| In order to explore the effects and influence of sodium persulfate on removal of fuel hydrocarbon BTEX and ethanol,which are the main components of ethanol blended gasoline in different aquifer media,a batch experiment was carried out at room temperature by using five kinds of media including lime soil,basalt weathered soil,granite weathered soil,dolomite and river sand.The results showed that:(1)Under natural attenuation conditions,the sequence of degradation rates of ethanol and BTEX was basalt weathered soil > lime soil > river sand > granite weathered soil >dolomite.The microbial action in the first four media was strong and the ethanol was completely removed.The microbial effect in the dolomite medium was not obvious,and the removal rate of ethanol was only 4.4 %.Ethanol is easily degraded by microorganisms,and its intermediate product is mainly acetic acid,ethanol and acetic acid hinder the microbial degradation of BTEX.Microorganisms in various media have good removal effect on DOC.The sequence of removal rate was lime soil(84.4 %)> granite weathered soil(82.7 %)> basalt weathered soil(80.0 %)> river sand(74.3 %)> dolomite(1.1 %).(2)Under pure chemical oxidation conditions(sterilization),BTEX was more easily oxidized and removed by sodium persulfate than ethanol at the beginning of the experiment.Among them,the BTEX removal rates of lime soil and basalt weathered soil were 94.2 % and97.6 %,respectively,and the ethanol removal rates were 16.9 % and 37.0 %,respectively.The removal rates of river sand,granite weathered soil and dolomite BTEX were all greater than99.8 %.The rates of ethanol were between 67.4% and 73.6%.With the exception of lime soil media,the results are similar to those of unsterilization.Toluene was most easily removed during chemical oxidation of sodium persulfate,and benzene remains the longest.Sodium persulfate does not easily remove BTEX completely,which may be related to more residual ethanol.There are residues in the BTEX components in the lime soil medium,and the removal effect is the worst.(3)Under the condition of adding sodium persulfate and unsterilization,the chemical oxidation process of sodium persulfate leads to a decrease in pH value,which significantly inhibits the microbial action in basalt weathered soil,granite weathered soil and river sand,but had a little influence on lime soil medium.Ethanol can be completely removed,and the removal rate of DOC is also the largest.(4)The organic matter inherent in the medium consumes sodium persulfate and reduces the removal efficiency of pollutants,which was most obvious in lime soil and basalt weathered soil.The pH reduction caused by sodium persulfate will further activate sodium persulfate to enhance the removal of contaminants;the iron oxide in the medium has no obvious promoting effect on the oxidation of pollutants by sodium persulfate and needs further evaluation. |
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