Immobilization Of Powdered Zeolite And Its Application In The Treatment Of Low Concentration Ammonia Nitrogen Wastewater

Low concentration ammonia nitrogen in industrial water,especially regenerated cooling water,will corrode copper metal parts in transportation pipe network.However,there are few studies on the removal of low concentration ammonia nitrogen.Powder artificial zeolite with small particle size and pore structure,which has the advantages of selective exchange of ammonia nitrogen and good ammonia nitrogen adsorption effect,becoming a prominent effective low concentration ammonia nitrogen remover.The disadvantage of powder artificial zeolite is the poor controllability,which is not conducive to separation and recovery.In order to solve the above problems,using artificial zeolite as the core material,this study adopted two methods to improve the manipulability of powder zeolite,and basically does not affect its adsorption of low concentration ammonia nitrogen.The first one is the composite material method.On the basis of our research group existing studies on artificial zeolite-cellulose acetate composites,the factors such as the film forming method,the filling method,the dosage and the flow rate of the composites in the column adsorption experiment were optimized.The results showed that the artificial zeolite was fully exposed by the film forming method of gently scraping the film surface with glass plate before acetone volatilized completely.The removal rate of ammonia nitrogen reached 82.8%,and the forming time was short,only 15 min.The composite materials can be prepared quickly and efficiently by this method.The optimum conditions in the composite adsorption of low concentration ammonia nitrogen column were as follows:shear sheet（2 cm×2 cm square）was used to fill the column,the filling amount was 15.0 g,and the flow rate was 0.6 m³/h.Under the optimal conditions,12.0 L ammonia nitrogen wastewater with a concentration of 5mg/L can be reduced to less than 1 mg/L.The composite material is suitable for the removal of low concentration ammonia nitrogen from water as the filling material of adsorption column.The second one is the magnetic zeolite method.Load a certain amount of magnetic particles in zeolite powder,and achieve solid-liquid separation through magnetic separation technology to achieve rapid enrichment and recovery.Using chemical deposition method,adding artificial zeolite powder with particle size of 10μm to magnetic Fe₃O₄system prepared by chemical co-precipitation method,adding polyacrylamide as binder,the magnetic zeolite prepared by this method has super paramagnetic properties.With the help of external magnetic field,the magnetic adsorbents in the wastewater were separated,so as to achieve the purpose of enhancing the manipulation of zeolite powder.The results show that in the process of preparing magnetic zeolite,the magnetic susceptibility of magnetic zeolite increases with the increase of Na OH concentration when the concentration of Na OH is between 1mol/L-7 mol/L,but when the concentration of Na OH reaches 10 mol/L,the magnetic susceptibility of magnetic zeolite decreases instead of increasing,and the removal effect of magnetic zeolite on ammonia nitrogen does not change significantly with the increase of Na OH concentration.When the concentration of Na OH was 7 mol/L,the saturation magnetization reached 15.45 emu/g.When the p H value of water sample is 7,the temperature is set at 25℃,and the initial concentration of ammonia nitrogen is 5mg/L,the magnetic zeolite has the best effect on the treatment of low concentration ammonia nitrogen,and the removal rate of ammonia nitrogen reaches 90.8%,and the effluent concentration of ammonia nitrogen reaches less than 1 mg/L.By comparing the magnetic zeolite with the artificial zeolite of the same mass,the ammonia nitrogen removal rate of artificial zeolite is 92.7%,which is only 1.9%higher than that of magnetic zeolite.The Langmuir isotherm model and Freundlich isotherm model R²of the magnetic zeolite adsorption process of low concentration ammonia nitrogen are both above 0.9,indicating that both chemical adsorption and physical adsorption exist in this process.Adsorption exchange process follows quasi-second-order kinetics After six times of simple regeneration and circulation of magnetic zeolite,the concentration of ammonia nitrogen in wastewater with initial concentration of 5 mg/L can still be reduced to less than 1 mg/L.When the actual low concentration ammonia nitrogen wastewater is treated,the actual wastewater can be effectively treated by increasing the dosage of magnetic zeolite,and the ammonia nitrogen concentration in the treated water sample is less than 1 mg/L,which proves that magnetic treatment of the actual low concentration ammonia wastewater is feasible.The magnetic zeolite is suitable for the adsorption of ammonia nitrogen in the reactor containing ammonia nitrogen wastewater.