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The Launch of FOG @ NC State

Welcome to FOG@NC State! FOG, which is an acronym for Fat, Oil, and Grease, is a pollutant that poses a major threat to sewer infrastructure. When released into the collection system FOG leads to the blockage of sewer lines and greatly increases the likelihood of sanitary sewer overflows (SSOs). As you may expect, a large portion of FOG release occurs at food service establishments (FSEs). A report for the National Renewable Energy Laboratories estimated that FOG waste is produced at a rate of 13.7 lb/person*yr. Despite the presence of FOG abatement technologies at FSEs, collection systems still become occluded. A 2004 EPA report to congress on combined and sanitary sewer overflows indicated that FOG blockages were the single largest cause of blockage-based SSOs. The scientific understanding of the treatment of FOG-laden water, the Over the past 5+ years NC State has been involved in research on a wide range of topics associated with this challenge. This goal of this website is to act as a central repository for that research and relevant FOG related research.



  • Tarek N. Aziz
  • Francis L. de los Reyes III
  • Joel J. Ducoste


  • Xia He
  • Erin Gallimore
  • Michael Carpenter
  • Rupa
  • Yi Wang
  • James Hunter Long
  • Troy Gilmore
  • Colleen Bowker
  • Catherine Hoffman
  • Akin Omofoye
  • Marc Mueller
  • Ryan Blair
  • Phillip Pressley


Fate of Fats, Oils, and Grease (FOG) Deposit Forming Precursors in Sewer Systems

F.L. de los Reyes III (PI), Joel J. Ducoste (co-PI)

NC Water Resources Research Institute | (3/1/2010 – 2/28/2012)

The overall objective is to test the hypothesis that FOG formation in sewers is caused via a saponification-like reaction involving major chemical precursors: free fatty acids, a metal cation, and surfactant. The specific objectives are: 1) To determine the effect of type and amount of free fatty acids in kitchen wastewater on the saponification reaction. 2) To demonstrate that calcium leaching from concrete (for example, from pre-cast concrete grease interceptors) at realistic conditions is the source of calcium for the saponification reaction. 3) To determine the effect of surfactant levels on FOG formation. 4) To develop a new FOG Deposit Formation Potential Test (FFP) that can be used to determine the propensity of a given food service wastewater to form FOG deposits, and to determine the applicability of this test to several full-scale grease interceptor effluents.

Factors Affecting the Formation of Fats, Oils, and Grease (FOG) Deposits in Sewer Systems

F.L. de los Reyes III (PI), Joel J. Ducoste (co-PI)

NC Water Resources Research Institute | (3/1/2009 – 2/28/2011)

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. The proposed research represents one of the first comprehensive and direct efforts to quantify FOG deposit formation rate in sewer collection systems. To the PIs’ knowledge, this proposed project will be among the first to perform the following: (1) quantify the impact of kitchen wastestream and food service establishment (FSE) effluent quality on the FOG deposit formation rate utilizing a pilot scale pipe-loop system (2) assess the impact of FOG from food disposal units on the FOG deposits formation rate; and (3) assess the impact of pipe surface material on FOG deposit formation rate. Such information will be important to provide wastewater municipalities with strategies to maintain a sustainable sewer collection system in high density metropolitan cities that are experiencing significant growth and alleviate the potential environmental and public health harm from FOG related SSOs.

Effects of Biological Drain Products on Grease Interceptors: Microbiological and Chemical Characterization

F.L. de los Reyes III (PI)

Consumer Specialty Products Association | (08/2007-1/2009)

The overall objective of the project is to determine the chemical and microbiological effects of biological drain products on grease interceptor (GI) characteristics and performance. The specific objectives are: (1) to identify the effects of bioaugmentation on the microbial community structure and function in grease interceptors; (2) to determine if there is a negative effect to downstream effluent from use of biological additives (i.e., determine if biaougmentation results in passing grease downstream); and (3) to start to address regulatory ordinances concerning biological drain products.


Journal Publications

He, X., M. Iasmin, L. Dean, S. Lappi, J. J. Ducoste and F. L. de los Reyes III (2011). Evidence for How Fat, Oil, and Grease (FOG) Deposits Form in Sewer Lines. Environmental Science and Technology , in press.

Gallimore, E. M., Aziz, T. N., Movahed, Z., and Ducoste, J. J. (2011). Assessment of Internal and External Grease Interceptor Performance for Removal of Food Based Fats, Oil, and Grease from Food Service Establishments. Water Environment Research, in press.

Long, H., T. Aziz, F. L. de los Reyes III, and J. J. Ducoste. Anaerobic co-digestion of Fat, Oil, and Grease (FOG): A Review of Gas Production and Process Limitations . Process Safety and Environmental Management , Submitted Feb. 2011.

He, X., and F. L. de los Reyes III. Physico-Chemical Characterization of Grease Interceptors with and without Biological Product Addition . Submitted

Aziz, T. N., Holt, L. M., Keener, K. M., Groninger, J., and Ducoste, J. J. (2010). Field Characterization of Grease Abatement Devices. Water Environment Research . Accepted

Aziz, T. N., Holt, L. M., Keener, K. M., Groninger, J., and Ducoste, J. J. (2011). “Performance of Grease Abatement Devices for Removal of Fat, Oil, and Grease.” Journal of Environmental Engineering, 137(1).

Keener, K. M., Ducoste, J. J., and Holt, L. M. (2008). “Properties Influencing Fat, Oil, and Grease Deposit Formation.” Water Environment Research, 80(12), 2241-2246.

Conference Proceedings

He, X., and F. L. de los Reyes III (2010) Microbial Ecology of Grease Interceptors for Removing Fats, Oils, and Grease (FOG) in Sewer Lines . 83rd Water Environment Federation Annual Conference and Exposition (WEFTEC 2010) , New Orleans, LA. Oct. 2-6, 2010.

He, X., M. Carpenter, and F. L. de los Reyes III (2010) Microbial and Chemical Characterization of Grease Interceptors for Removing Fats, Oils, and Grease (FOG) in Sewer Systems . IWA Leading Edge Technology Conference , Phoenix, AZ. June 2-4, 2010.

He, X., M. Carpenter, and F. L. de los Reyes III (2009) Characterization of Grease Interceptors for Removing Fats, Oils, and Grease (FOG) in Sewer Systems . NC American WaterWorks Association/Water Environment Association Annual Conference , November 15-18, Raleigh, NC.

Aziz, T. N., Ducoste, J. J., Buckley, T., Movahed, Z., Card, C., and Gallimore, E (2008). “Design Considerations for Volume Based Grease interceptors.” Chesapeake Water Environment Association (CWEA) Collection Systems Committee – F.O.G. Continued (Fats, Oils, and Grease), Maritime Institute of Technology – Linthicum Heights, Maryland.

Ducoste, J. J., and Aziz, T. N.(2008) “WERF Collection Systems Research Update” WERF Web Seminar.

Ducoste, J. J., and Aziz, T. N.(2008) “WERF FROG Project – Field Analysis and Lab Modeling.” WEF Fats, Oils and Grease (FOG) Management Seminar , Raleigh, NC.

Aziz, T. N., Holt, L. M., Keener, K. M., and Ducoste, J. J. (2007). “Pilot and CFD Analysis on the Performance of Grease Interceptors.” NC AWWA-WEA Annual Conference, Westin Hotel & Charlotte Convention Center – Charlotte, NC.

Ducoste, J.J., Aziz, T. N., and Frank, O. (2005) “WERF Research on FOG and Roots.” Fats, Oils, and Grease: Evolving Science and Management Strategies, NCSU MiKimmon Center – Raleigh, NC.

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