Nitrification process

Mariotti, A., Germon, J.C., Hubert, P., Kaiser, R, Letolle, R., Tardieux, A. and Tardieux, P. 1981 Experimental determination of nitrogen kinetic isotope fractionation some principles illustration for the denitrification and nitrification processes. Plant and Soil 62 413-430. 

Annachhatre, A.P. and Bhamidimarri, S.M.R., Aerobic treatment of meat industry wastewater COD removal and nitrification, process industries power the Pacific rim Sixth conference of the Asia Pacific confederation of chemical engineering Twenty first Australasian chemical engineering conference Official proceedings of combined conference 1993 137-142, 1993. 

The emission of N20 from manure occurs directly by both nitrification and denitrification of nitrogen contained in the manure. This emission mainly depends on the N and C content of the manure during various types storage and treatment. The nitrification process strictly needs oxygen, while subsequent denitrification is an anaerobic process. 

Total Nitrogen was reduced by 20-30% in the tanks without treatment and in the one with agitation, and by more than 80% in the tank with aera tion. In the latter case a marked nitrification process was also noted 7% of the Total Nitrogen, initially present, was nitrified. 

Gomez J., R. Mendez, and J.M. Lemna (1996). The effect of antibiotics on nitrification processes. Applied Biochemistry and Biotechnology 57/58 869-876. 

Numerous organic chemicals have been identified as nitrification inhibitors. The inhibition is due to the toxicity of these chemicals to organisms that convert ammonium nitrogen to nitrite, which is the first step of the nitrification process. 

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. 

The reactions in the nitrification process are mediated by two types of autotrophic bacteria Nitrosomonas and Nitrobacter. The ammonia comes from the nitrogen content of any organic substance, such as proteins, that contains about 16% nitrogen. As soon as the ammonia has been hydrolyzed from the organic substance, Nitrosomonas consumes it and in the process also consumes oxygen according to... 

Nitrification is the process that converts NH4+ to N02 and then N03. There are four main methods for measuring nitrification—bioassays, incubation with C02 with N-serve inhibition, incubation with NH4+ or N02, and N isotope dilution (see method comparison by Enoksson, 1986). We offer a brief review here but direct the reader to Chapter 5 by Ward (this volume) for a more detailed discussion of the nitrification process and its measurement. 

Nitrous oxide (N2O) is a long-lived (120 yr) trace component of the atmosphere (Prinn et al., 1990). It is a climate-active gas as it has a radiative forcing 300 times that of CO2, although N2O presently contributes only 5% to the total greenhouse effect (Schimel, 1996). N2O also acts as a source of nitric oxide in the stratosphere and therefore participates in the catalytic removal of ozone (Crutzen, 1970). It is produced as a reaction intermediate in both microbial denitrification and nitrification processes and at greater rates under conditions of low O2 (Law and Owens, 1990) (see Chapter 6.11 by Emerson and Hedges for more details). 

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