| Brown grease and trap grease are very different from fryer grease. The term “brown grease” refers to a group of fats, oils and greases with a free fatty acid number over 15%. Since free fatty acid numbers increase as the oils decrease in quality, brown greases are low-value, unwanted materials. Brown grease may have free fatty acid numbers as high as 100%. Many oils and greases fall into the category of brown grease, such as trap grease, sewer scum (residential and commercial grease that pools at wastewater treatment plants), dissolved air flotation scum, and the most rancid fryer oils. “Yellow grease” is a term for fats, oils, and greases with a free fatty acid number below 15%. Yellow greases are cleaner and a higher quality than brown greases and are often used in animal feeds. Recycled oil from a deep fryer is a common yellow grease. BlackGold’s technology is specially designed to handle brown greases and can also handle yellow greases, fresh plant oils, and animal fats. Conventional biodiesel processing technology can low levels of free fatty acids, below 15%. |
