| Polycyclic aromatic hydrocarbons(PAHs)are widely distributed in the environment,and a large proportion of them are toxic and carcinogenic,which have important harmful effects on the natural environment,people,animals and plants.Three strains which could degrade naphthalene,Phenanthrene and pyrene at the same time were screened from laboratory bacteria by increasing the carbon source concentration gradient,and the bio-activated carbon and bio-activated pellets were prepared by adsorbing the best strain in three kinds of strains using granular activated carbon and a colophony and gelatinate pellet.Granular activated carbon and small pellets can adsorb strains very well,and have a protective effect on microorganisms,the strain can still maintain high activity after adsorption.The bio-activated carbon and bio-activated pellets can degrade naphthalene,phenanthrene and pyrene effectively.The results obtained are as follows:(1)Three degrading bacteria of naphthalene,Phenanthrene and pyrene at the same time were isolated from the bacteria stored in the experimental laboratory and named SYS-1,SYS-2 and SYS-3 respectively.The results showed that three strains can be used to biodegrade naphthalene,Phenanthrene and pyrene effectively..The growth curves of three strains were determined by three strains in pyrene-inorganic salt medium,phenanthrene-inorganic medium and naphthalene-inorganic medium,which showed that the growth curves of SYS-1 was best in three kinds of medium.The three free bacteria were used to degrade the naphthalene,Phenanthrene and pyrene whose initial concentration was 100mg/L,among which the strain SYS-1 had the best degradationeffect on naphthalene,Phenanthrene and pyrene,and the degradation rate was 95.68%,91.43% and 54.21% respectively.(2)Biological activated carbon was prepared by adsorption and immobilization of SYS-1 strains by granular activated carbon.At first use,the adsorption amount of naphthalene,Phenanthrene and pyrene in the system of granular activated carbon was59.69%,89.66% and 65.08% respectively.The bio-activated carbon can eventually degrade the concentration of naphthalene,Phenanthrene and pyrene with the initial concentration of 100mg/L to 1.93mg/L,0.27mg/L and 1.12mg/L respectively.The removal rate of total organic carbon in naphthalene,phenanthrene and pyrene system was 96.98%,98.41% and 95.76% respectively.When biological activated carbon is recycled,each round of bio-activated carbon can degrade the concentration of naphthalene,Phenanthrene and pyrene with the initial concentration of 100mg/L to2mg/L below.And the biological activated carbon will not disintegrate with the increase of degradation time,and the degradation effect of naphthalene,Phenanthrene and pyrene is enhanced significantly.(3)Furthermore,The SYS-1 strains were adsorbed and immobilized into the bio-activated pellets by a colophony and gelatinate ball as a contrast.The pellet also has the adsorption effect on the naphthalene,phenanthrene and pyrene in the system.At first use the adsorption capacity of naphthalene,Phenanthrene and pyrene in the system was32.83%,35.13% and 26.03% respectively.The bio-activated pellets could degrade the concentration of naphthalene,Phenanthrene and pyrene with the initial concentration of100mg/L to 0.81mg/L,7.47mg/L and 10.34mg/L finally.In the system of naphthalene,Phenanthrene and pyrene,the removal rate of total organic carbon in the system was96.76%,90.21% and 85.6% respectively.When bio-activated pellets is recycled,each round of bio-activated pellets can adsorb the concentration of naphthalene,Phenanthrene and pyrene with the initial concentration of 100mg/L to 10mg/L below.(4)Free bacteria,bio-activated carbon and bio-activated pellets have certain degradation ability to naphthalene,Phenanthrene and pyrene.For pyrene,the removal rate of pyrene with the initial concentration of 100mg/L was 54.21%,98.88% and89.66% in the system of three kinds of removal methods of free bacteria,bioactive carbon and bioactive pellets respectively.For phenanthrene,the removal rate ofphenanthrene in the system was 91.43%,99.73% and 92.53% respectively in three methods: free bacteria,bio-activated carbon and bio-activated pellets.For naphthalene,three kinds of ways:free bacteria,bio-activated carbon and bio-activated pellets,the removal rate of naphthalene in the system was 95.68%,98.07% and 96.76%,respectively.The removal effect of naphthalene,Phenanthrene and pyrene,biological activated carbon was significantly better than that of bio-activated pellets and free bacteria.In the case of the four-ring pyrene,this effect is particularly obvious. |
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