2013 Progress Report: An Integrated Approach to Understanding and Reducing Fat, Oil, and Grease (FOG) Deposit Formation for Sustainable Sewer Collection Systems

EPA Grant Number: R834264
Title: An Integrated Approach to Understanding and Reducing Fat, Oil, and Grease (FOG) Deposit Formation for Sustainable Sewer Collection Systems
Investigators: Ducoste, Joel
Institution: North Carolina State University
EPA Project Officer: Page, Angela
Project Period: August 1, 2009 through July 31, 2012 (Extended to July 31, 2014)
Project Period Covered by this Report: July 29, 2012 through July 29,2013
Project Amount: $569,568
RFA: Innovative and Integrative Approaches for Advancing Public Health Protection Through Water Infrastructure Sustainability (2008) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , Sustainability , Water

Objective:

The objectives of this study are as follows: (1) perform bench-scale experiments that attempt to recreate FOG deposits and determine parameters that significantly influence their formation rate, (2) develop a numerical model that describes FOG deposit formation kinetics, (3) perform bench-scale tests to explore enhanced treatment methods to improve the removal of FOG deposit chemical precursors with grease interceptors, (4) perform pilot scale experiments on a continuous flow sewer collection system to explore spatial variations in FOG deposit formation, and (5) develop a modified EPA storm water management model (SWMM) to predict FOG deposit formation in sewer collection systems.

Progress Summary:

Significant progress has been made on this research project.

Studies in Tasks 2-4 revealed significant insights about the kinetics of FOG deposit formation. Presence of free fatty acids and detergents in the kitchen wastewater effluent will likely increase the rates of FOG deposit formation compared to their absence. More importantly, more palmitic acid would enhance solidification and therefore collection of fats, greases, and saponified solids downstream of grease interceptor effluents. The free fatty acid analysis and calcium content of the final saponified solids are expected to provide more insights to enhance the understanding of the FOG deposit formation process, and will be reported in the final report of this project.

The Cotte saponification model seemed to perform significantly well among the three models investigated. The mechanistic model, however, is better able to capture the rises and changes in saponification data with few exceptions for calcium sulfate based saponified solids. The mechanistic model also explains the chemistry of the FOG deposit formation process better than the empirical Cotte saponification model. Preliminary results suggest the use of both the saponification models (empirical or mechanistic) at user’s discretion with large-scale FOG deposit prediction models.

Task 4 results revealed that palmitic, out of the three primary fatty acids found in FOG used in food service establishments (FSEs), makes significant statistical contribution to the FOG deposit formation process. Also, pH and temperature affect fat hydrolysis and calcium solubility that lead to significant changes in rates of chemical reactions that lead to FOG deposit formation. Additional experiments are still in progress that involve the effects of the presence of oleic acid, higher fraction of anionic detergent (5% by weight of source fat), and lipase driven hydrolysis on kinetics of FOG deposits and their compositions.

The FOG deposit formation model in CITYDRAIN 2.0.3 was successful in predicting many of the hotspots or regions of high rate of FOG deposit accumulation for a section of a full-scale sewer collection system. However, many other sites were not predicted by the model that were reported as high FOG deposit accumulation zones. Possible reasons for the difference between the model and actual reported sites of high FOG deposit accumulation in the sewer system is that the model does not currently include spatial variations in hydraulic characteristics, types of pipes, or age of pipes that may affect pipe surface characteristics (i.e., only straight sewer pipes are simulated). Further, there may be pipes in the sewer collection system that are deformed such as pipe sags. Finally, the model was not simulated under dynamic conditions (i.e., only constant wastewater background flow and FSE wastewater flow were initially simulated). These additional characteristics may change the spatial FOG deposit accumulation rate. In the final year, a dynamic flow rate profile will be simulated to see if there are any subsequent changes in the spatial FOG deposit accumulation rate.

As the urban landscape continues to change with the revitalization of major metropolitan cities, the use of this FOG deposit formation rate collection system model could be helpful to assess changes in the wastewater quality in the sewer system. These hotspot predictions can be performed for any sewer collection system if the necessary GIS data are provided. Predictions from a sewer collection system model that includes FOG deposit formation kinetics will help assist municipalities to plan periodic maintenance schedules to avert detrimental FOG deposit-related sanitary sewer overflows (SSOs).


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 22 publications 5 publications in selected types All 5 journal articles
Type Citation Project Document Sources
Journal Article Dominic CCS, Szakasits M, Dean LO, Ducoste JJ. Understanding the spatial formation and accumulation of fats, oils and grease deposits in the sewer collection system. Water Science & Technology 2013;68(8):1830-1836. R834264 (2012)
R834264 (2013)
R834264 (Final)
  • Abstract from PubMed
  • Full-text: ResearchGate-Full Text PDF
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  • Abstract: IWA Publishing
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  • Journal Article He X, Iasmin M, Dean LO, Lappi SE, Ducoste JJ, de los Reyes III FL. Evidence for fat, oil, and grease (FOG) deposit formation mechanisms in sewer lines. Environmental Science & Technology 2011;45(10):4385-4391. R834264 (2012)
    R834264 (2013)
    R834264 (Final)
  • Abstract from PubMed
  • Full-text: ES&T-Full Text PDF
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  • Abstract: ES&T-Abstract
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  • Other: ResearchGate-Full Text PDF
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  • Journal Article He X, de los Reyes III FL, Leming ML, Dean LO, Lappi SE, Ducoste JJ. Mechanisms of fat, oil and grease (FOG) deposit formation in sewer lines. Water Research 2013;47(13):4451-4459. R834264 (2012)
    R834264 (2013)
    R834264 (Final)
  • Abstract from PubMed
  • Full-text: ScienceDirect-Full Text HTML
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Iasmin M, Dean LO, Lappi SE, Ducoste JJ. Factors that influence properties of FOG deposits and their formation in sewer collection systems. Water Research 2014;49:92-102. R834264 (2012)
    R834264 (2013)
    R834264 (Final)
  • Abstract from PubMed
  • Full-text: ScienceDirect-Full Text HTML
    Exit
  • Abstract: ScienceDirect-Abstract
    Exit
  • Other: ScienceDirect-Full Text PDF
    Exit
  • Supplemental Keywords:

    Chemical transport, chemicals, pollution prevention, treatment, engineering, modeling, sewer collection system, SSO, FOG, separation, storm water management;

    Progress and Final Reports:

    Original Abstract
  • 2010 Progress Report
  • 2011 Progress Report
  • 2012 Progress Report
  • Final Report