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wasted

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Foam
Apr 19^th, 2012, 7:18am

Im running a wasterwater plant which only takes municipal wastes. The approx amount of incoming waste is about 160-190 m3/d. But due the spring and lots of waters coming in, its about 300-400 m3/d.
Now there has been some changes at the aeration tanks. Plant has 2 sections totally seperate. Incoming is divided into 2 sections equally(more or less). From the spring starting things have gone worse and worse. There has come a thick layer of foam onto the aeration tanks surface which is quite brown and the oxygen bubbles cant disolve/remove it. The sludge volume is 70% 1. section and 60% second section, but the water itself is quite cloudy and yellowish.
I imagine that the problem is because of the high SRT or bulking sludge bad bacteria ? Or it might also be because the incoming wastewater is quite water-ish because of the springwaters ?
Maybe someone can help to solve the problem and maybe i should take some pics to make it more clear to understand ?

PS. sry for my english
Thnx in advance
Ardi

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The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: Foam Reply #1 - Apr 19^th, 2012, 8:46am This is likely filamentous foam (Nocardia/ M Parvicella) but you need to have someone with training look at it under the microscope for you to be sure. Identify it first and proceed from there. What is your SRT? What Are is the DO? you able to get incoming oil and grease tested? regards, Ryan
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sobisch

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Re: Foam
Reply #2 - Apr 19^th, 2012, 12:06pm

Dear Waster,

I am not sure about it, however, if you receive a lot of water from rainwater containing lots of natural compounds from litter etc. it maybe also a similar effect as seen in natural streams and sometimes in lakes. These foams are derived from natural degradation products.

Maybe you can skimm off the foam?

Kind regards
T. Sobisch

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T. Sobisch
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wasted

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Re: Foam
Reply #3 - Apr 20^th, 2012, 12:28am

I have no clue what my SRT might be because dont have any equipment to measure MLSS. DO is 6-7 mgO2/l at night and mornings and drops due the heavy flow to 2-4 mgO2/l. I was using SV to run the plant. Everything was fine almoust 2 years until now.
Plant has 3 sections in a row:
1.anaerobic
2.anoxic
3. Aeration tank
After that a clarifier
Mudpump pumps from clarifier to anaerobic tank 17 m3/h.
Tsirkulation pump pumps from AT to anoxic with about 403 m3/d (that should take off the N from the process)
Oh and i use PIX to take the P out.

If the clarifier went cloudier i used to add some m3 to mudpump and intense sludge removal. Worked well since now....Cleary i was running the plant wrong.

Cheers
Ardi

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C. Gillen God Member Offline Applied Environmental Biotechnology Posts: 773 Ireland Gender: Company or Organization: BioFuture Ltd.	Re: Foam Reply #4 - Apr 20^th, 2012, 10:14am Hi wasted, What is the SV30? Is the foam thick and sticky when you touch it? Is there a scum on the clarifier? Is there a scum trap on the clarifier? If so where does the removed scum go? How is final effluent quality? Best regards, Cgillen
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wasted

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Re: Foam
Reply #5 - Apr 23^rd, 2012, 1:18am

SV30 is about 650 ml/l. I wouldnt say its sticky either, its quite foamy and contains alot of small "airbubbles".
Yes, to the clarifier raises quite alot of scum which is removed from the surface and it goes back to the anaerobic chamber.
Effluent is quite cloudy.
Did some test last week and results were P=1,5 and N=17. Which is quite ok. But effluent aint pretty and aeration tank is covered with foam.

Ardi

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The sludge judge

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Re: Foam
Reply #6 - Apr 23^rd, 2012, 10:18am

If this is filamentous foam trapping it and sending it back to the head of the plant will only make the issue worse. First you should get it analyzed to tell exactly what it is>

If it indeed is filamentous removing it from the plant (vacuum it off) is a commonly used strategy. Longer term, you attack the source- possibly oil and grease.

What is your dissolved oxygen level in your aeration tank?

best regards,

Ryan

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C. Gillen God Member Offline Applied Environmental Biotechnology Posts: 773 Ireland Gender: Company or Organization: BioFuture Ltd.	Re: Foam Reply #7 - Apr 23^rd, 2012, 11:04am I agree with Ryan that you need to break the cycle and not recirculate the scum from the secondary clarifier to the anaerobic tank. It needs to be wasted from the system. Is it possible that you had a hydrocarbon spill into the plant? Best regards, Cgillen
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