Fat, Oil and Grease (FOG) Determination
There is a general consensus that oil, grease, gasoline and other hydrocarbon petroleum based chemicals are harmful to the environment and need to be effectively removed. Waste water from the environment contains fats, oils, waxes, etc. If these compounds are not removed before the treated waste water is discharged, oils and fats can form unsightly films and interfere with the biological life in surface waters. Fats and oils are present in domestic wastewater in the form of butter, lard, margarine and vegetable fats and oils. Fats are also commonly found in meat, germinal areas of grains, in seeds, in nuts and in certain fruits.
Kerosene, lubricating and highway oil come from petroleum and coal tar and contain essentially carbon and hydrogen. These oils reach sewers in considerable quantities from stores, garages and streets. The mineral oils coat surfaces to a greater extent than fats, oils and soaps, and these particles can interfere with biological action and cause maintenance issues. Fats, oils and grease (FOG) is often described as a pollutant because it is discharged in waste water, leading to buildup and subsequent blockage of sewers. Numerous industries need to ensure they are not exceeding their oil/grease discharge permit limits. Therefore, it is an important parameter for environmental monitoring by environmental authorities. Solvent extraction and weight determination are often used for the determination of FOG.
Application of FOG Determination
- Effluent containing high levels of FOG can be stopped before it stops the flow of sewers
- Assist in regulating and reducing the accumulation of fats, oils and grease in sewers
Our Method
N-hexane extracts non-volatile hydrocarbons, vegetable oils, animal fats, waxes, soaps, oils and greases. Our experts use n-hexane as an extraction solvent for oils and greases and other extractable substances not adsorbed by silica gel in surface and SALINE waters, as well as industrial and domestic aqueous wastes. Total petroleum hydrocarbons (TPH, or the hydrocarbon portion of oil and grease) are determined using an infrared spectrophotometer. In addition, we can determine TPH by employing gravimetric method.
- Liquid-liquid extraction with hexane
For oil and grease analysis, our laboratory verifies the preservation of the pH and adds additional acid if the pH is not lower than 2. To determine the hydrocarbon portion of the oil and grease analysis, we perform more than two extraction procedures using n-hexane to remove all oil and grease compounds.
- Treatment with silica gel
The hexane extract is cleaned up with 100% activated silica gel using either an in-situ or column based process.
- Gravimetric determination (PBM)
After silica gel treatment, the extract is filtered and then evaporated to dryness at ambient temperature. Following evaporation, residual water, solvent, and other volatiles are removed by heating in an oven at 50-60ºC for 30-60 minutes or by continued evaporation at ambient temperature, prior to gravimetric determination of the residue using an analytical balance. The difference in mass is the amount of oil and grease in the collected sample.
Advantages of Our FOG Determination
- Simple and reliable
- Requires minimal sample preparation and increases throughput with automated analysis
- Technology is non-destructive and allows for post-analysis solvent extraction verification