Preventing and Managing the Formation of ‘Fatbergs’ in Sewer Systems from Homes and Commercial Food Facilities: Two Promising Lines of Research: More Efficient Traps and Coatings to Prevent Accumulation Along Insides of Sewer Pipes

    When I was in my early 20s, I had a job for a time cleaning the grease out of restaurant grease ducts. It was gross scraping grease out of those ducts. We would also make up a solution that included caustic soda and spray it from the top, usually from the roof. My work partner was a retired Marine drill sergeant who rarely spoke but was a good supervisor. Fats, oils, and grease, also known as FOG, have long been problematic in sewer systems as well as in household septic systems. In sewer systems where there is a lot of commercial cooking, it can cause a lot of problems, clogging the system. Grease traps are designed to divert and retain the FOG, but finer fat particles and emulsified fats easily get through and join with other solids, such as baby wipes  and sanitary products (which should never be flushed), to form strong clogs. It is estimated that grease traps only catch about 40% of the FOG.

     Older sewage systems connect to stormwater catchment, which can bring in more solids to join with the FOG. In 2021, a fatberg in Birmingham, England, which may be the largest ever recorded, measured three feet high and more than half a mile in length. Fatbergs lead to clogs, which can cause large sewage overflows, as happened in Baltimore in 2017.

     Municipal sewer systems are gravity-fed. Blockage is often first discovered in backed-up basement toilets. Such backups of hazardous wastewater can cause disease. According to the Johns Hopkins Bloomberg School of Public Health:

“These underground, hard-as-concrete masses require manual removal. Sanitation workers use high-powered water jets, saws, and pick-axes to break fatbergs apart into smaller chunks that can then be removed from the sewer, either by hand or using an industrial vacuum. Clearing a single blockage can take hundreds of hours. A 40-ton fatberg in London took three weeks to clear with eight people working nine hours a day, and others have taken even longer.”

     The age of the sewer system is a factor, and those older systems, some more than a century old, are vulnerable to fatbergs. The older systems often have smaller pipe sizes and may no longer meet capacity needs for the city, which makes clogs more likely.

     Current prevention methods involve educating people about the dangers of flushing anything aside from toilet paper and human waste, and not disposing of grease in the sinks. For commercial food facilities, the goal is to capture more grease in grease traps and reduce the amount that gets into the sewer system. There are hotlines where sewer system leaks can be reported as well.

     According to an article in Popular Science, New York City spends about $18.8 million removing these “fatbergs,” as the accumulations are called, each year. Thus, redesigning sewer line fatberg prevention and maintenance actions is desirable. The cost to dig up city streets and remove fatbergs can take large chunks of a city’s budget, and billions are spent nationwide.

 

A Redesigned Grease Interceptor That More Than Doubles the Amount of Grease Trapped

 

     A new wastewater treatment system has been devised by engineers at the Royal Melbourne Institute of Technology (RMIT) in Australia that utilizes redesigned grease interceptors along with chemical treatments to optimize water flow. It is described in a paper in ACS ES&T. First, they designed a grease trap that traps more grease, including the smaller particles and emulsified fats that often make it through conventional grease traps. The redesigned grease interceptor uses a series of physical barriers (called baffles) to slow water flow and also includes dosing the water within the trap with a small amount of alum (aluminum sulfate) to make it clump for easier removal. As noted in the abstract of the paper below, the alum dosing is the key to the interceptor's success.

     According to study co-author and civil engineer Nilufa Sultana:

“While traditional interceptors only remove around 40% of fats, our system achieved up to 98%—even when tested with actual kitchen wastewater.”

     According to Popular Science:

“The team says that this technology could be scaled for use in kitchens of all sizes, even commercial kitchens, which are large contributors to fatbergs. It can also be retrofitted to existing grease management systems. If implemented in an already established grease management system, it could be a more cost-effective way to protect sewer infrastructure.”

 

A Zinc-Enhanced Polyurethane Coating Reduces Calcium from Leaching Out of Concrete Sewers by 80%

     In late 2024, the same researchers at the Royal Melbourne Institute of Technology (RMIT) in Australia developed a coating for concrete sewers that drastically reduces (by 80%) the amount of calcium released from the concrete. This led to a 30% reduction in FOG buildups. The smoother surface of the zinc-enhanced polyurethane led to less sticking than the rough-surfaced calcium-leached concrete. Their work was explained in a paper in the Chemical Engineering Journal. According to study co-author and RMIT University civil and infrastructure engineer Biplob Pramanik:

“Traditional coatings like magnesium hydroxide, widely used for over two decades, are effective in controlling sewer corrosion but can inadvertently contribute to FOG build-up by interacting with fatty acids.”

     The zinc-enhanced polyurethane also exhibits a self-healing effect if scratched. It is expected to remain durable and to be very long-lasting.

  

 

 

References:

 

Stopping fatbergs before they cost millions to remove. Laura Baisas. Popular Science. August 21, 2025. Stopping fatbergs before they cost millions to remove

The battle against fatbergs has a new weapon: An experimental zinc coating may reduce the build-up of fat, oil, and grease clumps in sewer pipes. Laura Baisas, Popular Science. November 13, 2024. The battle against fatbergs has a new weapon | Popular Science

Performance Optimization for the Removal of Fat, Oil, and Grease from Food Service Establishment Wastewater Using a Novel Grease Interceptor. Nilufa Sultana, Felicity Roddick, Muhammed Bhuiyan, and Biplob Kumar Pramanik. ACS ES&T Water. Vol 5/Issue 8. Performance Optimization for the Removal of Fat, Oil, and Grease from Food Service Establishment Wastewater Using a Novel Grease Interceptor | ACS ES&T Water

Novel hybrid coating material with triple distinct healing bond for fat oil and grease deposition control in the sewer system. Sachin Yadav and Biplob Kumar Pramanik. Chemical Engineering Journal. Volume 499, 1 November 2024, 156226. Novel hybrid coating material with triple distinct healing bond for fat oil and grease deposition control in the sewer system - ScienceDirect

Fatbergs: Menaces to Public Works and Public Health: Fatbergs are a potent symbol of how we’ve come to take our aging water infrastructure systems for granted. John Hopkins Bloomberg School of Public Health. Fatbergs Remind Us of Water Infrastructure’s Critical Role | Johns Hopkins | Bloomberg School of Public Health