| Trap grease is one of the most common types of brown grease. Trap grease or sewer grease is the fats, oils, and greases that have gone down a drain at a commercial kitchen from dishwashing and food preparation. After going down the drain, trap grease is totally different from the cleaner fryer grease that is put into its own special container directly from a deep fryer. Commercial kitchens are required by law to have a grease trap or interceptor that is pumped out on a regular basis so that the grease doesn’t clog up the sewer. The mixture of water, grease, and solid waste that is pumped out of the trap is called “trap grease.” Since anything that goes down the drain enters the trap, there are also a lot of food wastes and kitchen trash in trap grease. More about the supply chain, logistics and economics of trap grease and why it is so different from fryer grease can be found in the lifecycle section. Since trap grease is so chemically degraded and contaminated by other wastes, there are very few disposal options for it, let alone ways to recover value from it. One of our collaborators at the US Department of Agriculture put it simply and bluntly: “trap grease is the foulest, ugliest, chemically most-challenging crud I have ever brought into my lab.” A typical trap for a suburban restaurant holds 2,000 gallons, is located underground, and is accessed through a manhole. Crude trap grease direct from a commercial kitchen is typically only 2-3% grease. Even though that is only a little bit in each load, it adds up quickly. The National Renewable Energy Laboratory estimates that there is about 13 lbs of grease for every person in a major city – that’s more than fryer grease. With this enormous volume, trap grease can be a costly pollutant - or with BlackGold’s technology, a valuable energy resource. |
