ust.hk.

MeSH

ChloratesChloridesChlorineChlorine CompoundsDisinfectionDrinking WaterFerrous CompoundsIronOxidation-ReductionOxidesWater Pollutants, ChemicalWater Purification

Pub Type(s)

Journal Article

Language

eng

PubMed ID

35725064

Citation

Cassol, Gabriela Scheibel, et al. "Dosing Low-level Ferrous Iron in Coagulation Enhances the Removal of Micropollutants, Chlorite and Chlorate During Advanced Water Treatment." Journal of Environmental Sciences (China), vol. 117, 2022, pp. 119-128.
Cassol GS, Shang C, Li J, et al. Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment. J Environ Sci (China). 2022;117:119-128.
Cassol, G. S., Shang, C., Li, J., Ling, L., Yang, X., & Yin, R. (2022). Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment. Journal of Environmental Sciences (China), 117, 119-128. https://doi.org/10.1016/j.jes.2022.03.022
Cassol GS, et al. Dosing Low-level Ferrous Iron in Coagulation Enhances the Removal of Micropollutants, Chlorite and Chlorate During Advanced Water Treatment. J Environ Sci (China). 2022;117:119-128. PubMed PMID: 35725064.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment. AU - Cassol,Gabriela Scheibel, AU - Shang,Chii, AU - Li,Juan, AU - Ling,Li, AU - Yang,Xin, AU - Yin,Ran, Y1 - 2022/03/25/ PY - 2021/12/28/received PY - 2022/02/24/revised PY - 2022/03/14/accepted PY - 2022/6/20/entrez PY - 2022/6/21/pubmed PY - 2022/6/23/medline KW - Advanced oxidation process KW - Chlorine dioxide (ClO(2)) KW - Disinfection byproducts (DBPs) KW - Ferrous iron KW - Micropollutants SP - 119 EP - 128 JF - Journal of environmental sciences (China) JO - J Environ Sci (China) VL - 117 N2 - Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control. Pre-oxidation by chlorine dioxide (ClO2) followed 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 aluminum sulfate. ClO2- negatively affects the post-UV/chlorine process due to its strong radical 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-µmol/L FeSO4 effectively eliminated the ClO2- generated from the pre-oxidation using 1.0 mg/L (14.8 µmol/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 enhanced degradation was verified to be attributed to the increased steady-state concentrations 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. SN - 1001-0742 UR - https://www.unboundmedicine.com/medline/citation/35725064/Dosing_low_level_ferrous_iron_in_coagulation_enhances_the_removal_of_micropollutants_chlorite_and_chlorate_during_advanced_water_treatment_ DB - PRIME DP - Unbound Medicine ER -