Study On MBR Treatment Efficiency And Microbial Characteristics Of High-salt Ammonia-nitrogen Wastewater

Fresh water plays an important role on human evolution,but also in the condition of human race inherited.With the development of economic,the shortage of fresh water resources gradually and the polluting by thigh salt has become the factors that cannot be ignored in the restricted industrial developmentand the social stability.In recent years,with the application of rare earth in various fields more and more widely,the amount of rare earth smelting wastewater is also gradually increasing.Therefore,actively develop rare earth smelting high salt containing ammonia nitrogen wastewater harmless research has great practical significance.Based on the course of some rare earth smelting company actual production wastewater as the research object,from microbial characteristics,this paper studies the activated sludge domesticated salt-tolerant structure of microbial community structure in the process of change,the influence of operating conditions on the MBR operation efficiency and the effect of salt on MBR microbial characteristics,come to the conclusion as follows:In the process of domestication,with the rising water salinity,MLSS within the system of relatively slow growth.After 70 d of domestication,the numerical grows from the original 4.0 g/L up to 5.2 g/L,SVI value increased from 76.56 mL/g and 76.56 m L/g,System of CODCr,NH-4⁺-N removal effect is stable,reached 81.88 %,82.82 %.With the increase of feed water salinity,sludge floc structure is more and more closely,sedimentation velocity gradually accelerated,and turbidity in supernatant was increased;Microbial community structure of community gradually by the protozoan and metazoan and bacterial diversity state of being turned into a native animals and microbes,and in the late domestication,filamentous bacteria in the sludge flocs,large metazoan basic disappear.The removal efficiency of CODCr and NH-4⁺-N was studied on different HRT,DO,pH and SRT by changing the operating parameters in the MBR.The results showed that the system to operate optimally at the condition of HRT = 12 h,DO = 4.0 mg/L,SRT≥45 d,pH = 8.0 to 8.5.Under that condition,the average removal rate of CODCr and NH-4⁺-N was achieved 81.17 % and 86.60 %.In stable operation after a period of time,the system of CODCr and NH-4⁺-N removal effect with decrease with the rising of feed water salinity.When the water salinity increase to 51.02 g/L,the system of CODCr and NH-4⁺-N removal rate was only 58.16 % and 58.16 %,compared with 30.50 g/L reduced by 27.67 % and 54.18 %,respectively,the phenomena of NO₂^--N accumulation of different level was appeared during the experiment.That salinity of denitrifier inhibitory effect stronger than decarburization bacterium,the nitrite oxidizing bacteria inhibition degree than ammonia oxidizing bacteria is also.However,The system of CODCr and NH-4⁺-N removal rate were increased from 85.83 % and 83.62 % to 86.11 % and 86.36 % with the water salinity gradually from 30.50 g/L decreased to 5.08 g/L or so.The results indicating that the microbial cells gradually it was restored,but it requires more than increase the concentration of inorganic longer time to adapt to the new environment.Under different salinity environment by means of soluble organic matter（DOM）in the sludge,the mixture composition analysis shows that less number of characteristic peak under the environmengt of low concentration of inorganic salt;With the increase of salinity,tryptophan,fulvic acid,UV-humic acid,humic acid appeared,fluorescence peak appeared,and its fluorescence intensity increases with the increase of salinity.