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Maintaining and Cleaning a Grease Trap Properly

February 8, 2023

Maintaining and cleaning a grease trap correctly is essential in keeping them unclogged. Such would not only interfere with your restaurant operations, but also cause a municipal sewage blockage or backup, drawing the ire of environmental authorities—and the consequent fines and sanctions and having to hire a sewage disposal service. 

This article entry provides essential information about maintaining grease traps properly. Q&As include: 

1. What is a grease trap? 
2. How does a grease trap work?
3. What are the different kinds of grease traps?
4. What is a manual grease trap?
5. What is an automatic grease trap?
6. What is a gravity grease trap?
7. How can grease traps malfunction?
8. Can you add chemicals to degrease a trap and clear FOG faster?
9. What is line-jetting?
10. Where can you find help maintaining grease traps properly?

1. What is a grease trap? 

A grease trap is a plumbing fixture that exploits the convenient truth that FOG does not mix with water. In this instance, “FOG” isn’t referring to a thick cloud of tiny water droplets suspended at or near the earth’s surface.

Instead, FOG is the acronym for fats, oils, and grease in restaurants and commercial kitchens. Each is of which is significantly less dense than water, causing it to float to the top where it can be easily removed—”easily” being a relative adverb here (see source).

2. How does a grease trap work?

Grease traps are designed to slow the flow of wastewater and cool it. It then causes the FOG to come out of suspension in the water, where it can be skimmed: similar to removing fat from the top of (new) chicken soup. Meanwhile, solids (e.g., small bits of food debris) sink to the bottom, where they can be retrieved and disposed of as solid kitchen waste. 

(N.B. You cannot install a grease trap downstream from an in-sink “garbage disposal” unit. The solids would be too large, and the FOG would cling to them instead of floating.)

3. What are the different kinds of grease traps?

There are three main types of grease traps (see source):

  1. Manual (see Q.4)
  2. Automatic (see Q.5)
  3. Gravity (See Q.6)

4. What is a manual grease trap?

Manual or “passive hydromechanical” grease traps have been ubiquitous in restaurants and commercial kitchens for the last century. Typically made of stainless steel or plastic, these traps must be manually cleaned regularly. Not your typical DIY job, especially if you have other distractions like hiring kitchen and waitstaff, developing menus, and creating work schedules. (You need to get expert help.)

5. What is an automatic grease trap? 

Automatic grease traps are known as “automatic grease removal units” or “AGRUs” among grease-trap insiders. AGRUs do the same thing as their manual counterparts; only they have a motorized mechanism for removing the grease from the tank and isolating it in a container. 

The container can be emptied daily and made available for scheduled collection by a hazardous waste disposal service. In contrast, a manual grease trap must be emptied and cleaned by a technician every two-to-four weeks. Thus, while the upfront cost of an AGRU is more, it can be a maintenance money-saver over time. 

 6. What is a gravity grease trap?

These traps are also called “gravity grease interceptors” or “GGI’s,” which are typically 500-gallon concrete vessels buried in a restaurant’s backyard. Government regulations dictate that they be pumped out whenever the proportion of grease reaches 25 percent. GGIs are seldom practical for kitchens that produce limited amounts of fats and oils as they are located on small sites (see source). If your restaurant sits on a large parcel of land, you’ll require the services of a pump truck and its specialized equipment about every 90 days. Get expert help

7. How can grease traps malfunction?

Whether manual or automatic, maintaining grease traps properly is essential. What could occur if a grease trap isn’t properly maintained? If trapped and FOG isn’t removed from a grease trap when needed, it can thicken and begin to ooze from the trap’s outlet tee. Also, if the pipes downstream from the grease trap start to clog with FOG sludge, the grease trap can be overwhelmed. This will cause your kitchen to flood with wastewater, leading to the shutdown of your restaurant by local sanitary authorities. 

8. Can you add chemicals to degrease a trap and clear FOG faster?

You so don’t want to do that! 

Like our intestines, grease traps depend on bacteria to help break down organic wastes. Adding bleach, emulsifiers, enzymes, or any other chemical or degreaser cleaner to a grease trap can kill the natural bacteria dining on the FOG therein. 

Also, many of these substances don’t break down FOG, only separate it from the wastewater. This can lead to it flowing downstream and clogging pipes, causing odors, performing other expensive unfortunate charges, and hiring a wastewater treatment service. If your grease trap misbehaves, don’t let someone turn it into a junior-high science experiment (see source).see source ). Maintaining grease traps properly requires that you get expert help.

9. What is line-jetting?

If you suspect the plumbing downstream from your restaurant grease trap is clogged with FOG, line-jetting or sewer line jetting is an effective way to clear the blockage. A highly-pressurized hose is sent down the pipework to blast away clogs and wash them down the line and into the municipal sewer. You can find out more here.  

10. Where can you find help maintaining grease traps properly?

Restaurants and commercial kitchens require grease traps to catch and separate FOG from any wastewater destined to municipal sewer lines. Not maintaining grease traps properly and attempting to use heavy-duty degreasers can result in foul odors, blockages, or overflow. Kitchen calamities will severely hinder your operations or even cause a temporary shutdown, laying waste to your restaurant’s reputation and brand image. Expert grease trap cleaning and pumping is your best insurance against such calamities, and you can find your best local resource here at Hazardous Waste Experts.   

Disposal of hazardous waste doesn’t have to be painful.