Removal of Ammonia Nitrogen by the Precipitation Method, on the Example of Some Selected Waste Waters

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Abstract
The topic of the paper was finding a possibility of ammonie nitrogen removal by the precipitation method, on the example of municipal wastes and two kinds of liquid industrial wastes, from a coking plant and Nitrogen Works. The concentrations of this component were of such a kind that they could inhibit both the processes of biological purification and the processes of self-purification, and cause far-reaching eutrophication. The initial concentration was:70 mg/dm3 NH4+ in municipal wastes, 3600 mg/dm3 NH4+ in coking plant wastes, and 16.142 mg/dm3 NH4+ in the liquid wastes from Nitrogen Works. The industrial wastes were diluted to about 156 mg/dm3 NH4+ in the case of coking plant wsates, and to about 170 mg/dm3 NH4+ in the case of wastes from Nitrogen Works. The precipitants for the municipal wastes were magnesium chloride and 85% phosphoric aoid, and for the remaining wastes also magnesium oxide and phosphoric acid. The reaction time used was 5-30 minutes, the reaction -pH 8.0 : 9.5 and 10.5. The quantities of the precipitants - from 0-200% of the stoichiometric dose. The precipitation of ammonia nitrogen in municipal wastes was most effective with wastes reaction pH about 9.5 and precipitants doses 0.80 g/dm3 MgCl2 and 0.47 g/dm3 H3PO4, and the reaction time of 25 minutes.The effect of ammonia nitrogen removal was 36.0% which corresponded to 100% stoichiometric doses, Whereas an increase of the doses to 200% increased the effects by only 1%. The effects of ammonia nitrogen removal from the coke plant wastes were 470% with the precipitants doses of 4.54 g/dm3 MgCl2 and 1.28 g/dm3 H3PO4 which is 100% of the stoichimetric dose, and after increasing the dose to 200% they were increased by 35%. The degree of ammonia nitrogen removal from the liquid wastes from Nitrogen Works was 62.9% with 100% dose and increased to 81.2% at 200%. The use or magnesium oxide and phosphoric acid for the removal of ammonia nitrogen from industrial wastes in analogical conditions gave much worse results.

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