Grease Traps, Separators and Interceptors
What are Grease Traps?
The purpose of a grease trap is to collect and therefore reduce the amount of fats, oils and greases (FOG’s) that enter the main sewers. Grease entering the main sewer system will over time create blockages, foul odours and pest infestation. Grease traps have been in use since Victorian days and in simple terms are boxes positioned within the wastewater drain run from the sinks and appliances in a kitchen to the foul sewer system. They are design only to have kitchen wastewater flowing through them and should never have wastewater from other drainage system sources such as toilets.
They can be made from a number of different materials including Stainless Steel, Mild Steel, Plastics, Concrete and the new innovative disposable liner Renflo. Effective commercial models range from 40 litres capacity to 45000 litres and above.
They can be located above ground, below ground, inside the kitchen or outside the building.
How do they work?
They work on the basic principal that FOG’s float on water and solid particles sink. Baffles within the trap slow the inflow of wastewater from the kitchen sinks. This allows for a settlement period where the separation of oils, water and food particles within the unit. A trap on the outlet prevents FOG’s from flowing directly through the unit with the FOG’s retained within the unit along with food particles allowing clean water to flow through. The retained waste will build up over time and requires regular servicing and removal of waste for environmental disposal.
How effective are they?
The effectiveness of a grease trap depends on a number of factors including design, kitchen location, drainage systems, and size and kitchen practice. Each location and circumstance is unique. On average a single stage grease trap will retain from 50% to 90% of the FOG’s that enter it. Most commercial grease traps are single chamber units. To increase the effectiveness of a grease control and management 2 or more units can be used in tandem where each unit or chamber separates between 50% and 90% of the FOG’s that enter it.
Where are they needed?
Revised Building Regulation requires all new builds and refurbishments of hot food premises to have an effective means of grease removal on site. They are required on all sites that prepare hot food for the public or staff. Sites include the following: