Experimental Study Of Removal Ammonia Nitrogen In Simulation Wastewater Of Two Grade Treatment Effluent By Modified Zeolite

In recent decades, with the rapid development of industry, water consumption continues to increase. Environmental pollution has also ted to fresh water resource is shortage, and at the same time, industrial wastewater and sewage containing a large number of nitrogen and phosphorus discharged into the water, the effluent ammonia nitrogen concentration did not reach the discharge standards, seriously affected the people’s health level and restricted the development of economy.As a kind of bw-cost adsorbent, zeolite has a good selective adsorption ability for ammonia nitrogen. The adsorption capacity for NH4+-N of natural clinoptilolite is limited, but it can be greatly improved by modification treatment. For the ammonia nitrogen removal in wastewater, which ammonia nitrogen concentration of the two grade treat-ment effluent can not reach at the Class 1 Level A discharge standard (limit is 15mg/L), this reaserch used the natural zeolite as raw materials, after the screening to get size is 60-80 mesh, then modified by acid, alkali, salt, high temperature calcination and two kinds of combination treatment modification methods after pretreatment, finally choose the best modified zeolite to complete experimental study of removal ammonia nitrogen in wastewater of simulation two grade treatment effluent. The main research contents of this subject including modification experiment, static experiment, dynamic experiment and regeneration experiment. Draw the following conclusions:Modification experiment treated clinoptilolite in a variety of ways, including high temperature, NaOH solution, hydrochloric acid, NaClsolution, high temperature and NaCl solution, NaCl solution and high temperature. Result shows that clinoptiblite treatmented by 60g/LNaCl solution and 400℃ high temperature, then removal effect of simulation ammonia nitrogen wastewater was the best.Static experiment discussed that in the condition of simulation ammonia nitrogen wastewater concentration is 15mg/L, and clinoptilolite treatmented by 60g/L NaCl solution and 400℃ high temperature, the influence of factors such as dosing quantity, reaction time, temperature, pH and initial ammonia nitrogen concentration to removal effect of ammonia nitrogen. The results show that; In the case of dosing quantity of 1.5 g reaction time of 40 min, reaction temperature of 30℃ and pH value of 8, the removal rate of ammonia nitrogen was above 91.4%; Adsorption isotherm model in both line with the Langmuir and Freundlich equation, and better in accordance with the Freundlich equation, and the correlation coefficient R2 is above 0.98, and the reaction is spontaneous and endothermic; Adsorption kinetics model more in line with the Langmuir first order kinetics equation, and the correlation coefficient R2 is above 0.99.Dynamic experiment discussed the influence of factors such as filter layer thickness and filtration velocity to the breakthrough curve of ammonia nitrogen. The results show that the higher filter layer thickness, the longer the breakthrough time; The bigger filtration speed, the shorter the breakthrough time; Under the condition of experiment, when filter layer thickness is 80cm, achieve breakthrough point time was 570min;When filtration speed is 5ml/min, achieve breakthrough point time was 690 min; In the case of filter column inner diameter is 4cm, filter layer thickness of modified zeolite is 80cm, filtration speed of adsorption column is 5ml/min, the removal effect of ammonia nitrogen in wastewater was better. It shows that using modified zeolite filter column to remove ammonia nitrogen in wastewater is feasible and effective.Regeneration experiment discussed the influence of factors such as coneentration of NaCI regeneration solution, regeneration time and regeneration times to the regeneration rate of saturated modified zeolite. Result shows that when coneentration of NaCI solut-ion of 0.6mol/L, regeneration time of 2.5h, the regeneration rate of saturated modified zeolite was above 84.5%. In the same conditions, regeneration treatment of the former eight times all can made the adsorption capacity of recycled modified zeolite recovery between 78% and 85%, effluent concentration of ammonia nitrogen were less than 5 mg/L, reached effluent concentration of experimental requirements.It shows that regeneration ability of this experimental zeolite is strong, and can be used once again.