State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
Water Res. 2020 Jan 1;168:115144. doi: 10.1016/j.watres.2019.115144. Epub 2019 Sep 30.
Bromide and natural organic matter (NOM) are both precursors of halogenated disinfection byproducts (DBPs) in drinking water. During drinking water treatment process, chloride-form anion-exchange resin adsorption is expected to be capable of removing these DBP precursors and in the meantime releasing chloride ions. The released chloride as well as the chloride initially present in source water could be oxidized through electrolysis to generate free chlorine for disinfection. Based on the above assumptions, we developed a new disinfection approach using chloride-form anion-exchange resin adsorption followed by electrolysis to control halogenated DBPs. Parameter setup and optimization were performed for resin adsorption and electrolysis processes. Results showed that 93.7% of NOM and 90% of bromide could be removed at a resin dose of 20 mL per 2 L of simulated source water sample with a contact time of 1 h. Meanwhile, 49.5 mg/L of chloride was released from the resin to the water sample via anion-exchange, and the released chloride was further oxidized by electrolysis (Ti/RuO-IrO anode and graphite cathode, current intensity of 0.4 A) to generate free chlorine (5 mg/L as Cl) within 192 s. With this new approach, formation of total organic halogen, four trihalomethanes, and five haloacetic acids was reduced by 86.4%, 98.5%, and 93.2%, respectively, compared with chemical chlorination alone. Although the new approach might enhance the formation of some phenolic DBPs by decreasing bromide levels in source water, the overall cytotoxicity of the water samples treated with the new approach was significantly decreased by 68.8% according to a human hepatoma cell cytotoxicity assay. Notably, disinfection ability evaluation showed that the new approach achieved 3.36-log reductions of three seeded bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) in 19 s, suggesting that it was not only effective to E. coli but also effective to the chlorine-resistant bacteria (P. aeruginosa and S. aureus).
溴化物和天然有机物（NOM）都是饮用水中卤代消毒副产物（DBP）的前体。在饮用水处理过程中，预期氯化物形式的阴离子交换树脂吸附能够去除这些 DBP 前体，同时释放氯离子。释放的氯离子以及原水中最初存在的氯离子可以通过电解氧化生成游离氯进行消毒。基于上述假设，我们开发了一种使用氯化物形式的阴离子交换树脂吸附，然后进行电解的新型消毒方法，以控制卤代 DBP。对树脂吸附和电解过程进行了参数设置和优化。结果表明，在模拟原水水样中，每 2 L 水样使用 20 mL 树脂，接触时间为 1 h，可去除 93.7%的 NOM 和 90%的溴化物。同时，通过阴离子交换从树脂中向水样释放 49.5 mg/L 的氯离子，释放的氯离子通过电解（Ti/RuO-IrO 阳极和石墨阴极，电流强度为 0.4 A）进一步氧化生成游离氯（水样中 5 mg/L 为 Cl），在 192 s 内完成。采用这种新方法，与单独化学氯化相比，总有机卤素、四种三卤甲烷和五种卤乙酸的生成量分别减少了 86.4%、98.5%和 93.2%。虽然新方法通过降低原水中的溴化物水平可能会增加一些酚类 DBP 的生成，但根据人肝癌细胞细胞毒性测定，用新方法处理后的水样的整体细胞毒性显著降低了 68.8%。值得注意的是，消毒能力评估表明，该方法在 19 秒内对三种接种细菌（大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌）实现了 3.36 对数减少，这表明它不仅对大肠杆菌有效，而且对耐氯细菌（铜绿假单胞菌和金黄色葡萄球菌）也有效。
