Coolant Recycling

Recycling is a way to reuse old coolant. Sooner or later, the water and antifreeze mixture in every cooling system needs to be replaced. As the corrosion-inhibiting additives are gradually used up, the coolant is less and less able to prevent corrosion. Eventually, the coolant loses its ability to protect the metal parts in the system and corrosion gets the upper hand. If left unchecked, it can lead to radiator and heater core failure, erosion of the water pump impeller, a buildup of rust and scale inside the engine and radiator, and a loss of cooling performance.

For years, most vehicle manufacturers and aftermarket antifreeze suppliers have recommended changing the coolant every two years or 30,000 miles in passenger cars and light trucks. With the arrival of extended life additive packages, the recommended replacement interval has stretched out to five years and 150,000 miles on most late model vehicles.

To take some of the guesswork out of deciding when a coolant change is due, chemical test strips are now often used to reveal the condition of the coolant. If the reserve alkalinity is gone and the coolant tests acidic, it may be overdue for a change.

REPLACE OR RECYCLE COOLANT?

When a change is due, the old coolant can either be dumped or recycled. Recycling is the environmentally friendly alternative because it keeps ethylene glycol and all the nasty stuff it picks up inside the cooling system out of the environment.

Yet, of the more than 180 million gallons of antifreeze that are sold each year in the U.S., less than 15% is currently being recycled! Ethylene glycol, which is the main ingredient in most antifreeze, almost never wears out. In the open air, it will slowly evaporate and can oxidize breaking down into water and carbon dioxide. But when mixed with water and sealed inside an air-tight cooling system, it can almost last forever.

What does not last forever is the corrosion-inhibiting additive package in the antifreeze. Nor does the coolant remain clean forever. When the additives become depleted, the coolant either needs to be replaced or replenished.

Adding a dose of chemicals to the radiator may help extend the coolant's corrosion resistance, but it won't remove all the impurities that have accumulated over the years. The coolant picks up a lot of junk from inside the cooling system as well as from make-up water that may be added to the radiator.

Though vehicle manufacturers all recommend using deionized or distilled water in a cooling system, most people use ordinary tap water. This is bad news for the coolant because ordinary water contains a lot of minerals.

Minerals form scale and react with the additives in the coolant to reduce their effectiveness. Softened water is even worse because it contains chlorides (from sodium chloride), and, as we all know, salt equals corrosion. As rust and corrosion eat away at the metal, debris enters the coolant causing it to discolor. The debris can damage the water pump seal, cause thermostats to stick and clog radiator and heater tubes. The only way to get rid of the contaminants is to replace the coolant with either new coolant or coolant that has been recycled using an OEM-approved method.

The coolant also picks up lead from soldered joints and seams in copper/brass radiators. Though most vehicles today have aluminum radiators (over 90% of new vehicles, and about 60% of all vehicles that are on the road), there are still a lot of vehicles that have copper/brass radiators and heater cores. Newer applications use lower lead content solder, but older vehicles as well as some aftermarket replacement radiators still use solder that is 92% to 98% lead. Lead does the cooling system no harm, but it creates a potential disposal problem. Lead is one of the heavy, toxic metals that we do not want in the environment. So even if your local water treatment facility allows used antifreeze to be dumped down your sanitary sewer drain, the lead will still end up in the environment.

Speaking of dumping, the worst thing anybody can do is dump used coolant down a storm sewer or onto open ground. Ethylene glycol is poisonous to humans, animals and plants. Though it will eventually break down, it can do a lot of environmental damage in the meantime especially if it seeps into ground water. A single gallon of used antifreeze can make 10,000 gallons of ground water unsafe to drink!

The U.S. Environmental Protection Agency does not consider used antifreeze to be a hazardous waste - provided it does not contain more than 5.0 parts per million of lead. The waste generator (your shop) is responsible for having the lead content of the coolant tested before it is disposed. Unless you have some way of separating used coolant from vehicles with copper/brass radiators from those with aluminum radiators, there is no way to know how much lead might be in a 55-gallon drum full of used antifreeze. Testing is the only way to know for sure. Yet many people do not. Some do not even worry about such regulations and take their chances when it comes to dumping their used antifreeze. Others try to abide by the rules and end up paying high fees to licensed hazardous waste haulers (which can cost from as little as 50 cents a gallon to $1.50 or more for antifreeze).

Recycling antifreeze solves the environmental issue by keeping lead and other contaminants out of drains and sewers. It also allows a valuable resource to be reused almost indefinitely. Ethylene glycol is made from natural gas, which is in no short supply for now. But producing it consumes energy. Recycling is more energy-efficient and lessens the demand for virgin antifreeze - which helps keep the overall price of antifreeze down.

ANTIFREEZE

A typical jug of antifreeze contains 95% ethylene glycol (EG) by weight, 2% corrosion inhibitors (silicates, phosphates and/or borates) and 3% water (a little water is added to help blend the inhibitors with the glycol). The proportions are about the same for propylene glycol (PG) antifreeze, but PG is only used in a few applications as original equipment (Audi and VW), though it is readily available in the aftermarket as a "safer" (less toxic) alternative to ordinary antifreeze.

Ethylene (or propylene) glycol is the part of the coolant that is recycled. Coolant should normally contain about 50% antifreeze by volume, but depending on how much make-up water and/or antifreeze have been added over a period of time, the mix could be almost anything. But it really doesn't matter because the coolant from a number of vehicles is combined before being treated to remove impurities and restore the additives.

COOLANT RECYCLING PROCESS

Coolant recycling can be completed a variety of ways, but the most common is to pull the old coolant out of a vehicle using some type of flush and fill machine. The old coolant is then stored in a drum with that which has been collected from other vehicles for recycling in a separate machine, by a recycler who visits repair shops, or by an off-site recycler.

Most of the shop recycling machines use some type of filtration process and chemical reaction to remove contaminants from the coolant. The coolant is pumped though a filter (sometimes more than once), and additional chemicals (flocculants) may be added to precipitate out other impurities such as emulsified oils and heavy metals. After filtering, an additive package and dye is added to restore the corrosion inhibitors of the antifreeze. The effectiveness of the cleaning process can vary from one manufacturer's equipment to another, as can the quality of the additives that are used (some meet OEM specs, others do not).

The additive package can be an issue depending on the application. The additives used in North American and Asian coolants usually differ from those used by European manufacturers. The Europeans usually specify an additive package that contains no phosphates and uses borates and low silicates. Their reason for doing so is because Europe has hard water which can react with phosphates to form calcium and magnesium sediments. Asian vehicle manufacturers, on the other hand, typically use phosphates but no borates and low or no silicates. They do not want borates in the system because they believe borates can corrode aluminum if the coolant is neglected for too long.

Using an antifreeze that does not meet the OEM requirements may void the vehicle manufacturer's warranty. Even so, filling European or Asian cooling systems with a typical North American additive package (which contains silicates, phosphates and borates) should cause no problems. And once a vehicle is out of warranty, it should make no difference what type of antifreeze is used in the cooling system as long as it provides adequate corrosion protection.

Large off-site recyclers use a more sophisticated process, either reverse osmosis or distillation to separate out the ethylene or propylene glycol from the water and contaminants. These two processes are the only ones that can remove chloride salts from the solution, and deliver a virgin glycol product. But such a high level or purity really is not necessary say those who market equipment that have OEM approval for repair shops.

A group called the American Society of Testing Materials (ASTM) has developed coolant recycling standards that assure a certain level of quality. Critics say the standards are too stringent on chloride levels, requiring less than 33 parts per million in recycled predilute antifreeze (new antifreeze must contain less than 25 ppm chlorides to meet ASTM standards). The only recycling processes that meets such standards are reverse osmosis and distillation - both of which are too expensive for small in-shop recycling applications.

A typical filtration type of coolant recycling machine costs $2,500 to $3,800 - plus supplies which include chemicals and replacement filters. A reverse osmosis or distillation machine may cost from $50,000 to hundreds of thousands of dollars. Plus, the latter require a high level of skill to operate.

ENVIRONMENTAL & ECONOMIC BENEFITS OF COOLANT RECYCLING

Though coolant recycling has been around for over a decade now, interest has waned due to environmental regulations (or threatened regulations) and the price of virgin antifreeze. There are only a few producers of antifreeze in the U.S. A plant explosion several years ago created a shortage of antifreeze, driving the price up. Supply and demand dictate the selling price of antifreeze.

When prices are low (under $4 a gallon), the economic incentive for recycling is not there. But when prices are $6 a gallon or higher, recycling makes economic sense.

Recycling helps keep ethylene glycol and heavy metals out of sewers, streams and ground water. But it also eliminates the disposal costs of paying someone to haul away your old antifreeze. It also eliminates the need to dispose of plastic jugs that new antifreeze comes in (though #2 HDPE plastic jugs themselves can be recycled if your have a plastic recycling program in your area).

COOLANT RECYCLING EQIPMENT

Coolant recycling suppliers:

Make sure recycling equipment meets applicable local regulations. California, for example, has adopted standards for recycled coolant. SO have some other states.