Oils are simply esters made by organic acids and alcohols. According to their sources, fats are classified as animal and vegetable fats, or according to their physical condition, fats and oils. generally Oils and grease are referred together. In fact, although it is composed of the same material and the structure of the grease is the same as that of the oils, substances are added to the extra grease in order to increase its resistance to high temperatures and crushing, in part to increase its density.

The major compounds present in oils and fats are mainly: fatty acids, glycerides, phospholipids, sterols, waxes, colorants and natural antioxidants. The most important of these is fatty acids. The character of the oils depends on the fatty acids they contain and the amount of their presence. The number of known fatty acids is above 200.

Grease is a mixture of a viscous oil and a thickening agent. In greases, the fluid part is generally a synthetic fluid or a petroleum-based mineral oil. The thickener is a metallic soap. It is especially used in the industry for the smooth operation of mechanical equipment and the prevention of wear. Its most important advantages are that it does not drip and drip due to its density.

Oils and grease do not easily decompose in water and are not easily separated from their environment. Therefore, they cause problems in surface waters and aquatic environments in terms of environmental conditions. In order to prevent this, certain restrictions have been imposed on the release of oils and grease into the receiving waters and sewage systems. It is mandatory to apply pre-treatment processes in all oil and grease waste forming sectors. During pre-treatment, oil and grease must be recovered before discharge.

The authorized laboratories carry out the determination of oil and grease in wastewater within the scope of chemical analyzes. During these activities, the relevant legal regulations and standards issued by national and international organizations are followed.