A UH Manoa Engineering team says microorganisms in wastewater grease traps may be contributing to a clogged sewer system. Restaurant grease traps are designed to trap fat, oil, and grease (FOG) from getting into the sewer.
But microorganisms within these grease traps could produce “long-chain fatty acids” that harden fat, oil, and grease in sewer pipes. Those hardened deposits of fat, oil, and grease are sometimes called “Fatburgs” and can cause system degradation and in worst-case scenarios cause them to overflow.
Tao Yan and post-doc Xia He with UH’s college of Civil and Environmental Engineering replicated the conditions within grease interceptors – where microorganisms from food waste can thrive – in their laboratory. It was found that the process increased the concentration of fatty acids within the traps and in the water that would flow into a sewer pipeline. Unsaturated fatty acids produce stickier deposits, thus are a menace for sewer upkeep as they are harder to dislodge, and corrode concrete pipes even more.
Yan says the people who design grease traps should consider microbial activities to maximize their effectiveness.
Yan’s research was recently published in Environmental Science, Water Research & Technology.