nitrification Dotaz Zobrazit nápovědu
Aerobic nitrification is a key process in the global nitrogen cycle mediated by microorganisms. While nitrification has primarily been studied in near-neutral environments, this process occurs at a wide range of pH values, spanning ecosystems from acidic soils to soda lakes. Aerobic nitrification primarily occurs through the activities of ammonia-oxidising bacteria and archaea, nitrite-oxidising bacteria, and complete ammonia-oxidising (comammox) bacteria adapted to these environments. Here, we review the literature and identify knowledge gaps on the metabolic diversity, ecological distribution, and physiological adaptations of nitrifying microorganisms in acidic and alkaline environments. We emphasise that nitrifying microorganisms depend on a suite of physiological adaptations to maintain pH homeostasis, acquire energy and carbon sources, detoxify reactive nitrogen species, and generate a membrane potential at pH extremes. We also recognize the broader implications of their activities primarily in acidic environments, with a focus on agricultural productivity and nitrous oxide emissions, as well as promising applications in treating municipal wastewater.
The influence of industrial (pharmaceutical and chemical) wastewater composition on membrane bioreactor (MBR) performance was investigated in a pilot-scale installation. The study focussed on nitrification performance, which was evaluated based on influent and effluent parameters as well as batch nitrification rate tests. The industrial wastewater was pumped into the MBR in a mixture with municipal wastewater at constant flow rate. The loading of the MBR with industrial wastewater was increased stepwise from 0 to 75% share in the mixed influent to study the adaptation of nitrifying bacteria. Stable nitrification performance was observed until the content of industrial wastewater in the influent reached 40%, with effluent values of around 0.56 mg L(-1) NH4-N and 98.3% ammonia removal. Breakdown of nitratation was observed at a 40% industrial wastewater dose and breakdown of nitritation at a 50% dose, respectively. However, after several months of adaptation, both processes recovered. No nitrification was observed when the industrial wastewater share exceeded 50%. Adaptation of nitrifying bacteria in the MBR was also confirmed by results of kinetic tests. The inhibition effect of the concentrated industrial wastewater to the MBR sludge decreased substantially after several months of exposure, while the inhibition of referential activated sludge remained constant.
- MeSH
- bioreaktory * MeSH
- čištění vody * MeSH
- dusík izolace a purifikace MeSH
- filtrace MeSH
- membrány umělé * MeSH
- měření biologické spotřeby kyslíku MeSH
- nitrifikace * MeSH
- odpad tekutý - odstraňování MeSH
- odpadní voda MeSH
- odpadní vody chemie MeSH
- permeabilita MeSH
- pilotní projekty MeSH
- průmyslový odpad analýza MeSH
- velkoměsta MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- velkoměsta MeSH
The nitrification of the liquid phase of digestate (LPD) was conducted using a 5L completely stirred tank reactor (CSTR) in two independent periods (P1 - without pH control; P2 - with pH control). The possibility of minimizing nitrogen losses during the application of LPD to the soil as well as during long-term storage or thermal thickening of LPD using nitrification was discussed. Moreover, the feasibility of applying the nitrification of LPD to the production of electron acceptors for biological desulfurization of biogas was assessed. Despite an extremely high average concentration of ammonia and COD in LPD reaching 2470 and 9080mg/L, respectively, nitrification was confirmed immediately after the start-up of the CSTR. N-NO3-concentration reached 250mg/L only two days after the start of P1. On the other hand, P1 demonstrated that working without pH control is a risk because of the free nitrous acid (FNA) inhibition towards nitrite oxidizing bacteria (NOB) resulting in massive nitrite accumulation. Up to 30.9mg/L of FNA was present in the reactor during P1, where the NOB started to be inhibited even at 0.15mg/L of FNA. During P2, the control of pH at 7.0 resulted in nitrogen oxidation efficiency reaching 98.3±1.5% and the presence of N-NO3-among oxidized nitrogen 99.6±0.4%. The representation of volatile free ammonia within total nitrogen was reduced more than 1000 times comparing with raw LPD under these conditions. Thus, optimum characteristics of the tested system from the point of view of minimizing the nitrogen losses as well as production of electron acceptors for the desulfurization of biogas were gained in this phase of reactor operation. Based on the results of the experiments, potential improvements and modifications of the tested system were suggested.
- MeSH
- amoniak MeSH
- bioreaktory * MeSH
- dusík MeSH
- dusitany MeSH
- nitrifikace * MeSH
- Publikační typ
- časopisecké články MeSH
The influence of sludge age, ammonia and nitrite concentrations, temperature and the ammonia loading rate on biological treatment of reject water from sludge treatment was tested on laboratory scale. Nitrification of ammonia in reject water at the sludge age 4–5 days produced nitrites and nitrates. At high concentrations of ammonia and nitrites, nitrates were produced. The nitrification proceeds almost completely at 10 °C. The high ammonia loading rate seems to be most efficient of the tested factors, leading to nitrite accumulation.
A soil naturally containing montmorillonite (M) was amended with 10% M and sequentially perfused with glyeme, with fresh glyeme being added every 16--17d after nitrification of the previously added glycine-nitrogen had reached a plateau. In some systems, the old perfusates were replaced each time with a fresh glycine solution; in others, the initial perfusate was not replaced but only adjusted each time to the original 200 ml volume and a comparable glycine concentration (140 micrograms NH2-N/ml). The incorporation of M enhanced the rates of heterotrophic degradation of glycine and subsequent autotrophic nitrification, but these stimulatory effects decreased with each successive perfusion. The reasons for these decreases are not known, but they did not appear to be related to inorganic nutrition, as perfusion with a mixed cation solution after five perfusion cycles did not significantly enhance nitrification in either the check or M-amended soils during three subsequent perfusions with glycine. The enhancement of nitrification by M appeared to be a result, in part, of the greater buffering capacity of the M-amended soil, as indicated by lesser reductions in the pH of perfusates from the M-amended soil, by titration curves of the soils, and by the greater and longer stimulation of nitrification in the check soil amended with 1% CaCO3, which had a greater buffering capacity than did M. The stimulation by CaCO3 may also have been partially the result of providing CO2 for the autotrophic nitrifyers. Significant concentrations of nitrite accumulated only in perfusates from soil amended with CaCO3. Air-drying and remoistening the soils enhanced nitrification of subsequently added glycine, especially in the check soil. The importance of pH-mediation, of the production of inhibitors, and/or of feed-back inhibition was indicated by the lower rate and extent of nitrification in systems wherein the perfusates were not replaced between successive additions of glycine. Although the results of these studies confirmed previous observations that M enhances the rate of nitrification in soil, the mechanisms responsible for this stimulation are still not known.
Mine waters contains high concentrations of ammonia nitrogen (Nam), sulfates, Fe and Mn. Their concentrations must be decreased before release to surface waters. This work is aimed at removing Nam by biological oxidation (nitrification). The total efficiency of the removal for the initial concentrations 10–11 mg L–1 Nam was ca. 86 %, both with and without using biomass carrier. The reaction time was 15 h. The nitrification bacteria in mine waters were monitored by the FISH (fluorescence in situ hybridization) method. Of ammonia oxidation bacteria, Betaproteobacteria were detected. The Nitrospira bacteria predominated in nitrite oxidation. Genus Nitrobacter was not detected in this process.
The temperature dependence of nitrification can be expressed by the Arrhenius equation while the time course of nitrate production can be expressed by the Gomperz function. These two findings served as a basis for a mathematical model which makes it possible to calculate nitrate production in the soil even when the temperature changes once or more times during the incubation.
