Study On The Treatment Of Ammonia-Nitrogen High Salt Wastewater By SBR Short-cut Nitrification And Denitrification Process

As a kind of pollutant,ammonia nitrogen was harmful to water body directly,it was easy to cause algae propagation in water,destroy the balance of water environment at the same time bring harm to human health,so the standard of ammonia nitrogen drainage in our country was becoming more and more strict day by day.However,in the process of ammonia-nitrogen wastewater treatment,high salinity was often encountered,so how to realize the denitrification of wastewater in high-salt environment becomes a big problem.In this study,the SBR short-cut nitrification and denitrification process was used to treat ammonia-nitrogen high-salt wastewater.The realization of short-cut nitrification and denitrification and the treatment of ammonia-nitrogen high-salt wastewater were analyzed in detail.The main research results are as follows:The DO,pH curve of the whole nitrification and denitrification cycle was analyzed before start-up,and the critical point of aeration time was determined to be350 min considering the DO jump point and the lowest point of pH.After 39 days of start-up with limited aeration time,short-cut nitrification and denitrification were achieved.The NO₂^--N accumulation rate of the reactor was 65.86%and the ammonia-nitrogen removal rate was over 97%.The optimized experiment of short-cut nitrification and denitrification showed that the accumulation rate of NO₂^--N increased gradually with the increase of pH,and the maximum NO₂^--N accumulation rate reached 77.70%when pH was 8.2.The removal rate of ammonia nitrogen increased with the increase of DO concentration.When the concentration of DO was 0.8mg/L,the NO₂^--N accumulation rate reached86.67%after the reactor was stable.It is concluded that DO concentration control in the range of 0.8-1.0mg/L was beneficial to the removal of NH4^--N and the accumulation of NO₂^--N in short-cut nitrification process.The removal rate of ammonia nitrogen increased gradually with the increase of sludge age,and the removal rate of ammonia nitrogen could reach over 94%when the sludge age was controlled for 15 days,and the NO₂^--N accumulation rate could gradually increase to85.24%.Therefore,the SRT of the reactor was determined to be 15 days.The increase of temperature is beneficial to the accumulation of NO₂^--N in the reactor.Considering the comprehensive economy,the water temperature of the reactor is controlled at26?,and the optimum experimental conditions are applied to the reactor for 20 days.The removal rate of ammonia nitrogen is more than 95%,and the NO₂^--N is more than 95%.A step-by-step influent salinity gradient approach was used to acclimate the already obtained short-cut nitrification and denitrification process.The results show that the SBR reactor system adapts well to the environment of 4,7,10g/L salt concentration,and the rate of exit of each monitoring index is high.However,when the salt concentration reached 15g/L,the system was restrained,the effluent value of each indicator increased,the removal rate of COD decreased to about 77%,the removal rate of ammonia nitrogen was about 80%,and the removal rate of TN was only 64.5%.The activity of nitrate bacteria was close to 0.The final SBR short-cut nitrification and denitrification process was used to treat simulated ammonia-nitrogen high salt wastewater.After the system was stable,the ammonia-nitrogen removal rate remained above 90%.After the reactor was stable,the removal rate of TN was about 88%,and the anti-shock ability of the reactor was tested.The results showed that the impact of salt concentration of 20g/L had little effect on the removal rate of ammonia-nitrogen,but the denitrification process was greatly affected.Under the impact of the salt concentration of 30g/L,the reactor is damaged and difficult to recover.The reactor has good adaptability to the great change of ammonia-nitrogen concentration in the influent.