Study On The Metabolism Of Phenanthrene By Pseudomonas Aeruginosa GTX4 And Simulated Waste Gas Treatment

Air pollution is an important issue and problem that threatens human health and the ecological balance of the earth.PAHs,which are widely distributed in the global environment,are a type of persistent organic pollutants that are difficult to degrade.Their"triple effects"have caused tremendous harm to human life and health and the ecological environment.It has long attracted the attention of environmental researchers in various countries.In this study,based on the source reduction strategy,a strain of Pseudomonas aeruginosa that can produce rhamnolipids was used as a test object.The degradation of Phenanthrene by the strain was investigated by microbiology and other methods.The metabolite pathway and the simulation of a small elution device were also investigated.The main results are as follows.1.In this study,a strain of Pseudomonas aeruginosa GTX4 was subjected to UV mutagenesis.After the mutagenesis,the degradation rate reached a maximum of 46.36%when the degradation conditions were 150r/min,35°C,p H=6.5 and the initial concentration was 75mg/L,while the maximum degradation was 27.25mg/L.It was found that the degradation of five kind of low-boiling PAHs was obviously raise after the mutation of GXT4,and the degradation rate of fluorene and anthracene increased by 19%,18.22%respectively.The degradation rate of Phenanthrene and pyrene was increased by 11.42%and11.28%respectively,while the degradation of fluoranthene was not satisfactory.The degradation rate of tricyclic PAHs remained at 46%⁵8%,while the pyrene degradation rate in the four rings was 53.55%,but the degradation rate of fluoranthene was only 5.32%.2.Through the analysis of mass spectra of gc-ms,the biodegradation products of Phenanthrene were preliminarily speculated to be 1-hydroxy-2-naphthalic acid,1-naphthol and salicylic acid.This study inferred that the pathway for the degradation of Phenanthrene by the bacterial strain was the double oxygenation pathway o f Phenanthrene's c-1,2 and c-3,4,via 2-hydroxy-1 naphthalic acid and 1-hydroxy-2-naphthalic acid,and then it enters the stage of degradation of salicylic acid and finally enters the TCA cycle.3.In the simulator experiment,the concentration of rhamnolipids was higher than critical micelle concentration?CMC?.The apparent absorbance of Phenanthrene is linear with the concentration of rhamnolipid,R²=0.9505.When water,rhamnolipid and GTX4bacterium as absorption liquid and the amount of Phenanthrene was served 20mg?concentration of exhaust<5g/m³?,the absorption of Phenanthrene by water was only 0.26%which by GTX4 was 9.15%and the removal rate of Phenanthrene from exhaust entering the elution device was 61.7%.In the optimization experiment of temperature,the rate of Phenanthrene removal at different temperatures was higher than that of the other three,when concentration of rhamnolipids was 500mg/L.Moreover the Phenanthrene gas removal rate reached 80.76%at 50°C and the corresponding aqueous Phenanthrene concentration was16.15 mg/L.4.This study also investigated the effect of rhamnolipids'concentration on PAHs absorption.The dosage of PAHs is 70mg and the system temperature is 35?.When Crhamnolipid<400 mg/L,the order of the PAHs removal rate in exhaust is fluorene?58.97%?>Phenanthrene?15.69%?>anthracene?12.82%?>pyrene?5.34%?>fluoranthene?3.19%?.When 800mg/L>C_rhamnolipid?400mg/L,the removal rate was fluorene?93.49%?>anthracene?26.27%?>Phenanthrene?22.66%?>pyrene?9.39%?>fluoranthene?7.93%?.When C_rhamnolipid?800mg/L,the removal rate of Phenanthrene in exhaust is higher than that of anthracene.