Water and Wastewater.com Help Forums - Is DAF, Best way to reduce COD 13000mg/l ?

daraghgarde YaBB Newbies Offline I love Water and Wastewater.com Posts: 5 Gender: Company or Organization: Microdyn nadir	Is DAF, Best way to reduce COD 13000mg/l ? Apr 18^th, 2012, 3:57am We are trying to design plant to treat leachate, with COD 13000mg/l and BOD 9000. Is DAF the best way to do this and Follow it up with anoxic and aerobic tanks.
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Andres YaBB Newbies Offline I love Water and Wastewater.com Posts: 40 Gender: Company or Organization: Tallinn University of Technol.	Re: Is DAF, Best way to reduce COD 13000mg/l ? Reply #1 - Apr 18^th, 2012, 6:51am From the few models I have seen, DAF will not lower COD. Refrence: have a high COD influent also and trying to find a solution
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Arshad YaBB Newbies Offline I love Water and Wastewater.com Posts: 1 Company or Organization: Etch2o	Re: Is DAF, Best way to reduce COD 13000mg/l ? Reply #2 - Apr 18^th, 2012, 7:53am If you could forward me an official inquiry to my email. I can offer you a Solution. Thanks, Muhammad mohammed.arshad@etch2o.com 00966 535055529
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Jeff Naumann

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Re: Is DAF, Best way to reduce COD 13000mg/l ?
Reply #3 - Apr 18^th, 2012, 9:30am

daraghgarde wrote on Apr 18^th, 2012, 3:57am:

We are trying to design plant to treat leachate, with COD 13000mg/l and BOD 9000. Is DAF the best way to do this and Follow it up with anoxic and aerobic tanks.

DAF is appropriate for removal of stuff that tends to float, such as oil and grease and some suspended solids. Will the leachate have significant oil and grease, or suspended solids. It is totally useless for dissolved pollutants.

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aquaticonsult Senior Member Offline WaterandWastewa ter.Com is the best! Posts: 490 Company or Organization: Aquatic Technologies	Re: Is DAF, Best way to reduce COD 13000mg/l ? Reply #4 - Apr 18^th, 2012, 9:04pm Dissolved fats, oils, grease, paints, etc are best coagulated using a polymer and then sent to settling tank and filter press. DAF would breakthe coagulation.
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Dan Keys

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Re: Is DAF, Best way to reduce COD 13000mg/l ?
Reply #5 - Apr 19^th, 2012, 1:08pm

The choice of DAF depends on the nature of the COD/BOD. The DAF will remove about 90% of suspended solids in most cases, so its application in this case depends on the nature of the solids in the water.

For example, if all of the COD/BOD is dissolved sugar with no suspended solids, the DAF will do nothing at all. But if most of the COD/BOD is in the form of biodegradable suspended solids, the DAF will remove most of it.

You should run a soluble BOD or COD test to determine how much is dissolved and how much is in the form of suspended solids or O&G. From that, you can plan for a DAF to remove about 90% of the portion which is NOT soluble (suspended biodegradable components).

If you need further clarification, please ask.

Dan Keys

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Dan Keys
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daraghgarde YaBB Newbies Offline I love Water and Wastewater.com Posts: 5 Gender: Company or Organization: Microdyn nadir	Re: Is DAF, Best way to reduce COD 13000mg/l ? Reply #6 - Apr 19^th, 2012, 10:10pm Thanks everyone for your replies very helpful. The total SS is 1000mg/l so it is quite high so i think using DAF here makes sense to remove the COD BOD, I will see can we conduct a soluble COD test to determine how much is dissolved. Thank you again
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Dan Keys

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Re: Is DAF, Best way to reduce COD 13000mg/l ?
Reply #7 - Apr 20^th, 2012, 8:21am

Removal of suspended solids of 1000 mg/l may not give you much improvement, depending on what those solids are composed of.

A test for soluble COD/BOD is essential before making a decision that can cost a lot of money with the potential of doing little to reduce COD/BOD.

In addition, I would have a good chemical supplier conduct jar tests to make sure the solids can be separated and then run an additional soluble test on the water after straining it through a crude filter such as strong paper towel. This kind of test will accurately predict the potential performance of DAF in your application.

As a caution, I would expect suspended solids more in the range of 6000 mg/l if the solids are the source of COD/BOD. When you have TSS of 1000 mg/l and 13,000 mg/l COD, I would expect most of it to be soluble or dissolved and not removable by DAF.

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Dan Keys
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argfin

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Re: Is DAF, Best way to reduce COD 13000mg/l ?
Reply #8 - Apr 20^th, 2012, 8:43am

Hi Daraghgarde,

Wow! That is high!! The leachate at all 3 of my plants comes in at <100mg/l!! Shocked

Firstly I would say look at why the leachate is so high in solids and can you reduce it? If you can, you might not need a DAF at all.

Are you pumping direct from the landfill? If so, try working out the head of leachate and raising your pumps off the bottom as far as you can.

Could you not run the leachate through a settlement pit first? This might help to balance it and remove solids. The residual solids can be dug out with a digger or grab and dumped back to the landfill (permits allowing).

Just a thought, Roll Eyes

when you say total SS, I assume you mean 'Total Suspended Solids' (TSS)? Are you sure that is the result you are getting and not Total Solids (TS), which will include dissolve solids and could well be thousands of mg/l??

Regards,
argfin

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Eric Raj God Member Offline As long as it flows, I'll treat it! Posts: 518 Gender: Company or Organization: City of Bedford	Re: Is DAF, Best way to reduce COD 13000mg/l ? Reply #9 - Apr 20^th, 2012, 11:55am DAF only reduces COD that is tied to TSS. To reduce soluble COD one must figure out how to coagulate it and then cause it to form flocs that can be floated to the surface for removal. Same applies to soluble BOD. ~Eric
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