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 3 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, 2241Res., 80, (2008.

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BSTRACT: This study characterized some of the physical and chemical features of large outside field grease abatement devices (GADs). 24-hour measurements of several food service establishments' (FSEs') influent GAD fiowrates indicated highly intermittent conditions with hydraulic retention times (HRTs) that exceeded the common recommendation (30 minutes) by two to five times. Investigation into the chemical characteristics of GADs indicated highly variable influent and effluent fat, oil, and grease (FOG) concentrations. Low pH and dissolved oxygen values were measured throughout the GAD, indicating the likely occurrence of anaerobic microbial processes. Detailed spatial and temporal observations of the accumulation of FOG and food solids were also discussed. Though the FOG layer remained relatively constant for all GAD configurations investigated, results indicated that commonly-used GAD configurations with a straight submerged inlet tee or no-inlet tee configuration may result in the transport of food solids into the second compartment. The present research showed increased accumulation of food solids in the first compartment with a retro-fit fiow distributive inlet. This retro-fit displays promise for potentially improving the separation characteristics of existing GADs. Water Environ. Res., 84, 237 (2012).

Root intrusion in sanitary sewers is a significant contributor to the alarming rate of sanitary sewer overflows occurring in the US. A better understanding of popular root control methods is required for the development of an optimal root removal protocol. This research focuses on experiment design and data collection for the comparison of popular root control methods in a pilot scale sewer environment. Two chemical treatments are observed, RootX and Razorooter. Both herbicides stopped root growth for some time; however, some samples treated by RootX began to regrow roots within a year.

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