Used, but not useless

This is a hazchem feature, yes, but not in the sense that you would expect. GAVIN MYERS takes you for a slightly different ride, on this slippery hazchem slide.

We know the series of advertisements well: “One litre of used oil can contaminate one million litres of water”, was the basic message. Being a mechanically-minded automotive kind of guy, the message and the images have stuck with me. Walking into a workshop, dumpsite, or anywhere used oil has not been disposed of in a proper manner, brings my mind back to those same adverts – and I get rather upset.

Not because I am an environmentalist of sorts, but merely because, if you do the maths, a few carelessly disposed-of oil changes a week by a single workshop can have a disastrous effect. There’s also the fact that motor oil can be re-refined and used over and over again in an ongoing cycle. And, in this day and age of changing climates, dwindling resources and the subsequent push to recycle most used products, it does make absolute sense to recycle our used oil as well.

The National Recycling Forum (NRF) states that, in South Africa, approximately 80 million litres of used oil is collected annually for recycling, although the amount of used oil generated every year is said to be closer to 120 million litres. It must be noted that there is a difference between “used” oil and “waste” oil.

In general, the term “used oil” refers to oil – whether petroleum or synthetic – that is unsuitable for its original purpose due to the presence of contaminants (dirt, metals, water, or chemicals) or loss of its original properties following use. This encompasses engine, gearbox and hydraulic oils, and can extend to grades 1, 2, 3 and 4 fuel oils.

The term “waste oil” refers to oil that has been either mixed with hazardous waste (such as chemicals), or disposed of in a manner other than recycling. This definition also extends to oil spills and sludge. Used oil is considered hazardous waste, the disposal of which into landfills is actually outlawed by the National Environmental Management Waste Act, no. 59 of 2008.

It is probably fair to assume that most modern-day workshops recycle their used oil. But what actually happens to it once it is removed from the vehicle? The ROSE (Recycling Oil Saves the Environment) Foundation – the chaps responsible for those thought-provoking ads – manages the collection, storage and recycling of used oils in South Africa, while the National Oil Recycling Association of South Africa (NORA-SA) was formed to create a body for the environmental management of the collection, transportation, storage, recycling and utilisation of used oil. Primarily through these two institutions, used oil is collected and recycled.

The ROSE Foundation, for example, supplies 1 000-litre mini-tanks for on-site disposal of oil. When these are full, a tanker collects the product, which is pumped directly into the tank using sealed couplings to avoid spillage or leakage. Once the old oil is collected (or disposed of at an oil collection facility located at most municipal dumps) it is stored in used oil storage depots and bulking points. Bulk transport is then used to take it to environmentally-approved processors, where there are various options for disposal.

Most oil is recycled for use as heating/industrial burner fuels, rather than being converted back into base oil. Re-refining oil is very energy intensive, however it is becoming more prevalent due to dwindling natural resources.

The re-use of oil as industrial fuels takes place on three levels. The untreated used oil – even with all its harmful components – can provide a cheap and effective fuel, however this will result in the release of heavy metals and other harmful by-products of combustion into the atmosphere.

Simple processing can remove solids and water and a small amount of heavy metal contaminants, but the fuel will still contain significant concentrations of dissolved metals. Complex reprocessing can, however, produce a very useful low sulphur industrial fuel, which is still cost effective and doesn’t result in harmful gas emissions.

One of the most environmentally acceptable ways to dispose of used oil at the moment is as fuel for cement and lime kilns. The advantage is that contaminants or toxic organic molecules in the used oil are converted into carbon dioxide and water at temperatures exceeding
1 100° C (1 300° C in the cement kiln), with no harmful by-products. With the cement kiln, some contaminants in the used oil can be captured, milled and blended with the gypsum to produce cement.

Interestingly, used oil can also be processed into blasting explosives.

But, says the ROSE Foundation, by far the best way to recover the value associated with used oil is to re-refine it. This, however, requires large volumes of used oil to justify a full, modern re-refinery – which South Africa does not currently have.

Another problem is that users of lubricants require high performance oils that meet specifications set by OEMs, and there is the perception that re-refined base oils cannot meet these requirements. However, it is widely accepted within the industry that these re-refined oils have the same specifications as virgin oils.

So, next time you’re confronted with used oil – think of those advertisements and remember all the possibilities for re-using it.