MLSS Performance Problem

Question

Hello team,
I am running MBR system constituting Mbr module, Aeartion module and Aanoxic module. This is an 8 train system.
The challenge is that one of the trains has literally got no MLSS, reads about 100-500 mg/l against a target of 7000 mg/l.
What could be the problem? What established way exists for improving MLSS in activated sludge systems?

Sean Roop · Answer

If you are not building mass, then the bacteria are not acclimated, being starved and then overloaded organically, or you have some toxic and recalcitrant compounds.  I would reseed from another train (may want to make a jumped to pull off recirculation back to the train just in case it is needed in the future).  If you use POTW sludge in an industrial application, then count on 70% attrition of the bacteria, because you have changed their food source.  In any event you have to reseed.  In addition, I would use freeze-dried bacteria cultures from an abundance of different bio-enhancement companies (i.e. Novozymes), and possibly some micronutrients to top it off.  If there are NO cultures in this train as you say, then I am betting you have a toxic stream.  In that event, you may want to segregate the stream and perform Advanced Oxidation Process (there are several, but for specific toxicants and pollutants there are many papers in circulation as to which AOP has worked previously.  Now, there are always scavengers (whatever else is in your stream) and byproducts that can affect the AOP greatly.  That is just bench work  To shorten things up at the bench you can use algorithms for Simplex Optimization Methods.  This is a bit challenging unless you are a good math student, but there is enough written to give you a handful of choices.  Could cut down on testing by up to 10x.  Good luck and keep us posted.  Thanks, Sean L. Roop - Senior Water and Wastewater Consultant - Industrial and Engineering Consultants, LLC.

MOHAMMED NAZEER · Answer

Hello,RAS return sludge system  could be not proper.Check the sludge pumps for functionality.Check intake MLSS in Aeration tank it as per specification.Check the DO levels in all area.

Andrew Hulsman · Answer

Hi Kelvin.  I have come across this problem when the return activated sludge line is not working properly.  That would be the problem for the 1st train when recycling from the last to the 1st.  It could also be related to poor mixing or poor aeration.  In short, the system is not completely mixed.

Michel Delgado Ruvalcaba · Answer

You can start by increasing your recirculation, You could also pass SSLVM from one train to the other

Rajendrakumar Saraf · Answer

Likely reasons are
BOD load is very low. Adequate BOD is required to develop MLSS For MBR Anoxic treatment is always before MBR. Please check inlet outlet BOD of Anoxic Treatment BOD: N: P ratio also plays a major role in development of MLSS. Check the ratio Presence of toxic chemicals also inhibits the MLSS growth. Inadequate aeration If aeration tank is not designed as complete mix tank then probability of settling of MLSS is dead pockets of tank. Is the aeration module is before the MBR. This may be reducing BOD further.
Please confirm above and get back to me on sarafrv@virajenvirozing.com
 
Prof. Rajendrakumar V Saraf

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