Performing a variety of gravimetric tests or spending a huge sum of money with a contracted testing laboratory is unavoidable for wastewater professionals in order to comply with industrial effluent standards for fats, oil and grease (FOG). However, infrared analysis helps them to save both money and time by providing an alternative solution.
Advantages of Infrared Analysis
Infrared analysis is advantageous in many ways:
Low Solvent Consumption
The EPA method 1664 needs 100ml of hexane for extracting a sample volume of one liter. It is not possible to reduce the solvent volume with this method because of the low weight of the residual oil otherwise producing less accurate results for lower levels of grease and oil. Conversely, the hexane/infrared extraction technique requires only 50µl of extract for analysis, thus allowing reduction of the sample volume to 100ml for a well-mixed waste stream.
Hence, 10ml of hexane is adequate for the hexane/infrared extraction technique for extracting 100ml of sample. Besides reducing solvent costs, low solvent consumption means operators are exposed to less of the fumes given off by them. In addition, the risk of fires is less with low volatility fumes.
Shortened Analysis Time
It requires up to two hours getting a final result for the hexane/gravimetric method, which is very laborious. Conversely, the analysis can be performed within 10 minutes using the hexane/infrared method, therefore reducing analysis as well as laboratory technician time.
Easy to Perform
The hexane/infrared method is simple to perform. The first step is the addition of hexane to the sample, followed by stirring for 2 minutes (Figure 1).
Figure 1. Addition of hexane to the sample, followed by shaking for 2 minutes
The sample is then allowed to partition. This is followed by taking 50µl from the hexane extract top layer and depositing it on to the sample plate of the analyzer (Figures 2 and 3).
Figure 2. 50µl of sample is taken from the top layer of hexane extract
Figure 3. The extract is deposited on to the sample plate of the analyzer
The analyzer is then started by pressing the “run” button. The readings of the analysis are then displayed after the timer countdown of 5 minutes.
Ability to Perform On-Site Analysis
Fixed filter infrared analyzers, such as the InfraCal TOG/TPH Analyzer – Model HATR-T2, have a smaller footprint (below 6” square) and lighter weight (below 5lbs). In addition, They are operable from a vehicle using a 12V power supply, thus allowing on-site analysis of wastewater effluent. This means high oil and grease offenders can be easily identified.
Furthermore, fixed filter infrared analyzers help reducing the number of samples acquired, transported, and analyzed in the laboratory through on-site analysis of out-of-compliance effluent discharges.
This is also applicable for in-laboratory testing by allowing quick screening of samples and subsequent analysis of effluent samples exceeding the accepted oil and grease level as outlined in the EPA 1664 method. This way solvent consumption and associated labor time and costs can be reduced.
Less Glassware to Clean
The hexane/infrared extraction technique uses only one piece of glassware for the analysis, thus avoiding the use of large separatory funnels with a fragile tip, and consuming less solvent.
In the petroleum industry, performing infrared measurement of oil and grease levels in generated water has been followed on highly regulated on-shore and off-shore oil platforms for more than three decades. The InfraCal TOG/TPH Analyzer – Model HATR-T2 is widely used to perform this kind of infrared measurement.
This information has been sourced, reviewed and adapted from materials provided by AMETEK Spectro Scientific.
For more information on this source, please visit AMETEK Spectro Scientific.