Submerged membranes operation modes

Immersed/submerged membranes operate in the outside-in mode, and a partial vacuum is created within the hoUow fibers by the operation of a centrifugal pump. The feed water to be treated passes through the membrane (outside-in configuration), entering the hollow... 

In the case of PMRs with submerged membranes, the treatment can be conducted either in continuous or in intermittent suction mode. Intermittent permeation could improve permeate flux and reduce membrane fouling, as was described in Section 6.7.1. However, no significant difference between the quality of permeate obtained during continuous and intermittent operations was observed. Similarly, no significant influence of the intermittent frequency (IF) on the efficiency of organics removal in the PMRs was found (Chin et al., 2007a Ryu et al., 2005). 

The application of MF and UF technology in water treatment is still relatively new, as many full-scale plants are less than 10 years old. Consequently, the design of MF and UF systems varies from plant to plant as no single design has proved itself to be the best (see Table 6.2). For example, MF/UF systems may be positioned horizontally or vertically, operate in deadend or cross-filtration mode, the membranes may be immersed/submerged in a feed tank where permeate is sucked (via vacuum) into the inside of the hollow fiber (outside-in filtration) or the membranes may be housed in modules where pressurized feed water is forced through the fiber and permeate is collect on the outside (inside-out filtration). 

---