The Research Of Nitrogen Removal By Adsorption From Tail Water Of Urban Sewage Treatment Plant

In response to China's increasingly stringent urban tailwater discharge standards and the urgent need for upgrading,large-scale urban sewage plants have successively added denitrification and denitrification units at the end,and achieved good results.However,the cost and area of nitrogen removal have also increased significantly.In order to solve this problem,this study explored the use of fast and efficient ion exchange technology to remove and recover nitrate,to achieve the purpose of reducing processing costs and resource recovery.In this paper,201×7 strong basic anion exchange resin was used to treat the tail water of secondary treatment in actual urban sewage treatment plants.The effect of NO₃^-adsorption and removal under different test conditions was investigated,and the adsorption mechanism was studied.The research results are as follows:?1?The static adsorption experiment results show that the adsorption equilibrium time of the resin is 30min,the adsorption capacity increases with the increase of the initial concentration,and the temperature has little effect on the adsorption effect. When the initial concentration is 14 mg/L and the resin dosage is 7 g/L,the equilibrium adsorption capacity of the resin is 1.96 mg.N/g;the optimal solution concentration is Na Cl with a mass fraction of 7%.The adsorption of NO3-by the resin conforms to the Freundlich adsorption isotherm model;the adsorption kinetics conforms to the quasi-second adsorption kinetic model,and the adsorption rate is controlled by particle diffusion.?2?The results of dynamic adsorption experiments show that the higher the initial concentration,the shorter the time for the resin to reach the penetration point,and the smaller the penetration volume;as the height-to-diameter ratio increases,the penetration volume of the resin increases;the lower the water intake The flow rate can increase the penetration time,which is conducive to resin adsorption;when the influent NO₃^-14 mg/L,TP 0.5mg/L,SO₄^2-50mg/L,the influent flow rate 20BV/h and the adsorption column height to diameter ratio 2.5,the resin The dynamic adsorption capacity is 3.44 mg/ml.?3?Static and dynamic single-factor tests show that the main anions SO₄^2-and PO₄^3-in the tail water will have an effect on the adsorption of NO₃^-by the resin,and its effect will increase with the increase of ion concentration.In the concentration range of this experiment,the anion that has the most obvious effect on the adsorption effect of the resin is SO₄^2-,and the low concentration of PO₄^3-basically does not affect the adsorption of NO₃^-by the resin.?4?During resin analysis,the slower the flow rate of the analysis liquid,the better the analysis effect;as the amount of analysis liquid increases,the regeneration rate continues to increase.When the flow rate is 20BV/h in 7%Na Cl solution of 6.7BV,the analysis of each ion is greater than 96%,so the resin can be used for many times.