Nitrogen ammonia nitrite

Kjeldahl nitrogen. Of all the species of nitrogen, ammonia, nitrite, and nitrate are used as nitrogen sources for synthesis. They are to be provided in the correct amount in wastewater treatment. They also cause eutrophication in receiving streams. 

Oxidized species of nitrogen, chiefly nitrite and nitrate, occur in all soils and in the soil solution. Nitrite in the environment is of concern because of its toxicity. Its occurrence is usually limited because the oxidation of nitrite to nitrate is more rapid than the oxidation of ammonia to nitrite. Both nitrite and nitrate move readily in soil and nitrate is available to plants as a source of nitrogen and can move to plant roots with water. 

A. Analysis of Wastewater and Natural Waters. The presence of certain anions in wastewater effluents can cause deterioration of natural water systems. Phosphorous and nitrogen can be present in several chemical forms in wastewaters. Phosphorous is usually present as phosphate, polyphosphate and organically-bound phosphorus. The nitrogen compounds of interest in wastewater characterization are ammonia, nitrite, nitrate and organic nitrogen. Analyses are often based on titrimetric, and colorimetric methods (3). These methods are time consuming and subject to a number of interferences. Ion Chromatography can be used to determine low ppm concentrations of these ions in less than thirty minutes with no sample preparation. 

Nitrogen compounds are also usually present in rain water in the form of ammonia, nitrites, and nitrates, the two latter particularly during and after a thunderstorm owing to the combination of oxygen and nitrogen induced by the lightning and electric disturbances generally. 

Nitrosomonas—Genus of bacteria responsible for the conversion of ammonia-nitrogen to nitrite-nitrogen. 

Total nitrogen—The sum of the organic, free ammonia, nitrite, and nitrate nitrogens. 

We now consider in turn the various forms in which nitrogen may occur in the environment, ammonia, nitrite, nitrate, cyanide and cyanate. 

The colorimetric responses to equivalent amounts of nitrogen as ammonia, nitrite ion, nitrate ion, and hydroxylamine are identical within experimental error. Diethylamine, ethylamine, alanine, and acetamide, each present at a concentration of 0.50 p.p.m. nitrogen, yield null response. Phosphate at a concentration of 0.50 p.p.m. phosphorus does not interfere in the determination of 1.0-p.p.m. nitrogen. There is no interference by Cu Zn-, Cd Ni-% Fe-, Pb, or Ca- each at a concentration of 10 p.p.m, in the determination of 1.0 p.p.m. nitrogen. 

Ninety-five percent or more of the nitrogen in surface soils is usually present in organic form. The remainder is present as ammonia, nitrites and nitrates. In certain subsoils, as pointed out in Chapter 11, fixed ammonium may be present in amounts of up to 40% of the total nitrogen. 

The comprehensive method determines the nitrogen content for all forms of nitrogen compounds (nitrite, nitrate, urea, organic nitrogen, and ammonia), which upon distillation can be collected in a known amount of sulfuric acid and titrated with sodium hydroxide. A great deal of time is consumed in performing this classical nitrogen method. Note Boric acid may be used for collection of ammonia in the distillation step rather than sulfuric acid. 

Nitrogen-containing species The nitrate content in waters is usually low but can rise to appreciable levels in farming wastewater as a result of soil fertilization. Nitrite originates from the microbiological reduction of nitrate or the oxidation of ammonia. Nitrite is usually determined spectrophotometrically using the Griess reaction. Nitrate is determined by the same method after prereduction to nitrite. 

Qualitative Analysis. Nitric acid may be detected by the classical brown-ring test, the copper-turnings test, the reduction of nitrate to ammonia by active metal or alloy, or the nitrogen precipitation test. Nitrous acid or nitrites interfere with most of these tests, but such interference may be eliminated by acidifying with sulfuric acid, adding ammonium sulfate crystals, and evaporating to alow volume. 

Industrial production of sodium nitrite is by absorption of nitrogen oxides (NO ) into aqueous sodium carbonate or sodium hydroxide. NO gases originate from catalytic air oxidation of anhydrous ammonia, a practice common to nitric acid plants ... 

Ammonia, hydrazine, nitrites, and azides ate oxidized by bromine. Nitrogen is often a product of such reactions. 

When organics containing reduced nitrogen are degraded, they usually produce ammonium, which is in equilibrium with ammonia. As the pK for NH3 NH4" is 9.3, the ammonium ion is the primary form present in virtually all biological treatment systems, as they operate at pH < 8.5 and usually in the pH range of 6.5-7.5. In aerobic reactions, ammonium is oxidized by nitrifying bacteria (nitrosomonas) to nitrite... 

There is also considerable current environmental interest in hyponitrite oxidation because it is implicated in the oxidation of ammonia to nitrite, an important step in the nitrogen cycle (p. 410). Specifically, it seems likely that the oxidation proceeds from ammonia through hydroxylamine and hyponitrous acid to nitrite (or N2O). 

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