Types

• There are three types of grease traps: large underground grease traps used for restaurants and high-production food facilities, smaller above-ground grease traps usually in the shape of a 50 gallon barrel, and automatic grease removal units (AGRUs) that use mechanical skimmers to collect floating grease from water surfaces. The most common of these is the smaller above-ground grease trap because it is cheaper to purchase and easier to install. However, these traps only collect about 85 percent to 90 percent of grease. The second most common type and the most cost efficient is the large underground unit which removes about 99 percent of all grease. AGRUs are not so common because they are more expensive and have less volume than underground grease traps. However, that can be more effective because they are constantly removing built-up grease, allowing for cleaner water and less chance for blockages.
  
  

How It Works

• Essentially, a grease trap is one large container with two water tanks inside. The first water tank collects all of the waste water from the drain and then cools it to room temperature. Here, the hardened grease and fats float to the top of the tank where they becomes "trapped." Meanwhile, the heavier foods and solids that have passed into the tank sink to the bottom and the rest of the water, free from most of the pollutants, continues into the second tank through a crossover pipe. This process repeats itself again in the second tank before heading out to the sewage system.
  
  

Disposal

• Once grease enters a machine it is labeled as "brown grease" and in most cases must be collected and thrown away at a specific location. Yet recycling is possible if there is a fats, oils and grease (FOG) recycling center nearby. Sometimes FOG waste is used to make bio-diesel fuel.
  
  

Problems

• As with any mechanical device, maintenance is sometimes needed to keep things running smoothly. A common problem for grease traps is when there is a blockage in one of the pipes that disperses water. These blockages usually occur in pipes leading into the grease trap, the crossover pipe dispersing the water inside the grease trap or the outgoing pipe leading to the septic system.
  
  

Lowering FOG Production

• One way to make grease traps last longer is to lower the amount of grease that's contained in them. Preventing oil spills by kitchen workers will help. Baking more foods instead of frying them also helps, and reusing leftover oil from cooking will greatly reduce the amount of grease entering the trap.