FOG REMOVAL
FOG Removal for Sewers, Lift Stations and Wet Wells: Grease Digested in the Pipe
FOG, short for fats, oils and grease, is the layer of cooking fat and grease that cools, congeals and sticks to the inside of sewer pipes, lift station wet wells and force mains. It arrives from restaurant kitchens, food processing plants, dairies washing down parlors and equipment, and ordinary household drains, and once it drops below body temperature it stops flowing and starts building. A grease cap and the solids settled beneath it use up dissolved oxygen, and the bacteria in that oxygen-starved water turn to sulfate instead, which is how hydrogen sulfide (H2S), the gas behind the rotten egg smell and the corrosion, gets made. Waste Water Innovations (WWI) works on the cause: DRP Accelerator carries usable oxygen to the bacteria already living in your collection system, so aerobic bacteria multiply and digest the grease and settled solids that anaerobic conditions left alone. We add no bacteria and no enzymes, and nothing of the accelerator remains once those bacteria use up its oxygen. Grease interceptors, FOG ordinances and jetting a blocked line still matter; this program handles the grease and solids that get past them and settle into the system itself.
Fats, oils and grease do not have to be jetted out. They can be eaten.
- Fats, oils and grease (FOG) enter sewer collection systems from restaurant kitchens, food processing plants, dairies, wash-down water and household drains.
- FOG cools below body temperature inside a pipe or wet well, congeals and sticks to interior walls instead of continuing to flow downstream.
- A grease cap and the settled solids beneath it consume dissolved oxygen, and bacteria in an oxygen-starved wet well strip oxygen from sulfate instead, which is how hydrogen sulfide forms.
- A severe, longstanding FOG buildup that fuses with wipes and debris into a solid mass is known as a fatberg.
- Grease interceptors and FOG discharge ordinances address grease at its source and remain standard practice regardless of any downstream treatment program.
- Sand and grit are inorganic material and are not broken down by biological treatment.
- Aerobic bacteria require usable oxygen to digest fats, oils, grease and organic sludge, and anaerobic conditions leave that material largely undisturbed.
What FOG is and where it comes from
Fats, oils and grease, FOG, enter a collection system from every kitchen and wash-down line tied into it. Restaurant fryers and dish pits are the classic source, but food processing plants, dairies rinsing down parlors and equipment, and ordinary household drains all contribute their share. Cooking oil, animal fat, dairy fat and soap scum leave a sink or floor drain as a warm liquid and travel through the line as a liquid for as long as the water around them stays warm. None of that FOG is unusual or avoidable in a system serving restaurants, food plants, dairies or homes: it is a normal part of the flow. What determines whether it becomes a problem is not how much enters the system but what happens to it once it cools.
Why FOG builds up instead of washing through
Warm grease stops behaving like a liquid as soon as it cools below body temperature. It congeals into a soft solid, and the first cool surface it meets, most often the crown or walls of a pipe or the inside of a wet well, is where it sticks. Each new slug of warm grease adds another layer on top of the last, and the buildup narrows the pipe or caps the wet well from the top down. Anaerobic conditions, the oxygen-starved conditions inside most sewer lines and wet wells, do nothing to break that layer apart, because the bacteria that could digest it are not getting the oxygen they need to do the work. Left long enough, and combined with wipes, rags and other debris that get trapped in it, that buildup can fuse into a fatberg, the extreme case of the same process happening at a much larger scale.
Why a greasy station is usually a smelly one
A grease cap does more than narrow a pipe or cover a wet well. The cap itself and the organic solids that settle beneath it consume dissolved oxygen as they slowly decompose, and a wet well that was already short on oxygen loses what little it had left. Once the water runs out of dissolved oxygen, the native bacteria still need oxygen to survive, so they strip it from sulfate instead, and the sulfide left behind becomes hydrogen sulfide (H2S), the gas responsible for the rotten egg smell and for corrosion of concrete and steel. That is why a station with a persistent grease problem is so often also the station with the persistent odor complaint. FOG buildup and H2S formation are not two separate problems with two separate causes. They both start the same way, with bacteria starving for oxygen in water that has none left to give them.
How we remove it
DRP Accelerator carries usable oxygen to the bacteria already living in your collection system. We add no bacteria and no enzymes. With that oxygen available, the aerobic bacteria already present multiply and go to work on the grease and the settled organic solids beneath it, digesting material that anaerobic conditions had left alone, with no chemical additives. Grease that had been sticking to pipe walls and capping a wet well lifts off and is broken down in place rather than scraped out and hauled to a landfill. The early weeks of treatment on a line carrying a longstanding FOG buildup can look and smell worse before they look better: grease already loosened from the walls moves through the system, and suspended solids can rise before they settle out and the line runs clean. That cleanup period is expected, and it passes as the buildup already in the pipe works its way through.
What this program does not replace
Biological treatment upstream is not a substitute for the grease controls already in place at the source. Grease interceptors and traps at restaurants, food plants and dairies still need regular pumping and inspection, and local FOG discharge ordinances still apply: nothing about dosing a collection system changes what a business upstream is required to install or maintain. A line that is already blocked solid needs to be jetted clear first; biological treatment works on grease and organic solids that are still soft enough for bacteria to digest, not on a plug that stops flow entirely. And not everything that collects in a wet well is FOG: sand, grit and other inorganic material settle out of the flow the same way solids always have, and no biological program, ours included, breaks down material that was never organic in the first place.
How the program runs
We dose DRP Accelerator as far upstream as we can reach water and power, usually a lift station wet well, a headworks channel, or a wash-down line close to the source. We start by reviewing flow data and any complaint history, calculate a dose and frequency for the line, and survey the site for the delivery point. The product arrives dry. We mix and activate it in a tank on site, and it drips into the flow continuously. Tank levels are monitored remotely, and we return to replenish on a schedule set by tank size. There is no capital purchase and nothing new for your crew to operate. You pay monthly, for as long as you want the result, and testing continues alongside the program so the change shows up in your own readings.
COMMON QUESTIONS
Straight answers.
What is FOG in wastewater?+
FOG stands for fats, oils and grease, the cooking fat, animal fat and oil that enter a collection system from restaurant kitchens, food processing plants, dairies and household drains. It stays liquid while the water around it is warm, then cools and congeals inside pipes, wet wells and force mains. Left alone, it sticks to whatever surface it meets first and keeps building from there.
Why does FOG build up in a sewer or lift station instead of washing through?+
FOG builds up because it stops behaving like a liquid as soon as it cools below body temperature and congeals into a sticky solid. It clings to pipe walls and the inside of a wet well, and each new slug of warm grease adds another layer on top of the last. Anaerobic conditions inside most collection lines do nothing to break it apart, since the bacteria that could digest it are not getting the oxygen they need.
Does FOG buildup cause hydrogen sulfide odor?+
FOG buildup and hydrogen sulfide (H2S) formation share the same root cause rather than one causing the other directly. A grease cap and the solids settled beneath it consume dissolved oxygen, and bacteria in that oxygen-starved water strip oxygen from sulfate instead, which is how H2S forms. A station with a persistent grease problem is often the same station with the persistent odor complaint, because both start with bacteria starving for oxygen.
How do you remove FOG from a collection system?+
We supply usable oxygen to the bacteria already living in your collection system with DRP Accelerator, an inorganic compound, and add no bacteria and no enzymes. With that oxygen available, aerobic bacteria multiply and digest the grease and settled organic solids that anaerobic conditions had left alone. Grease that was sticking to pipe walls lifts off and is broken down in place rather than scraped out and hauled away.
Does this replace our grease interceptors or FOG ordinance?+
Biological treatment in the collection system does not replace grease interceptors or a FOG discharge ordinance. Interceptors and traps at the source still need regular pumping and inspection, and local ordinances still apply to what businesses install and maintain. This program addresses the grease and solids that get past those controls and settle into the pipes and wet wells themselves.
What happens right after treatment starts on a greasy line?+
Expect a cleanup period on any line carrying a longstanding FOG buildup, when things can look and smell worse before they get better. Grease already loosened from pipe walls moves through the system and suspended solids can rise before they settle out. That period is expected, and it passes as the existing buildup works its way through and the line runs clean.