Understanding One of the Biggest Challenges in Modern Wastewater Systems
- What Fats, Oils and Grease (FOG) are.
- Why FOG is one of the leading causes of sewer blockages.
- How FOG affects grease traps, drains, pump stations and treatment plants.
- Why traditional cleaning methods often provide only temporary relief.
- How FatDigest® supports long-term biological FOG management.
7.1 What Is FOG?
FOG is the collective term used for Fats, Oils and Grease generated during food preparation, cooking and food processing.
Every day, restaurants, hotels, shopping centres, hospitals, schools, food factories, butcheries, bakeries and commercial kitchens produce significant quantities of FOG.
While hot cooking oil may appear harmless as it flows down a drain, it begins to cool almost immediately. As it cools, it thickens. Eventually it solidifies.
Once this happens, it starts trapping food particles, paper, hair and other debris, gradually forming stubborn deposits inside pipes and drains. These deposits continue growing until they restrict the flow of wastewater or completely block the pipeline.
7.2 Why Is FOG Such a Serious Problem?
Unlike many other forms of organic waste, FOG does not readily mix with water. Instead, it floats, coats surfaces and clings to pipe walls. Over time it forms thick layers that become increasingly difficult to remove.
The consequences can be serious:
- Blocked drains and sewer lines.
- Overflowing grease traps.
- Pump station failures.
- Unpleasant odours.
- Increased maintenance costs.
- Environmental pollution.
- Sewer overflows that create health risks.
- Reduced treatment efficiency at wastewater treatment plants.
FOG is now recognised worldwide as one of the leading causes of preventable sewer blockages.
Nature can digest fats and oils—but only when healthy biological communities are present in sufficient numbers and given enough time to do their work.
7.3 Grease Traps Are Only the First Line of Defence
Grease traps play an important role by slowing the flow of wastewater and allowing fats and oils to separate before they enter the sewer network.
However, grease traps do not eliminate FOG. They simply collect it. Unless the accumulated grease is managed correctly, the trap eventually loses its effectiveness.
Overflowing grease traps allow FOG to pass into downstream pipework, where blockages become much more difficult and expensive to remove.
A grease trap should therefore be viewed as part of a complete FOG management programme—not the entire solution.
7.4 Why High-Pressure Cleaning Alone Is Not Enough
Blocked drains are often cleaned using mechanical equipment or high-pressure water jetting. These methods are effective at restoring flow quickly.
However, they usually remove only the symptom. A thin layer of grease often remains attached to the pipe wall. This layer provides the perfect surface for new grease deposits to accumulate.
As a result, the blockage slowly reforms, and the cleaning cycle repeats. Many facilities find themselves cleaning the same pipelines over and over again without addressing the underlying biological imbalance.
Mechanical cleaning restores flow. Biological treatment helps restore the pipe to its original condition by continuously digesting residual organic deposits that mechanical cleaning cannot completely remove.
7.5 Working With Biology Instead of Against It
Healthy bacterial communities naturally produce enzymes that target fats, oils and grease. These enzymes begin breaking complex FOG deposits into smaller molecules that bacteria can consume as food.
As bacterial populations grow, enzyme production also increases. This creates a continuous biological cleaning process that works every hour of every day.
Unlike mechanical cleaning, biology continues working long after the maintenance team has left the site. Rather than waiting for another blockage to occur, healthy biological activity helps prevent deposits from becoming established in the first place.
7.6 How FatDigest® Supports FOG Management
FatDigest® has been specifically developed to support the biological digestion of fats, oils and grease within commercial wastewater systems.
By introducing a high concentration of carefully selected living bacteria, FatDigest® helps establish healthy microbial populations capable of producing the specialised enzymes required to digest FOG. As these bacterial colonies develop, they continue producing fresh enzymes, allowing the biological treatment process to operate continuously.
FatDigest® is ideally suited to:
- Restaurants.
- Hotels.
- Commercial kitchens.
- Shopping centres.
- Food processing facilities.
- Hospitals.
- Schools.
- Grease traps.
- Pump stations affected by FOG.
- Sewer systems experiencing recurring grease blockages.
Where FOG has migrated beyond the grease trap into larger sewer networks, FatDigest® works exceptionally well alongside SewerDigest®, providing a comprehensive biological solution from the source of the grease through to the downstream sewer infrastructure.
7.7 Prevention Saves Money
FOG management should never begin after a blockage has occurred. The most successful facilities adopt a preventative approach.
Regular grease trap maintenance, responsible kitchen practices and healthy biological treatment significantly reduce emergency call-outs, minimise downtime and extend the life of wastewater infrastructure.
Experience has shown that preventing a blockage is almost always less expensive than responding to one.
FOG is one of the leading causes of preventable wastewater problems. While mechanical cleaning restores flow, healthy biological treatment provides continuous protection by digesting fats, oils and grease before serious blockages develop.