MBR membrane pool design

3.7.1 Split and Integrated

There are two types of membrane arrangement: separate type and integrated type. The separation type is to place the biological treatment unit and the membrane separation unit separately, that is, a single oxidation pool and a membrane pool. The integrated approach is to place the membrane separation element directly in the biological processing unit.

In general, small systems tend to use one-piece, so that the system is simpler. The large system is more inclined to adopt the split type, the membrane separation unit is placed in a separate membrane pool, the system is more flexible, and the maintenance is more convenient. If the system is designed for in-situ immersion cleaning, it must be split-mounted, and the membrane pool is usually divided into small, independently operated units. Another advantage of the separate type is that it is not easy to short-circuit the water flow, because the water always enters the aeration tank before entering the membrane tank.

3.7.2 Layout of membrane components

No matter the biological treatment unit is designed as push-flow or fully hybrid, MBR membrane components can be arranged in it to improve the efficiency of biochemical treatment.

If the integrated arrangement is used, the biochemical pool serves as a membrane pool, and its size is determined according to the biochemical reaction load and residence time, usually the volume is much larger than the volume required for the placement of the membrane component, at this time, in order to avoid short circuit of the water flow, the membrane component is generally placed at the tail of the biochemical pool, and meet the clearance requirements described below.

If a separate arrangement is used, the size of the membrane pool should meet the clearance requirements described below.

Clearance requirements for membrane components in the membrane pool:

 Clearance between membrane component and pool side: ≥300mm;

 Clearance between membrane components: ≥300mm;

 Clearance between the diaphragm and the pool bottom: 300 ~ 500mm, in which the bottom of the diaphragm is 200 ~ 300mm away from the gas pipe, and the gas pipe is 200 ~ 250mm away from the pool bottom.

 From the top of the membrane assembly to the liquid level: ≥400mm;

 Height of membrane pool: ≥500mm.