Advancements in Nutrient Removal Technologies for Wastewater

Nutrient (nitrogen and phosphorus) removal from wastewater is becoming even more important due to climate change. The basic principles of both aerobic and anaerobic processes, including microbiological characteristics for industrial, stormwater and municipal wastewater systems are described. Nitrogen removal is often a two-step process including nitrification and denitrification. More recent attention has been given to the annamox process, an anaerobic ammonium oxidation process that converts ammonia and nitrite to nitrogen gas without the addition of carbon containing compounds. A combination of aerobic and anaerobic conditions is needed for phosphorus removal. In addition, combined nitrogen and phosphorus systems can also be considered. Various reactor configurations are described for nutrient (nitrogen and/or phosphorus) removal including aerated tanks, sequencing batch reactors, biofilters, fixed film, UASB, airlift, and membrane bioreactors, among others. Applicability, design parameters, monitoring, maintenance, and operational requirements for each reactor type are discussed. In addition to conventional nutrient removal processes, nature-based solutions such as wetlands will be described. Challenges and future research directions are identified.