Sometimes chemical reactions are happening in places you wouldn’t expect, causing problems that weren’t anticipated. Researchers at North Carolina State University have discovered how fat, oil and grease (FOG) can create hardened deposits in sewer pipes, contributing to overflows. These overflows, in turn, may cause environmental and public safety issues, leading to costly repairs and perhaps fines. Fourier Transform Infrared (FTIR) spectroscopy can help identify the substances creating the deposits and, in that way, work toward a solution to correct the problem.
The research team used FTIR analysis to determine what the FOG deposits were made of at the molecular level. Infrared light was discharged into a sample material at various wavelengths. It’s the sample’s absorption of the light’s energy which is measured and determines the material’s molecular composition and structure. This is how Dr. Joel Ducoste, professor of civil, construction and environmental engineering at NC State, learned that the chemical reactions in the sewer collection systems basically turned the FOG into “a huge lump of soap.”
Obviously, this is not the type of “soap” that cleans wastewater; by blocking the system, the flow of wastewater in the pipes is reduced.
Growth of Commercial Food Sector Creates Rise in Sewer Overflows
The state studied this issue in 2004. According to the State of North Carolina, 23-28% of Sanitary Sewer Overflows (SSOs) are due to FOG or as much as 19 million gallons over a three year period. (Source: Rapid On-site Analysis of Fats, Oils and Grease FOG). This was attributed to the growth in the commercial food sector.
As part of the Clean Water Act, industries such as metal processors, meat packers, cosmetic manufacturers and industrial laundry establishments have faced stricter FOG regulations over the last several years. These new limits are forcing industries to monitor their effluent more closely prior to discharge, which means more frequent measurements to ensure compliance.
An important feature of any FOG program is locating and monitoring industries and food service establishments dumping high levels of FOG in the sewer line. For industries and treatment plants waiting for remote laboratory results, this can add costs in time and dollars. An accurate, quick and simple form of on-site FTIR analysis can greatly assist regulators and industries that want to insure their pretreatment system is operating properly.
Identifying the FOG Offenders
Regulators from a water treatment plant can immediately determine who their “FOG clog” offenders are and how much they are releasing into the sewage system. Plant operators have the advantage of taking samples before and after treatment to see how a system functions under heavy loads.
Most importantly, effluent that is above the FOG regulatory limits can be stopped before it stops the flow of the sewer line.
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