Effects Of Heavy Metals On Biodegradation Of BDE209in Water/Sediment System By White Rot Fungi

This paper studied the effects of heavy metals on BDE209biodegradation byP.chrysosporium in water/sediment system. The main works included investigating onbiotransformation efficiencies of BDE209by the strain and optimizing the degradationconditions through orthogonal experiments, researching the effects and the mechanis of heavymetals on degradation of BDE209by the biomass and extracellular enzyme, and transformationin water/sediment system, and then following the metabolites of BDE209. The results are asfollows.The optimal degrading conditions of BDE209in water system are temperature30℃, pH5,BDE2091mg·L^-1, and reaction time7d. Heavy metals (Cu, Cd, Pb) had great influence on thedegradation. Cu(≤1mg·L^-1) and Cd(≤0.5mg·L^-1)could accelerate the process, but at elevatedlevels (>1mg·L^-1) depressed effects were presented by the metals in the order of Cd>Pb>Cu.Degradation of BDE209by the cell, extracellular enzymes and intracellular enzymes ofP.chrysosporium were investigated, and60.17%,54.14%, and22.32%of BDE209(1mg·L^-1)was decomposed respectively. Infrared scanning analysis showed that the degradation ofBDE209was related to the group such as Br-C, CH₂-O-CH₂, etc. The GCMS chromatogramanalysis of the metabolites showed that Br was released from BDE209. Correlation analysis ofdegradation between extracellular enzyme and the cell suggested that the fomer played vital rolein the bioreaction process and heavy metals affected the enzyme degradation.Partion of BDE209in aqueous and sediment phase was important for the biorecovery ofBDE209-contaimnated water body. Heavy metals could accelerate the adsorption of BDE209bysediment in the order Pb>Cd>Cu. The adsorption of BDE209by sediments confirmed to theFreundlich adsorption model(R=0.9908). Adsorption mainly had relation to DOC (dissolvedorganic carbon) inside the sediments and it had higher adsorption capacity than the undissolvedorganic carbon in sendiment. Constituent analysis by NMR (nuclear magetic resonance) foundthat the main composition of DOC was aliphatic moieties. Heavy metals could combine withDOC and reduce its solubility.Comparing to water system, higher degradation efficiency and shoter degradation periodwere obtained in water/sediment system, which attributed to the indigenous microorganisms. Cu had a positive effect on the degradation, the same to the low concentrations of Pb and Cd. Butnegative effect was cuased by Pb and Cd at high levels.