School of Civil Engineering & Architecture, Wuhan University of Technology, Wuhan, 430070, PR China.
School of Civil Engineering & Architecture, Wuhan University of Technology, Wuhan, 430070, PR China.
Environ Res. 2022 Sep;212(Pt C):113449. doi: 10.1016/j.envres.2022.113449. Epub 2022 May 11.
To investigate the effect of residual coagulant after coagulation pretreatment on activated sludge system of wastewater treatment plants (WWTPs), comparative evaluation of lab-scale sequencing batch reactors under different poly-aluminum chloride (PAC) concentrations (20 and 55 mg/L), presenting the performance differences of reactors. Results showed that the PAC concentration of 20 mg/L slightly enhanced the average removal efficiencies of chemical oxygen demand (COD) and total nitrogen (TN), up to 93.43% and 72.52%. Whereas, an inhibition effect was exerted at the PAC concentration of 55 mg/L, the average removal efficiencies decreased to 88.56% and 57.80% respectively. Similarly, the residual aluminum salts showed a concentration effect of low promotion and high inhibition on sludge activity index. The content of specific oxygen utilization rate (SOUR) and dehydrogenase (DHA) sharply decreased by 30.17% and 53.56% under the high PAC concentration of 55 mg/L. Activity recovery phase showed that the suppression of aluminum salt coagulant on biological system was reversible. High-throughput sequencing presented that the relative abundance of microbes showed obvious variations at different PAC concentrations, and certain bacteria in Chloroflexi and Bacteroidota exhibited better adaptability to the high PAC concentration environment. Nevertheless, the antagonism action between denitrifying genera and other genera as well as the downregulation of functional enzymes regarding nitrogen metabolism gave rise to the deterioration of denitrification under the high PAC concentration of 55 mg/L. This study revealed the influence mechanism of residual aluminum salt coagulant on activated sludge system, providing strategies for efficient decontamination and long-term stable operation of biological system in wastewater treatment plant under the condition of adding PAC.
为了研究混凝预处理后残留混凝剂对污水处理厂（WWTP）活性污泥系统的影响，本研究采用不同聚合氯化铝（PAC）浓度（20 和 55mg/L）的实验室规模序批式反应器进行对比评价，以展示反应器的性能差异。结果表明，PAC 浓度为 20mg/L 时，COD 和 TN 的平均去除效率略有提高，分别达到 93.43%和 72.52%。然而，在 PAC 浓度为 55mg/L 时，抑制作用明显，平均去除效率分别降至 88.56%和 57.80%。同样，残留的铝盐对污泥活性指数表现出低促进高抑制的浓度效应。高 PAC 浓度 55mg/L 下，比耗氧速率（SOUR）和脱氢酶（DHA）的含量分别急剧下降 30.17%和 53.56%。活性恢复阶段表明，铝盐混凝剂对生物系统的抑制作用是可逆的。高通量测序表明，不同 PAC 浓度下微生物的相对丰度表现出明显变化，绿弯菌门和拟杆菌门中的某些细菌对高 PAC 浓度环境表现出更好的适应性。然而，高 PAC 浓度 55mg/L 下，反硝化菌属与其他属之间的拮抗作用以及氮代谢功能酶的下调导致反硝化作用恶化。本研究揭示了残留铝盐混凝剂对活性污泥系统的影响机制，为 PAC 投加条件下污水处理厂生物系统的高效净化和长期稳定运行提供了策略。
