Biosorption and biodegradation of polycyclic aromatic hydrocarbons by Phanerochaete chrysosporium in aqueous solution

Abstract

Biosorption and biodegradation of phenanthrene and pyrene by live and heat-killed Phanerochaete chrysosporium are investigated to elucidate the bio-dissipation mechanisms of polycyclic aromatic hydrocarbons (PAHs) in aqueous solution and its regulating factors. The effects of nutrient conditions (carbon source and nitrogen source concentrations), the co-existing Cu2+, and repeated-batch feed of PAHs on the biosorption and biodegradation are systematically studied. The removal of PAHs by dead bodies of P. chrysosporium is attributed to biosorption only, and the respective partition coefficients of phenanthrene and pyrene are 4040 and 17500 L/kg. Both biosorption and biodegradation contribute to the dissipation of PAHs by live P. chrysosporium in water. After a 3-d incubation, the removal percentage via biosorption are 19.71% and 52.21% for phenanthrene and pyrene, respectively. With the increase of the incubation time (3–40 d), biodegradation gradually increases from 20.40% to 60.62% for phenanthrene, and from 15.55% to 49.21% for pyrene. Correspondingly, the stored-PAHs in the fungal bodies decrease. Under the carbon-rich and nitrogen-limit nutrient conditions, the removal efficiency and biodegradation of phenanthrene and pyrene are significantly promoted, i.e. 99.55% and 92.77% for phenanthrene, and 99.47% and 83.97% for pyrene after a 60-d incubation. This phenomenon is ascribed to enhanced-biosorption due to the increase of fungal biomass under carbon-rich condition, and to stimulated-biodegradation under nitrogen-limit condition. For the repeated-batch feed of phenanthrene, the pollutant is continuously removed by live P. chrysosporium, and the contribution of biodegradation is enhanced with the repeated cycles. After 3 cycles, the biodegradation percentage is up to 90% with each cycle of a 6-d incubation.