Removal of disinfection by-product precursors by Al-based coagulants: A comparative study on coagulation performance

• Published in: Journal of hazardous materials 2021-10, Vol.420, p.126558, Article 126558
• Main Authors: Wang, Pin, Ding, Shunke, An, Guangyu, Qu, Ruixin, Liu, Xiaoyu, Fang, Chao, Chu, Wenhai
• Format: Article
• Language: English
• Subjects: Al-based coagulants; Coagulation; Covalently bond hybrid coagulant; Disinfection by-products; Precursor
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126558

Coagulation is well-established for controlling regulated disinfection by-products (DBPs), but its effectiveness for controlling unregulated DBPs remains unclear. The efficiency of coagulation in controlling unregulated DBPs requires clarification owing to their relatively high toxicity. In this study, three Al-based coagulants, aluminum sulfate (Alum), polyaluminum chloride (PAC), and a novel type of covalently bond hybrid coagulant (CBC, synthesized using AlCl3) were selected, and the coagulation performance of these Al-based coagulants in controlling DBPs and DBP-associated toxicity was compared over 5 classes of DBPs, including trihalomethanes, haloacetic acids, haloacetaldehydes, haloacetonitriles, and halonitromethanes. The results showed that Alum was the least efficient in removing DBP precursors among the three coagulants. The effectiveness of CBC and PAC for DBP control varied with the characteristics of source waters. CBC had an advantage in water with a low content of humic acids, and reduced DBP concentration and DBP-associated toxicity by 47% and 25%, respectively. For water rich in aromatic organics, CBC might serve as DBP precursors at a high-required dosage, suggesting that a trade-off between enhanced DBP control and serving as DBP precursors should be considered for CBC coagulation; PAC achieved the most reduction in DBP concentration and DBP-associated toxicity by 50% and 34%, respectively. [Display omitted] •Coagulation performance and DBP control of three Al-based coagulants were evaluated.•CBC showed higher removal of turbidity and UV245 compared to PAC and Alum.•CBC outperformed Alum and PAC in the control of nitrogenous DBP formation.•A trade-off between enhanced DBP control and being DBP precursors is required for CBC.•Effectiveness of CBC and PAC for DBP control varied with the characteristics of source waters.