Water and Wastewater.com Help Forums - treating grease trap waste

Bud

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treating grease trap waste
Feb 25^th, 2011, 4:13pm

We would like to build a new process line to handle 35-50,000 gallons per day of grease trap waste hauled from restaurants and food processors.

Can someone point me in the direction of a successful process flow design for treating grease.
Our discharge limit for BOD is 300 mg/l. Assuming we screen, de-grit, and decant the FOG we will be left with a high BOD emulsion. What is the best method for knocking down the BOD? Anaerobic digestion? Aerobic Digestion? Both? MBBR? DAF?

Are we better off saving the FOG, refining it and selling it as a low grade fuel oil or should we feed it to an aerobic digester and just get rid of it or should we feed it to an aerobic digester and make biogas with it?

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Steve Caudle

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Re: treating grease trap waste
Reply #1 - Feb 25^th, 2011, 4:51pm

We treat grease trap waste as a separate unit here. It actually acts as a separate system but discharges directly into our activated sludge basin for final treatment. We use specific bacteria developed by a professor at Stephen F. Ausitn Unversity. It works well. If you want more info I can give you his contact. He is now a professsor at Abilene but still provides our bacteria.

50,000 gpd is a LOT of grease. Are you in a huge town?

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Steve Caudle
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Vice President Northeast Texas Water Environment Association of Texas

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NorCal_Wastewater1

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Re: treating grease trap waste
Reply #2 - Feb 25^th, 2011, 5:33pm

I agree with Steve; that is a LOT of FOG! (Makes SF jealous) Roll Eyes

I am curious as to why there isn't a FOG abatement program in place to mitigate most of the FOG at its source? Undecided

I would think that in the long run that would be the more effective way of approaching this, and would also increase the prodcutive lifespan of the collection system.

Dallas

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Dallas

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grrun

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Re: treating grease trap waste
Reply #3 - Feb 25^th, 2011, 7:50pm

I would try on a bench scale heating and lowering the pH to liquify the oils and to break the emulsions. If I remember correctly, high MW cationic polymers (see your friendly water treatment chemical representative) may assist in dewatering the emulsions. The economics of this treatment depend on the concentration of the oil in the waste and the price of the oil in the marketplace.

grrun

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NorCal_Wastewater1

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Re: treating grease trap waste
Reply #4 - Feb 26^th, 2011, 6:28pm

I have a question regarding the trap systems in place; you mention 35-50K gpd being hauled to the treatment plant. What % of the total grease being generated is actually being captured?

Also what is the total number of sources involved? My concern is that with that high amount of FOG being generated the capture mechanisms in place are overwhelmed by the loads and a high enough % of the total FOG is escaping capture thus adding to the fouling already accumulating in the collection system by other sources.

Dallas

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Dallas

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Bud

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Re: treating grease trap waste
Reply #5 - Feb 28^th, 2011, 12:07pm

Steve, this is my first reply on this web site. Bear with me while I figure out how to use it.

Thanks for offering to help. I dont think it is time to speak to your professor about bacteria. We need to sort out our process first. Like you, we intend to keep it separate. We do have a lot of grease that we are currently paying a lot to get rid of.

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OilTrap Environmental YaBB Newbies Offline www.oiltrap.com Posts: 18 Company or Organization: OilTrap Environmental Products	Re: treating grease trap waste Reply #6 - Feb 28^th, 2011, 12:15pm Contact Mike Davis, Application Engineer for Electrocoagulation Waste water treatment systems at support@oiltrap.com or 1(360)943-6495. OilTrap Environmental has had success with similar water streams.
Back to top	Electrocoagulation is the Environmentally friendly future of water treatment! Chemical & Filter free, see www.waterrecycling.net to see how OilTrap Environmental has been offering groundbreaking solutions since 1993! or Email support@oiltrap.com to talk to an engineer. www.oiltrap.com www.twitter.com/oiltrap support@oiltrap.com IP Logged

grrun God Member Offline WaterandWastewa ter.Com is the best! Posts: 3525 Pekin, IL Gender: Company or Organization: Freelance Environmental Engine	Re: treating grease trap waste Reply #7 - Feb 28^th, 2011, 1:01pm Oil recovery may depend on the concentration of the oil in your wastewater. What is the concentration of the FOG? grrun
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Chromo Full Member Offline Water and Wastewater.com is the best! Posts: 128 Gender: Company or Organization: Koundakjian	Re: treating grease trap waste Reply #8 - Feb 28^th, 2011, 7:23pm Have you thought of putting it directly into an anaerobic digester once you take out the spoons, knives, etc.. Many cities do this process. http://www.jgpress.com/archives/_free/002278.html#more
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sobisch

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Re: treating grease trap waste
Reply #9 - Mar 1^st, 2011, 2:41am

Dear Bud,

treating the oil and grease aerobically as main treatment is a huge waste of money at least when in high concentration as it should be in case of grease traps. For polishing the separated waster it is o.k.
The reason is that you will have to provide a lot of oxygen through aeration and you will lose the energy contaned in the waste.
Based on preliminary experiments you have to deside whether separation and selling of waste oil as fuel or for biodiesel is feasible.
Besides pH shift, elevated temperature mentioned cationic polyelectrolytes whith high charge density are used for splitting emulsions.

Kind regards
T. Sobisch

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T. Sobisch
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http://AppliedColloidsSurfactants.blogspot.com
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http://www.lum-gmbh.com

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brfuels

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Re: treating grease trap waste
Reply #10 - May 30^th, 2012, 9:59pm

Bud wrote on Feb 25^th, 2011, 4:13pm:

We would like to build a new process line to handle 35-50,000 gallons per day of grease trap waste hauled from restaurants and food processors.

Can someone point me in the direction of a successful process flow design for treating grease.
Our discharge limit for BOD is 300 mg/l. Assuming we screen, de-grit, and decant the FOG we will be left with a high BOD emulsion. What is the best method for knocking down the BOD? Anaerobic digestion? Aerobic Digestion? Both? MBBR? DAF?

Are we better off saving the FOG, refining it and selling it as a low grade fuel oil or should we feed it to an aerobic digester and just get rid of it or should we feed it to an aerobic digester and make biogas with it?

We have found it profitable to refine the grease trap wastes. Depending on the out put products you select with our system this can be a major business in and of its self.
We would be happy to help you with the process technology needed to turn your problem into cash flow. We have been refining grease trap waste at a profit since 2004

If you are interested please give us a call at 207-930-5247

Thank you
Ralph Howe
Bio Renewable Fuels Corp
4 Industrial rd.
Fairfield, ME 04937
www.biorenewablefuels.com
207-323-0679

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sobisch God Member Offline Posts: 1777 Gender: Company or Organization: L.U.M. GmbH	Re: treating grease trap waste Reply #11 - May 31^st, 2012, 1:05am it does not make sense to continue a thread after more than 1 year. Again I would like to ask to prevent this by technical means.
Back to top	T. Sobisch for@appliedcolloidssurfactants.info http://AppliedColloidsSurfactants.blogspot.com http://www.AppliedColloidsSurfactants.info http://www.lum-gmbh.com IP Logged