Water and Wastewater.com Help Forums - Grease (FOG) in Influent

JRapp

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Grease (FOG) in Influent
Apr 23^rd, 2012, 8:43am

Hello All,

Currently we are experiencing problems with high Phos. in our influent and effluent. For four years we have treated Phos. biologically through our treatment process. Now in order to meet DEP limits, we are dosing large amounts of Alum per day. We have enacted a pretreatment program/ordinance for commercial businesses. Our main problem seems to be coming from food establishments. As part of our pretreatment process, we have a grease separator, which seems to do an ok job. My feeling is an excess of FOG getting into the treatment process. Any thoughts on how to remove this excess FOG in order to decrease and/or eliminate our use of chemicals?

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The sludge judge

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Re: Grease (FOG) in Influent
Reply #1 - Apr 23^rd, 2012, 10:07am

I'd recommend testing the oil and grease concentration on the influent and primary clarifier effluent as well as doing a microscopic eval to see if there's any signs of oil and grease (Microthrix, nocardioforms) in your MLSS. This will give you an idea if this is posing a problem to you.You can also tell the abundnace of Polyphoshate accumulating bacteria (PAOs) through the neisser stain.

There's not a strong correlation between oil and grease and biological phoshorus removal although ideally you want as much of the BOD possible in the anaerobic selector as readily available as possible.

More data is helpful to try to improve your Phos removal. What is your incoming BOD and total Phos. and What is your ORP in the selector?

best regards,

Ryan

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Eric Raj

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Re: Grease (FOG) in Influent
Reply #2 - Apr 23^rd, 2012, 12:25pm

Test for O & G to get a definite answer on that front. If it is excess FOG you can install a small DAF to remove it before it goes further into your process train. Good primary clarification removes a majority of the FOG as long as it is removed on a consistent basis and not allowed to pass through to your aeration basins.

Proper dosing of alum does remove phosphorus, just keep an eye upon the pH and alkalinity values coming out of the aeration basins. Maintian sufficient dissolved oxygen in aeration.

~Eric Shocked

Kinda' spooky weather today in this neck of the woods!

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grrun God Member Offline WaterandWastewa ter.Com is the best! Posts: 3525 Pekin, IL Gender: Company or Organization: Freelance Environmental Engine	Re: Grease (FOG) in Influent Reply #3 - Apr 23^rd, 2012, 6:10pm You may want to test for soluble and insoluble P in your discharge. TSSs containing insoluble P may be a contributor to the problem of high P. grrun
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