GREASE TRAPS

A grease trap is a receptacle into which wastewater containing fats, oils and greases (FOG) flows through before entering a drainage system. The receptacle is designed to intercept or “trap” the FOG while allowing clear water to escape. Grease traps work on the basis that animal fats and vegetable oils (grease) are 10 to 15 percent less dense than water and that grease won’t mix with water. Thus, fats and oils float on top of water.

When wastewater enters a grease trap, the flow rate is reduced enough so the wastewater is given enough time to cool and separate into 3 layers. The grease rises to the top inside the interceptor and is trapped using a system of baffles. Solids settle at the bottom and the separated clear water escapes under an outlet baffle. Many grease traps also have strainers for collecting solid debris, which reduces the amount of solids that settle at the bottom of the trap.

Over time, solids and grease build-up, and if left to accumulate for long enough they can start to escape through the outlet and in some circumstances, they can back-up through the inlet. For this reason, the trap must be cleaned / pumped out on a regular basis.

Maintenance and Cleaning

Accumulated grease at the top of middle compartment need to be cleaned periodically by collecting grease through the outlet provided on the grease trap body. Frequency of cleaning depends on the size of the trap and the amount of incoming grease.