Properties Influencing Fat, Oil, and Grease Deposit Formation

Fat, oil, and grease ( FOG) deposits are the reported cause of 50 to 75% of sanitary sewer overflows in the United States, resulting in 1.8 X 10(6) m(3) ( 500 mil. gal) of raw wastewater released into the environment annually. The objective of this research was to characterize the chemical and physical properties of FOG deposits. Twenty-three cities from around the United States contributed FOG samples for the study. The FOG deposits showed a wide range in yield strength ( 4 to 34 kPa), porosity ( 10 to 24%), and moisture content ( 10 to 60%), suggesting uncontrolled formation processes. A majority of these deposits display hard, sandstonelike texture, with distinct layering effects, suggesting a discontinuous formation process. The results found that 84% of FOG deposits contained high concentrations of saturated fatty acids and calcium, suggesting preferential accumulation. Water Environ. Res., 80, 2241 ( 2008).