Ammonia-oxidizing archaea and complete ammonia-oxidizing Nitrospira in water treatment systems

How to Provide Nitrite Robustly for Anaerobic Ammonium Oxidation in Mainstream Nitrogen Removal

“…The occurrence of AOA in the activated sludge in WWTPs was first evidenced by Park et al in 2006. So far, AOA have been discovered in diverse environments, and can be classified into five main clusters based on phylogeny of the ammonia monooxygenase subunit A ( amoA ) . In WWTPs, most AOA are affiliated with Group I.1b cluster, while their relevance to wastewater treatment systems is controversial, because the gene encoding for amoA has shown a high variability in the relative abundance. , AOA have higher ammonia and oxygen affinity ( K m,NH3 = 0.003–1.01 μmol/L, K m,O2 = 2.13–3.47 μmol/L) than that of AOB ( K m,NH3 = 0.01–33.3 μmol/L, K m,O2 = 0.10–30.3 μmol/L) (Table ).…”

“…In WWTPs, most AOA are affiliated with Group I.1b cluster, while their relevance to wastewater treatment systems is controversial, because the gene encoding for amoA has shown a high variability in the relative abundance. , AOA have higher ammonia and oxygen affinity ( K m,NH3 = 0.003–1.01 μmol/L, K m,O2 = 2.13–3.47 μmol/L) than that of AOB ( K m,NH3 = 0.01–33.3 μmol/L, K m,O2 = 0.10–30.3 μmol/L) (Table ). , Specifically, AOA possess a wide range of ammonia affinities, endowing them a flexible lifestyle in both ammonium-limited (0.1–1.0 mg/L) and high ammonium (20–500 mg/L) environments. , Also, AOA are capable of outcompeting AOB at DO ≤ 1.5 mg/L, , as well as surviving and coexisting with AnAOB under hypoxic conditions (DO < 0.1 mg/L), , which makes them more likely to provide nitrite for AnAOB than AOB at a low DO circumstance. Recently, AOA were proven to be able to convert nitrite to NO and then to N 2 via NO dismutation, by which the nitrogen removal performance was improved through consuming the excess nitrite …”

“…59,142 Specifically, AOA possess a wide range of ammonia affinities, 123 endowing them a flexible lifestyle in both ammonium-limited (0.1−1.0 mg/L) and high ammonium (20−500 mg/L) environments. 124,127 Also, AOA are capable of outcompeting AOB at DO ≤ 1.5 mg/L, 133,136 as well as surviving and coexisting with AnAOB under hypoxic conditions (DO < 0.1 mg/L), 118,124 which makes them more likely to provide nitrite for AnAOB than AOB at a low DO circumstance. Recently, AOA were proven to be able to convert nitrite to NO and then to N 2 via NO dismutation, by which the nitrogen removal performance was improved through consuming the excess nitrite.…”

“…and freshwater settings. 126,127 Recent studies have shown that these novel AOMs can also be enriched and play an important role in nitrogen turnover of ammonium-sufficient wastewater ecosystems, 128−130 where the ammonium concentration is at orders of magnitude above geochemical ecosystems. Nowadays, novel AOMs have been deemed as an attractive alternative to AOB in WWTPs for sustaining ammonia oxidization under stressful conditions, e.g., low temperature (10−20 °C) 131,132 and low DO (<1.0 mg/L), 133,134 and have exhibited advantages of maintaining the stability of a microbial community, saving energy consumption and reducing GHG emissions.…”

“…AOB are long thought to be exclusively responsible for ammonia oxidization, however, increasing evidence showed that AOA and comammox bacteria (an oxidizer by which the conversion of ammonium to nitrate can be achieved solely) are two other major AOMs responsible for ammonia oxidation. ,, Previously, owing to the high ammonia and oxygen affinity, it was believed that the AOA and comammox bacteria likely contribute to the nitrogen conversion in oligotrophic ecosystems with limited ammonium and oxygen, such as in drinking water treatment, estuaries. and freshwater settings. , Recent studies have shown that these novel AOMs can also be enriched and play an important role in nitrogen turnover of ammonium-sufficient wastewater ecosystems, − where the ammonium concentration is at orders of magnitude above geochemical ecosystems. Nowadays, novel AOMs have been deemed as an attractive alternative to AOB in WWTPs for sustaining ammonia oxidization under stressful conditions, e.g., low temperature (10–20 °C) , and low DO (<1.0 mg/L), , and have exhibited advantages of maintaining the stability of a microbial community, saving energy consumption and reducing GHG emissions. , …”