The Effect On Degradation Of PAHs Polluted Soil By Microbial Reinforcement Remediation

Polycyclic aromatic hydrocarbons(PAHs)are typical hydrophobic pollutants,which have stable chemical properties,also called posistent organic pollutants.PAHs appear in environment,a serial circulation will happened,PAHs will enter the pedosphere finally. Once PAHs enter soil,they will be combined compact with soil organic matter. Then they become aged soil under Physical, chemical, biological combined function. These kind of PAHs have Low biological availability. Hence,it will effect the degradation of PAHs from soil。With the Long-term retention in the soil,PAHs can cause irreversible damage to the soil microorganisms and soil animals,and then can damage to the soil properties. Besides,PAHs also have the toxic effect to the surrounding environment. therfore, it is urgent to develop various remediation technology aiming at agricultural soils.The main conclusions are as follows:1、The results show that during 4 weeks cultivating,The group of HPD-2 had the highest removal rate of PAHs. Besides,the study of PAHs removal performance in soil at different periods in different particle sizeshowed that after cultivating 2 weeks and 4 weeks,5-ring PAHs has the highest degradation than other rings.And Low rings of PAHs have higher degradation in Small particle size fraction. The removal of PAHs in different particle size have significant differences,In order to further explore the causes of the removal of differences, the different treatment of soil respectively to determine the three kinds of soil enzyme activity. H+M group had higher soil enzyme activity than others. And after 4 weeks cultivating,Three kinds of soil enzyme activity achieved maximum,it illustrated that the intensity of soil respiration and soil microbial activity during 4 weeks to achieve the best state. This also matched with soil PAHs degradation rate reached the maximum at 4 weeks.2、Using tenax TA consecutive extraction method extracted PAHs before and after repair,and Simulated the third stage desorption kinetics process. According to dynamics analysis, the study found that the treatment of adding MCD, proportion of slow and extremely slow parse components was increased than other treatments. Fsl and Fvl of the treatment adding MCD were 1.9418 and 2.3628. In the process of remediation, Fsl and Fvl value increased gradually. It also showed the MCD can grow the solubilization of PAHs.3、The results showed that the degradation rate of PAHs in soil treated with Rhizobium meliloti with alfalfa was 60%. The distribution of 16 PAHs concentrations in different soil particle size composition was in the order of fine sand >silt >fine sand > clay, besides. Low-molecular(2, 3-ring) PAHs was not degradated but transferred in different size of particles(degradation rate less than 20%). The degradation of 4-ring PAHs occurred mainly on silt and fine sand soil particles and 5-ring PAHs degradation on the clay. Hence, the distribution and degradation of PAHs in different size of particles has a great significance on remediation of PAHs polluted soil.