Antifreeze purification and recycling using membrane filtration and ion exchange

Remco Engineering has designed and built deionization and membrane filtration systems since 1987. We have built systems for water treatment, waste water treatment, metal recovery, hog farm wasted, and glycol recycling. We decided to build our own system for glycol recycling several years after we built our first one for another recycling company. We had gotten many inquires each year from recyclers out of our area and through lengthy discussions, discovered what the major problems most recyclers were encountering. We decided to build a system for our own use and to resell that would maximize our up time and minimize labor requirements. As this market gets more competitive, the profit per unit time must go up to make any money in this business.

The problems as we see them are as follows:

Most recyclers do not understand the chemistry of the coolant/antifreeze system.
Most recyclers are trying to recycle solution in place with mobile van systems.
Most customers do not know the difference between a good product and a bad product.
In-house systems only recycle small batches at a time and this drives costs up and quality down.
Most system being used now use multiple cartridge filters and only filter down to 1 micron. The "recycling" is filtering and addition of more inhibitor, not a true recycling when everything is removed and you start fresh.

Our system purifies the ethylene glycol solution to cleaner than new "antifreeze grade" ethylene glycol specifications. This is a multistep, automated and continuous process that can be computer monitored and controlled.

We were asked to design an antifreeze recycling system for recycler on the East Coast of the USA. The system was to take the raw material, returned from the various sources (car dealers, garages, etc.) and turn it into pure 50% glycol/water mixture. We decided to provide a system using prefiltration, oil/water separation and Nanofiltration for the final product. Due to cost considerations, an ultrafilter prefilter (recommended) was not a part of the system.

The antifreeze was collected and delivered in 55-gallon drums. The drums were pumped into a 5000 gallon holding tank where the oil was allowed to separate from the glycol mixture. A feed from this tank was filtered into a 500 gallon tank that fed the RO system.

The RO feed was pH adjusted to reduce precipitation and clogging of the RO membranes. The reject was recycled back to the 500 gallon tank to obtain a 90-95% recovery rate. The reject stream was filter again to catch any precipitants. Special membranes were used to reduce the time between cleaning. With proper cleaning procedures, the system could be returned to full production. A daily cleaning cycle was required to maximize production.

Results -

The system produced a clear, colorless 47%-48% glycol solution with a recovery rate of over 95%. Total Dissolved Solids (TDS) is near zero with no metals in the solution. With post treatment of the concentrated reject and reprocessing of the purified solution, the recovery could run over 98%. The system ran between 7 and 14 gallons per minute over a 12 hour working day. Cleaning took an hour at the end of the day. The system would start at 14 gpm and slowly reduce the flow to 7 gpm and hold that for most of the day. It was felt that an Ultrafilter in front of the RO would allow a much higher production rate. The RO flow reduction was easily reversible and thought to be due to oil passing through the minimal pretreatment. Permanent fouling by what is thought to be lead, limited the useful life (30% of original flow) of the system to about 13000 gallons per 8" module.

Remco Engineering Automated Coolant/antifreeze recycling systems for 1-20 gpm flow rates-

1. We only sell fully automated systems. Less support work for us and much less downtime for you. Automations reduces your labor costs. There is no operator except for cleaning cycles.

2. Product is better that cosmetic grade glycol. Basically, water white with very low dissolved solids after the ion exchange component.

3. General Process -
· Separation tank, settles nuts and bolts down and free oil up (24 hr holding). Customer supplied.
· Pump and prefilter – Bag Filter
· Ultrafilter (removes suspended oil and suspended solids)->
· Nanofilter (removes Dye, hardness and sulfates- water white product)->
· Carbon (removes organics such as esters and gasoline residuals)->
· Ion exchange (removes salts such as chlorides)
· Product is water white with dissolved solids less than 10 ppm.
· Recovery up to 95% of material

4. Cost per gallon to operate is about $0.26 USD with estimates on additive. Less expensive with lower overhead and higher flow rates. This was calculated at 10500 gallons per month in 2003.

5. Systems are designed to run 24/7 with about 1.5 hrs/day cleaning. A 1 gpm system will recycle about 500,000 gallons per year.

6. Waste hauling is a factor. 2-10,000 gallons per month of waste water from ion exchange regeneration. If your sanitary district won't allow high TDS (5000 ppm salt) discharges, you will have to haul the waste.

7. Space - Up to 3 gpm in a 120 sq/ft area. All mounted on one skid with tanks mounted next to system. 10-gpm system adds about 4 meters on all sides.

8. Limits - The nanofilter is limiting. This runs at high pressure and low effective recovery so scaling up a system usually requires increasing the size of the nanofilter. The ion exchange would be regenerated more often and the carbon would be exchanged sooner.

9. Cost. A 3 gpm would run (estimated, not calculated) around 120K. Includes Computer monitor and control so we can help you run it. Add another 15K to make everything but the Nano capable of running a 10gpm system. Size/price breaks at about 4 gpm and 12 gpm

Who we are:
· We've been in business since 1987.
· We make automated water and wastewater treatment systems.

What else have we built?
· A 100-gpm water treatment system for the US Embassy in Tajikistan,
· A 50-gpm groundwater remediation system for Hanford nuclear site,
· A well water treatment system for a high school in Minnesota,
· Heavy metals recovery for a recycler in Cali, Columbia,
· Glycol recovery for a recycler in Pennsylvania,
· 180-gpm system for metal recovery and waste treatment for a printed circuit facility in China.

What are the advantages of our antifreeze recycling system?
· If you are doing this manually, it will save you 95% of your labor.
· If you all ready have a nanofilter system, you know how much cleaning you have to do now. This system greatly reduces the cleaning of the nano filter by moving it forward to the ultrafilter which has a much higher flow rate so the overall production is not reduced by the downtime of the nano.
· 1 person can process 400,000+ gallons per month (10 gpm system).
· It will run itself, you just have to fill a tank on one end and remove glycol from the other. You will have to clean periodically.
· It will automatically shut down and tell you if there is a problem.
· We monitor pressures, flow, levels and conductivity and can remotely connect to your system to read the graphs and tell you what you need to do to correct the system. We can also train new operators remotely. See www.remco.com/scada.htm

Click here to see a drawing of a complete system.