Around half a million tons of grease and fat from commercial eateries and households in the UK clogs main sewerage lines. The more fat and grease waste enters the water treatment plant, the cost of treatment increases before the final discharge. The accumulated fats and grease cause congestion and damages water treatment plant equipment. If the untreated fats, oils and grease (FOG) flush into water bodies, it contaminates the environment. To prevent this contamination, strict legislatures are imposed to implement apt FOG treatment by restaurants and other eateries. Polluters are slapped with heavy fines if not correct wastewater treatment is applied. The FOG clogs internal sewerage pipes causing expensive and time-consuming repairs.
The Mechanism of FOG Interceptors
Grease trap pumps are an effective instrument in wastewater management, perhaps the most preferred choice for FOG management. This equipment has been around for hundred years and is called in different names such as grease interceptors, convertors, recovery or FOG traps. Mainly FOG traps are installed in restaurants, cafes, pubs, bars, hotels, takeaway, bakeries and schools/colleges. A grease interceptor is placed between the internal sewerage line and the main drainage system designed to collect FOG waste while allowing the water to flow.
The mechanism of FOG interceptors are based on the principal animal fat, and vegetable oil (grease) is ten to fifteen times less dense than water. Thus the FOG wastes glide over the water. The grease trap reduces the water flow, so there is adequate time to cool and segregate into three layers. The top layer of grease in the interceptor is trapped by a system of baffles that does not disturb the scum level. The clear water flows through the outlet baffle as solid waste stays at the bottom. Many grease recoveries are incorporated with filters for accumulating solid waste reducing the solid residue waste at the base.
As the solid waste and FOG accumulates over time, they can overflow through the outlet and, in some conditions, can inflow through the inlet baffles. For this purpose, the grease trap must be uncontaminated or pumped out at the regular interval. The maintenance interval depends on the amount of production and accumulated FOG and solid waste and the size of the grease converter. But it is usually between two to four weeks. The period can be extended up to eight weeks by adding biological grease treatment solution to the system. The non-pathological bacteria break down the FOFG with enzymes and nutrients, enhancing the grease trap’s performance. This biological process is known as dosing.
There are three categories of grease traps; passive hydromechanical (manual), automatic and gravity grease trap pumps. There are several maintenance steps in cleaning the grease trap. First, the technicians browse the grease surface and debris from the interceptor. A submerged vacuum machine sucks the solid waste accumulated at the base. Next, the water is flushed out, and the sides and base of the grease trap are thoroughly cleaned. The inlet and outlet baffles are checked to see if there is no debris trapped inside. The interceptor is systematically checked to make sure it is crack free. After pumping and cleaning, the cover is placed, secured and sealed.