Oil, fats and grease in cafeteria wastewater have caused problems for many years. Oil and grease in the wastewater coat the inside of the pipes. Solid food particles in the wastewater stick to the oil and grease on the inside of the pipes, which clogs the pipes in the facility. When wastewater contains a certain amount of oil and grease, oil and grease traps are used. These devices employ the principle of gravity; the lighter fats and oils immediately separate, rise to the top and remain trapped in the retention area of the tank. The heavier, clean water portion of the flow is allowed to exit and be discharged into drain lines.

Grease trap maintenance is usually performed by a facility’s maintenance staff. When it is done properly and at the right frequency, grease trap maintenance can greatly reduce the discharge of fats, oils and grease into the wastewater collection system. The required maintenance frequency for grease traps depends on the amount of fats, oils and grease a facility generates. It is a good idea for facilities to establish best management practices (BMPs) that will reduce the amounts of fats, oil and grease that are discharged into sewers. In many cases, a facility that implements BMPs will end up saving money because they end up lowering the frequency at which their grease traps require maintenance.

Follow along through this section of the EVC to learn about BMPs for the grease traps in the cafeterias on your campus.