| At present, the means of improving the water pollution by bioretention devices have been widely recognized, but the studies of bioretention were always focused on rain and flood prevention problems or common indicators of water quality. If the effect of polycyclic aromatic hydrocarbons (PAHs) polhition on bioretention and the removal efficiency of PAHs by bioretention device can be founded,then it can be possible to provide the remcdiation of PAHs with a path of green economy. The aim of this study was to isolate the strains with high efficiency and the effets of PAHs on bioretention system and their ecological effects were studied. The results were as follows:(1) This paper studies three different removal efficeency of common water qualityfillers by the soil, the soil lava-coal ash,and the soil-coal ash, under the condition of the rainfall reappearing peried was specified as 2a, based on the water quality of rainwater runoff in Xi’an.The water experiment was carried out for three months, the removal rate of CODCr, P and N were all increased with time. With the increase number of shocks of pyrene,removing effect of different fillers on the pollutants were changed. Among them, the removal cfficiency of the control group of soil-coal ash was the best. The removal rate of CODCr reached 67.71%. the removal rate of TN reached to 90.63%,and the removal rate of TP reached to 85.76%. The worst removal effect was the impact column of natural soil packing group, the renvnaul rates of CODCr, TN and TP were 27 21%, 71.53%, and 75.21%.(2) Five enzymse,including dehydrogenase, invertase, urease, polyphenol oxidase and catalase were sclceted to monitor the effect of pyrene on the packing state.In the five enzymes,the activitles of urvase,invertase and catalase in the three groups were decreased compared wiht that in the blank column,these results suggest that pyrene can inhibit the activity of these enzymes.The comtent of polyphenol oxidase was not detected in this experiment may be related to the absence of plants in this system becausr polyphend oxiduse is mainly produced by therocts of plants.(3) Take PAHs sa the surarbce source,filter out the PAHs-degrading flom from Xi’an Univerisity of Technology PAHs-contaminated soil samples succeassfully.Three strains of PAHs degrading bacteria were separated through enrlehment,domestieation and seclction from thePAHs-degrading flora.After thd physlological biochemistry rature experiments,the API reagent strip examiestion,16S rDNA gene bank measred and the system growth tree construction,the three kind of stralms were identified as Achronobacter SP.ZH24(HM103344),Stenotrophortionas mpltophillia straln T215,Pseudomonss talwanensls straln P5.On thd 25th day of degradation,the initial conceetration of 5mg/L pyrene degradation rate of S12 was 36.12%, degradation rate of S22 was 36.47%,and the degradation rate of S32 was 31.17%.(4) High throughput sequereing results of soil samples in the bioretention show that the most abundant is prodeobacteria,induding beta-Proteobacteria cooupied thd highest abundance,the most abundant orders is Burkholderiales,and the five relatively high abundaree were Comamonadaceae,Oxalobacteraceae,Pseudonomadacere,Xanthomandacene and Baellaccse.The four dominant genera were Azohydromonis,Pscudomoras,Comamonadaceas andOxaltovaeteraceae.There was a slight difference in the proportion of dominant bacteria indifferent modia,and the distrbution of deainant found that the aburdance of dorniant bacteria group were sinilar.At thd same time,it was found that the aburdance of doninant bacteria nereased with the inerease of pyrene sbock time.The resuits showed that,after the impact ofpyrene,the microbial community in the system formed acommurity structure of PAHs degrading bacteria. |
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