Research Progress of Partial Denitrification Coupled with Anammox: A Review

Anaerobic ammonium oxidation (anammox) has been extensively investigated for cost-efficient nitrogen removal from wastewater. However, the full-scale application of the anammox process is limited because the anammox reaction produces an amount of nitrate, which cannot be removed further and deficient in nitrite supply. Therefore, it is urgent to develop a new process coupled with anammox. Partial denitrification (PD), first proposed by Chinese researchers, that is, the reduction of $${\text{NO}}_{3}^{ - }$$ -N to $${\text{NO}}_{2}^{ - }$$ -N is stopped, which is considered as a new method of substrate $${\text{NO}}_{2}^{ - }$$ -N for anammox bacteria. This review comprehensively reviews the new important achievements of partial denitrification and anammox and discusses the application of the coupled process of partial denitrification and anammox.