ZUOHui-wen,JINXin,JINPeng-kang.Formation Characteristics of Bromate Disinfection By-product in Hybrid Ozonation-Coagulation Process[J].China Water & Wastewater,2024,40(21):73-80.
臭氧混凝耦合工艺的溴酸盐消毒副产物生成特性
- Title:
- Formation Characteristics of Bromate Disinfection By-product in Hybrid Ozonation-Coagulation Process
- Keywords:
- hybrid ozonation-coagulation (HOC) process; effluent from secondary treatment process; bromate; disinfection by-product; ozonation
- 摘要:
- 为了控制臭氧混凝耦合（HOC）工艺在处理污水厂二级出水过程中消毒副产物溴酸盐（BrO3-）的生成，考察了HOC工艺在不同反应条件下的BrO3-生成特性，明确了控制BrO3-生成的最佳条件，揭示了BrO3-的生成途径。结果表明，HOC工艺能够高效去除二级出水中的残余有机物，但会生成BrO3-而导致急性毒性增强；pH升高与臭氧投加量的增加均会促进BrO3-的生成，采用氯化铝作为混凝剂时生成的BrO3-量略高于以硫酸铝为混凝剂时的，而有机物可通过控制中间产物次溴酸来抑制BrO3-的生成。基于上述结果，确定HOC最优反应条件如下：pH=7，臭氧投加量为1.0 mg/mg（以TOC衡量）、混凝剂采用氯化铝且投加量为15 mg/L（以Al计）、反应时间为8 min，在该条件下，有机物去除率可保持在30%以上，且BrO3-的生成量<10 μg/L，满足《生活饮用水卫生标准》（GB 5749—2006）的要求。BrO3-生成途径包括臭氧直接氧化和羟基自由基（·OH）间接氧化两种，其中臭氧氧化是主要途径，贡献率高达90%。
- Abstract:
- To control the formation of bromate (BrO3-), a disinfection by-product in the secondary effluent from the wastewater treatment plant, the characteristics of BrO3-formation in the hybrid ozonation-coagulation (HOC) process under diverse reaction conditions were investigated, the optimal conditions for controlling BrO3- formation were determined, and the formation pathway of BrO3- was revealed. The HOC process effectively eliminated the residual organic matters in the secondary effluent. However, it generated BrO3-, thereby leading to an increase in acute toxicity. The elevation of pH and the augmentation of ozone dosage facilitated the formation of BrO3-. The quantity of BrO3- generated when aluminum chloride was employed as the coagulant was marginally higher than that when aluminum sulfate was utilized as the coagulant, and organic matters could impede the formation of BrO3- by regulating the intermediate product hypobromous acid. Based on the aforesaid results, the optimal reaction conditions of HOC were determined as follows: pH was 7, the dosage of ozone was 1.0 mg/mg（calculated by TOC), the dosage of aluminum chloride was 15 mg/L (calculated by Al), and the reaction time was 8 min. Under these circumstances, the removal efficiency of organic matter could be maintained above 30%, and the yield of BrO3- was less than 10 μg/L, meeting the limit specified in Standards for Drinking Water Quality (GB 5749-2006). The formation pathway of BrO3- encompassed direct oxidation by ozone and indirect oxidation by hydroxyl radical (·OH), among which ozonation constituted the primary pathway, accounting for up to 90%.
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