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Cheng X, Song W, Tan F, Luo X, Zhu X, Yang T, Zhou Z, Xu J, Wu D, Liang H. Novel calcium hypochlorite/ferrous iron as an ultrafiltration membrane pretreatment process for purifying algae-laden water. Environ Res 2024; 240:117572. [PMID: 37939809 DOI: 10.1016/j.envres.2023.117572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/31/2023] [Indexed: 11/10/2023]
Abstract
Algal fouling has become one of the most critical factors hindering the large-scale development of membrane processes in algae-laden water treatment. Herein, novel calcium hypochlorite (Ca(ClO)2)/ferrous iron (Fe(II)) process was proposed as an ultrafiltration (UF) membrane pretreatment technology, and its effects on membrane fouling and water properties were systematically studied. Results showed that the terminal specific fluxes were significantly elevated to 0.925 and 0.933, with the maximum removal ratios of reversible resistance reaching 99.65% and 96.99% for algae-laden water and extracellular organic matter (EOM), respectively. The formation of cake filtration was dramatically delayed, accompanied by a significant reduction of the adhesion free energy, and the contaminants attached to the membrane surface were effectively decomposed. With respect to water quality, the removal ratios of OD685 and turbidity achieved 81.25-95.31% and 90.16-97.72%, individually. The maximum removal rates of DOC, UV254 and fluorescent organics in influent water reached 46.14%, 55.17% and 75.77%, respectively. Furthermore, the generated reactive species (e.g., •OH, Cl•, Cl2•- and ClO•) could efficiently degrade EOM, which appreciably reduced the electrostatic repulsion between the algal foulants while ensuring the integrity of algal cells. At the Ca(ClO)2/Fe(II) dosage of 0.04/0.24 mM, the zeta potential changed from -32.9 mV to -10.8 mV, and a large range of aggregates was formed. The macromolecules in the algal solution were significantly removed, and the proportion of micromolecular organics was increased to some extent. Coagulation of in-situ formed Fe(III) dominated the membrane fouling mitigation, and the reactive species also contributed to the improvement of filtration performance. Overall, Ca(ClO)2/Fe(II) pretreatment has an exceptional prospect for efficient degradation of algal pollutants and enhancement of UF capability.
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Affiliation(s)
- Xiaoxiang Cheng
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China; Resources and Environment Innovation Institute, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Wenxin Song
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Fengxun Tan
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Xinsheng Luo
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Xuewu Zhu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China.
| | - Tao Yang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, 529020, PR China.
| | - Zhiwei Zhou
- College of Architecture & Civil Engineering, Faculty of Urban Construction, Beijing University of Technology, Beijing, 100124, PR China
| | - Jingtao Xu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Daoji Wu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, PR China; Resources and Environment Innovation Institute, Shandong Jianzhu University, Jinan, 250101, PR China
| | - Heng Liang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China
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