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m.maz YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Gender: Company or Organization: Movalledan	Max COD removal May 20^th, 2012, 7:56am Dear Experts , What is maximum COD removal that could be done with general biological / chemical method ? We have 50 m3/d wastewater from a scrubber with 120,000 ppm COD only , no BOD . B.R m.maz
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Tom Keenan - nesa

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Re: Max COD removal
Reply #1 - May 20^th, 2012, 2:00pm

If, as you say the wastewater has 12,000 COD, and no BOD, then this means that the "pollutants" cannot be oxidized by bacteria, and can only be oxidized using chemicals.
If this is the case, and if you can identify the best oxidizing agent, it is theoretically possible to fully oxidize all of the COD.
Bear in mind that hot acidified potassium dichromate is the oxidizing agent used in the COD test, so if you use hot acidified potassium dichromate as the oxidizing agent in the treatment process, there should be no COD remaining.
(P.S. I would not be recommending this latter treatment process)

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grrun

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Re: Max COD removal
Reply #2 - May 20^th, 2012, 8:30pm

What is the chemical composition of the COD? If the COD contains chemicals that are toxic to bacteria, then the BOD would, of course be zero. What chemicals is the scrubber removing? What is the composition of the scrubber fluid before contamination? As Tom relates, the reagents used in the COD determination could be used but that is not a practical solution. More information is needed to propose a practical solution.

grrun

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m.maz YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Gender: Company or Organization: Movalledan	Re: Max COD removal Reply #3 - May 22^nd, 2012, 3:49am Dear Grrun , Thanks for your help , please consider it's composition is : Maleic acid , 17% wt Phthalic acid , 2.4% wt Benzoic acid , 1 % wt Citraconic acid , 1.6 % wt water , 78% wt B.R m.maz
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grrun

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Re: Max COD removal
Reply #4 - May 22^nd, 2012, 12:37pm

Organic acids may be an end point for aerobic biological activity (but I'm uncertain about the salts of organic acids and about anaerobic biological treatment or a combination of both treatments for this wastewater). I'll have to defer to others on the Forum for treatment recommendations. However, the chemical composition of your wastewater removes some of the confusion from your first posting.

grrun

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Jeff Naumann

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Re: Max COD removal
Reply #5 - May 22^nd, 2012, 1:38pm

m.maz wrote on May 22^nd, 2012, 3:49am:

Dear Grrun ,
Thanks for your help , please consider it's composition is :

Maleic acid , 17% wt
Phthalic acid , 2.4% wt
Benzoic acid , 1 % wt
Citraconic acid , 1.6 % wt
water , 78% wt

B.R
m.maz

Are you saying that the "scrubber water" is literally 22 percent pure acids? That's pretty strong stuff! I would assume that the "scrubber water" mentioned is the "blowdown" from the system, with continual fresh water makeup???

I suspect that either evaporation or a membrane technology would be more effective in separating the acids from the water.

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Tom Keenan - nesa

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Re: Max COD removal
Reply #6 - May 23^rd, 2012, 4:13am

A number of these organic acids are likely to be unsuitable for biological treatment as the products of degradation are listed as being more toxic than the product itself, (i.e. Benzoic Acid, Phthalic Acid), so the waste water may not be suitable for biological treatment.
You have 50m3/day from the scrubber, .. that equates to about 2 m3 per hour over 24 hours operation, or maybe even as high as 3 m3 per hour if the scrubber is only operating over 8 hours.
In any event this seems like a very large volume of "waste water" or "blow-down" to be arising from a scrubber. Have you considered ways of reducing this volume of water?
Also have you considered perhaps using cyclones and / or bag filters to control some of the losses of these materials?

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m.maz YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Gender: Company or Organization: Movalledan	Re: Max COD removal Reply #7 - May 23^rd, 2012, 5:38am Dear Grrun , Dear Tom , Thanks in advanced for your attention . Of course , I said about blow down of system and we use fresh water as makeup . Also we use an incinerator for this waste water . But , let me know more about membrane separation for these carboxilic acids . B.R m.maz
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