Oil Water Seperator

Occasionally, simple gravity type O/WSs do not remove enough oil for the resulting wastewater to meet regulatory discharge requirements. In these cases, coalescing oil/water separators, which are essentially enhanced gravity-type O/WSs, are needed to achieve greater separation efficiency.

A drain connected to an oil/water separator may be perceived as a convenient place to dispose of any type of liquid waste or sludge. This erroneous assumption can result in illegal discharges of hazardous substances to installation sewer systems (which eventually discharge to surface waters) or wastewater treatment plants. The illustration in Figure 1 shows, in simplified form, the operation of a typical gravity O/WS system.

The type of O/WS most frequently used by the Air Force is the gravity separation system. The performance of gravity separation systems is a function of the relatively low water solubility of petroleum products in water and their different specific gravities. (NOTE: The specific gravity of a petroleum product is defined as its density divided by the density of water. Since the density of petroleum products is less than that of water, they will float.) Solids, if present in the waste stream, will generally collect at the bottom of the O/WS holding tank and can be periodically removed when the tank is drained for maintenance.

Oil/water separators are "in-line" devices used to remove oils and greases from industrial waste streams and storm water discha