Traditional passive grease traps simply slow the flow of wastewater to allow it to cool and separate into 3 layers; FOG, solids and clear water. The FOG forms a “grease mat” at the top of the unit and solids either accumulate at the bottom of the unit or collect inside a strainer which is located just after the inlet. The clear water escapes via the outlet. Automatic systems, also known as AGRU’s (automatic grease removal units), perform many of the same operations as a manual grease trap. Much like a manual system the flow of wastewater is slowed to allow it to cool and separate though automatic systems almost always feature the addition of a removable strainer basket for solids collection. This means the wastewater inside the unit will mainly contain FOG with only small amounts of solid waste escaping the strainer and settling at the bottom of the unit.