Nitrate is a nitrogen compound produced in wastewater by the conversion of ammonium via nitrite to nitrate (nitrification). Nitrate is one of the main nutrients in nature. Too much nitrate in the water leads to increased algae growth. In ground water, nitrate leads to contamination. If too much nitrate reaches drinking water, the human body can form toxic substances. Nitrate is removed by the process of denitrification in small sewage treatment plants of discharge class D.