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Introduction to Treatment Wetlands

Wetlands are areas with saturated soils or shallow standing water. They include habitats such as wet prairies, cattail marshes, fens, and swamps. Characterized by diverse populations of microbes, plants, and wildlife, wetlands have long been recognized for their ability to naturally purify water containing dissolved or particulate pollutants.

Since the early 1970s, wetlands have been engineered specifically for water quality treatment, both in the United States and worldwide. These treatment wetlands have been designed as integral components in wastewater and stormwater management programs for municipal, industrial, and agricultural discharges. Of particular interest to the petroleum industry, several large-scale treatment wetland projects are underway at oil refineries, and numerous pilotscale research and demonstration studies have been conducted at terminals, gas and oil extraction and pumping stations, and refineries.

Treatment wetlands hold promise for managing a variety of wastewaters generated by the petroleum industry. This is important because the oil and gas industry generates different types and concentrations of pollutants than do municipal and other industrial sources. This pamphlet, prepared by the American Petroleum Institute (API), summarizes issues critical to using treatment wetlands in managing petroleum-industry wastewaters.

As a result of the number of existing treatment wetland projects, a considerable body of publi shed information is now available about their permitting, deSign, cost, and performance. (Refer to the For More Information section .) For example, more than 600 natural and constructed wetlands are being used to treat wastewater and stormwater in North America, with the size of individual treatment wetlands ranging from a fraction of an acre to more than 3,000 acres. Many of these systems are designed with specific treatment objectives and have reported operational data that display consistent and predictable performance for meeting permit limitations. In addition, cost information indicates that treatment wetlands can be a cost-effective alternative to more conventional technologies.