A review of research progress of heterotrophic nitrification and aerobic denitrification microorganisms (HNADMs)

Traditional nitrogen removal relies on the autotrophic nitrification and anaerobic denitrification process. In the system, autotrophic microorganisms achieve nitrification under aerobic condition and heterotrophic microor-ganisms complete the denitrification in anaerobic condition. As the two types of microorganisms have different tolerance on oxygen concentration, nitrification and denitrification are normally set in two compartments for high nitrogen removal. Therefore, large land occupying is required. In fact, there isa special type of microorgan-ism called heterotrophic nitrification & aerobic denitrification microorganisms (HNADMs) which can oxidize am-monium nitrogen, and perform denitrification in the presence of oxygen. HNADMs have been reported in many environments. It was found that HNADMs could simultaneously achieve nitrification and denitrification. In addi-tion, some HNADMs not only have the ability to remove nitrogen, but also have the ability to remove phosphorus. It suggests that HNADMs have great potential for pollution removal from wastewater. So far, individual work on single strain was carried out. Comprehensive summary of the HNADMs would provide a better picture for under-standing and directing its application. In this paper, the studies related on HNADMs were reviewed. The nitrogen metabolism pathway of HNADMs was summarized. The impact of pH, DO, carbon source, and C/N on HNADMs growth and metabolism were discussed. In addition, the extracellular polymeric substance (EPS) production, quorum sensing (QS) secretion and P removal by HNADMs were displayed. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Traditional nitrogen removal methods rely on autotrophic nitrification and anaerobic denitrification, but heterotrophic nitrification & aerobic denitrification microorganisms (HNADMs) have the potential to simultaneously achieve nitrification, denitrification, and even phosphorus removal. This suggests that HNADMs could be a valuable tool for wastewater pollution removal.