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| | | Forum Newbie
Group: Forum Members
Last Login: 6/9/2008 5:55:51 PM
Posts: 7, Visits: 34 |
| | Dear Mr. Koch, I send you a PM, anyways. Before you said it would be good to put down the waste line and the return sludge. But now you mention somthing about putting the return line up. I didn't get that very clear. Thank you
Nadia |
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Forum Member
Group: Forum Members
Last Login: 10/6/2008 10:58:48 AM
Posts: 41, Visits: 58 |
| | Nadia, I'm checking in on this discussion 8 days after it started and 6 days after last post. Assume you're building MLSS per your give and take in the discussion. You never did mention whether you are treating industrial or municipal waste in response to another questioner and you only gave what I take to be a DO concentration at the end of the aeration tank, not at earlier points. Low DO concentrations can contribute to bulking if experienced outside a controlled anoxic zone, although I would normally expect that to be filimentous bulking. It is important to first assure you have a good environment (consistently aerobic DO levels, say 1.5 to 3.0 mg/L) and consistent pH levels (say 6.5 to 7.5). To my experience zoogleal (non-filimentious) bulking can be caused by nutrient deficiencies, and or toxic chemical influences. I believe the earlier questions re. industrial waste was to see if you are limited in any nutrients (which might cause bulking, possibly P since it would appear you have plenty of N if you have significant levels of ammonia in the effluent) or other issues such as varying pH below say 6 or above say 9, highly varying influent, etc. If low nutrients or the presence of toxics are effecting you, then increasing MLSS may or may not help (likely not) and the better approach is to address the root cause of the problem (adding nutrient or removing toxics). I assume you're calculating F/M based on influent BOD load to the aeration tank ratio'd to the weight of MLSS under aeration (not including clarifiers). The sludge age and F/M you cite are typical of extended aeration and while 1,600 mg/l is a bit low presumably it is low because your influent BOD is also low, presumably lower than design levels, and I'm not sure that changing your MLSS through reduced wasting will help in this instance. Your recycle (assume you mean return sludge) should be set based on what is happening in your final clarifiers primarily and if blanket levels are low you are probably returning enough but if high you may want to increase the return rate. With poor settling however, you may reach a point at which higher return rates hurt rather than help (solids loading limited) so you will want to experiment carefully with return rates taking your cues for proper return rate from the sludge blanket levels in your clarifier(s). I don't know where those are currently or if you've had solids washout problems. The more process info you share on line the better various folks who check in can help you so would encourage you to keep feeding information in.
Wiff Peterson |
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