ABSTRACT
To comply with stringent standards of the National Pollutant Discharge Elimination System (NPDES) promulgated by the EPA in the early 1970s, a study was undertaken by Amoco's Mandan, North Dakota refinery to evaluate alternate wastewater treatment systems. This evaluation reviewed carbon adsorption, activated sludge, and expanding the refinery's existing biooxidation system. The Mandan Refinery’s original wastewater treatment facilities consisted of an American Petroleum Institute (API) oil-water separator as primary treatment and an aerated biooxidation lagoon as secondary treatment. Primary treatment of wastewater from the refinery process units is accomplished in a conventional API separator in which oil and other contaminants are separated and recovered. Superior wastewater quality and cost-effectiveness are only two advantages of the refinery’s artificial wetlands. Establishing the cascade ponding system has created a natural habitat for wildlife. Shortly after the development of the ponding system, a sharp increase in the number of wildlife species inhabiting the area was noticed.
