School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China.
Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad Campus, 22060, Pakistan.
Sci Total Environ. 2019 Jun 20;670:149-157. doi: 10.1016/j.scitotenv.2019.03.170. Epub 2019 Mar 15.
NaClO based chemically enhanced backwash (CEB) is often administered to maintain membrane permeability during the operation of MBR. However, the effect and working mechanism of NaClO concentrations in CEB were rarely investigated. The current investigation examined the changes in membrane resistance, permeate production and membrane morphology with or without CEB in an anammox MBR to reveal the scrubbing effect of different NaClO concentrations (0-596 mg/L). Good cleaning effect indicated by membrane fouling rate of 1.98-2.26 kPa/day and membrane permeate production of 80-88 L was observed when NaClO concentration of 149-596 mg/L was used. The best cleaning effect was observed when 298 mg/L of NaClO was used. To explore the mechanism of CEB action, backwashing foulants were also analyzed. Insoluble EPS transformed into soluble forms like S-EPS or SMP after the sludge was exposed to NaClO. The NaClO based CEB removed 112-675 mg of polysaccharide (PS)/m in foulants at NaClO concentration of 149-596 mg/L, which was significantly higher than the value obtained by pure water (35 mg PS/m). The possible mechanisms behind the detachment of soluble PS seemed as oxidation and sterilization by NaClO. The current investigation provides useful guidelines on NaClO concentrations applied during CEB for anammox MBR.
基于次氯酸钠的化学增强反冲洗（CEB）常用于在 MBR 运行过程中维持膜的通透性。然而，CEB 中次氯酸钠浓度的效果和作用机制很少被研究。本研究通过在厌氧氨氧化 MBR 中考察有无 CEB 时膜阻力、渗透液产量和膜形态的变化，揭示了不同次氯酸钠浓度（0-596mg/L）的擦洗效果。当使用 149-596mg/L 的次氯酸钠时，观察到膜污染速率为 1.98-2.26kPa/天和膜渗透液产量为 80-88L，表明具有良好的清洁效果。当使用 298mg/L 的次氯酸钠时，观察到最佳的清洁效果。为了探索 CEB 作用的机制，还分析了反冲洗污染物。污泥暴露于次氯酸钠后，不可溶的 EPS 转化为可溶性的形式，如 S-EPS 或 SMP。在 149-596mg/L 的次氯酸钠浓度下，CEB 从污染物中去除了 112-675mg/m 的多糖（PS），明显高于纯水（35mg/m PS）获得的值。次氯酸钠氧化和杀菌作用可能是可溶性 PS 脱附的背后机制。本研究为厌氧氨氧化 MBR 中 CEB 应用的次氯酸钠浓度提供了有用的指导。
