Anammox for wastewater treatment
Anammox is a wastewater treatment method that uses special bacteria to remove nitrogen. These bacteria do not need organic carbon to grow. They take ammonium and nitrite and turn them into nitrogen gas, which escapes into the air.
Anammox bacteria live in wastewater plants and in some natural areas like lakes and sediments. They grow best in warm water (about 30–40°C) and a pH of around 6.5–8.3. They have a unique internal area where the reactions happen.
In many plants, ammonia is first converted to nitrite by other microbes. Then anammox bacteria use the nitrite and remaining ammonium to produce nitrogen gas, helping clean the water.
This approach is being added to treatment facilities to improve ammonia and nitrogen removal, often without needing extra organic carbon.
Wastewater treatment also enables nutrient recovery. The solid material left after treatment, called sludge, can become ash used as fertilizer. Struvite, a mineral containing magnesium, ammonium, and phosphate, can also form and be used as fertilizer.
By removing nitrogen and phosphorus, anammox helps protect rivers, lakes, and oceans from eutrophication, a harmful overgrowth of plants and algae. In conditions with high nitrite, high ammonia, and little oxygen, natural anammox processes can further help clean the water.
This page was last edited on 2 February 2026, at 15:53 (CET).