In this study, a pressure decay test (PDT) was applied to microfiltration (MF) and ultrafiltration (UF) membranes that were in use for more than 7 years at a wastewater treatment plant. Laboratory-scale hollow-fiber membrane modules were made from treatment plant used membranes having areas of 0.18 and 0.027 m² for MF and UF membranes, respectively. Filtration was performed on a feed solution containing organic, inorganic and turbidity elements as foulants for 1 h followed by clean-in-place (CIP) with 1 N HCl and 3000 mg L⁻¹ NaOCl solutions for 3 h and continued for 6 CIP cycles. Membrane characteristics were analyzed by using Fourier-transform infrared analysis, scanning electron microscopy and atomic force microscopy. Changes in mechanical strength were estimated with a universal testing machine and integrity was evaluated by comparing the upper control limit (UCL) of the pressure decay rate (PDR) with the experimental PDR of these membranes. Results showed that UCLs of both membranes were less than the actual decay rate, confirming the compromising of 4 log removal value (LRV) removal in both membranes in a P_test of 100–160 kPa, with a maximum of 3.78 LRV at the end of the experiments at a 100 kPa P_test. Membrane characterization revealed the loss of hydrophilicity and strength due to the oxidation and dehydrofluorination of the membranes, particularly in MF membranes. Scratches on membrane structures due to complex foulants and exposure to CIP chemicals are the most likely causes of integrity loss associated with membrane operation in a treatment plant.

在这项研究中，压力衰减测试 (PDT) 应用于在废水处理厂使用超过 7 年的微滤 (MF) 和超滤 (UF) 膜。实验室规模的中空纤维膜组件由处理厂使用的膜制成，MF 和 UF 膜的面积分别为 0.18 和 0.027 m ²。^{对含有有机、无机和浊度元素作为污垢的进料溶液进行过滤 1 小时，然后用 1 N HCl 和 3000 mg L -1}就地清洗 (CIP)NaOCl 溶液 3 小时并持续 6 个 CIP 循环。使用傅里叶变换红外分析、扫描电子显微镜和原子力显微镜分析膜特性。使用通用试验机估计机械强度的变化，并通过将压力衰减率 (PDR) 的控制上限 (UCL) 与这些膜的实验 PDR 进行比较来评估完整性。结果表明，两种膜的 UCL 均小于实际衰减率，证实了在 100-160 kPa 的 P_测试中，两种膜的 4 log 去除值 (LRV) 去除率均有所下降，在结束时最大为 3.78 LRV 100 kPa P_{测试下的实验}. 膜表征揭示了由于膜的氧化和脱氟化氢作用导致的亲水性和强度的损失，特别是在 MF 膜中。由于复杂的污垢和暴露于 CIP 化学品而导致的膜结构划痕是与处理厂中的膜操作相关的完整性损失的最可能原因。