High Concentration Of Ammonium-nitrogen Removal From Wastewater By Ferric Sulfate

The Fe3+ and NH4+ generating ammonium jarosite in the reaction is the basic principle in this study and the formation conditions of ammonium jarosite has been studied. On the basis of the conditions, the pH value, temperature, ferric sulfate dosage, reaction time, initial concentration of ammonium-nitrogen, ammonium jarosite seed and other reaction conditions were investigated to confirm the influence of using sulfate to remove ammonium nitrogen from artificial wastewater. At the same time, the impact of factors of ammonium-nitrogen removal in leather waste and landfill has been studied and the optimum reaction condition was obtained and the formation mechanism of ammonium jatosite has been studied. The results show that:(1) The study of artificial water shows that when the reaction pH value is 1.3, NH3-N concentration is 2800mg/L, ferric sulfate dosage is n[Fe2(SO4)3]:n[(NH4)2SO4]=4:1, the reaction time is 8h, the NH3-N removal is 82.1%, residual NH3-N concentration is 501mg/L; When the pH value of the solution is between1.2 to 1.4, the ammonium-nitrogen removal efficiency is much higher. With the reaction temperature increased, the ammonium-nitrogen removal rate is also rising,80℃～90℃is much better. Increasing the concentration of iron could help the formation of ammonium jarosite, and increased the ammonium-nitrogen removal rate, both from the removal rate and the reagents consumption, the appropriate dosage is n[Fe2(SO4)3]:n[(NH4)2SO4]=4-6:1. Extended the reaction time could help to improve nitrogen removal, and the appropriate time is 6-8h; when some ammonium jarosite seed was added to the solution,it can significantly speed up the reaction rate.(2) Using the method to treatment landfill leachate, the NH3-N concentration is 1408mg/L. The results show that when the pH value of the solution is 1.3,the reaction temperature is 80℃, the ferric sulfate dosage is n[Fe3+]:n[NH4+]=5:1,the reaction time is 8h,adding 0.5g seed to the solution, the rate of ammonium-nitrogen removal is 70%, residual NH3-N concentration is 422mg/L.(3)Using the method to treatment leather wastewater, the NH3-N concentration is 710mg/L. The results show that when the pH value of the solution is 1.2,the reaction temperature is 80℃, the ferric sulfate dosage is n[Fe3+]:n[NH4+]=5:1,the reaction time is 8h,adding 0.5g seed to the solution, the rate of ammonium-nitrogen removal is 72%, residual NH3-N concentration is 199mg/L.(4) The reaction is divided into five stages for the color change of the reaction process. Through the analysis of sediment quality change and XRD of the 5 stages of the formation of ammonium jarosite, it can be infer the reaction mechanism of the formation of ammonium jarosite. The formation of ammonium jarosite is believed to start with the species FeSO4+ and Fe(OH)3. [Fe(OH)2]2SO4 and Fe(OH)SO4, may be precursors for the formation of ammonium jarosite and through a series of reaction to generate ammonium jarosite.