Grease traps have become a major part of any catering and foodservice set-up. Legislation has clamped down on the effects that FOG laden waste water has on the sewer system and the environment and therefore buying the right grease trap has never been more important. Here we discuss exactly what grease traps are in all their forms, how they prevent dreaded fatbergs and how to make sure you buy the right type and size for your business.
What is a Grease Trap?
A grease trap is a small tank that is installed between the wastewater outlet of your kitchen and the sewerage system. It works by allowing water to flow through while trapping FOG (fat, oil and grease) in the tank. This separation prevents FOG from entering the sewerage system where it can cause blockages (a.k.a fatbergs).
There are two main types of grease traps; passive and automatic or GRU (grease removal unit). Passive grease traps are the most common type and rely on gravity to separate FOG from water. Automatic grease traps use mechanical means such as pumps or filters to remove unwanted cooking oils, fats and grease from waste water. GRUs are the most effective type of grease trap as they combine passive and active separation methods.
How Do Passive Grease Traps Work?
Passive grease traps work by using gravity to separate FOG from water. The tank is usually installed below floor level and has a inlet and outlet pipe. As waste water enters the tank, it slows down and starts to cool. This cooling process causes FOG to start solidifying and rise to the top of the tank while clear water drains out through the outlet pipe.
The solidified FOG forms a layer on top of the tank which acts as a barrier, trapping any more incoming FOG. Grease traps need to be cleaned regularly (depending on usage) in order to remove this.
What Are the Benefits of Passive Grease Traps?
Passive stainless steel grease traps have a number of benefits:
- They are relatively low cost to install and maintain.
- They don’t require any external power source to operate.
- They have a smaller footprint so can be easily installed in most commercial kitchens.
Passive grease traps are common in commercial kitchens as they offer an effective solution at a low cost. If you are looking to install a passive grease trap, make sure you choose the right size for your business. Grease traps come in a range of sizes so it’s important to choose one that is big enough for your needs.
What Are the Disadvantages of Passive Grease Traps?
Whilst passive grease traps are a low cost option, they do have some disadvantages:
- They require regular cleaning in order to prevent FOG from building up and overflowing into the sewerage system.
- They can be difficult to clean if they are not installed in an easily accessible location.
- They can be susceptible to freezing in cold weather conditions.
If you are considering a passive grease trap for your business, make sure you take these disadvantages into account.
Regular cleaning is essential to preventing blockages and keeping your grease trap working effectively. If your grease trap is difficult to access, this can make cleaning more difficult and time consuming.
What Are Automatic Grease Traps?
Automatic grease traps are a more recent innovation and use mechanical means to remove FOG from waste water. The most common type of automatic grease trap is a GRU or Grease Recovery Unit. Bio-dosing units such as the GreasePak are also a popular choice and work by adding bacteria to the tank which breaks down FOG into water and carbon dioxide. Bio-dosing units are a common variation to standard of automatic grease trap and are highly regarded by most businesses.
Other types of automatic grease traps use filters or pumps to remove FOG from waste water.
What Are the Benefits of Automatic Grease Traps?
Automatic grease traps and bio-dosing units have a number of benefits over passive units:
- They require less frequent cleaning as FOG is broken down by bacteria.
- Easier to clean as FOG is separated out into a separate tank which can be easily disconnected and disposed of responsibly.
- They are more effective at preventing blockages as they remove FOG before it has a chance to solidify.
- They are less susceptible to freezing in cold weather conditions.
If you are considering an automatic grease trap for your business, make sure you choose one that is appropriate for your needs. Automatic grease traps come in a range of sizes and with different features, so it’s important to find one that will work well for your business.
What Are the Disadvantages of Automatic Grease Traps?
Automatic grease traps have some disadvantages that should be considered before making a purchase:
- They require a larger initial investment as they are more expensive than passive units.
- They require regular maintenance in order to keep them working effectively.
- Bio-dosing systems will have additional expense of replacement chemicals.
- They can be susceptible to breakdowns if not maintained properly.
Areas to Consider When Buying a Grease Trap
- The number of sinks used on the premises and the volume. Use a quick formula to approximate the volume of each - calculate volume of a single sink be multiplying the height, width and depth. Multiply this value by 0.003 to find the GPM (gallon per minute). If you have multiple sinks multiple the volume of a single sink by the total number of sinks before multiplying by 0.003.
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- The approximate usage of each sink. The more FOG that the kitchen produces the larger the grease trap needed.
The number of sinks in use and the usage of each sink will directly affect the size of the grease trap required. If the intended grease interceptor is too small then it will not work effectively, wastewater may flow too quickly taking FOG out into the sewer system before the grease trap has had time to do its job.
- The cost of installation and the availability of parts should any replacement be required. The initial outlay is only part of the total outlay. Always consider the cost of repair when required, cleaning, chemicals if needed and responsible disposal of waste materials and FOG.
Read more about The True Cost of a Grease Trap
By understanding the importance of grease traps and the consequences of dismissing them or installing the wrong size prior to purchase you can guarantee that your kitchen is fighting the fatbergs as quickly and efficiently as possible.