本研究旨在探討逆洗的操作條件對沈浸式薄膜過濾效能的影響。以平均孔徑為5.6μm之薄膜過濾粒徑為5μm之聚甲基丙烯酸甲酯(PMMA)粒子為例，探討逆洗時間、逆洗頻率及逆洗通量等操作條件對濾速恢復與逆洗效率的影響。研究結果顯示：在過濾初期，過濾阻力之主要來源是薄膜的阻塞，等到過濾500秒後，則轉變成濾餅過濾模式，但薄膜孔洞阻塞之阻力仍佔總阻力之50%以上。操作在低逆洗通量時，長時間的逆洗比短時間的逆洗更能去除內部阻塞約達23%。比較第一次逆洗的濾速回升率，則在低逆洗通量下，可將濾速提升約39%，高逆洗通量則可將濾速提升約56%。而高逆洗通量對於附著在薄膜孔道內的粒子具有良好的沖刷效果，並可以有效的去除薄膜表面上的濾餅，故更能讓濾速提升；因此在長時間且高通量的逆洗條件之下，效率值平均可達40%，可以比低通量的逆洗高出2倍的效率值。 The effects of backwash conditions, such as filtration time, backwash duration, backwash flux, on the filtration rate recovery and membrane blocking in submerged membrane filtration are studied. A ceramic membrane with a mean surface pore size of 5.6 μm is used to filter 5 μm PMMA particles. The experimental results show that the filtration resistances due to cake formation and membrane blocking play the major roles on the overall filtration resistance, but the latter one is always dominant. The filtration rate can be increased by increasing backwash flux and backwash duration because of the reduction of membrane internal fouling. In the first backwash cycle, the filtration rate can be recovered reaching about 39% and 56% of the original under the low and high backwash fluxes, respectively. It is because the particles blocked in the membrane pores can be washed out causing by shear stress and the cake formed on the membrane surface can be scoured out. It can be concluded that to operate under the conditions of long backwash duration and high backwash flux is optimum. In such conditions, the overall filtration efficiency can be increased as high as 40%. A higher backwash flux may make a 2-fold efficiency than a lower one would be under the same backwash duration.
