Bioremediation Of Soil Contamined With PAHs And Chlorophenols By White-rot Fungi

The soil statement was closely related with our daily life. It is seriously harmful to human health and the stability of the ecological environment when the organic contaminants penetrated into soil. The contaminants can be enriched and aging by the porous medium in soil, resulting in higher concentration of pollutants in partial places, which will be more difficult to be degraded. To release the enormous pressure of pollutants to the environment, a screening system for white rot fungi was adopted in this research to investigate the degradation of Polycyclic Aromatic Hydrocarbons(PAHs) and chlorophenols in soil based on tolerance to pollutants and the ability of anti-bacteria. On this basis, two white rot fungi, efficiently bio-remediating the soil with organic pollutants, were screened out from 90 white rot fungi, and the general rule of the bioremediation for these two fungi was investigated.Seven white rot fungi,Pleurotus sp. CQ2, Perenniporia sp. BL8, Pleurotus sp. CQ3, unknown JI7, Xylaria sp. DD4, Xylaria sp. DE4 and Xylaria sp. CA3, which can not only bear the organic pollutants, but also grow well in soil, were firstly selected due to the high tolerance to contaminants and excellent ability of anti-bacteria. Among them, the comprehensive tolerance factor of Pleurotus sp. CQ3 was 58.6%, while the factor of Perenniporia sp. BL8 was 77.1%, which means, its biomass declined 22.9% by the influence of organic pollutants.Further study for the bioremediation effect of these seven selected fungi indicated that Pleurotus sp. CQ3 showed the greatest degradation rates towards phenanthrene and 2,4-dichlorophenol. After seven days of treatment, 46.3% of phenanthrene and 99.9% of 2,4-dichlorophenol were decomposed by this strain, followed by Perenniporia sp. BL8, which showed a 6.3% and 94.2% degradation ratio for phenanthrene and 2,4-dichlorophenol in soil respectively.Finally, factors that affected phenanthrene and 2,4-dichlorophenol degradation rate of Pleurotus sp. CQ3 and Perenniporia sp. BL8 were explored. The results showed that the degradation ratio of contaminants by these two fungi were both positive correlation with the incubation time and both negative correlation with the initial concentration of contaminants. However, they showed a different trend in the situation of inoculum amount. The degradation ratio of organic pollutants by Pleurotus sp. CQ3 showed a downward trend after the first rise with the increase of inoculum amount. While the degradation ratio of organic pollutants by Perenniporia sp. BL8 showed a sustained upward trend with the increase of inoculum amount. Particularly, when 1.2 mg/g phenanthrene was added into the soil, 27.5% and 2.8% of the pollutant could be degraded by Pleurotus sp. CQ3 and Perenniporia sp. BL8 respectively in 20 days. The degradation rates of 2,4-dichlorophenol with the same initial concentration was higher in soil. It could be degraded by 97.2% and 92.4% within 14 days using Pleurotus sp. CQ3 and Perenniporia sp. BL8, respectively. Overall, the bioremediation ability of Pleurotus sp. CQ3 was stronger than that of Perenniporia sp. BL8.