Application Of SBR Short-cut Nitrification Of Low Carbon Ammonia Nitrogen Wastewater In Rare Earth Mining Area

A large amount of ammonium sulfate leaching solution was injected into in-situ leaching,while the ammonium sulfate leaching solution of abandoned rare earth ore would remain and leak after leaching.Under the action of surface runoff,rainwater leaching and leakage,this kind of leachate will flow into the surface water body of mining area through the leachate collection outlet,further affecting the surface water quality,resulting in the surface water ammonia nitrogen index exceeding the standard.There are some shortcomings such as high treatment cost,secondary pollution and difficulty to meet the current strict wastewater discharge standards in the treatment of such wastewater by physicochemical method.Traditional biological denitrification needs sufficient carbon and oxygen sources,while the carbon source content of ammonia-nitrogen wastewater in rare earth mining area is low,and further carbon sources need to be added to meet the need of reaction,so it increases the difficulty of treatment and operation cost.Based on the above reasons,it is particularly important to find an economical and effective method to deal with such water bodies.Short-cut nitrification and denitrification technology is a new biological denitrification technology in recent years.Compared with traditional biological denitrification technology,its advantages are mainly embodied in saving oxygen consumption,carbon source and excess sludge.It is favored by many scholars.Short-cut nitrification and denitrification was realized in SBR reactor.The stability of short-cut nitrification system was investigated by changing the operating conditions of the system.Finally,the kinetics of pollutant removal in the system was analyzed.The experimental results show that:?1?Based on the domesticated whole nitrification sludge,the domestication of short-cut nitrification and denitrification sludge was completed under the conditions of 28±1?temperature,65 L/h aeration and 8 pH.After that,the SBR short-cut nitrification and denitrification process was started by using actual wastewater,and the ammonia-nitrogen removal rate was maintained at about 92%,which was 3%lower than that of simulated wastewater;Finally,the sludge before and after the start-up of short-cut nitrification was detected by high-throughput sequencing.After the start-up of short-cut nitrification,AOB was the dominant bacteria in the reactor,accounting for 11.5%.?2?By increasing the aeration rate of the system,it is concluded that the amount of aeration is inversely proportional to the time required for nitrification;the effect of high aeration rate on the stability of the system is not obvious in the short term,but the nitrite accumulation rate will decrease to 82%after 7 days of operation,which is under the condition of 120 L/h aeration rate.?3?By changing the C/N ratio in SBR system,it was found that the change of C/N ratio had little effect on ammonia-nitrogen degradation and nitrite-nitrogen accumulation.The insufficient carbon source was not the inhibitory factor for ammonia-nitrogen removal.When C/N ranged from 3.5 to 7.6,the removal rate of NH₄⁺-N can be stabilized at about 95%,and the accumulation rate of nitrite-nitrogen can reach over 93%.?4?Over-aeration can easily lead to the change of nitrification type.The nitrite accumulation rate dropped to 85%after the 5th day of excessive aeration,and to 48.89%at the 8th day,indicating that the system has been transformed from short-cut nitrification to full-course nitrification.?5?Through the kinetic analysis of short-cut nitrification and denitrification,the kinetic model of short-cut nitrification suitable for this experiment was obtained.It is found that the kinetic parameters are in good agreement with the actual values.