Our biological looks quite horrible these days. Foam on the 2 reactor, brown foam and althought I don't see a lot of filamentous we are thinking about adding hipoclhoridre as a solution to get rid of the foam.
The MLSS are much higher than what they used to be around14000 but only 60% is MLVSS. soluble DQO is around 300. At the inlet the feed has 2500 soluble DQO but 14000 total DQO.
A lot of a microorganims (we think it could be an amoeba but not sure), some paremecium, some vorticella and some filamentous but do you think is a lot? Can these amount of filamentous be the problem?
I'll be very glad if some of you can help me with this as this is the first time I have to cope with foaming.

DQO soluble inlet 2608
DQo total 13368
Solids inlet 8174
MLSS 27000
MLVSS 16200
F/M (calculated with soluble DQO 0,02 with total 0,08)
Slude age 30
Decanted after 30' 950

Not able to attach pictures! if somebody wants to help I can send  the pictures to see if they know what our microo are and what they mean.

The secondary clarifier (decanter) works quite well lowering the solids to around 30. Little foam but just a little bit. All started after a sudden failure of the DAF, a lot of DQO and solids incoming. Inlet from DQO total 4600 to DQO total 28000.
We had some trouble too with the centrifugal decanter for the waste, but if was fixed and now it is working fine. We purged more to get rid of the solids but finally we had to recirculate the plant for some days.

Since then the soluble solids are low and we recover part of the fauna (first small microor, then getting better). Right now we still have foam (actually I think we are having more) and we are starting to think it can be a filamentous issue although I think I dont see very much at the microscope.

DQO at the 2 reactor 350
DQO at the final reactor before the secondary clarifier 290.
Total solids at the final reactor 13500.
Capacity of the biological 2000 m3, % volatil 60.

MlSS = 2000*13500/1000
MLVSS = 2000*13500*0.6/1000

We do not see any rotifer only small and fast free swimmers, paramecium and some vorticella.

DO at 2 reactor 1,5
Do at final reactor 0,8

Thanks both or you.
Grunn you think the foam is caused by the high solids in the system then?.
If I understand you well, you think by purging more sludge at the clarifier, we will be able to get rid of the problem. We will reduce the sludge age and raise the F/M ratio. Is that right?

What do you think about the MLVSS = 60% MLSS shouldn't be higher. I was afraid to purge to much and reduce the MLVSS by doing this

Thanks to you too.

We have been running on low load and with the DAF working fine for about 2 weeks now. Actually we are getting at the homogeneization pond low soluble cod but still high total cod (although getting lower). The thing is everytime we try to feed the homoge. pond with new influent from our other ponds the DQO tends to increase quite fast (even with the DAF working) and as we need to continue feeding from this points the problems tends to continue all time

Hi again,
You say that
DQO soluble inlet 2608
DQo total 13368.
What are these solids?
Is it possible to remove some of them by simple settling before it gets to the biological stage?
By feeding such high solids levels to the biological stage, you can expect the MLSS (or MLVSS) to read as a false high, and then when using either of these values to calculate either sludge age or f/m the error is compounded.
While you may have 27,000 mg/l MLSS with 16,200 MLVSS, and with over 8,000 mg/l suspended solids in the feed, it is possible that you have accumulated a significant amount of MLSS & MLVSS that is not "active" and comprises only solids from the feed.
I believe that there is an urgent need to address the high solids in the feed, and then correct the sludge age & f/m to optimum levels.

Can you provide a basic flow schematic of your plant? What are your permit levels on discharge and what BOD/TSS etc are you currently discharging?

What is your MLSS in your aeration tank? (I was assuming before the 27000 mg/L was in your centrifugal decanter?)

Get Tom Hobsons book on activated sludge.  There are some very simple tests in there anyone can do without high end equipment.  I adapted it for my plant and it simplified operations so much.  Every plant is different so some of it can seem bogus, but he does a great job playing devils advocate.  It is a cheap resource you will not regret.  I fought long and hard with my process, finally we all agreed to CL2 dosing in the RAS line.  I do not regret it at all.  Now it is a no brainer.  My flow was only 9000gpd. I added 12ml/min to the Ras flow of 42gpm for 5 days.  Foam on the plant was 90% gone in a day.  5th day the plant turned a bit cloudy and we lost nitrification.  Every day since it has been better and better.  Take good notes and observations.  It is the only way to learn from any mistakes.  My mistake was I should have stopped at 4 days.

Make sure to clean the settled sludge in the ponds in the event the sludge blanket is high.

Make sure to divert all incoming septic tanks septage to the centrifuge without allowing the septage into the liquid stream.

Best Regards,

Prepi??