LARGE AMOUNTS of FOG WILL DECREASE TREATMENT EFFICIENCY
FOG is a component of sewage that originates from the oils and fats in food, soaps and lotions.
FOG stands for Fats, Oils and Grease
WHERE DOES FOG COME FROM?
The fats and oils found in onsite wastewater treatment systems come from cooking oils, animal fat, and grease that are washed down the drain.
FOG is lighter than water, and less dense, so it floats to the top of tanks. This allows it to be trapped in pre-treatment components, such as grease traps and septic tanks, and separated from the wastewater stream.
FOG can accumulate inside pipes and clog the downstream components, so it is important to contain it early in the system. In large amounts, FOG will interfere with aerobic biological processes and cause decreased treatment efficiency.
The FOG in domestic wastewater is usually generated from the kitchen or bathroom.
- Most kitchen FOG comes from disposing of food scraps and liquids down the sink that are animal or vegetable based.
- Fat is added to the system from cooking, dishwashing and cleaning.
- Sources of bathroom FOG include lotions, hair conditioners, bath oils and moisturizers.
FAT – Animal fat is relatively easy to hold in a tank because it becomes a solid at 80 degrees F, and the temperature of wastewater is usually cooler than that.
Animal fat will eventually break down in the soil, but it takes more energy to break down than organic matter. If a system has a lot of animal fat, it will usually stay in the septic tank, and may not be observed in the FOG measurements in downstream components.
OIL – Vegetable oil typically does not solidify, and can pass through the system. Oil will rise to the surface of the tank and is easily separated. It can be broken down, but it takes more energy than the organic matter.
GREASE – Grease comes from soaps, hair products and lotions. Because it is petroleum-based, it can be toxic to a system. It does not break down, but it can be separated. Grease can build up over time, and inhibit treatment of other constituents in the wastewater.
SOME OF THE WAYS WE CAN HELP YOU DEAL WITH FOG
- Evaluate and determine the sources of FOG.
- Help you reduce the levels of FOG in your system.
- Design a system that can better handle the measured or anticipated levels
- Install an external grease interceptor.