Comparison of Flat type MBR Module and Hollow Fiber MBR Module Operation

Flat MBR has the following significant advantages compare to Hollow Fiber MBR:

(1) Much better Anti-pollution performance

Flat MBR can maintain stable operation under continual high flow rate at higher activated sludge concentrations than hollow fiber MBR. In most projects, although there are screen, depilation machines and other equipment in the pretreatment process, it is inevitable to enter some objects such as hair in the MBR tank. These filaments are wound around the membrane wire. When the sludge concentration reaches a certain level, mud cake will appear, and more and more membrane wire will be entangled together, which greatly reduces the effective membrane area of the hollow fiber MBR, then causing a sharp drop in membrane flow rate, and such problem is very difficult to repair, have to replace the module. The applicable activated sludge concentration (MLSS) of the flat MBR ranges from 3,000 to 15,000 mg/L, which is much higher than hollow fiber MBR (max. about 6000 mg/L).

The special structure of the flat MBR module can keep the stable gap between the two plates, which can use CIP by air flow, and has superior anti-pollution performance. In the case where difficult pollution occurs, the plates can also be taken out and use a low-pressure water jet to wash it, flow rate can recover very well, no chemical request. So the membrane can be operated efficiently for a long period of time, but hollow fiber MBR cannot be cleaned by this method.

(2) Good mechanical stability and without membrane wire broken

In the actual use process, the hollow fiber MBR module will inevitably break the membrane wire, usually caused by two reasons, one is the low quality, and customer can avoid this by purchase high quality products. The second is the root fracture caused by the fatigue of the spinning material. We know that due to the aeration, the hollow fiber membrane wire will always be in a large amplitude vibration under working conditions, and will always be at its root. It causes fatigue of the material, and the broken membrane wire caused by the fatigue of the material is often happen large-scaled, this damage is fatal, and the effluent water quality is deteriorated. The material strength of the flat MBR is much higher than that of the hollow fiber, and there is no similar phenomenon at all, which can completely guarantee the quality of the effluent water.

(3) The cleaning method is more convenient and the cleaning cycle is longer.

The flat MBR can effectively wash the membrane by controlling the aeration rate of the blower at the bottom of the module, that’s to say, flat MBR module can control the contamination of the membrane surface during the operation.

The chemical cleaning of the flat MBR module (Online cleaning) is also simpler. It is only need to refill the prepared chemical cleaner from the suction port into the membrane and soak for a period of time. Unlike the hollow fiber MBR module, the module needs frequently taken out for backwash. At the same time, the flat MBR membrane has a longer cleaning cycle than the hollow fiber MBR, and the cleaning cycle can be more than 3 months, and if the working pressure is always low, it may not need to clean at all. The flat MBR module can also recover flow rate by physical cleaning, which is almost impossible for hollow fiber MBR.

(4) Long life and low operating costs

According to incomplete statistics, the average working life of hollow fiber MBR is about 2 years, which means that there will be a large membrane replacement rate in 2 years. While, the average working life of flat MBR is 5-8 years, which means no necessary to change the membrane for a long time, so the operating cost is relatively reduced, and good operating conditions are guaranteed. The flat MBR has a high-strength support, the membrane damage is low, and the replacement rate is low; at the same time, the flat MBR can be replaced by a single plate, and the replacement cost is relatively reduced.

(5) The membrane plate replacement is simple

Due to the special design of the flat MBR module, the membrane plate can be replaced byn a single piece during the membrane damage replacement process, without the need to replace the frame. However, when the hollow fiber MBR breaks a certain amount, the entire module needs to be replaced, and the cost is greatly increased.

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