Grease Trap Interceptors for Sewer & Health Systems

Grease that collects in sewers and treatment plants is a problem shared by all wastewater treatment and collection system operators. In the past, engineers and operators designed systems to remove grease after it got to the plant. In the meantime; however, the grease would clog pipes, create huge grease balls, and damage equipment.

Construction of most sewer lines is in the form of metal or plastic pipe. These materials are oleophilic, which is to say they "love oil." Grease and oils adhere to surfaces that are oleophilic, where they gradually build up and begin to restrict flows. Another problem is that this grease coating begins to capture solids like rice, cole slaw and toilet paper over time. This action drastically compromises free flow of effluent coming out of a commercial user. Thus, blockages form, ultimately resulting in sewage back-ups and flooding. With no grease trap removal system, woe is the user of the collection system just upstream of the clog!

Another problem site along the collection system involves lift stations. Lift stations collect and pump sewage up to a higher elevation along the sewer line, thus enabling gravity to allow the sewage to flow downhill again. In lift stations, there may be three or more floats to trigger the operation of pumps (there are generally two pumps in a lift station: a primary one and one that will activate during high flow periods or emergencies) if the static sewage level gets too high. As grease floats on water, the float balls constantly expose themselves to a static grease layer. Again, the metal/PVC floats are oleophilic. This grease adheres to the float. Solids present in the lift station then adhere to the grease, causing the float's size and geometry to change. Hand-sized float switches frequently "grow" to the size of basketballs! Therefore, the floats often cannot trigger the pumps when they need to, and back-ups are a result. Grease clogging in the pumps is another problem all its own.

Today, wastewater treatment plant operators are lowering operating costs and making their plants significantly more efficient by eliminating grease from influent before it reaches the plant. Requiring system users to install automatic grease interceptor removal units or properly sized and maintained manual interceptors is doing this. Most importantly, operators have designed ongoing, comprehensive pretreatment programs funded by system users known to discharge large amounts of kitchen wastewater containing fats, oil and grease (FOG).