Metabolic patterns reveal enhanced anammox activity at low nitrogen conditions in the integrated I‐ABR

Abstract

Substrate concentrations greatly influence bacterial growth and metabolism. However, optimal nitrogen concentrations for anammox bacteria in nitrogen‐limited environments remain unclear. Here, we observed enhanced nitrogen metabolism and anabolism of anammox bacteria at low nitrogen conditions. Efficient nitrogen removal was achieved at ammonium and nitrite influent concentration of 30 mg/L under HRT of 1 hr, with an average nitrogen removal rate (NRR) of 0.73 kg N/(m3·day) in I‐ABR composed of four compartments. The highest anammox activity of 6.25 mmol N/ (gVSS·hr) was observed in the fourth compartment (C4) with the lowest substrate levels (ammonium and nitrite of 11.6 mg/L and 7 mg/L). This could be resulted from the highest expression level of genes involved in nitrogen metabolism in C4, which was 1.49–1.67 times higher than that in other compartments. Besides, the second compartment (C2) exhibited the most active anabolism at ammonium and nitrite of 17 mg/L and 13 mg/L, respectively, which contributed to the most active amino acid synthesis and thus the highest EPS (1.35 times higher) in C2. This enhanced amino acid auxotrophy between anammox bacteria with heterotrophs, and consequently, heterotrophs thrived and competed for nitrite. These results hint at the potential application of anammox process in micro‐polluted water. Practitioner points High nitrogen removal and efficient biomass retention at low nitrogen concentrations under short HRT was achieved in I‐ABR. Optimal concentrations for anammox nitrogen removal and anabolism were discussed under low nitrogen concentrations. More active anabolism contributed to enhanced amino acid synthesis and thus higher EPS contents. Low substrate levels led to enhanced expression of genes involved in nitrogen metabolism and thus high anammox activity.

Effects of ultraviolet radiation on the community structure and metabolic pathways of A2O process at Plateau environment

“…The plateau environment has a strong inhibitory effect on the functional genes, enzymes, and metabolic pathways related to the two metabolisms of Nitri cation and Anammox, causing the part of the nitrogen metabolism map to be missing. The absence of Anammox will prevent ammonia from being oxidized to nitrite or nitrate in an anaerobic state (Pan et al, 2021), and the removal e ciency of ammonia will decrease. The lack of Nitri cation will cause obstacles in the conversion of ammonia to nitrate or nitrite (Tang et al, 2020).…”

Tailored Bimetallic Ni–Sn Catalyst for Electrochemical Ammonia Oxidation to Dinitrogen with High Selectivity

“…Ammonia is widely used as a nitrogen fertilizer, whereas it is a major pollutant in industrial and sanitary wastewater, as it can cause serious environmental problems such as eutrophication and malodor of water. − Nitrifying bacteria degrade ammonia in wastewater by nitrification, , but the process of microbial degradation requires a salt-free condition and suffers from sluggish kinetics . Direct electrocatalytic ammonia oxidation reaction (eAOR) is a sustainable approach to wastewater ammonia treatment.…”

Nitrogen removal and microbial mechanisms in a novel tubular bioreactor‐enhanced floating treatment wetland for the treatment of high nitrate river water

“…High nitrogen concentrations in water bodies can lead to adverse consequences such as eutrophication and algae blooms, which are detrimental to river ecosystems (Li et al, 2018; Yu & Gan, 2022). However, low nitrogen removals are typically achieved when treating polluted river water (Pan et al, 2021). Accordingly, there is a pressing demand to find novel methods to improve the efficiency of total nitrogen (TN) removal.…”