Nitrification temperature

As in all biological reactions, nitrification is a function of temperature. For municipal wastewaters, a minimum sludge age of 3.5 d is required at 20°C while the minimum sludge age must be increased to 12 d at 10°C in order to achieve nitrification. 

The low temperatures and low soil pH that usually prevail at higher altitudes and latitudes (e.g., heathlands) restrain nitrification and (to a lesser extent) ammonification (92). Studies of N relations in temperate and boreal ecosystems have dem-... 

Isaka K, Yoshie S, Sumino T et al (2007) Nitrification of landfill leachate using immobilized nitifying bacteria at low temperatures. Biochem Eng J 37 49-55... 

The rate of nitrification is assumed to be first order with respect to nitrate concentration, and the value of the rate constant, Kn, is a function of temperature. 

Continuous Multicomponent Distillation Column 501 Gas Separation by Membrane Permeation 475 Transport of Heavy Metals in Water and Sediment 565 Residence Time Distribution Studies 381 Nitrification in a Fluidised Bed Reactor 547 Conversion of Nitrobenzene to Aniline 329 Non-Ideal Stirred-Tank Reactor 374 Oscillating Tank Reactor Behaviour 290 Oxidation Reaction in an Aerated Tank 250 Classic Streeter-Phelps Oxygen Sag Curves 569 Auto-Refrigerated Reactor 295 Batch Reactor of Luyben 253 Reversible Reaction with Temperature Effects 305 Reversible Reaction with Variable Heat Capacities 299 Reaction with Integrated Extraction of Inhibitory Product 280... 

Chau and Terry [146] reported the formation of penta-fluorobenzyl derivatives of ten herbicidal acids including 4-chloro-2-methyl-phenoxy acetic acid [145]. They found that 5h was an optimum reaction time at room temperature with pentafluorobenzyl bromide in the presence of potassium carbonate solution. Agemian and Chau [147] studied the residue analysis of 4-chloro-2-methyl phenoxy acetic acid and 4-chloro-2-methyl phenoxy butyric acid from water samples by making the pentafluorobenzyl derivatives. Bromination [148], nitrification [149] and esterification with halogenated alcohol [145] have also been used to study the residue analysis of 4-chloro-2-methyl phenoxy acetic acid and 4-chloro-2-methyl phenoxybutyric acid. Recently pentafluorobenzyl derivatives of phenols and carboxylic acids were prepared for detection by electron capture at very low levels [150, 151]. Pentafluorobenzyl bromide has also been used for the analytical determination of organophosphorus pesticides [152],... 

Emissions of nitric and nitrous oxides are the result of microbial nitrification and denitrification in soils, controlled principally by soil water and mineral N contents, labile organic carbon, and temperature. Nitric oxide is a direct intermediate of both nitrification... 

The nitrogen supplies on land consist of the assimilable nitrogen in the soil VS2 0.19-104tkm-2, in plants (12 1091), and living organisms (0.2 1091). A diversity of nitrogen fluxes is formed here of the processes of nitrification, denitrification, ammonification, fixation, and river run-off. The intensities of these fluxes depend on climatic conditions, temperature regime, moisture, as well as the chemical and physical properties of soil. Many qualitative and quantitative characteristics of these dependences have been described in the literature (Hellebrandt et al., 2003). Let us consider some of them. 

Denitrification takes place in anoxic environments where nitrate and nitrite act as electron acceptors (oxidizers) and nitrification reactions then reverse NOf => NO2 => NO. The processes of denitrification (H2) on land are important channels for nitrogen to get into the atmosphere. The intensity of these processes depends on temperature, humidity, pollution of soils with poisonous chemicals, and pH. The quantitative and functional characteristics of these dependences have been well studied. The global model need only take into account temperature and humidity ... 

Davidson et al. (1978a) also used first-order kinetics for nitrogen transformations, but they considered that some of the transformation rate coefficients were dependent on several factors including environmental ones The rate for nitrification was empirically adjusted for water suction. Overall, most of the nitrogen models assume first-order kinetics. Some of them also consider the effects of temperature on rate coefficients. 

Nitrification Inhibitors. Nitrogen fertilizers in the ammonium form are immobilized by sorption on clay particles and hence are resistant to leaching. However, the ammonium form is converted to the nitrate form under aerobic conditions by microbiological processes known as nitrification. The rate of conversion depends on the temperature below 10°C it is very slow, but at 20°C and higher it is rapid. The nitrate form is more readily available to most plants although some plants (e.g., rice) can readily use the ammonium form. Thus, some of the purposes of controlled release (resistance to leaching, pre-... 

The rate of bacterial growth and hence the rate of nitrification is both temperature and pH dependent. Maximum bacterial activity occurs at about 28°C and a pH of about 8, Below a temperature of about 2°C, the reaction is very slow (Fig. 8.7). Below pH 5.5, the nitrifying bacteria decrease their activity, and below pH 4.5 the nitrification process is severely restricted lack of oxygen also inhibits nitrification. As noted above, oxidation of NH to NO is an enzyme-driven reaction and commonly the Km (see Chapter 7) under optimum conditions is observed to be somewhere around 2.5 mM. Some Km values below 2.5 mM are observed under high pH values when a large fraction of the ammonium is in the NH3 form. 

Figure 8.7. Temperature influence on nitrification in soil (unpublished class notes, Broad-bent, U.C. Davis, 1978).

The kinetics of nitrification are a fnnction of several factors the most important of which inclnde pH, temperature, and the concentrations of ammoifia and dissolved oxygen. Experience has shown that the optimum pH of nitrification lies between 7.2 and 8.8. Outside this range, the rate becomes limited. As shown in the nitrification reaction, acidity is produced. If this acidity is not buffered by addition of sufficient alkalinity, the pH could control the process and the kinetics become pH limited. We have not addressed the mathematics of this issue. 

Net N mineralization and net nitrification values were obtained from laboratory incubations (7 days) at room temperature. 

Nitrogen is transferred to the atmosphere by low- and high-temperature processes. The high-temperature processes are biomass combustion and fossil-fuel combustion the low-temperature processes are volatilization of gases from soils and waters and turbulent injection of particulate matter into the atmosphere. The gases are generated primarily as a result of microbial activity (e.g., nitrification, denitrihcation, and ammonification). 

The nitrifying bacteria are also very sensitive to high temperatures. Their populations are substantially reduced by exposures to temperatures of 212°F (100°C), and they are virtually eliminated at temperatures hotter than 284°F (140°C). As a result, nitrifying bacteria are often uncommon after a ground fire. The rates of nitrification are correspondingly small, even if there is an abundant substrate of ammonium. 

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