Grease Interceptors are more commonly known as Grease Traps. They are generally used in commercial applications to capture and remove up to 90% of grease oil and fats from wastewater. Fats, oils, and grease (FOG) are common waste matter in commercial kitchens and in restaurants. They are not used on other wastewater removal areas such as from bathrooms.
Grease traps have been around since the Victorian era, but were first patented in the late 1800’s. Today, restaurants, fast food places, school cafeterias, commercial cooking facilities and more are often required by municipalities to use grease interceptors so that these materials don’t drain into the sanitary sewer system.
It is not uncommon for states to require that the grease interceptors be installed by a state-certified plumber. They need to be regularly serviced and maintained by a qualified contractor in order for them to work properly.
Since oils float, they form a scum layer on the water. This scum is hard to be rid of and can be released into the environment. High viscosity fats and cooking greases like lard will solidify when cooled and will combine with other solids to create clogged drains.
Once the drains clog, the wastewater can backup into facilities or can contaminate fresh water systems. It’s imperative to remove the FOG so that it doesn’t clog drains and create a contamination that likely contains bacteria and waste matter.
Grease traps are constructed out of hard plastic or metal, or concrete. They are commonly made of stainless steel or concrete. As wastewater flows through the system, the oils and solids are filtered out. Oil and grease will float on the water surface and accumulate behind baffles. It will be removed during the cleaning.
The baffles help to retain grease toward the upstream section of the trap. This helps to prevent the grease from moving further downstream where it can cause blockage problems in the pipes.
Some grease traps have an outlet at the end of the trap. This is used to sample the quality of the grease trap discharge. Water is discharged through the outlet pipe and continues to the grease interceptor or the sanitary sewer system.
While grease traps are very common in commercial applications, they are also very useful for septic systems because they cut down on the undigested materials.
Smaller grease interceptor units can handle about 4-8 gallons of wastewater per minute, while larger units process about 25 to 50 gallons per minute. They range from a 35 liter capacity to 45,000 and above. They can be located above ground, below, or inside or outside the building.
The size needed is determined by the monthly water usage and how many drains the kitchen has. Bigger units don’t have to be cleaned out as often. The National Plumbing Code lists drainage fixture-unit values of plumbing fixtures. The discharge rate determines the model needed.
Since it’s estimated that over half of sanitary sewer overflows are caused by grease blockages, grease traps are very useful in preventing raw sewage spills. They help keep our environment cleaner and offer a way for this waste matter to be recycled. North Carolina grease traps help to prevent clogged drains.