Imma Perfetto
Cosmos science journalist
Teenage mutant ninja turtles may not lurk in city sewers worldwide, but fatbergs do.
These conglomerations of non-biodegradable solids, fat, oil and grease form rock-like masses, which cling to and clog the inside of sewer pipes. They cause 40% of all sewer blockages in Australia and cost A$100 million each year to deal with.
Some Sydney beaches were recently closed when globules of fatbergs washed up in their thousands.
But engineers from RMIT University have come up with a fatberg solution and it’s as simple as changing the coating inside concrete pipes.
According to a new study in the Chemical Engineering Journal, their new zinc-enhanced polyurethane coating reduced build up of fat, oil, and grease (FOG) on concrete by 30% compared to non-coated concrete.
Dr Biplob Pramanik, director of Water: Effective Technologies and Tools (WETT) Research Centre at RMIT, says this reduction of FOG build-up can be attributed to: “significantly reduced release of calcium from coated concrete, as well as less sticking of FOG on the coating surface compared to the rough, uncoated concrete surface.”
Fatbergs need calcium, free fatty acids, FOG, and water to form. They also trap other debris that shouldn’t be flushed down the drain, like wet wipes and sanitary products.
The protective coating reduced the release of calcium from concrete by 80%, compared with uncoated concrete, over 30 days.
“Traditional coatings like magnesium hydroxide, widely used for over 2 decades, are effective in controlling sewer corrosion but can inadvertently contribute to FOG build-up by interacting with fatty acids,” says Pramanik.
The new invention is also stable in water, can withstand temperatures of up to 850°C, and has spontaneous self-healing properties at 30°C through reforming broken chemical crosslinks between the polyurethane polymers.
Co-researcher Dr Sachin Yadav says the team examined the healing performance of the coatings by inflicting surface scratches with a blade.
“The creation of surface scratches on the self-healing polyurethane coating sample triggered the healing process,” Yadav said.
“After the healing period, we observed a noticeable improvement in the surface scratches.”
The researchers now aim to improve the coating’s properties to achieve even greater reduction in FOG deposition, mechanical strength, and self-healing capabilities.
