Study On Simultaneous Nitrogen Removal And Cr(?) Reduction By Pseudomonas Aeruginosa LX

Ammonia and Cr??? are common pollutants and often co-exist in wastewater.Ammonia and Cr???have been a major threat to ecological equilibrium and public health and increase the difficulty of wastewater treatment.In this work,we isolated a Pseudomonas aeruginosa LX from activated sludge,which could simultaneously degrading ammonia and reducing Cr???.In this study,the ability of strain LX to remove ammonia and reduce Cr???was investigated and the practical application value of strain LX in wastewater treatment was also explored.The main findings are as follows:?1?The optimal conditions for the three nitrogen sources removal were as follows:sodium succinate as carbon source,C/N of 12,pH of 7,temperature of 30?,shaking speed of 160 rpm.Under the optimal condition,the removal rate of ammonia and nitrate were both above 95% within 24 h.Nitrogen tolerance studies have shown that strain LX could tolerate high concentration nitrogen sources.Compared with the removal of high concentration nitrate,stain LX was more efficient to remove high concentration ammonia.?2?In the mixed nitrogen source system,strain LX preferentially utilizes ammonia and nitrite was the most difficult to be removed.The utilization priority of the three N-sources was NH₄⁺-N>NO₃^--N>NO₂^--N.The key genes related to denitrification were successfully amplified through PCR amplification.Through the qPCR,the heterotrophic nitrification-aerobic denitrification pathway of strain LX was proposed NO?N₂O?N₂.?3?The initial Cr??? concentration could affect the ability of strain LX to simultaneously degrade ammonia and reduce Cr???.When the Cr???concentration increased from 5 mg/L to 30 mg/L,the ammonia and Cr???removal efficiency also decreased,however,the ammonia removal efficiency of ammonia was over 80%at all Cr??? concentrations.When the ammonia concentration increased from 100 mg/L to500 mg/L,the ammonia removal efficiency decreased while the Cr??? reduce efficiency increased slightly.Properly increasing the concentration of ammonia would promote the reduction of Cr???.?4?After inoculating the immobilized strain LX into the SBR system,immobilized strain LX could remove approximately 75%ammonia,90% Cr???,90% COD throughout the operation.Moreover,the removal efficiency of ammonia and Cr??? separately increased by about 36.36% and 67.71%.These results indicated that strain LX possessed great application potential in wastewater treatment.