Characterization of a Sequential UV Photolysis-Biodegradation Process for Treatment of Decabrominated Diphenyl Ethers in Sorbent/Water Systems.

Yi-Tang Chang,Yi-Tang Chang,Stephen A Boyd,Hui Li,Wei-Liang Chao,Hsin-Yu Chen

doi:10.3390/microorganisms8050633

Yi-Tang Chang, Yi-Tang Chang + Show 4 more

Open Access

https://doi.org/10.3390/microorganisms8050633

Copy DOI

Journal: Microorganisms	Publication Date: Apr 27, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: Michigan State University, Soochow University

Abstract

Decabrominated diphenyl ether (BDE-209) is a primary component of the brominated flame retardants used in a variety of industrial and domestic applications. BDE-209 bioaccumulates in aquatic organisms and has been identified as an emerging contaminant that threatens human and ecosystem health. Sequential photolysis-microbial biodegradation processes were utilized here to treat BDE-209 in clay- or soil-water slurries. The removal efficiency of BDE-209 in the clay-water slurries was high; i.e., 96.5%, while that in the soil-water slurries was minimal. In the clay-water slurries the first order rate constants for the UV photolysis and biodegradation of BDE-209 were 0.017 1/day and 0.026 1/day, respectively. UV wavelength and intensity strongly influenced the BDE-209 photolysis and the subsequent biodegradation of photolytic products. Facultative chemotrophic bacteria, including Acidovorax spp., Pseudomonas spp., Novosphingobium spp. and Sphingomonas spp., were the dominant members of the bacterial community (about 71%) at the beginning of the biodegradation; many of these organisms have previously been shown to biodegrade BDE-209 and other polybrominated diphenyl ether (PBDE) congeners. The Achromobacter sp. that were isolated (NH-2; NH-4; NH-6) were especially effective during the BDE-209 degradation. These results indicated the effectiveness of the sequential UV photolysis and biodegradation for treating certain BDE-209-contaminated solids; e.g., clays; in bioreactors containing such solids as aqueous slurries. Achieving a similar treatment effectiveness for more heterogeneous solids containing natural organic matter, e.g., surface solids, appears to be significantly more difficult. Further investigations are needed in order to understand the great difference between the clay-water or soil-water slurries.

Highlights

Polybrominated diphenyl ethers (PBDEs), especially the penta, octa- and deca- brominated congeners, constitute a major class of the commercial brominated flame retardants (BFR)
The total BDE-209 removed by the sequential UVB photolysis-biodegradation was c. 96.47% in the clay/water slurry system over a period of 140 days
The dominant bacterial communities identified have been shown in prior studies to have the capacity for PBDE biodegradation

Summary

Introduction

Polybrominated diphenyl ethers (PBDEs), especially the penta-, octa- and deca- brominated congeners, constitute a major class of the commercial brominated flame retardants (BFR). These BFRs are used in plastics, textiles and in wire insulation, and are found in many commercial products such as automobiles. BDE-209 is the most dominant congener of PBDEs present in contaminated soil/sediment samples collected throughout the world. One detailed investigation of sediments from the Laurentian Great Lakes (GL) showed that BDE-209 was the dominant congener, accounting for more than 90% of the total mass of the five major PBDE congeners present [2]. BDE-209 remains an important and continuing source of PBDEs in the GL region

Methods

Results

Discussion

Conclusion