Study On Steady State Operation Mechanism Of Aniline Wastewater Biological Treatment Based On Electrical Stimulation

Aniline is a very important industrial organic raw material.Its complex structure makes it difficult to be chemically oxidized and reduced,and its severe biological toxicity also increases the difficulty of biodegradation.In addition,the biodegradation of aniline will remove ammonia and release ammonia nitrogen.High concentration of ammonia nitrogen will not only inhibit the activity of microorganisms,but also cause the content of ammonia nitrogen and total nitrogen in effluent to exceed the standard and endanger the water body.Electro biological system based on electrical stimulation has become a new direction in the field of environmental treatment.It can not only improve the degradation efficiency of complex pollutants,but also effectively save energy consumption and reduce the cost of wastewater treatment.Taking aniline wastewater as the research object,this paper systematically investigated the effects of voltage intensity（0 V,1.5 V,3 V,4.5 V,6 V）,voltage action mode（continuous electrical stimulation,on for 2 h,off for 2 h,on for 12 h,off for 12 h,continuous aerobic electrical stimulation,continuous anoxic electrical stimulation）and salinity（0%,0.5%,1.5%,2.5%,3.5%）on the degradation of aniline by electro biological system,and deeply analyzed the physiological and biochemical characteristics of sludge,and explore the changes of microbial community structure and the law of growth and metabolism.The main conclusions are as follows:（1）An electro biological system based on electroenhanced sequencing batch reactor was constructed to explore the characteristics of E-SBR in aniline degradation and denitrification.E-SBR achieves more efficient decontamination performance based on enhanced electron transfer.The aniline removal rate of E-SBR is more than99%,and the total nitrogen removal rate is about 80%.The activities of physiological and biochemical indexes（SOUR,TTC-DHA,AMO,Nar）of E-SBR were higher than those of the control biological system without power on,and the sludge performance was more stable.Electrical stimulation changed the original microbial community structure,and Luteococcus,Thauera,Arenimonas and Deniratisoma in activated sludge and biofilm gradually became the dominant bacteria.The abundance of nitrogen metabolism and carbohydrate metabolism in E-SBR increased.（2）Explore the effects of voltages on E-SBR.The experimental results show that each system can achieve nearly 100%aniline removal rate.The aniline degradation rate of the system increases successively under 0 V,1.5 V and 3 V electrical stimulation,and the aniline degradation rate is inhibited by 4.5 V and 6 V electrical stimulation.1.5V electrical stimulation promoted the nitrification performance of the system.4.5 V and 6 V electrical stimulation would lead to the loss of nitrogen removal ability and the significant accumulation of NH₄⁺-N.Physiological and biochemical indexes（SOUR,TTC-DHA,AMO,Nar）showed that low voltage promoted the improvement of sludge activity,while high voltage was on the contrary,and the stability of sludge became worse under high voltage.With the increase of voltage,the dominant bacteria of each system are Saprospiracee,NS9＿marine＿group,Ferruginibacter,Chitinophagaceae and Rhodocooccus respectively.1.5 V electrical stimulation increased the abundance of aniline degradation and denitrification related genes in the system.（3）The effects of different voltage action modes on the performance of E-SBR were investigated.The experimental results show that the change of electrical stimulation mode has a significant impact on the denitrification performance.The nitrification and denitrification effect of the system is the best under the mode of opening for 2 hours and closing for 2 hours.The continuous aerobic electric stimulation mode will improve the nitrification performance,and the continuous anoxic electric stimulation mode is conducive to the improvement of denitrification performance.On for 2 hours and off for 2 hours,electrical stimulation increased the activity of sludge.Intermittent electrical stimulation will improve the richness and diversity of microorganisms in the system,and the microbial community structure will be more uniform.The abundance of some functional genes involved in aniline and nitrogen metabolism is relatively high.（4）The effects of salinity on the performance of E-SBR were investigated.The results showed that the degradation rate of aniline decreased under high salinity stress.In addition,the nitrification effect of the system with 0.5%salinity is improved,and higher salinity will lead to poor nitrification and denitrification performance and system collapse.The gradual increase of salinity leads to the deterioration of sludge stability.At the same time,the activities of SOUR,TTC-DHA,AMO and Nar of sludge were significantly inhibited.The analysis of microbial diversity showed that the microbial community structure of 0%,0.5%and 1.5%salinity system was more abundant and uniform,in which olb8 was the dominant genus,while under 2.5%and3.5%high salinity stress,the microbial structure was unevenly distributed,and the Halophilic Bacterium Xanthomarina occupied a dominant position in the high salinity system.The results of picrust function prediction showed that the abundance of genes involved in aniline degradation and denitrification was higher in the 0%salinity system.In this study,the treatment of aniline wastewater by E-SBR system based on electric enhancement was explored,the reactor was constructed,the operation condition optimization of the system was successfully started,the characteristics and laws of aniline biodegradation and nitrogen metabolism under electric stimulation were revealed,and the theoretical basis for the application of E-SBR to the treatment of pollutants in practical engineering was provided.