Recycling, Reclamation, and Reuse of Used Oils
Recycling, Reclamation and Reuse of Used Oils
Used Oil
Used oil originates from refining crude oil or synthetic oil. Due to use, handling, and storage, it becomes contaminated and no longer serves its original purpose. This contamination arises from chemical impurities and physical changes that cause the oil to lose its original properties.
Used oil includes synthetic oils, transmission oil, brake oil, and other oil or grease.
Deterioration Factors
Petroleum lubricants are hydrocarbons that decompose when subjected to high temperatures, leading to oxidation or curing. A broken-down oil can produce soluble or insoluble products. Soluble products are generally acids that form stable emulsions in the presence of water and chemically attack metal surfaces.
Operating Temperature
Oil deterioration is primarily caused by vapor condensation in the atmosphere or, in some cases, leakage from oil cooling systems.
Water
Water contaminates oil due to its passage through the combustion chamber and into the housing, where it interacts with the oil and causes dilution.
Solids and Dust
Solid contaminants primarily originate from worn gaskets and seals, which allow environmental pollutants to enter the oil.
Phases of Used Oil Management
Generation
This phase involves the transformation of new oil into used oil through various transactions.
Collection
Used oil is collected and stored in a metal or plastic container placed under the motor vehicle.
Storage
Used oil is temporarily accumulated in a tank or cylinder labeled “USED OIL” and located near the oil change area.
Recycling and Reclamation of Oils
Recycling refers to processes that restore certain properties to a residue, enabling its reuse. Used oil, due to its nature and composition, can be used as a carrier medium for toxic or hazardous organic products that have been mixed with the oil to dispose of them at a low cost. Recycling used motor oil conserves this valuable natural resource and benefits the environment.
Regeneration
The most effective method for managing waste oil is regeneration and reuse. Regeneration involves deriving a new base oil from used oil for commercial purposes. Although almost all waste oils can be regenerated, the difficulty and cost make it impractical for waste oils with high contents of vegetable oils, synthetic oils, water, and solids.
A regeneration process consists of three phases:
Pretreatment: This phase aims to eliminate a significant portion of contaminants in used oil, such as water, light oil, sludge, and heavy particles. Each process employs a specific method or a combination of methods.
Regeneration: This phase removes additives, heavy metals, and asphalt sludge. It is the crucial stage for each method, as it produces a contaminant-free oil with a strong color that makes it commercially viable. A final finishing stage is necessary to improve the oil’s appearance.
Finish: The methods used in this phase depend on the intended end-use of the oil.
Processes for Regeneration
- Conventional Acid-Clay Process
- Meinke Process
- Select Propane-Hydrofinishing Process
- Select Propane Acid-Clay Process
Reuse
Reuse involves reusing goods or products. The utility can be derived by the user through improvement or restoration, without changing the product or making it suitable for a new user.
From an environmental perspective, reuse is the second step in waste reduction. The first step is reduction, and the third and final step is recycling. By contributing to reduced production of new goods that consume natural resources and energy, reuse helps improve the environment.
Reuse involves giving a new purpose to a good or product. For example, a discarded laptop can be repurposed as a chessboard.
Product reuse can be understood as giving a waste product a new life of a different nature to make it useful.
Environmental Problem
The absence of regulations and laws, lack of environmental awareness and culture, coupled with inadequate practices in handling waste oils, lead to water and soil pollution (when disposed of down the drain) and air pollution (when burned as fuel without environmental controls in brick kilns, foundries, etc.).
The concentration of metals in used oil is primarily due to the degradation of metal-organic additives in new lubricating oil, as well as wear caused by friction on moving engine parts.
If not collected properly, used motor oil causes serious environmental problems:
- When disposed of on land, used oil contains hydrocarbons that are not biodegradable, destroying humus and reducing soil fertility.
- When discharged into water bodies, either directly or through sewage, used oil has a significant capacity for environmental degradation. It creates a vapor barrier on the water’s surface, preventing oxygen absorption and potentially suffocating aquatic life. One liter of oil can pollute one million liters of water. Used oil also has a low biodegradation rate.
- When burned without proper treatment and adequate control, used oil, either alone or mixed with fuel oil, creates significant pollution problems and emits toxic substances due to the presence of lead, chlorine, phosphorus, and sulfur compounds. Five gallons of oil burned in a stove contaminated with lead and other harmful substances can pollute 1,000,000 m3 of air, equivalent to the amount of air a person breathes in three years.