Nitrification, chemical

Steam stripping Air stripping Biological nitrification Chemical oxidation Ion exchange Solvent extraction Biological oxidation (aerobic) Wet oxidation Activated carbon Chemical oxidation Chemical precipitation Ion exchange Adsorption Nano-filtration Reverse osmosis Electrodialysis... 

S. P. Landels, M. M. Smart,. Bakker, and. Shimosato, "Controlled Release Fertilisers and Nitrification Inhibitors," Chemical Economics Handbook, SRI International, Menlo Park, Calif., 1989. 

Conventional wastewater treatment techniques consist of physical/chemical treatments, including oil separation, dissolved gas flotation, and ammonia distillation (for removal of free cyanides, free sulfides, and ammonia) followed by biological treatment (for organics removal) and residual ammonia nitrification. Almost all residuals from coke-making operations are either recovered as crude byproducts (e.g., as crude coal tar, crude light oil, ammonium sulfate, or other sulfur compounds)... 

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. 

PROFILE is a biogeochemical model developed specially to calculate the influence of acid depositions on soil as a part of an ecosystem. The sets of chemical and biogeochemical reactions implemented in this model are (1) soil solution equilibrium, (2) mineral weathering, (3) nitrification and (4) nutrient uptake. Other biogeochemical processes affect soil chemistry via boundary conditions. However, there are many important physical soil processes and site conditions such as convective transport of solutes through the soil profile, the almost total absence of radial water flux (down through the soil profile) in mountain soils, the absence of radial runoff from the profile in soils with permafrost, etc., which are not implemented in the model and have to be taken into account in other ways. 

Although an unequivocal quantitative mass balance could not be obtained, a plausible reaction sequence was deduced that accounts reasonably well for the residual chemical water composition. The amount of CaC03 that had to be dissolved to establish the residual water composition is about what can be accounted for by wind-blown calcite dust. The neutralization of the acidic precipitation by NH3 was, subsequent to its deposition, largely annulled by the H+ ions produced by nitrification and NHJ assimilation. 

Uses Rubber accelerator solvent in fiber and plastic industry rocket fuels lubricants condensers to increase dielectric constant industrial solvent antioxidant nematocide softener of copolymers research chemical plasticizer in acrylonitrile polymers inhibit nitrification in soil chemical intermediate for 1,1-dimethylhydrazine. 

Crutzen, P.J. 1981. Atmospheric chemical processes of the oxides of nitrogen, including nitrous oxide. In Delwiche, j. (ed.) Denitrification, Nitrification and Nitrous Oxide. Wiley and Sons, New York. pp. 17-44. 

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 ... 

Chemical Name 5-ethoxy-3-(trichloromethyl)-l,2,4-thiadiazole ethyl 3-trichloromethyl-l,2,4-thiadiazolyl ether Uses as fungicide for control of Phytophthora and Pythium spp. in cotton, ornamentals, vegetables, groundnuts, cucurbits, tomatoes, and other crops also used as a nitrification inhibitor in maize, cotton and wheat. 

In some cases, the effects of complex environmental mixtures could be accounted for in terms of concentration-additive effects of a few chemicals. In sediments of the German river Spittelwasser, which were contaminated by chemical industries in its vicinity, around 10 chemicals of a cocktail of several hundred compounds were found to explain the toxicity of the complex mixture to different aquatic organisms (Brack et al. 1999). The complex mixture of chemicals contained in motorway runoff proved toxic to a crustacean species (Gammarus pulex). Boxall and Maltby (1997) identified 3 polycyclic aromatic hydrocarbons (PAHs) as the cause of this toxicity. Subsequent laboratory experiments with reconstituted mixtures revealed that the toxicity of motorway runoff could indeed be traced to the combined concentration-additive effects of the 3 PAHs. Svenson et al. (2000) identified 4 fatty acids and 2 monoterpenes to be responsible for the inhibitory effects on the nitrification activity of the bacteria Nitrobacter in wastewater from a plant for drying wood-derived fuel. The toxicity of the synthetic mixture composed of 6 dominant toxicants agreed well with the toxicity of the original sample. 

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. 

Another nitrification inhibitor that has received much attention in Japan is 2-ami no-4-chloro-6-methyl pyrimidine. It is manufactured by Mitsui Toatsu Chemicals, Inc. (formerly Toyo Koatsu Industries, Inc.) under the trade name AM. Other nitrification inhibitors that have been used in Japan in compound fertilizers are sulfathiazole, dicyandiamide, thiourea, N-2, 5-dichorphenyl succinamide, 4-amino-l, 2, 4-triazole hydrochloride, and guanylthiourea.50... 

Even if rate measurements in sediments are made using whole core incubations, e.g., when the inhibitor is a gas, it is still difficult to obtain a depth distribution of the rate (usually, an areal rate is obtained). A sophisticated measurement and model based system that avoids direct rate measurements has been used to overcome this problem. Microelectrodes, which have very high vertical resolution, are used to measure the fine scale distribution of oxygen and NOs" in freshwater sediments. By assuming that the observed vertical gradients represent a steady state condition, reaction-diffusion models can then be used to estimate the rates of nitrification, denitrification and aerobic respiration and to compute the location of the rate processes in relation to the chemical profiles (e.g., Binnerup et ai, 1992 Jensen et ai, 1994 Meyer et ai, 2001 Rysgaard et ai, 1994). Recent advances and details of the microelectrode approach can be found in the Chapter by Joye and Anderson (this volume). 

As an alternative to partial assimilatory NOs reduction by phytoplankton, oxidation of NH4+ by Bacteria and Archaea (the first step in the 2-step process of nitrification) can produce N02 as an intermediate product. Nitrifying bacteria were first isolated from the marine environment by Watson (1965) and are now known to be ubiquitous in the global ocean. Wada and Hattori (1971) used a sensitive chemical assay to measure changes in N02 in incubated samples, to conclude that NH4+ was the major source of N02 in the PNM in the central North Pacific Ocean. Miyazaki et al. (1973, 1975), using a N tracer method, found that, in Sagami Bay and in the western North Pacific, NH4+ and NOs were both important sources ofN02. ... 

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