astewater treatment plants, also called sewage treatment plants or water pollution control plants, remove most pollutants from wastewater before it is released to local waterways. At the plants, physical and biological processes closely duplicate how wetlands, rivers, streams and lakes naturally purify water. Treatment at these plants is quick, taking only about seven hours to remove most of the pollutants from the wastewater. In the natural environment this process could take many weeks and nature alone cannot handle the volume of wastewater that New York City produces.