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What are you doing with your waste water?

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StoneCold

StoneCold

Chemical
Mar 11, 2003
992
What method do you use at your chemical plants to dispose of your waste water? Waste water being water that contains solvents as well as some solids? Are you evaporating the water and separating the solvent out either as a descrete phase or with carbon and then recycling the water? Are you incinerating it, either on site or off site? Are you filtering it and running it through membranes?
I am looking for some suggestions as to a practical way to dispose of 15,000 gallons a week of water contaminated with solvents,organic molecules and miscelaneous salts.
 
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I am not a waste-water treatment specialist, so please excuse me if I am stating the obvious:

1. I would suggest that you (or your factory) in parallell started to look at the alternative costs of minimizing the pollution and polluted water amount at the originating process stages. This could be cheaper over time than running large-scale cleaning processes.

2. For cleaning processes and equipment: this would be dependent on your type of process. If you are not located in Europe, try looking into different European suppliers/ countries and fora to get ideas. Requirements and amount of different solutions and available equipment may be higher than in your location.

3. If authorities are setting the parameters for cleaning, they would also more than likely have opinions and experiences on different practical solutions along with practical measuring and testing procedures of the end result.

4. Authrities, or their inspectors, could advice you on finding similar cases in the district (or otherwhere?) with running 'good solutions'.

 
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You can do underground injection at an DEQ/EPA approved facility.
 
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Over the years I've used steam stripping, extraction, coagulation, settling, filtering, ultrafiltration, and biological treatment to treat various waste waters.

I would encourage you to strive for zero discharge, as that is the ultimate goal.

Good luck,
Latexman
 
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WE HAVE USED SEVERAL DIFFERENT METHODS WITH CUSTOMERS BUT YOU WOULD NEED TO TELL ME A LITTLE MORE ABOUT YOUR PROCESS. OF THE 15,000 GALLONS A WEEK WHAT ARE THE PERCENTAGES THAT MAKE UP YOUR WASTE STREAM? DO YOU RUN 24/7? WHAT PROCESS ARE YOU USING NOW? WHAT DO YOU WANT TO ACCOMPLISH? WHAT LEVELS DO YOU NEED TO GET TO?

 
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Pumpguykc
All of the 15,000 gallons are trucked off to an incinerator.
There is no possibility of sending the water to the city sewer as they are having problems meeting discharge levels now and they are in trouble with the state. (Housing boom but no infrastructure boom.)
The water stream is made up of three sources.
The first is cooling water/ boiler water blowdown.
The second is water from washing the plant floor, equipment etc.
The third source is from aqueous separations.
The blowdown stream has high solids both desolved and suspended. Chemistry is a minimal problem.
Wash water is contaminated with dissolved salts (MgCl, MgBr) as well as large and organic molecules. Contamination is probably less than 1000ppm of most compounds.
The aqueous separations water is saturated with salts (NaCl, MgCl,MgBr) It may have a large ph range 3 to 10.
The contain saturation levels of ethyl ether, tetrahydrofuran, toluene, etc.

The streams are about equal in volumes.

Thanks
StoneCold
 
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Unfortunately the prevailing technique for dealing with this seems to be: Shutter the plant. Relocate in a third world country. Pour the waste stream into the river/onto the ground.
Note: I do not agree with or endorse this strategy. However if you doubt it visit your favorite third-world or former Eastern-Bloc country and see if you are brave/foolish enough to drink the water.
 
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JimCasey
I hear you. My favorite angle to attack this is to burn waste solvent in a waste boiler and use the steam to flash the water and solvents off the solids. Then either steam strip the water to remove the solvents or use what is called a "macro-molecular polymer" to adsorb the solvents.
I think that would be good enough to feed the water back into my cooling towers without any problems. Unless I end up with more water than I can use in the cooling tower. Then I guess I will inject the dirty water into the waste heat boiler to vaporize it. Like an incinerator. I am unsure what the EPA would say about my ideas. I need to get that worked out.

Thanks
StoneCold
 
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Can you isolate the solvent stream from the other two streams?

This if nothing else should reduce your cost due to the fact that would reduce the amount that contains the solvent.

Can the Cooling tower / boiler water not go to drain? The pH should not be very high?


Chris
 
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Reduce the quantity of water and you reduce your problem.
I would attack the floor and equipments cleanings. Why not implement a non-cleaning procedure between batchs of the same product?
I don't know your industry but if in pharma is an acceptable procedure, it should be Ok for you.
Use Mop instead of waterjet clean the floor;
make equipmetn cleaning tests to know the minimum necessary water needed for and adequate cleaning.
Check your blowdown discharges. Is it the minimum for a proper work of the cooling towers?
Remember, water was a relativelyt cheap (if not free) commodity 20 years ago, now it is not. So practices that were acceptable before, today must be changed if you still want to be in the business.

Also, in the middle of 15.000 gallons of water you must have some that can meet your discharge limits. Discharge that one to the drain. Don't treat water that doens't need to be treated. This will only increase your bottomline costs.
Good luck
 
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I agree 100% with ck1999 and Medicine Eng. Many of the plants use the cooling water blowdown to dilute their effluent at the discharge end of the treating plant thus simultaneously reducing the treatment plant load as well as achieving the dilution effect.
 
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As an oil refinery we have on site our own waste water treatment. This water under controlled parameters of ph, phenols and sulphides, ammonia and oily matter is then discharged to an external industrial residuum treatment station owned by local authorities

regards

luís marques
 
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Thanks for the replies.
Obviously if we could discharge to the city sewer that would be great but there system is grossly undersized due to rapid housing expansion and they will not allow us to dump our water to the sewer. We have tried several times and all that happens is that they keep stalling us. We currently pay about $2/gallon for incineration. That is why we have to do something cheaper soon.

Regards
StoneCold
 
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Our liquid waste disposal is now using deep well injection. This waste stream carries all the bad stuff. We have one steam that is mainly cooling tower and boiler blowdown that is sent to the river after being aerated if everything is within limits. This stream can be sent to the well if necessary during process excursions. Our original disposal system consisted of bio-oxidation/remediation for the simple organic streams. We bred our own breed of bacteria. The heavy organics were disposed of by thermal oxidation, underwater. The was from this stream was sent through the bio plant. In the interim we had several small thermal oxidizers similar to the ones from the following company. I don't recall any major problems with their operation.


The newest scheme is to use part of the treated water from a large sewage treatment plant to be built on the plant site. The CTW purge will then be disposed of by spray fields located on site. They have several other permutations on this scenario that on has to have a chart. In case of upset of sewage plant any untreated water will be injected into the site deep well.



Food for thought.

 
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Sounds to me like your situation is crying out for a membrane system. You should be able to relatively easily reduce your quantity of water incinerated by 70% or more, leaving you a far smaller volume of material to burn at the same price per gallon. It should also result in a water stream worthy of some sort of re-use.

You probably should segregate your streams. The cooling tower and boiler blowdown streams will generate a concentrated waste stream consisting of a slurry/sludge which can be disposed of far cheaper than via incineration.

With the ethers (THF & diethylether) in your stream, you can forget about biological treatment- something about ethers makes them recalcitrant to bugs. And they're quite soluble in water, so they may be difficult to separate by standard liquid membrane technology, activated carbon, air stripping etc. But you may get somewhere with pervaporation, where their volatility may come in handy.
 
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How much does it cost to incinerate the resulting concentrated wastewater?
 
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tgmcg: guaranteed, the cost to incinerate doesn't go up in lock step with the concentration of stuff that's in the water, so the net cost will be lower. As I said in my post, I'd be surprised if it cost any more per gallon to "burn" concentrated wastewater as opposed to more dilute wastewater. If there are non-chlorinated organics involved, the opposite may be true as the wastewater may suddenly have a little beneficial fuel value to offset the huge heat of vaporization of the water itself.

It's a bit crazy to attempt to "burn" water at the best of times- there are so many better, cheaper options if you have enough water to deal with to make the capital cost worth the investment.
 
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moltenmetal
Pilot testing of a membrane system on the cooling water/ boiler blowdown shows only about a 30% recovery. It is pretty rough stuff. We could probably get considerably better results on the floor wash water but I would guess the process water would be about the same as the blow down water because it is often saturated with salts. I would like to go with one solution, even though that may not be the cheapest option. I am very limited on manpower in my enviromental department and I have no technical personell in that area.

Regards
StoneCold.
 
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moltenmetal,

Do you have any idea how much it costs to incinerate the wastewater. In the literature, I've seen rates all over the map and am looking for some concrete examples.

Some examples of chlorinated vs non-chlorinated would be very helpful.

Best regards,

Tom
 
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