The wastewaters from large-scale industries such as oil refineries, petrochemical plants, chemical plants, and natural gas processing plantscommonly contain gross amounts of oil and suspended solids. Those industries use a device known as an API oil-water separatorwhich is designed to separate the oil and suspended solids from their wastewater effluents. The name is derived from the fact that such separators are designed according to standards published by the American Petroleum Institute(API).