Denitrification biological

Nitrogen oxides are formed at various stages of the biological denitrification process. This process starts with nitrate as the nitrate is reduced through various steps, NO2, NO, N2O, and N2 can be formed and, depending on the conditions, released to the atmosphere. 

Kolb, E. et al., Potential nitrosamine formation and its prevention during biological denitrification of red beet juice, Food Chem. Toxicol., 35, 219, 1997. 

Biological denitrification has been studied for the purification of both waste water and drinking water (Soares et al. 1991). The technique, as applied today, consists of... 

Kurt, M., Dunn, I. J. and Bourne, J. R. (1987) Biological denitrification of drinking water using autotrophic organisms with H2 in a fluidized- bed biofilm reactor. Biotechnol. Bioeng. 29, 493-501. 

Fine P, Yaron B (1993) Outdoor experiments on enhanced volatilization by venting on kerosene components from sods. J Contam Hydrol 12 355-374 Fioressi S, Arce R (2005) Photochemical transformation of benzo(e)pyrene in solution and adsorbed on silica gel and alumina surfaces. Environ Sci Technol 39 3646-3655 Firestone MK (1982) Biological denitrification. In Stevenson FJ (ed) Nitrogen in agricultural sods. Agronomy 22 289-326... 

Nitrite (N02 ) as well as sulfide (H2S/S2 ) removal from waste waters is sometimes performed by ozonation. Both substances react fast with ozone (see Table 3-1). However, it must be emphasized that there are cost-efficient treatment alternatives, e. g. biological denitrification or sulfide removal. 

Sewage treatment has both ecological and economical importance. Ammonium and phosphate ions are the primary inorganic contaminants in municipal wastewater and these ionic compounds are responsible for the phenomenon of eutrophication. In common sewage treatment, ammonium is removed by biological denitrification and phosphates are precipitated with the help of aluminum and iron salts [56], However, the use of low-cost natural zeolites has been found promising for... 

Reduction of NO to N20 or N2 is important in biological denitrification where anaerobic organisms are involved and model studies using copper catalysts have been studied.42 Much study on other catalytic reductions of NO (and of N02) has been made in connection with atmospheric pollution.43... 

Biological denitrification is more complex to operate because it relies on the capabilities of active bacteria, but effectively convert nitrate to not toxic chemicals (N2). It can be subject to transient states generating malfunctions and requires thus greater care. Biological denitrification produces bacteria sludge, requires chemical additives (carbon source and other nutrients for bacteria) and especially requires large installations. 

Technology Ion Exchange Reverse Osmosis Biological Denitrification Catalytic Reduction... 

Firestone M. K. (1982) Biological denitrification. In Nitrogen in Agriculture (ed. F. J. Stevenson). American Society of Agronomy, Madison, Wisconsin, pp. 289-326. 

Most N2O is formed through biological denitrification in aerobic soils with anaerobic zones or in systems that are alternating between the anaerobic and anaerobic state (see below). 

This reaction may not actually acidify unless the NO3" is lost from the soil by leaching along with exchangeable base cations, leaving H to occupy exchange sites. Other possible fates of the NOs, such as plant uptake (see equation 5.42), generate alkalinity in the soil and may result in no net acidification. Similarly, biological denitrification of the NO ... 

Focht and Verstraete (1977), Knowles (1981), and Firestone (1982) have provided reviews of biological denitrification. As Fig. 9-1 shows, the reduc-... 

The catalytic destruction of ozone by NO is the most important process that occurs in the middle and upper stratosphere. We should stress here that this process is possible even in unpolluted atmosphere since small amounts of nitrous oxide, N2O, from biological denitrification have always been present in the stratosphere, which is the precursor of nitric oxide, NO, in reaction with atomic oxygen (reaction (11)). Most collisions with atomic oxygen form N2 and O2, but a few form NO (see also Section 4)... 

In natural conditions, the main source of nitrous oxide is biological denitrification (see more details in Chapter 13). This natural process is significantly uiCTeased in the whole World and in Asia as well by massive application of synthetic nitrogen fertilizers. Denitrification of fertilizer nitrogen leads to an increase of N2O concentration in the stratosphere (see Chapter 13 for details). 

The dominant input items were related to the application of mineral fertilizers and import of food and goods (abont 80% from total inpnt). Deposition (about 55% from abroad through transboundary air pollution) and non-symbiotic N fixation were responsible for the other 20% of input. The output was connected with N volatilization via direct NH3 volatilization and biological denitrification (33.7% from total input) and river discharge (23.2%). The sum of output was about 60% from input. 

The pH value can be markedly influenced by its biological processes. For example, during biological nitrification hydrogen ions are released which react with the hydrogen carbonates present to release free CO2 and the pH of the water decreases. Conversely the increase of pH of water can be observed during biological denitrification or reduction of sulphates. 

Biological denitrification and metal removal may be especially recommended as a treatment for bringing the level of these pollutants below the present stringent water quality standards the removal of the last traces of these pollutants probably can be done more efficiently by biological than by physical or chemical means. 

Ferris, J. S., Owens, R. W. Pilot scale, hlgh-rate biological denitrification. J. Water Poll. Control Fed. 47(8) 2043 (1975). 

Bailey, D. A. and Thomas, E. V. The removal of inorganic nitrogen from sewage effluents by biological denitrification. Wat. Poll. Cont. 74(5) 497 (1975). 

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