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sidar

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Dairy wastewater treatment problem
May 14^th, 2012, 2:01am

Hello to everyone
I have just become a member of wastewater forum. Thanks to everybody who contributed.

I have a problem with starting-up treatment plant designed to treat dairy wastewater. I could not create activated sludge flocs in aeration tank. I filled up to one third of aeration tank and activated blower. About a week later the color of wastewater changed into dark yellow. I conducted settling test and I observed that no flocs are present in mixed liquid. One hour later some sludge like dust accumulated on the base of settling vessel and the upper part of was cloudy. I think this result from dispersed growth but I am not sure. Influent COD value to aeration tank was about 7000 mg/L. Is it possible to create activated sludge with the wastwater that has high COD ? Please help. I send the settling test photograph.

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Peakman

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Re: Dairy wastewater treatment problem
Reply #1 - May 14^th, 2012, 3:02am

Hi, when we start up new plants or change from fixed film process to Activated sludge, we always start the new plant off with some fresh activated sludge from another site. It's usually in the form of SAS or WAS to save on tankering costs. I suggest you go down this route and you might see some change quite quickly..

Best of luck

Peakman

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C. Gillen

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Re: Dairy wastewater treatment problem
Reply #2 - May 14^th, 2012, 3:36am

Hi sidar,
Since the oxygen transfer is not going to be very good when the aeration tank is only 1/3 full it would be better to add water to fill the tank. This more dilute influent would be better for startup. Check pH and DO. I agree with Peakman about adding sludge from another dairy plant. As always make sure the sludge is of good quality. Also consider the use of sludge and bioaugmentation if there are no dairy plants locally.

Best regards,
Cgillen

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The sludge judge

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Re: Dairy wastewater treatment problem
Reply #3 - May 14^th, 2012, 11:24am

The more sludge you add, the less time to start up. Make sure there's enough oxygen present for the higher loading rate when starting up as well, make sure there's proper conditions to promote favorable growth in general (proper DO, nutrients, pH etc).

As for your question is it possible to grow bacteria with a COD of 7,000. Absolutely yes, you'll grow bugs like crazy/ you just need to keep your F/M ratio in line as best as possible so you're growing flocculated bacteria and not dispersed ones. Recycling the effluent back to the aeration tank if possible at first or with tertiary filtration will help to keep the bacteria from leaving the plant as TSS and also speed up the process.

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Tom Keenan - nesa God Member Offline Environmental Consultant - contact info@nesa.ie Posts: 2103 Gender: Company or Organization: nesa environmental consultants	Re: Dairy wastewater treatment problem Reply #4 - May 14^th, 2012, 4:03pm Starting up a plant like this without some sludge addition, (or bio-augmentation), is likely to be a pro-longed process. The "yellowish" or very light brown colour is not unusual in dairy water plants. You really should give serious consideration to introducing some "bugs" to help the start-up.
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