1. The MBR membrane flux design is not the higher the better
The flux of the membrane is determined by the membrane material and structure. For a particular membrane processing component, there is an upper limit for its porosity and flux. Filtering is essentially a physical process. While the membrane material reduces the pore size, the flux of the membrane will also decrease, and at the same time, the strength must be taken into consideration and long-term operation must be ensured. This leads to a fixed value of flux.
2. MBR can not 100% guarantee the quality of the produced water
MBR process is essentially a combination of activated sludge method and membrane filtration. It replaces the secondary settling tank with membrane filtration on the basis of the traditional activated sludge method, which brings advantages such as high rejection rate and high sludge concentration. But the removal of organic matter still relies on activated sludge and the biodegradability of organic matter.
3. MBR process requires mud removal treatment
Due to the excellent retention effect of membrane filtration, the activated sludge in the MBR process can reach a higher concentration, and the separation of hydraulic retention time and sludge age can be achieved without considering the influence of sludge concentration on the effluent. However, this advantage only increases the space for biochemistry. If the sludge is not discharged, the activated sludge will age, which will affect the performance of the biochemistry and also affect the aeration. The MBR process in the project can indeed reduce sludge discharge, but the sludge discharge is still necessary.
4. Can not reduce the sludge concentration indefinitely
Membrane blockage is a common problem in MBR application. MBR Membrane is blocked by sludge, especially when the sludge concentration is too high. Therefore, there is a misunderstanding that reduce sludge concentration to avoid membrane blockage. This leads to another misconception. Too low concentration and too high concentration of sludge will quickly block the membrane, the correct way is to maintain the concentration in a suitable range. In addition, aeration has the effect of scouring the surface of the membrane, and it should also be maintained at a corresponding amount.
5. MBR membrane could not 100% control BOD/COD
The principle of the membrane itself is filtration, which is a physical process. The removal of pollutants is mainly SS. Its significance for MBR membrane is to improve biochemical performance, but it can not filter soluble organic matter, so it can not be responsible for indicators such as COD. The removal of organic matter still depends on the design and operation management of the entire process chain.
6. MBR is not only applicable to domestic sewage
The MBR process is a combination of activated sludge method and membrane filtration, which is derived from the combination of traditional activated sludge method and secondary settling tank. In this sense, the MBR process is suitable for scenarios where the activated sludge method is used. However, for some sewage that is likely to cause membrane blockage, the pretreatment must meet the requirements.
7. MBR membrane could not improve the performance of the process
Except for good performance on disinfection performance and turbidity, other performance has nothing to do with the membrane. Moreover, the use of membranes has strict requirements on the changes in the water volume of the systems, and the flexibility of operation must have a large enough space, otherwise the membrane will be difficult to cope with the changes in water volume.