What is a grease trap?

You know that you need to have a grease trap — even if you’re not sure exactly what it is.

Yes, there are other things you’d rather be doing, like focusing on food and customer service. But by learning a little about grease traps, you’ll be able to make a better purchase decision. That means you’ll get back to your real priorities sooner, while still confident that your food service facility will be in compliance.

Let’s start with the basics: A grease trap is something kitchen wastewater flows through before entering the sewer waste system. This receptacle — technically a grease interceptor — intercepts, captures, or "traps" grease. How?

Grease is 10 to 15 percent less dense than water and doesn’t mix with water. This results in grease (FOG - fats, oils grease) floating on top of water.

When kitchen wastewater flows through a grease interceptor, the grease rises to the surface inside the trap and are trapped using a system of baffles. (What is a baffle? It is a plastic wall inside a grease interceptor tank to slow down and often control the flow of water.) The captured grease fills the trap from the top down. Grease-free water exits out of the bottom of the trap into the sewer lines.

Peer into a grease trap and you’ll see a mat of grease. When this mat of grease gets deep enough, the trap must be emptied.

See how a grease interceptor like Trapzilla works!

Why do I need a grease trap?

Sewer collection systems take wastewater to a treatment plant, but there are some things they’re not designed to handle. One of those is grease.

Grease, especially grease with animal fats (think bacon grease), cools and solidifies at normal temperatures in pipes. That cooling, as well as other chemical reactions in sewer lines, causes blockages in the sewer pipes, eventually causing backups called sanitary sewer overflows.  Overflows are a significant public health risk and require specialized equipment, time and manpower to clear.

For this reason, many cities require the use of grease traps, or called grease interceptors, at locations that prepare food items to ensure grease doesn’t block sewer lines and result in sanitary sewer overflows.

In some situations, a grease interceptor can save the food service establishment money as well.  Any location with long plumbing runs to the sewer collections system, such as a mall, hospital, or restaurant inside of a large building runs the risk of blockages in internal pipes. Those blockages could lead to backups, fines and even downtime while internal plumbing is repaired.

A traditionally designed passive trap that’s not cleaned out on a timely basis will begin to leak grease into the sewer system, where it can cause blockages and sewage backups.

Types of grease interceptors

The idea behind grease traps is pretty simple, grease floats on water. So why are there so many types of grease interceptors? And how are you supposed to know which is best for your commercial kitchen? After all, you didn’t get into this business so you could spend hours trying to figure what a grease interceptor is and which one has the right features at the right price.

Thermaco has been in this industry for more 35 years. Thermaco interceptors, like the Big Dipper and Trapzilla, are in tens of thousands of commercial kitchens on all seven continents. We’ve seen practically every type of grease trap and grease interceptor there is.

Types of grease interceptors

To make sense of all the grease interceptor options, we can start with the four major types of grease interceptors.

·    Small passive Hydromechanical Grease Interceptors (HGI)

Hydromechanical grease interceptors (most often referred to as grease traps) often sit inside the kitchen underneath the sink or in the floor.  They passively trap grease over time and need to be pumped frequently, sometimes as often as every week. They may be less expensive up front, but they cost more overtime due to frequency cleaning. If not cleaned out often enough, they may become inefficient and your commercial kitchen will be out of compliance.

·    Gravity Grease Interceptors (GGI)

Gravity grease interceptors are often made out of concrete, but can be made out of steel, fiberglass, or plastic. These interceptors often have more than 500 gallons in liquid capacity but can only hold a small percentage of that capacity in grease. They are not certified to meet any efficiency standards, so cities require them to be pumped out once the grease and solids amount to 25% of the contents. Gravity grease interceptors are usually pumped every 90 days with a pump truck and specialized equipment; this can cost hundreds of dollars in maintenance each year.

GGI's can also degrade, fail and require replacement as often as every 15 years.[MT3]  These are typically buried in the ground, and replacement is an expensive process requiring heavy equipment.

·    Automatic grease/oil recovery systems such as Big Dipper

Automatic grease removal devices or recovery units offer an alternative to hydromechanical grease interceptors in kitchens. While their tanks passively intercept grease, they have an automatic, motorized mechanism for removing the grease from the tank and isolating it in a container. These interceptors must meet the same efficiency standards as a passive HGI, but must also meet an additional standard that proves they are capable of skimming the grease effectively.

They are often designed to be installed unobtrusively in your commercial kitchen, in a corner or underneath a sink. The upfront cost of these units is higher, but maintenance can be handled by the kitchen staff. That eliminates regular pumping charges and reduces operating costs.

·    High Capacity Hydromechanical Grease Interceptors such as Trapzilla

High capacity HGIs have become more popular in recent years as restaurants open in nontraditional sites without the space for a gravity grease interceptor. These interceptors take up less space and hold more much grease as a percent of their liquid capacity. Often between 70-85%, or even higher as in the case of some Trapzilla models. Most are made out of plastic or fiberglass.

Like other hydromechanicals, these interceptors must meet efficiency standards and most manufacturers test beyond the minimum standard  and test to the fail point to demonstrate the full capacity of the unit.

Grease trap efficiency and design

One factor that’s important when choosing a grease trap is efficiency. More efficient grease traps can remove and store more grease from your kitchen waste water. That means a much lower chance of blockages and overflows. Higher grease storage capacity keeps your interceptor functioning properly and makes it simpler and less expensive to maintain.

Grease traps have been around since the 1880s, and many grease interceptors still use the same basic design as those early models. But design and engineering innovations in more recent years have allowed companies to develop new designs that are more efficient, longer lasting and easier to use and maintain.

Early grease traps were made of concrete, which tends to degrade over time and eventually fails. Modern grease interceptors come in a variety of materials, including concrete, steel, fiberglass and plastic. The material used in grease interceptors affects their cost, their weight, how easy or difficult they are to install or move, and how often they must be replaced.

Concrete can degrade, as can metal in some circumstances. Fiberglass tends to crack if moved. Modern plastics are lightweight and highly durable, and can make for long-lasting, highly efficient grease traps.

Compact, highly efficient grease interceptors, such as Thermaco's Trapzilla systems, are engineered so they never lose efficiency. They can hold upwards of 90 percent of their volume in grease before they must be cleaned out.

Automatic grease interceptor efficiency

Big Dipper systems work a bit differently than traditional grease traps. In them, grease is skimmed out automatically on a pre-programmed schedule based on the amount of grease produced by the kitchen.

Automation means employees don't have to check grease levels. The grease in these automatic systems accumulates in a separate chamber and is simply disposed of, usually by putting it into a grease rendering barrel.

While more expensive to purchase, automatic grease interceptors give food service establishments control over their grease waste management and save them from paying service companies weekly or monthly fees for emptying the grease interceptor.

How do I start?

Now that you understand what a grease trap is, how they work and the different types of grease interceptors available on the market, are you ready to figure out exactly which grease interceptor will work best for you?

We’ve got an easy three-step process:

1.     Use Thermaco’s easy online sizing calculator and proposal request system to determine the specifications for your commercial kitchen and receive a free proposal. We can also help with any regulatory issues and other considerations.

2.     Schedule installation by a qualified local contractor. If you don’t already have a contractor selected, we can help you find one[MT6] .

3.     After your grease interceptor is installed, go back to focusing on what matters most to you — the customer experience — knowing your commercial kitchen is in compliance with local water and sewer regulations.

Not quite ready yet? We understand.

Maybe you want more information on how to select the best grease trap for your food service facility. Click here for a free guide that walks you through, step-by-step, the pros and cons for each type of grease interceptor and how to choose the one that will work best for you.

Or maybe you have other questions about grease interceptors. Here are some additional resources to help.

·      Replacing a grease trap? Here’s a few factors to consider

·      How to calculate the total cost of ownership of a grease trap

·      Grease interceptor design: a life-or- death decision

·      Why concrete interceptors ought to be left in the history books

By understanding what a grease trap is and how different types of grease interceptors work, you’ve taken the first step in making the best possible decision for your commercial kitchen. ‘

Once it comes time to purchase and install an interceptor, you’ll be confident you’re making the right choice. You won’t have to worry about overflows, surprise expenses or other grease interceptor traps. Instead, you’ll be focused on creating a great customer experience.

Feel free to contact Thermaco directly for specific assistance on choosing the ideal grease interceptor for your commercial or institutional foodservice operation.