Two types of constructed wetlands are shown below. Both cell 1 and cell 2 of the Triangle School Wastewater Treatment Facility are deigned using variations of the low marsh and high marsh constructed wetlands. The plants grown in these plots are specifically chosen for their ability to assist in the biological treatment of water. Plants act like biological pumps, converting sunlight into chemical energy and carrying oxygen from their leaves to their roots. Pollution eating microbes colonize in the oxidized zone surrounding the root surface.
Microbes convert nitrates into a harmless gas.
Alternating aerobic and anaerobic environments work together to remove nitrogen from wastewater. BOD and phosphorus removal are relatively quick processes requiring an aerobic environment, while nitrogen transformation takes several days.