Waste Oil Treatment

Waste oil refers to the byproducts of oil used in automobiles and other machinery. The oil used for lubrication purposes in machines is often replaced regularly since it gets contaminated from deposits of dirt, water, metals and antifreeze. If this waste oil is disposed off without any treatment, then it poses a considerable threat to the environment.

Techniques

• Many techniques are employed to treat waste oil. Some of these include acid/clay treatment, distillation processes, hydro treatment, solvent treatment, cracking, blending and compounding. To increase the purity of the treated oils, it is further refined using a combination of technologies such as decanting, settling and filtering. Recycling of waste oil is very important since in United States alone, it can annually save the energy equivalent of 7 to 12 million bbl of crude oil.

Acid-Clay Process

• Acid-clay process is one of the popular treatment methods for waste oil. In this process, the waste oil is treated with sulfuric acid. This acid reacts conversely with oxygen compounds and some sulfur- and nitrogen-based compounds to form sludge. Further refining is done in order to remove paraffinic and naphthenic hydrocarbons. Even after refining, there would be still some color and odor bodies present in the oil which is later removed by treatment with activated clay. The problem with this method is that it produces a large volume of acid--sludge that is contaminated with petroleum. Because of these disadvantages, acid-clay process is now considered uneconomical since managing the residues incurs a huge cost.

Dehydration Method

• Dehydration method is a process by which the impurities are removed through low temperature distillation. The oil thus refined is used as "cutter stock" for combining with heavy bunker oils. This process significantly reduces impurities in waste oil such as antifreeze, water and other solvents. But, the disadvantage is that this process does not reduce ash and such other residues and this limits its use in other markets.

Hydro-Treatment and Cracking

• Hydro treatment, cracking and high temperature distillation are some of the other methods employed to refine waste oil. But these methods are generally uneconomic, unsafe and are inconceivable to be used in a small scale. In hydro-treatment process, the waste oil undergoes a process that includes distillation and condensation. The resultant oil is hydro-treated for color and odor correction. The oil is treated with nascent hydrogen in the presence of a catalyst.

Solvent Treatment Methodology

• Solvent treatment methodology significantly reduces the impurities present in waste oil. The resultant refined oil is used as higher quality oil. In this process, the impurities are removed by a solvent-mixing process that does not include sulfuric acid. This solvent consists of butanol, methyl ethyl ketone and 2-propanol. The process produces a waste sludge that can removed as non-hazardous waste.