Suitability of inorganic coagulants for algae-laden water treatment: Trade-off between algae removal and cell viability, aggregate properties and coagulant residue

Lili Wang; Naif Abdullah Al-Dhabi; Xin Huang; Zhiyuan Luan; Wangwang Tang; Zhenghe Xu; Weiying Xu

doi:10.1016/j.jhazmat.2024.134314

Suitability of inorganic coagulants for algae-laden water treatment: Trade-off between algae removal and cell viability, aggregate properties and coagulant residue

J Hazard Mater. 2024 Apr 16:471:134314. doi: 10.1016/j.jhazmat.2024.134314. Online ahead of print.

Authors

Lili Wang¹, Naif Abdullah Al-Dhabi², Xin Huang³, Zhiyuan Luan⁴, Wangwang Tang⁵, Zhenghe Xu⁶, Weiying Xu⁷

Affiliations

¹ School of Water Conservancy and Environment, University of Jinan, No. 336 Nanxinzhuang Western Road, Jinan 250022, Shandong, PR China.
² Department of Botany and Microbiology, College of Science, King Saud University, P. O. Box 2455, Riyadh 11451, Saudi Arabia.
³ Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Science, Chinese Academy of Science, No. 18 Shuangqing Road, Beijing 100085, PR China.
⁴ Jinan Environmental Research Institute, 25th Floor, Xinsheng Building, No. 1299 Xinluo Street, Jinan 250000, Shandong, PR China.
⁵ College of Environmental Science and Engineering, Hunan University, No. 8 Lushan South Road, Changsha 410082, Hunan, PR China.
⁶ School of Water Conservancy and Environment, University of Jinan, No. 336 Nanxinzhuang Western Road, Jinan 250022, Shandong, PR China. Electronic address: stu_xuzh@ujn.edu.cn.
⁷ School of Water Conservancy and Environment, University of Jinan, No. 336 Nanxinzhuang Western Road, Jinan 250022, Shandong, PR China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Science, Chinese Academy of Science, No. 18 Shuangqing Road, Beijing 100085, PR China. Electronic address: stu_xuwy@ujn.edu.cn.

PMID: 38640668
DOI: 10.1016/j.jhazmat.2024.134314

Abstract

Inorganic coagulants could effectively precipitate algae cells but might increase the potential risks of cell damage and coagulant residue. This study was conducted to critically investigate the suitability of polyaluminum (PAC), FeCl₃ and TiCl₄ for algae-laden water treatment in terms of the trade-off between algal substance removal, cell viability, and coagulant residue. The results showed that an appropriate increase in coagulant dosage contributed to better coagulation performance but severe cell damage and a higher risk of intracellular organic matter (IOM) release. TiCl₄ was the most destructive, resulting in 60.85% of the algal cells presenting membrane damage after coagulation. Intense hydrolysis reaction of Ti salts was favorable for the formation of larger and more elongated, dendritic structured flocs than Al and Fe coagulants. TiCl₄ exhibited the lowest residue level and remained in the effluents mainly in colloidal form. The study also identified charge neutralization, chemisorption, enmeshment, and complexation as the dominant mechanisms for algae water coagulation by metal coagulants. Overall, this study provides the trade-off analyses between maximizing algae substance removal and minimizing potential damage to cell integrity and is practically valuable to develop the most suitable and feasible technique for algae-laden water treatment.

Keywords: Cell integrity; Coagulant residue; Coagulation mechanisms; Floc morphology; Inorganic coagulants.