Membrane bioreactor (MBR) is relatively a new technology in wastewater treatment. It can efficiently remove soluble and suspended organics. However, it may constantly encounter bio-fouling and cannot efficiently remove nutrient pollutants. These two deficiencies have motivated researchers to upgrade the design and operation of conventional MBR (CMBR). This study evaluates the performance of hybrid fixed bed MBR (FBMBR) treating real domestic wastewater in different operational conditions. It also compares the experimental results of FBMBR with the CMBR. For this purpose, two identical reactors are constructed as CMBR and FBMBR. Each module contains the net volume of 140 L and is operated continuously in two aerobic (DO > 4 mg/L) and anoxic (DO < 1 mg/L) conditions with average organic loading rates (OLRs) of 0.58, 0.71 and 1.55 kgCOD/m³d. The pore sizes of flat sheet membranes are 0.2–0.8 μm with total surface area of 1.4m² per module. The experimental results revealed that the removal efficiencies of BOD, COD and TSS are above 95 % in both CMBR and FBMBR in all operating conditions. However, fouling occurs with lower rates in FBMBR. The growing rate of transmembrane pressure (TMP) in aerobic condition is 1.7mBar/day in CMBR, while it reduces to 1.2mBar/day for FBMBR in solid retention time (SRT) of 75 days and OLR of 0.58 and 0.71 kgCOD/m³d. In anoxic condition with SRT of 100 days and OLR of 1.55 kgCOD/m³d, the TMP in FBMBR is 59 % of CMBR. In addition, total nitrogen (TN) removal is between 12 % (aerobic) and 27 % (anoxic) in CMBR, while it is between 25 % (aerobic) and 49 % (anoxic) in FBMBR. Total phosphorous (TP) removal also ranges between 50 and 66 % in CMBR, while it is between 51 and 86 % in FBMBR. Consequently, using hybrid systems of FBMBR can reduce membrane fouling rate and improve nutrient removal efficiency in comparison with CMBR. This approach can reinforce the biological treatment efficiency and preserve permeate quality in higher OLRs or in lower DO level.

膜生物反应器（MBR）是废水处理中相对较新的技术。它可以有效去除可溶性和悬浮有机物。然而，它可能会不断遇到生物污垢，无法有效去除营养污染物。这两个缺陷促使研究人员升级传统 MBR (CMBR) 的设计和操作。本研究评估了混合固定床 MBR (FBMBR) 在不同操作条件下处理实际生活废水的性能。它还比较了 FBMBR 与 CMBR 的实验结果。为此目的，两个相同的反应器被建造为 CMBR 和 FBMBR。每个模块包含 140 L 的净体积，并在两种需氧 (DO > 4 mg/L) 和缺氧 (DO < 1 mg/L) 条件下连续运行，平均有机负荷率 (OLR) 分别为 0.58、0.71 和 1.55 kgCOD /米³天。平板膜的孔径为0.2-0.8 μm，每个组件的总表面积为1.4m ^{2 。}实验结果表明，在所有操作条件下，CMBR和FBMBR对BOD、COD和TSS的去除效率均在95%以上。然而，在 FBMBR 中，结垢发生率较低。CMBR在好氧条件下跨膜压（TMP）的增长速度为1.7mBar/天，而在固体保留时间（SRT）为75天、OLR分别为0.58和0.71 kgCOD/m ³时，FBMBR的增长速度降至1.2mBar/天d。在缺氧条件下，SRT 为 100 天，OLR 为 1.55 kgCOD/m ³d，FBMBR 中的 TMP 是 CMBR 的 59%。此外，CMBR 中的总氮 (TN) 去除率介于 12%（好氧）和 27%（缺氧）之间，而 FBMBR 中的总氮 (TN) 去除率介于 25%（好氧）和 49%（缺氧）之间。CMBR 中的总磷 (TP) 去除率也在 50% 到 66% 之间，而 FBMBR 则在 51% 到 86% 之间。因此，与 CMBR 相比，使用 FBMBR 的混合系统可以降低膜污染率并提高养分去除效率。这种方法可以提高生物处理效率并在较高的 OLR 或较低的 DO 水平下保持渗透质量。