How Does Your Restaurant Grease Trap Work?

Do you have a commercial kitchen? The local authorities require you to install a grease trap, for capturing all the grease coming in with the water that pours through the sink.

This trap is a specialized tank that is installed between the kitchen plumbing and the sewerage systems to capture and hold fats, oils, and greases from the kitchen.

When waste water flows from the sink, that is, the water used to wash dishes and foods, it contains small food materials. While installing a strainer on the sink can keep the food materials from escaping, it will not capture the liquid oil.

However, this liquid oil must not be allowed to get into the municipal sewerage system. Once it cools down, it solidifies, and clogs the pipes. This can cause costly pipe repairs, and make the effluent to start backing up to the streets, posing a serious health hazard.

But have you ever wondered how a grease tank works? It is not a complex system, but you still require a grease trap service to install, clean, and repair it.

1. All the water from the kitchen sink passes through the FOG tank

When you are washing cooking items, utensils and fryers, the water from the kitchen plumbing system goes down into the FOG tank.

This is the way it should be, and that is why only professionals should install the FOG tank, so that no water by-passes it.

Also, it should never be connected to the toilet water system. That can go straight to the sewerage, or to the septic tank.

When the waste water from the kitchen gets to the grease tank, a few things happen. These are:

• The solid materials, such as food, and soil in the water settle at the bottom, similar to decantation
• The fats, oils, and grease float on the water
• The water goes out to the sewerage system

The buildup of the FOG continues and when it gets to about ¾ of the tank, it needs to be emptied.

2. The FOG trap has two compartments

If you look inside the grease tank, you will see that it has two compartments. The inlet is in the first compartment, and the outlet is in the second one.

When the water from the kitchen comes in, it gets into the first compartment. It stays there, as the solid materials settle at the bottom, and the grease floats on top. This makes sense too, since grease has lower density than water.

So, as more water keeps coming from the kitchen into the first compartment, the level keeps rising, until it is high enough to pass over to the second compartment. Here, the level of the water (minus greases or solids) keeps rising, until it gets to the outlet. It flows out to the sewerage system.

As you might be able to deduce, there will always be some water in both tanks. When the grease tank company comes to empty the grease, they will open the first compartment. That is where the grease is.

However, they will also give the entire tank a thorough check to ensure everything is working as expected, and if there are any anomalies, they will do the repairs.

3. The parts that make the grease tank work effectively

There are other accessories inside the tank, and all of them must work correctly for the tank to perform as expected.

Apart from the lids, and the tank itself, the other accessories are:

Inlet pipe – This is the pipe that comes from the kitchen plumbing, which brings waste water from the sinks.

Outlet pipe – Connected to the second compartment of the grease tank, this pipe takes water out to the sewerage system.

Baffles – These are barriers that are usually made of metal, and their work is to slow down the flow of the waste water. This gives the grease time to separate from the water.

Flow rate controller – As its name suggests, this device controls the flow of water when it is entering the trap. The slowing of the flow speed enables the water to settle down so that the elements can separate.

There are other parts such as the vents, and it may also have one or two manways.  

4. Grease trap needs to be emptied in good time

For the grease tank to serve your needs properly, it needs regular emptying and cleaning. Usually, this takes place at least once every three months. However, the frequency may vary depending on the size of the tank, and your business.

If you let the tank stay too long with the grease, it can overfill and since the FOG floats, it could find its way into the second compartment. Eventually, it would find its way to the outlet, and either clog it, or flow out to the sewerage.

Letting the tank stay too long before it is emptied my get the grease to push back against the lid. It can spill over to the surrounding, and this can spread microbes to your food. If this happens, you could be fined heavily by the local authorities. You may even have to close your business for some time until the problem is rectified.

Please make sure that you contract a professional company like Grand Natural to clean your grease trap. They will check the condition of certain accessories such as the gasket, and if it is worn out, they will replace. The baffles, outlet and inlet pipes as well as the other parts also need to be checked.

Wrapping it up

Once installed, the grease tank runs pretty well, requiring zero to minimal human interference. However, you need to let your kitchen staff know that they cannot pour liquid oil down the sinks.

You also need to install strainers in all of your sinks so that the food materials are kept out of the grease tank. This is going to help you save money since the FOG interceptor will not fill up too fast. Therefore, you will not need to have it emptied too soon.

It is good to arm yourself with information about how a grease interceptor works. That way, you can know soon enough when something goes wrong and call the company that installed, and maintains it for you.