Experimental Study On Precipitation And Reuse Of Ammonia Nitrogen In The Wastewater From JianLong Vanadium Extracting Process

High ammonia nitrogen will change the environmental of water,and it will lead to the water pollution,even hurt the people’s health.There are vanadium,chromium and ammonia nitrogen in wastewater from Jian Long vanadium extracting process.This study used chemical precipitation method(MAP)to remove the high ammonia nitrogen and this method will be used after disposing the vanadium and chromium in wastewater.1.MAP:Using MAP method to deal with the ammonia nitrogen in the wastewater of Jian Long vanadium extracting process.In order to confirm the best process conditions of MAP process and confirm the constitute of precipitate,this study used single factor experiment and XRD,FTIR to analysis.It turns out that the best process conditions of MAP process were in the indoor temperature(25±1℃),used MgCl2·6H2O and Na2HPO4·12H2O as precipitating agent and the quantity of added precipitating agent were n(Mg2+):n(NH4+):n(PO43-)=1.3:1:1.2,adjusted pH of wastewater to 9.5 in the process of precipitation and took 20 minute and 30 minute respectively as the optimum reaction time and settling time.After the best process conditions of MAP process,the concentration of ammonia nitrogen in wastewater decreased to 52.1 mg/L.But the wastewater can not reach the emission standards of the country.The XRD and FTIR of precipitate indicated that the precipitate was made up of the MAP.2.Pyrolysising the precipitate:Using single factor experiment to confirm the best process conditions of pyrolysis treatment to the precipitate.The result indicated that when the quantity of added NaoH which was added into the precipitate was n(NaoH):n(NH4+)=2:1 and the pyrolysis was carry through 3 hours at 110℃,the effect of pyrolysis products dispose to the remove of ammonia nitrogen was the best.The XRD of pyrolysis products proved that the MAP was disappeared and the FTIR of pyrolysis products proved that the precipitate was transformed into some kind of amorphous phase.3.Reusing of pyrolysis product:The ammonia nitrogen in wastewater is releasing in a slow speed,in order to confirm the removal efficiency accurately,this study used the simulation wastewater which was compound of NH4CI and water and the concentration was 100mg/L.Using single factor experiment to confirm the best process conditions of reusing the pyrolysis product.The experiment indicated that the best process conditions of reusing of pyrolysis product were in the indoor temperature(25±1℃),adjusted the pH of wastewater to 9 in the reaction process,added quantity of pyrolysis product was n(MHP):n(NH4+)=2.2:1,took 30 minute as reacting time and settling time.Box behnken design multi factor modeling response method(BBD)is make the best conditions of the single factor experiment as a central point,and choice adjacent value at up and down area at the experimental design method.This method can analyze the relation among the influence factors accurately,and find out the best process conditions finally.According to the best conditions of reusing of pyrolysis product,this study use BBD to rearrange the relevant experiment.And finally acquired the best process conditions of influence factors.The result displayed that the best process conditions of reusing of pyrolysis product were put precipitate into wastewater as n(MHP):n(NH4+)=2.29:1,adjusted pH of wastewater to 9.33,and the reaction time was 37.18 minute.Result of this experiment shows that the theoretical value of removal rate of ammonia nitrogen was 92.79%.Through the experiment,we knew the actual removal rate of ammonia nitrogen was 92.24%.When we use the best process conditions to deal with the wastewater from Jian Long vanadium extracting process,the concentration of ammonia nitrogen match the emission standard of country.The XRD and FTIR of precipitate indicated that the precipitate was made up of MAP,and there was a little impurity like Mg3(PO4)2 and Mg(OH)2.