“Let’s Clear the FOG” Michael Keleman Manager, Environmental Engineering InSinkErator

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Background

• Limited Research on Formation Mechanism • Much in Last Five Years • Limited Number of Principal Investigators

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Overview • Background on Research of Deposit Mechanism

• Triglycerides 101

• Contemporary Research Conclusions

• Sources of Free Fatty Acids

• Properties of Free Fatty Acids

• Hypothesis of Deposit Mechanism

• Discussion

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• Fats

- Lard, Shortening

- Solid at Room Temperature

- Liquid With Some Heat Added

• Oils

- Vegetable (Corn, Soybean)

- Liquid at Room Temperature

• Grease

- Fryers

- Liquid at Room Temperature

- Able to Withstand High Temperatures

Triglycerides 101

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FOG or Something Else?

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Keener, Kevin M., Joel J. Ducoste and Leon M. Holt. 2008. “Properties Influencing Fat, Oil, and Grease Deposit Formation.” Water Environment Research. 80:12, pp.2241-2246.

• Characterized the Chemical and Physical Makeup of 27 Samples of FOG Deposits from Different Collection Systems.

• Deposits Contain High Amounts of Saturated Fats and Calcium - Higher Than Background Levels.

• Determined that FOG deposits are formed primarily by saponification and are metal soaps.

• Part of Water Environment Research Foundation’s “Fats, Roots, Oils and Grease in Centralized and Decentralized Systems.” (FROG Study)

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He, Xia, Mahbuba Iasmin, Lisa o. Dean, Simon E. Lappi, Joel J. Ducoste and Francis L. de los Reyes III. 2011. “Evidence for Fat, Oil, and Grease (FOG) Deposit Formation Mechanisms in Sewer Lines.” Environmental Science &Technology. 45 (10), pp. 4385–4391. • FOG Deposits Can Be Formed in Laboratory Using CaCl2

and Grease Interceptor Effluent.

• Without Free Fatty Acids (FFAs), Calcium Salts Do Not Form.

• Both Lab and Field Deposits Similar to Calcium Soap Based on Fourier Transform Infrared Spectroscopy (FTIR) Analysis.

• Field Deposits Contain Un-reacted FFAs.

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Williams, J.B., C. Clarkson, C. Mant, A. Drinkwater and E. May. “Fat, Oil and Grease Deposits in Sewers: Characterisation of Deposits and Formation Mechanisms.” Water Research. 46(2012), pp. 6319- 6328. Two Mechanisms May Affect the Physical Properties

of FOG Deposits.

1. Biodegradation with Transformation of Fatty Acids from Unsaturated to Saturated Forms. No Double Bonded Carbon Atoms

2. Biocalcification Where Higher Levels of Water Hardness Lead to Harder Deposits with Higher Melting Points.

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Dominic, Christopher Cyril Sandeep, Megan Szakasits, and Joel J. Ducoste. 2012. “Understanding the Spatial Formation and Accumulation of Fats, Oils and Grease Deposits in the Sewer Collection System.” WEFTEC 2012. • FOG Deposits Can be Formed in a Lab Pipe Loop Reactor.

• Deposit Formations More Likely to Occur at Pipe Fitting Ridges, Roots and Sags. - not in straight sections of pipe

• Higher pH Leads to Greater Solids Buildup.

• CaOH2 Released at the Surface of Concrete May Lead to Alkali Hydrolysis of FOG.

• Calcium Based Fatty Acid Salts Confirmed with FTIR-ATR, Attenuated Total Reflectance.

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Reyes, Francis de los and Joel J. Ducoste. 2012. “Factors Affecting the Formation of Fats, Oils, and Grease Deposits in Sewer Systems.” Water Resources Research Institute of the University of North Carolina. • FFAs Produced from Cooking Processes & Discharged with

Kitchen Wastewater to Sewer.

• FFAs Partition in FOG & Flow on Wastewater Surface.

• FFAs React with Calcium from Concrete or Wastewater to Form FOG Deposits.

• Sticky Solid Formed after Saponification Will Congregate and Adsorb FFAs, Calcium and Debris to Increase FOG Deposit.

• Surfactants Appear to Inhibit FOG Deposit Formation.

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Fatty Acid Profiles of Common Vegetable Oils and Animal Fats

Lipid Type Saturated Fat (%)

Primary Saturated

Fat

Unsaturated Fat (%)

Primary Unsaturated

Fat

Polyunsaturated Fat (%)

Primary Polyunsaturated

Fat

Canola 7.3 Palmitic 62.9 Oleic 30.5 LinoleicCorn 13.6 Palmitic 25.6 Oleic 60.8 LinoleicOlive 12.1 Palmitic 80.9 Oleic 7 LinoleicPalm 49.4 Palmitic 39.5 Oleic 11.1 Linoleic

Peanut 19.4 Palmitic 48.5 Oleic 32 LinoleicSoybean 15.4 Palmitic 23.3 Oleic 61.3 Linoleic

Chicken Fat 33 Palmitic 45.2 Oleic 21.4 LinoleicLard (pig) 41.8 Palmitic 47.9 Oleic 9.9 Linoleic

Tallow (beef) 47.9 Palmitic 47.4 Oleic 3.3 Linoleic

Animal Fats

Vegetable Oils

Free Fatty Acids

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So What Do We Know? • Sewer FOG Deposits

Insoluble Calcium Soaps • Precursor Sources ▫ Calcium Concrete Water Hardness Urine Dairy Products

• Free Fatty Acids ▫ Hydrolyzed FOG

Vegetable Oils Animal Fats

▫ Personal Care Products ▫ Feces

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Michael Keleman michael.keleman@emerson.com 262-598-5219

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