Study On Treatment Of Ammonia-nitrogen Wastewater By Two Oxidant With Different Metal Oxide Catalysts

Catalytic ozonation and catalytic oxidation with NaCl O were researched respectively by the way to catalytic oxidation in this study.The effect of treating ammonia-nitrogen wastewater was investigated by the two ways in different external conditions so that summarizing the directions,ways of nitrogen conversion and ways to oxidant utilization rate improving,concluding the favourable conditions of conversion of N2 and cutting treating cost.The main contents are as follows:CuO provides the best effect of catalytic ozonation by the comparison of treatments of ammonia-nitrogen wastewater over several kings of catalysts.The effects and products analysis of catalytic ozonation of ammonia-nitrogen wastewater were investigated under different conditions of pH,catalysts dosage,initial concentrations,ozone dosage and temperature.Preferable performance of ammonia-nitrogen removal presented in the case of pH?11 by the combine effect of ·OH and ozone.The best CuO dosage determined at the level of 10g/L and there is a bad effect on the transformation of ammonia-nitrogen in the case of overmuch and little dosage.The removal rate of ammonia-nitrogen was decreased with the increasing initial concentrations,but the producing of NO₃^-increase in the condition of low initial concentrations.The removal rate of ammonia-nitrogen was increased with the increasing ozone dosage and the removal of TN firstly increase,then decrease with the top of the removal at 4.5mg/min.Not only the removal of ammonia-nitrogen increased with the increasing temperature but decreased the producing of NO₃^-thereby the removal of TN increased to 26.6%.In catalytic ozonation for ammonia-nitrogen,reducing ·OH removal reaction,direct removal reaction of ·OH and O₃,direct ozonation of ammonia-nitrogen are the beneficial ways for N₂ conversion.Ni₂O₃ provides the obvious effect of catalysis by the comparison of treating ammonia-nitrogen wastewate by catalytic oxidation with NaCl O over several kinds of catalyzers.The facts and products analysing were investigated respectively in the conditions of appropriate NaClO dosage,catalyzer dosage,internal concentration,oxidant changing dosage,pH and temperature.The reaction rate was accelerated when adding Ni₂O₃,but the TN removal rate decreased due to the conversion to NO₃^-increased.Dosing of Ni₂O₃ can only accelerate the reaction rate and advance the end point but cutting the NaClO needed in direct oxidation in the same conditions.The suitable pH is 7in this experimental condition.There is a bad effect on catalytic oxidation because the effect of NaClO self decomposition is more obvious than improving catalytic reaction rate under high temperature.Residual chlorine reflect the situation of nitrogen conversion indirectly and final residual chlorine can be cut when dosing Ni₂O₃ by the comparison of direct oxidation.While in catalytic oxidation with NaClO for ammonia-nitrogen,adding Ni₂O₃,initial concentration,keeping neutral environment,properly raising temperature are the beneficial ways for reaction time cutting.The way of oxidant cutting was not found temporarily in this study.