Disposal of old coolant

[flatfnder]

Hello, I was wondering how you dispose of your old coolant. Right now when my coolant just can't hang anymore I have it hauled away from a waste management service. I was thinking though that it is mostly water so why not evaporate the water off and just pay to have the coolant/waste oil hauled away. Does anyone do this? I have seen drum evaporators that fully envelope a 55 gallon drum to a strap that clamps around the drum. Price on these vary from thousands to the involved ones to a few hundred bucks for the strap. Do they work well enough to justify the cost? It can't be too cheap to run the heater elements to get the drum boiling so it will cost a certain amount to boil off a gallon of water vs having it hauled away. What about the steam that comes off? Do you have to worry about environmental issues with it? Would love to hear from someone who might partake in this practice. Thanks, J

[Geof]

Evaporation is what we do.

We have a system using 55 gallon drums with the coolant from the machines going into the first one to get the tramp oil skimmed then into a drum with a wrap-around heater for evaporation. The coolant being evaporated is stirred and we have a fan blowing air over the top carry away the water vapor. The temperature of the evaporator tank is about 150 F, it is not necessary to boil it.

Initially the evaporator will loose about 10 to 15% of its volume in a day, but as the mix gets more concentrated the rate of evaporation goes down. We keep adding the skimmed waste coolant to the evaporator tank until the rate of evaporation is below about 5% per day then have this concentrated stuff picked up. Our total volume reduction is 80 to 90% I think.

We have never worried about the water vapor coming off, there is a bit of a smell but all this is done in a little shed outside the main shop and we do not have any close neighbors to complain.

[gsrmmeza]

We used to evaporate. Then one of our neighbors complained to the city about the smell. Luckily no fine. However the city employee told us we needed a permit to be able to use our evaporater. The permit was not for the
fumes or smoke. It was for the odor. We never bothered to look into getting a permit. What we do now is put all our oil and rancid coolant into 55 gallon drums and have some company haul it away.

[RICHARD ZASTROW]

Back in the old days when I actually did something, we used to change the coolant (white soluble oil) every Monday (Geof, remember Monday morning coolant halitosis?).

We solved the problem by switching to a semi-synthetic (TrimSol) and recycled the coolant in-plant. Never (actually seldom) had to dispose of coolant since.

The "seldom" qualifier was an occasional clean out of a grinder that wasn't used on a regular basis.

The other important part was the use of a "sump-sucker" to pump out the sumps of the machines on a scheduled basis and refill the sumps with recycled coolant.

Dick Z

[flatfnder]

I was thinking of looking for an old swamp cooler. Maybe heat the liquid first then pump it thru the swamp cooler..........between the warmth and evaporation it might work pretty quick.

[DareBee]

We have done installations of "absorbent clay systems".
The effluent is filtered through the clay.
The clay absorbs all the baddies.
The water out the other end goes int a holding tank.
Once the tank is near full a sample is tested and if it passes it goes down the drain. If it doesn't pass it is time for new clay and filter again. The clay goes for safe disposal when it is fully impregnated.
Sounds simple but the systems we have worked with have been expensive, in most cases they pay for themselves quickly. Some of these factories are putting out 50 gallons a day just in compressor effluent (which cannot be dumped legally BTW).

[JDenyer232]

You can de-emulsify your water soluble oil coolants and dispose of the waste water. Just add 12 pounds of epsom salts to a 55 gallon drum of used coolant, let it sit for a week. All the oil floats to the top, then you seperate the water and dispose of it in a sanitary sewer, you will need to check with your local sewer company, and get any permits needed for doing this. The oil is then sent out to an incinerator. This method only works with water soluble oils, it will not work with semi-synthetics or synthetics. We tried the evaporation method but it took over 2 months to cook down a 55 gallon drum to half it's volume.