Sewer blockages from fats, oil, and grease

摘要

Let's start with this truth: Fats, oils, and grease deposits are not just congealed fats, oils, and grease. According to the U.S. Environmental Protection Agency (EPA), the presence of hardened fats, oils, and grease (FOG) deposits are a leading cause of sanitary sewer overflows and known for increasing sewer maintenance costs. This phenomenon is nothing new - a patent for a grease trap was granted in 1883 to prevent wastewater pipes from being clogged by grease-laden discharge. Even though the occurrence of sewer FOG deposits is experienced by municipalities around the globe, they are not universally understood, even by experts in wastewater. Conventional thinking holds that FOG deposits are congealed fats, oils, and grease. But research has led to a much clearer comprehension of the chemical makeup and formation kinetics of these hardened deposits and has identified them as calcium soaps in which free fatty acids have reacted with calcium through saponification to form insoluble deposits or "sewer plaque."