ABSTRACT
Decabromodiphenyl ether (DBDE), which has been identified as an endocrine disrupting compound, is used as brominated flame retardant, and this can result in serious bioaccumulation within ecological systems. The objective of this study was to explore DBDE bioremediation (25 mg/kg) using laboratory scale soil slurry microcosms. It was found that effective biodegradation of DBDE occurred in all microcosms. Various biometabolites were identified, namely polybrominated diphenyl ethers congeners and hydroxylated brominated diphenyl ether. Reductive debrominated products such as tri-BDE to hepta-BDE congeners were also detected, and their total concentrations ranged from 77.83 to 91.07 ng/g. The mechanism of DBDE biodegradation in soil slurry microcosms is proposed to consist of a series of biological reactions involving hydroxylation and debromination. Catechol 2,3-oxygenase genes, which are able to bring about meta-cleavage at specific unbrominated locations in carbon backbones, were identified as present during the DBDE biodegradation. No obvious effect on the ecological functional potential based on community-level physiological profiling was observed during DBDE biodegradation, and one major facultative Pseudomonas sp. (99 % similarity) was identified in the various soil slurry microcosms. These findings provide an important basis that should help environmental engineers to design future DBDE bioremediation systems that use a practical microcosm system. A bacterial-mixed culture can be selected as part of the bioaugmentation process for in situ DBDE bioremediation. A soil/water microcosm system can be successfully applied to carry out ex situ DBDE bioremediation.
Subject(s)
Biodegradation, Environmental , Environmental Pollutants , Environmental Restoration and Remediation/methods , Flame Retardants , Halogenated Diphenyl Ethers , Soil Microbiology , Environmental Pollutants/analysis , Environmental Pollutants/isolation & purification , Environmental Pollutants/metabolism , Flame Retardants/analysis , Flame Retardants/isolation & purification , Flame Retardants/metabolism , Halogenated Diphenyl Ethers/analysis , Halogenated Diphenyl Ethers/isolation & purification , Halogenated Diphenyl Ethers/metabolismABSTRACT
The purpose of this study is to develop an aerosol generating system that can produce particles of micrometer size in a convenient and efficient way. This system is comprised of an ultrasonic atomizer, potassium sodium tartrate tetrahydrate (PST) as solute and a program-controlled solute feeding unit with different PST concentrations. Both the aerosol concentration and size distribution pattern can be easily controlled and reproduced in the developed system. While the initial size of droplets generated from atomizer may remain unchanged, the size of residual dry aerosols was controlled by the solute concentration adjusted by the mixing ratio of solute and water. In addition, PST concentration could be alternatively adjusted in any cyclic way to provide particles with relatively mono-disperse, bimodal, varying size as well as skew distribution to meet requirements for various applications. The main advantage of the generating system is to generate particles of specific size distribution in order to simulate aerosols in ambient air or working places.
