Characteristics And Mechanism Of White Rot Fungi Degradation Of Polycyclic Aromatic Hydrocarbons

The coking industry is a pillar and heavy polluting industry in Shanxi Province.Coking wastewater is a typical industrial wastewater containing polycyclic aromatic hydrocarbons?PAHs?.As a refractory organic pollutant,PAHs have the characteristics of low concentration,high toxicity and high residue in the water environment.It has become one the important potential ecological risk sources that threatens the health of water environment.Biodegradation is the main way to remove PAHs.White rot fungi have a large surface area and a special enzyme system,making it unique in the removal of difficult-to-degrade contaminants.In this study,Phanerochaete chrysosporium?Pc?strain?white rot fungi?was used to investigate the degradation performance of naphthalene,phenanthrene and pyrene in white rot fungi.The present study investigated the adsorption and degradation characteristics of naphthalene,phenanthrene and pyrene by the P.chrysosporiu.The effects of surfactants and metal ions on biodegradation of naphthalene,phenanthrene and pyrene were also analyzed in this study.The results showed the adsorption of inactivated bacteria to naphthalene,phenanthrene,and pyrene was higher than that of viable bacteria?contains NaN₃?when the initial concentrations of naphthalene,phenanthrene,and pyrene were 30 mg/L,1.0 mg/L,0.1 mg/L,respectively.The adsorption rates were 26.3%and 16.9%,38.5%and 19.7%,69.0%and 53.0%,respectively.Therefore,the inactivated bacteria and the viable NaN₃ bacteria had the strongest adsorption for pyrene,while the weakest adsorption for naphthalene.It can be known from the degradation performance of PHAs that the naphthalene,phenanthrene and pyrene was adsorped firstly and then was degraded by white rot fungi.The proportion of adsorption and degradation is related to molecular weight.The smaller the molecular weight,the greater the proportion of degradation,whereas the greater the molecular weight,the greater the proportion of adsorption.After14d culture,the adsorption rate of naphthalene,phenanthrene and pyrene by P.chrysosporiu were 16.9%?19.7%and 53.0%,respectively.The degradation rate were 36.5%?40.3%and 28.0%,separately.The surfactant can promote the removal of naphthalene,phenanthrene and pyrene by P.chrysosporiu,but there is a difference in the promotion efficiency.The maximum promoting effect of Tween80 on the removal of naphthalene,phenanthrene and pyrene by P.chrysosporiu were 11.8%,17.2%and 8%,respectively.The effect of Cu²⁺on the degradation of PAHs by P.chrysosporiu was significant,but the effect of Mn²⁺was not significant.When the concentration of Cu²⁺was 0.25 mmol/L,the removal of naphthalene,phenanthrene,and pyrene reached the maximum,which were85.2%,89.0%,and 92.0%,respectively.Laccase is the key enzyme during the degradation of naphthalene,phenanthrene,and pyrene by P.chrysosporiu,and its activity determines the degradation rate of naphthalene,phenanthrene and pyrene.