Treatment Of Polycyclic Aromatic Hydrocarbons Polluted Soil By Composting

Aiming at the pollution status of polycyclic aromatic hydrocarbons to soil, anthracene was used in thispaper as the typical representation of polycyclic aromatic hydrocarbons to confect anthracene polluted soil,which was treated by aerobic static composting technology. The composting time and anthracene'sdegradation were used as the controlling variable to study the influence of initial concentration ofanthracene, C/N ratio, moisture, ventilated amount, adscititious microbes and surfactant to the degradationof anthracene. At the same time, the changing rules of soil's organic content, total nitrogen content,moisture, pH value, bacteria amount and anthracene content alone with time and the microbial diversitieswere also discussed in the process of compost.The experimental results of indigenous microbes'compost showed that when the initial concentrationof anthracene was 500mg/kg, C/N ratio 25:1, moisture 60%, ventilated amount 0.2m3/h, the treatmenteffect of anthracene was best. Along with the extension of time, soil's organic content, total nitrogencontent, moisture and anthracene content decreased as a whole in the process of compost, while the pHvalue increased appreciably, the microbial amount first increased and then decreased,and then increasedagain. The study on the microbial diversity in the process of compost showed that with the extension ofcomposting time, the diversities of microbial populations in composting soils first decreased and thenincreased, and at the same time, the dominant microorganisms which degraded anthracene in compostingsoils had better diversities (9 species), which was beneficial to the treatment of anthracene polluted soil.The study on the influence of three kinds of surfactants(LAS,CTAB and Tween-80) to soil'santhracene adsorption showed that when the anthracene desorption amount of soil reached 50%, the dosageof LAS was the least, the amount of which was 197mg/g soil.Through examining the influence of LAS toanthracene's degrading rate in the process of compost showed that the degrading rate of anthracene incomposting soil could improved from 50.34% to 76.44%, which suggested that LAS had an intensive roleto the degradation of anthracene in composting soil.The experimental results of four kinds of bacteria (T1,T2,T3,T4) which were screened from petroleum polluted soil previously to the degradation of soil showed that the degrading rate of T2 to anthracene wasthe highest. The study on the cultivating conditions of strain T2 showed that when the inoculation amount ofT2, pH, temperature and the initial concentration of anthracene were 5%, 6.0, 35℃and 40mg/L,respectively, the strain grew better. The result of degrading kinetics experiment of strain T2 to anthraceneshowed that the residual quality of anthracene Y(mg) and time x (h) was in line with the equation Y =2.544e (-0.00275)x. The study on the influence of strain T2 to the degrading rate of anthracene in the process ofcompost showed that the degrading rate of anthracene could improve from 50.34% to 64.33% after addingstrain T2, which suggested that strain T2 had an intensive role to anthracene's degradation in compostingsoil.