SRT in MBBR systems

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Hi Dear Experts:

Is there anybody who has information about MBBR SRT?

It should be noted that MBBR is supposed to use in A2O process.

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2 Answers

  1. MBBR is the combination of attached & suspended growth. The analysis method is not available to estimate the active biomass in the reactor. Therefore question of SRT does not arise. The re-circulation may or may not be incorporated in the design. Design parameters for MBBR are not well established and available in the text book. For example the media varies from 20 to 50% of total volume of reactor. I trust the researcher will soon come out with the design parameters similar to activated sludge process.

  2. A MBBR system is based on fixed film growth on the media and hence is not like an activated sludge system where you control the sludge age through return activated sludge and waste activated sludge. This actually poses a challenge to configure the system for A2O where you would normally recycle the sludge and the nitrified effluent back to an anoxic reactor and/or anaerobic reactor.  So the option is to install media in the anaerobic tank and the anoxic tank to retain sufficient biomass in these reactors.  However for effective P removal you need to carry the phosphate uptake bacteria from the anaerobic tank to the aerobic zone, which will not happen if they are attached to the media. The anoxic zone can however function as it is not necessary for the biomass to be exposed to aerated conditions. MBBR then relies on the existence of anaerobic, anoxic and aerobic conditions all in the aerobic reactor as you would find in a bio-filter for improved P removal which is sloughed off and carried through to the clarifier.  I do not believe this is as effective as a suspended growth system for P removal.  SRT is also then dependent on the organic loading and growth conditions for biomass growth and sloughing of the biomass layers. Hopefully researchers can offer another perspective as I do like the MBBR concept.

    1 Comment

    1. Dear Ian:

       First of all thanks because of your complete answer. As you mentioned the using of MBBR interfere with the removal of Phosphor and hence we don't want to use it in anaerobic reactor. It is supposed to use in anoxic and aerobic tanks. My question was for those parts and SRT in that system.