The lowest cost method is to ...

The lowest cost method is to remove most fats and insoluble fatty acids prior to biological treatment. You can use dissolved air floatation (DAF), induced air floatation, or even some type of grease skimming device. While the treatment equipment is more expensive than a lagoon treatment system, it is saves money in the long run as the grease can be sold for biodiesel and other applications. In a biological treatment system grease can be treated, but it should always be at concentrations less than 200 mg/L for most system designs.