Wang Hao, Ma Defang, Shi Weiye, Yang Zhiyu, Cai Yun, Gao Baoyu
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237 China.
No.1 Institute of Geology and Mineral Resources of Shandong Province, Jinan, 250014 China.
Front Environ Sci Eng. 2021;15(5):102. doi: 10.1007/s11783-021-1389-3. Epub 2021 Jan 10.
Periodic chemical cleaning with sodium hypochlorite (NaClO) is essential to restore the membrane permeability in a membrane bioreactor (MBR). However, the chlorination of membrane foulants results in the formation of disinfection by-products (DBPs), which will cause the deterioration of the MBR effluent and increase the antibiotic resistance in bacteria in the MBR tank. In this study, the formation of 14 DBPs during chemical cleaning offouled MBR membrane modules was investigated. Together with the effects of biofilm extracellular polymeric substances (EPS), influences of reaction time, NaClO dosage, initial pH, and cleaning temperature on the DBP formation were investigated. Haloacetic acids (HAAs) and trichloromethane (TCM), composed over 90% of the DBPs, were increasingly accumulated as the NaClO cleaning time extended. By increasing the chlorine dosage, temperature, and pH, the yield of TCM and dichloroacetic acid (DCAA) was increased by up to a factor of 1-14, whereas the yields of haloacetonitriles (HANs) and haloketones (HKs) were decreased. Either decreasing in the chlorine dosage and cleaning temperature or adjusting the pH of cleaning reagents toward acidic or alkaline could effectively reduce the toxic risks caused by DBPs. After the EPS extraction pretreatment, the formation of DBPs was accelerated in the first 12 h due to the damage of biofilm structure. Confocal laser scanning microscopy (CLSM) images showed that EPS, particularly polysaccharides, were highly resistant to chlorine and might be able to protect the cells exposed to chlorination.
Supplementary material is available in the online version of this article at 10.1007/s11783-021-1389-3 and is accessible for authorized users.
使用次氯酸钠（NaClO）进行定期化学清洗对于恢复膜生物反应器（MBR）中的膜渗透性至关重要。然而，膜污染物的氯化会导致消毒副产物（DBP）的形成，这将导致MBR出水恶化，并增加MBR池中细菌的抗生素抗性。在本研究中，研究了化学清洗污染的MBR膜组件过程中14种DBP的形成。同时研究了生物膜胞外聚合物（EPS）的影响、反应时间、NaClO剂量、初始pH值和清洗温度对DBP形成的影响。随着NaClO清洗时间的延长，占DBP总量90%以上的卤乙酸（HAA）和三氯甲烷（TCM）逐渐积累。通过增加氯剂量、温度和pH值，TCM和二氯乙酸（DCAA）的产量提高了1至14倍，而卤乙腈（HAN）和卤代酮（HK）的产量则下降。降低氯剂量和清洗温度或向酸性或碱性调整清洗试剂的pH值都可以有效降低DBP造成的毒性风险。EPS提取预处理后，由于生物膜结构的破坏，DBP的形成在最初12小时内加速。共聚焦激光扫描显微镜（CLSM）图像显示，EPS，尤其是多糖，对氯具有高度抗性，可能能够保护暴露于氯化作用下的细胞。
补充材料可在本文的在线版本中获取，链接为10.1007/s11783-021-1389-3，授权用户可访问。
