State Water Resources Research Institute Program

Project Id: 2010NC148B
Title: Fate of Fats, Oils, and Grease (FOG) Deposit Forming Precursors in Sewer Systems
Project Type: Research
Start Date: 3/01/2010
End Date: 2/28/2011
Congressional District: NC-02
Focus Categories: Wastewater, Treatment, Water Quality
Keywords: FOG, sanitary sewer overflows
Principal Investigators: de los Reyes, Francis; Ducoste, Joel J
Federal Funds: $ 14,000
Non-Federal Matching Funds: $ 56,274
Abstract: Hardened and insoluble fats, oil, and grease (FOG) deposits is the primary cause of sewer line blockages leading to sanitary sewer overflows (SSOs). Despite the central role that FOG deposits play in SSOs, very little is known about the mechanisms of FOG deposit formation in sanitary sewers. Ongoing research in our laboratory, funded by WRRI and the Urban Water Consortium, is currently assessing the effects of kitchen wastestream water characteristics on the rate of FOG deposit formation. In the course of doing the batch tests, we gained some insights into a possible mechanism of FOG formation. The findings have been incorporated in a new hypothesis. In brief, we hypothesize that free fatty acids, metal cations, and possibly surfactant are needed to initiate the reactions that lead to FOG deposits. However, to prove the mechanism, we need to show that the different "reactants" can be generated in typical kitchen wastewater and in sewer lines, and that these reactions do occur. This would require laboratory testing, as well as data gathering from fullscale grease interceptors. These activities are not included in the on-going project; thus continuation funding is requested to prove this mechanism. The results of the project will lead to fundamental knowledge on FOG deposit formation, and help utilities formulate regulations and control measures for FOG accumulations in sewer lines.

Progress/Completion Report, 2010, PDF

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