I have a question regarding the sludge concentration in MBR

First of all, I must state that I am not familiar with this topic. From what I’ve found online, since the MBR system does not produce sludge, its microbial concentration can be 2 to 3 times higher than that in conventional biological treatment tanks, and the biological treatment efficiency increases by 10 to 30%. Spraying water to eliminate foam is one of the most practical methods, as it does not introduce any other substances that are difficult to degrade or salts. MBR also requires sludge removal, especially for industrial wastewater and wastewater that needs nitrogen removal. Those who are interested can take a look at the address: http://www.instrument.com.cn/search/BBSArchive_1410261_4.htm

It’s a nice piece; I’ve included some content. Topic: A collection of basic questions and answers on wastewater treatment technology. 1. When treating wastewater through biological processes, what measures should be taken if the biological treatment tank is subjected to a load shock and the microorganisms are damaged? During the operation of the biochemical tank, once the microorganisms are subjected to stress due to changes in water volume or concentration, the COD removal efficiency drops sharply; in severe cases, sludge detaches from the biological fillers, causing the effluent to become turbid. At this point, the water supply should be stopped immediately, and powdered activated carbon should be added to the biological treatment tank in order to reduce the sludge load. The dosage of powdered activated carbon is 10 kilograms per 100 m3 of the tank’s volume. Once the sedimentation properties of the sludge have improved, the rapid proliferation method for sludge acclimatization can be employed: domestic wastewater can be added to the biochemical tank, or waste alcohol or wet paste made from cooked dry flour can be used. The addition rate is 5–10 kilograms of dry flour per 100 m3 of the biochemical tank’s volume. Water is introduced after 2–3 days, with the amount of water added increasing day by day until the microorganisms return to normal activity. 2. How should the biological treatment tank operate when there is no production wastewater due to holidays or temporary shutdowns? In *** Company, it is common to encounter situations where no production wastewater is generated due to holidays or temporary shutdowns; in such cases, we can add domestic sewage to the biological treatment tank or pump in river water, and add a paste made from dry flour cooked to heat, in order to maintain the growth and reproduction of microorganisms. In the biochemical tank, 5-10 kilograms of dry flour can be added per 100 cubic meters of volume, or waste alcohol can be added in proportion; aeration should take place for 4-8 hours per day.

I’m afraid there is no relevant proportional relationship. What matters is F/M. The key concept is the total BOD entering a certain biochemical tank ； Effective volume of the tank + sludge concentration = total amount of microorganisms. Theoretically, a very high sludge concentration in the aeration tank can be maintained just like in a secondary sedimentation tank, only with a much larger surface area for the sedimentation tank.