Quantifying fat, oil and grease build up in drainage systems

Food service establishments (FSEs) are a major source of fat, oil and grease (FOG) getting into sewer systems. Build-up of FOG can cause major blockages in the systems, which cost the management companies a lot of money to clear, as well as problems for those whose drainage systems are backed up as a result. Therefore it is important to know how to manage FOG, and to do that we need to know how much is entering the system.

Unfortunately, current methods for quantifying FOG in FSE wastewater are unsuitable, due to the interference from other substances like surfactants (the chemicals in detergents and the like) and food residue, which interact with FOG and create a compound called an emulsion. 

Caroline Gurd (Cohort V) led research into a novel quantification method, based on the dairy industry Gerber method. This method negates the effect of surfactants, allowing for FOG to be quantified without interference, making it possible to quantify FOG in a realistic manner. On top of that, the method allows free oils and oils that are part of an emulsion to be quantified separately. This separation allows greater insight into FOG management. The method was tested in both synthetic and real FSE wastewater, which indicated that the novel method is more reliable than standard extractions in FOG-rich systems. 

If this method is implemented by sewer management companies, clearing the sewer systems will be easier and more efficient. This would lead to less money being spent clearing sewer systems, less drainage system blockages, and prevent FOG build up from becoming too big to manage effectively. 

Full article: Determination of fats, oils and greases in food service establishment wastewater using a modification of the Gerber method, C Gurd, B Jefferson, R Villa, C De Castro Rodriguez, Water and Environment Journal