From Arne Hendriks on Flickr
If you’ve spent any time in Food Grease Trapper blog archives, it should come as no surprise to you when we say “you shouldn’t dump grease down the drain.” However, some people ask why, and aren’t satisfied with the short answers of “your restaurant is required to have one, it can clog your pipes, and damage your sewers water treatment plants.” For those people who want the “why” behind it, we’ve written this blog to look at the science behind horrible things happening to your building and sewer when you don’t have a grease trap installed.
Part One: Fluid Dynamics, Warm Grease, and Cold Pipes
We’ve talked a lot about how FOG (Fat, Oil, and Grease) can affect your pipes. The first stage of this FOG is making it into your wastewater, usually one of three ways: being washed off dirty utensils and cookware, scraped off of plates into the garbage disposal, and poured down the drain directly (such as with fryer oil) or indirectly (such as the fats and oils in milk when dumping cream).
When Warm FOG Cools
With the case of food waste or warm oil, these FOGs tend to be pretty easy-going at room temperature, and even more so when they hit the sinks and dishwashers (and the reason it’s really important to clean kitchen utensils) as the turn from solids to liquids. As the grease hits the pipes and starts to cool, it also starts to harden. While you won’t have a chemical reaction in the sewers (see below), you will have water restriction on your business’s pipes, leading to backups in your wastewater systems.
Part Two: Chemistry of Grease Breakdown
When these FOGs hit the sewers, the true chemistry begins. These grease, fats, and oils break down into simpler compounds, specifically fatty acids and glycerol. These fatty acids combine with calcium in the sewers (usually leeched from stone or concrete, or from “hard water” sources) and form these hardened deposits… which are basically soap. Breaking it down:
FOGS ⟶ Fatty Acids + Glycerol
Fatty Acids + Calcium ⟶ Hardened Soap Deposits
It’s ironic, by glycerol is most often a byproduct of soap making, instead of the other way around! Want more info on how this works? Check out this report by researchers from North Carolina State University.
Creation of a Sewer Blockage or Overflow
Now, these deposits tend to adhere to two things: surfaces and each other. In older sewers, these can hang from sewer ceilings like stalactites, or extreme cases form with debris into massive “fatbergs.” Check out our two blogs: Fatberg Ahoy! How Could They Happen? and Fatbergs: A United States Without Grease Traps for more details on those. Both can contribute to sewer backups, overflows, and full blockages.
Isn’t science wonderful? Armed with this new knowledge, make sure to take measures to safeguard your kitchen and avoid getting in trouble with your local utilities. Food Grease Trappers are experts in the field of grease trap service and maintenance and waste vegetable oil (WVO) collections for the foodservice industry, and we have been doing so for over 20 years. If you need assistance with your grease trap in New England, make sure to contact us.
