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JustinD

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SBR Foam problem
Mar 26^th, 2012, 10:32am

I'm having problems with my SBR plant and can not seem to figure out why I'm having such bad problems with foaming. heres the stats about the plant to help with anyone that might have an idea.

its a small SBR serving only residential
.065 MGD inf
anoxic volume .022 MG
aeration basin volume .101 MG

inf BOD 195, TSS 212, pH 8.23
eff BOD 3.15, TSS 0.8, pH 7.11

aeration basin MLSS 1610, Sludge age 12 days, settle time 60 min settle 600/1000, .076 f/m, wasting is about 1200 gallons per day

here is a picture of the foaming promlems I'm having

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The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: SBR Foam problem Reply #1 - Mar 26^th, 2012, 10:46am From the picture this looks to be start up foam (very high F/M), a surfactant, or possibly type 1863 bacteria. A micro of the foam and the MLSS is needed for proper diagnosis and troubleshooting here. best regards, Ryan
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JustinD YaBB Newbies Offline I love Water and Wastewater.com Posts: 3 Company or Organization: Baca Grande Water	Re: SBR Foam problem Reply #2 - Mar 26^th, 2012, 11:09am Thanks for the reply Ryan, the plant has been in operation for 7 years now. it is not the first time ive had these foam problems, it kinda comes an goes. Also for your info the foam MLSS is 11,600 and the micro on the foam shows almost zero activity, looks like fillaments kinda to me
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The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: SBR Foam problem Reply #3 - Mar 26^th, 2012, 11:11am I'd be glad to take a look and see for sure. I pm'd you some mailing instructions/ address if you're intersted. best regards, Ryan
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grrun

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Re: SBR Foam problem
Reply #4 - Mar 26^th, 2012, 1:43pm

I would try skimming the foam from the surface to reduce reinfection of the SBR. The MLSSs in the foam are an indicator of high sludge age.
My guess is that you've lost control of your wasting somehow. If your WAS is drawn through a port in the side of the tank; then it could be creating a suction vortex to the sludge-supernatant interface which would reduce the volume of sludge removed. This is just speculation on my part because you have indicated that this has happened before. If this is the problem, then mixing the settled sludge before wasting is a solution to consistent wasting.

grrun

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The sludge judge

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Re: SBR Foam problem
Reply #5 - Mar 26^th, 2012, 1:49pm

don't be confused by MLSS concentration in the foam- These bugs are not in contact with the waste and are not available as active biomass. As an example if nocardia is very bad it call trap a very high percentage of the bugs within the foam. The foam's MLSS becomes super high, but the actual F/M in the plant is much lower.

don't make a process change until you know what you're dealing with. Not wise.

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WWT Disinfection Pro YaBB Newbies Offline I love Water and Wastewater.com Posts: 18 Menifee Gender: Company or Organization: City of Corona	Re: SBR Foam problem Reply #6 - Mar 26^th, 2012, 3:22pm The F/M is obviously high. This is most like caused by batch waste and have an inconstant RAS concentration. If the problem arise off and on I would not really think its a filament problem. I know there are de-foaming products to add to the basin when it gets bad. I hope this might help.
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JustinD

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Re: SBR Foam problem
Reply #7 - Mar 26^th, 2012, 5:23pm

thanks everyone for the reply.
my wasting is pretty easy to control. there are large pumps in the anoxic basin that pump up and into the aeration basin and mix air in at the same time and this flows and mixes back into the anoxic basin, to waste there is a valve that is on top of the line that is being pumped from the anoxic to the aeration that opens and returns waste to the beginning of the plant to the anaerobic tank. it opens 5 min per batch at 40 gpm and we do about 6 baches per day. so average its wasting 1200 gallons per day.
i dont know if the info help but the aeration basin runs for 6 min on and then 15 minutes off. it will do this all day long until the plant gets to a certain level and then it will settle for 90 min then discharge a batch. I have tried de-foam in the past with no effect. when i get foam problems its usually in the spring and fall when the temp changes.
I can add some pictures of my micro analysis if it will help?

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WWT Disinfection Pro YaBB Newbies Offline I love Water and Wastewater.com Posts: 18 Menifee Gender: Company or Organization: City of Corona	Re: SBR Foam problem Reply #8 - Mar 26^th, 2012, 6:28pm Got it, that's sounds logical. I was wondering were you keep the D.O ppm under aeration. One thing you might try is bring the D.O up like 1.5 and then dropped it to like 0.2ppm. You can length nite and denite times accordingly. This might help you build solids and oxidize the sludge for better settling.
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The sludge judge

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Re: SBR Foam problem
Reply #9 - Mar 26^th, 2012, 8:43pm

It sounds like you're getting some foaming as different thermo-tolerant bacteria take over as the temperature changes. If you've had this before and it's seasonal that's probably the case. To be sure do a proper micro. Otherwise try reducing the WAS rate for a few days by 10% and see what happens.

If it's a surfactant a defoamer may help (note that this will add alot of BOD though and if you're already at a high F/M it'll be even higher so maybe not the best idea unless you're afraid it'll overflow the basin). I'd jar test first if doing that.

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