Portable Infrared Analyzer For New Oil And Grease Limits On Wastewater Effluents

S. Norwalk, CT, November 15, 2002 -- As part of the Clean Water Act, industries discharging into Publicly Owned Treatment Works (POTW) are facing new and stricter regulations regarding wastewater. These new limits on oil and grease concentration levels are forcing industries to monitor their effluent more closely prior to discharge which means more frequent measurements to ensure compliance.

In the past, the measurement of oil and grease was done with Freon 113 as the extraction solvent and measured with an infrared analyzer or by a gravimetric process. Freon 113 is no longer an acceptable solvent as a result of the Montreal Protocol. EPA Method 1664 using hexane extraction and gravimetric analysis is now the standard method replacing freon methods. The gravimetric procedure requires a skilled laboratory technician and is a time and equipment intensive. Infrared procedures, on the other hand, are simple to use, require little equipment, can be used on site and require a fraction of the time and solvent. Infrared measurement of oil and grease concentration levels is easy, cost effective and can be done in the laboratory or in the field.

Wilks Enterprise, Inc. has developed a portable infrared instrument, the InfracalTM TOG/TPH Analyzer, Model HATR-T, that uses hexane for extraction of the oil and grease in the sample(s) being measured. In the new effluent limitation guidelines, the EPA lists oil and grease as "hexane extractable material". Because hexane contains hydrocarbons, it must be evaporated off in order not to interfere with the hydrocarbon measurement in oil and grease. Since the Infracal TOG/TPH Analyzer measures the "hexane extractable material" and uses an evaporation process, it will closely match the hexane/gravimetric method. This unique infrared instrument allows an industry to analyze their effluent on site in just 15 minutes.

The extraction and measurement procedure involves several simple steps allowing an operator with minimal training to do the analysis. The sample is collected in a container. Hexane is added at a ratio of one part solvent to 10 parts sample. After shaking for 2 minutes the hexane, being lighter that water, will rise to the top carrying dissolved oil and grease with it. Using a syringe or pipette, 50 microliters of hexane is deposited on the sample plate of the Infracal TOG/TPH Analyzer. The analyzer's "run" button is pressed and the measurement result is displayed in three minutes. Since the Infracal TOG/TPH Analyzer requires a small amount of extract for analysis, only 10ml of hexane is needed per sample extraction.

With the Infracal TOG/TPH Analyzer, operators of pretreatment systems can quickly and easily assess their system's efficiency and can see how it functions under heavy loads. They can also avoid discharging effluent that is above the regulatory limit.