UCOs are oils and fats that have been used for cooking or frying in the food processing industry, restaurants, fast foods and at consumer level, in households. The classifies them as Municipal Wastes (household waste and similar commercial, industrial and institutional wastes) including separately collected fractions, under the code 20 01 25 (edible oils and fats). UCO obtained from waste water treatment plants is also considered hazardous materials with a different code: 19 08 09 (grease and oil mixture from oil/water separation containing edible oil and fats.