Anaerobic degradation of brominated flame retardants in sewage sludge

Aerobic biotransformation of decabromodiphenyl ether (PBDE-209) by Pseudomonas aeruginosa

“…PBDE-208, formed by para debromination, and PBDE-207, resulted from meta debromination, increased significantly on the 3rd and 7th day, but the formation of PBDE-206 could not be detected conclusively. This result was similar to what Gerecke et al (2006) reported, in which PBDE-208 and PBDE-207 as well as a number of octabromodiphenyl ether congeners were formed in the anaerobic experiments. It indicated that microbially mediated debromination of PBDE-209 at the ortho po- sition was less frequently observed than that at the meta and para positions.…”

“…Therefore, it could be concluded that the main aerobic biotransformation mechanism of PBDE-209 by P. aeruginosa was debromination. Some studies on PBDEs biodegradation have shown that PBDEs are anaerobically transformed to lower brominated congeners by a variety of bacteria in sediment, digester sludge or other environmental samples (Gerecke et al, 2006;Yen et al, 2009;Lee and He, 2010). But very few works about aerobic degradation of PBDEs, especially PBDE-209, were reported to date.…”

“…However, this process requires a relatively long period of time, from several months to over a year. Gerecke et al (2006) reported that degradation of PBDE-209 into lower brominated diphenyl ether congeners in anaerobic mesophilic digester sludge took over 238 d and the degradation rate was only 50%.…”

Reductive transformation of hexabromocyclododecane (HBCD) by FeS

“…A similar phenomenon was reported by Lo et al (2012) who studied the abiotic transformation of HBCD by dissolved S n 2À and HS À (prepared as Na 2 S). In addition, Gerecke et al (2006) observed that the biodegradation rates of b-and g-HBCD in digested sewage sludge under anaerobic conditions were 1.6e1.8…”

“…Surprisingly, little such empirical research has been done. This study was among the first to study the abiotic transformation patterns of these BFRs under the same conditions, although their biodegradation patterns under anaerobic conditions in the same sewage sludge were investigated by Gerecke et al (2006) who found that the biodegradation rates were in the decreasing order of TBBPA > HBCD [ decaBDE. As indicated in Fig.…”