What is the appropriate sludge concentration for MBR process?

It is suggested that the MLSS sludge concentration in the membrane tank should be controlled between 6000-10000 mg/L. MBR is a new type of high-efficiency sewage treatment process which combines high-efficiency membrane separation technology with traditional activated sludge process. It is placed in an aeration tank with a unique submerged membrane module. After aerobic aeration and biological treatment, the water is filtered by a pump through a filter membrane and then pumped out. The biggest difference between it and traditional sewage treatment method is that it replaces the secondary sedimentation tank and tertiary treatment process in traditional biochemical process.

Using membrane separation technology, HRT and SRT are completely separated, and the sludge concentration can reach 6000- 10000 mg/L, which eliminates the harm caused by sludge bulking and greatly improves the removal rate of refractory organic matter. In MBR, microorganisms (that is, activated sludge) are still used to treat pollutants. The membrane is mainly used to retain sludge, and the effective components of sludge are mainly bacteria, and the diameter of bacteria is mostly above 0.5um. From an economic point of view, it is good that the pore size of membrane in MBR is slightly smaller than the diameter of bacteria, that is, between 0.2 and 0.45 um, which not only ensures that the number of required membranes is small and energy consumption is low under the same flux.