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
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 sanitary 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.