Short-cut Nitrification-anaerobic Ammonium Oxidation Process Salt Tolerance Characteristics And Treatment Of Rare Earth Mine Ammonia Nitrogen Wastewater

Partial nitritation/anammox process is expected to become the upgrading of wastewater denitrification process for the characteristics of without additional carbon source,low operation cost and high efficiency.However,in practical engineering,the process is susceptible to exogenous toxic.In this paper,a large amount of "high ammonia nitrogen,low C/N" salt wastewater produced during the leaching process of ionic rare earth ore was treated by partial nitritation/anammox process,and the effects of exogenous toxicants?High salt and rare earth elements?in ammonia nitrogen wastewater?Rare earth mine?on partial nitritation/anammox process was studied.Finally,the denitrification characteristics of ammonia nitrogen wastewater in simulated rare earth mine were studied in order to provide the theoretical basis and technical support for the treatment of ammonia wastewater in rare earth mine.The main conclusions are as follows:?1?Under normal temperature,the short-term nitrification can be started successfully within 35 days by limited providing oxygen?DO <0.5mg / L?.The NO₂^--N accumulation rate in the later stage is 0.95kg/?m³·d?,and remained above 95%.When the sludge is left at room temperature for 2 months,the NO₂^--N accumulation rate decreased by 82.11%,and recovered at 14 d,but the accumulation rate of NO₂^--N was only 51.58% compared with before the shelving,which says that short-range nitrification sludge should not be stored at room temperature;in addition,if the aeration time or aeration intensity controlled improperly,short-term nitrification is easy to turn to full nitrification,which can be determined by the abnormal rise of DO.?2?low salt environment?NaCl?20g/L?can promote short-range nitrification activity,too high salinity?40g/L?significantly inhibited sludge activity,its inhibition is reversible;In addition,the extracellular polymer?EPS?secretion is promoted with the increase of salinity,and the increase of polysaccharide?PS?content was more obvious.?AOB?and nitrite-oxidizing bacteria?NOB?in un-acclimated sludge were inhibited by different salinity,and inhibition was strengthening with the increase of salinity.Among them,NOB is more sensitive to salinity;In addition,the sludge activity decreased after high salt domesticated sludge transferred to low salt environment.?3?The addition of Ce³⁺ can prolong the initiation time of anaerobic ammonium oxidation and provided negative affect on the anammox bacteria,but it has little effect on the denitrification performance of the process,which can reduce the NO₃^--N production and increase the removal rate of TN.In addition,system was susceptible to the impact of nitrification and was easy to be instability in the low-load period?presence of O2?for long-term stability.The results show that the addition of Ce³⁺ inhibits the anaerobic ammonium oxidation sludge activity.When the amount of Ce³⁺ is 100 mg/L,the removal rate of TN is only 70.14% of the control group.When the amount of Ce³⁺ was 0.1 mg / L,the activity of AOB was 120.31% of the control group.When the amount of Ce³⁺ was 1 mg / L,the NOB activity was 116.50% of the control group.When the amount of Ce³⁺ was 100 mg/L,the activity of AOB and NOB was significantly inhibited.?4?The anaerobic ammonium oxidation was promoted under the low salt environment?NaCl?17.55g/L?,and the anaerobic ammonium oxidation was 14.44% of the control period when the salinity was 17.55g/L.High salt environment?NaCl> 17.55g/L?significantly inhibited the anaerobic ammonium oxidation of nitrogen,through the gradient to increase salinity,anaerobic ammonium oxidation reactor can adapt to 29.25g/L salinity,and the denitrification performance was similar to control period;In addition,During the process of salt acclimation,the increase of salinity leads to the increase of the average particle size of sludge and the secretion of EPS was suppressed,which was more likely to decrease the content of protein?PN?.Short-term experiments show that the activity of non-domesticated sludge reduced with salinity increased.And found that the IC₅₀ of salinity to anaerobic ammonium oxidation sludge was 13.81g/L.In addition,after acclimation,the inhibition of high salt was reduced and still had higher activity at higher salinity.At the same time,the high salt domesticated sludge was more sensitive to the fluctuation of salinity than the low salt domesticated sludge.?5?Partial nitritation/anammox process showed better performance in the simulation of rare earth mine ammonia nitrogen wastewater.Under normal temperature,the average concentration of NH4+-N,NO₂^--N,NO₃^--N and TN in effluent were?5.55±1.78?mg/L,?2.28±0.81?mg/L,?15.52±3.28?mg/L when the influent NH4+-N was?435.36±3.90?mg/L,and?23.36±3.70?mg/L,which could meet the requirements of "Rare Earth Industrial Pollutant Discharge Standard".