Oil and grease, also known as fats, oil, and grease (FOG), should not be a factor for land treatment of typical municipal wastewaters unless there is a spill somewhere in the municipal collection system. There is still no need to design the land treatment component for such an emergency, since standard containment and cleanup procedures can be used when needed.

Oil and grease are more likely to be a routine component in industrial wastewaters. The most likely sources are petroleum and animal and vegetable oils. Food processing, rendering, soap manufacturing, and margarine and wax production are all sources of animal or vegetable oils. Wastewaters from seafood processing, for example, can have up to 12,000 mg/L free or emulsified oil and grease. The intentional discharge of petroleum products to sewers is not expected, but leaky devices and the washdown of equipment and facilities can result in significant loadings. Oil concentrations ranging from 23 to 130 mg/L have been observed in wastewaters from 12 different refineries. Petroleum by-products have been successfully treated in soil systems for many years. Vegetation on these systems is not necessary; the waste material is mixed with the surficial soils, and with the presence of sufficient moisture and organic material the acclimated soil microorganisms completely degrade the hydrocarbons. Bausmith and Neufeld8 have successfully demonstrated the biodegradation of propylene glycol based deicing fluids using essentially the same technique.

The interactions between the soil-plant ecosystem and petroleum products have received the most attention. The major purpose has...