In situ chemical cleaning with sodium hypochlorite (NaClO) is frequently employed to maintain a constant permeability in membrane bioreactor (MBR) systems. In this study, the effects of NaClO shock on MBR performance under continuous operating conditions were investigated. A lab-scale MBR was operated for three runs with in situ chemical cleaning. Experimental results demonstrate an obvious increase of the membrane fouling rate (13.7, 23.5 and 23.3 kPa d⁻¹) on day 1 of cleaning, followed by a rapid reduction (6.4, −0.2 and 3.5 kPa d⁻¹) on day 2 of cleaning. This indicates the rapid self-recovery ability of the NaClO-shocked sludge. Furthermore, as the operating time increased, the sludge extracellular polymeric substance (EPS) content initially increased, followed by a subsequent decrease, with the gradual improvement of sludge filterability that consequently reduced membrane fouling. Thermodynamic analysis revealed that the shocked-sludge surface properties, including the surface electron donor component (γ⁻), hydrophobicity, adhesive energy and self-cohesive ability, were gradually restored to the raw sludge level, which reduced the membrane fouling potential.

中文翻译：

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NaClO冲击对连续运行条件下MBR性能的影响

通常使用次氯酸钠（NaClO）进行原位化学清洗，以在膜生物反应器（MBR）系统中保持恒定的渗透性。在这项研究中，研究了连续操作条件下NaClO冲击对MBR性能的影响。实验室规模的MBR使用原位化学清洁进行了三轮运行。实验结果表明，在清洗的第一天，膜污染率明显增加（13.7、23.5和23.3 kPa d ^-1），然后迅速降低（6.4，-0.2和3.5 kPa d ^-1））在清洁的第2天。这表明NaClO冲击的污泥具有快速的自回收能力。此外，随着操作时间的增加，污泥细胞外聚合物质（EPS）含量最初会增加，随后会随之减少，污泥可过滤性的逐步提高会因此减少膜污染。热力学分析揭示了震惊污泥表面性能，包括表面的电子供体组分（γ ^- ），疏水性，粘合能量和自粘结能力，逐渐恢复到原料污泥水平，减少了膜的结垢潜能。