Current Levels and Composition Profiles of Emerging Halogenated Flame Retardants and Dehalogenated Products in Sewage Sludge from Municipal Wastewater Treatment Plants in China

Abstract

Occurrence of new toxic chemicals in sludge from wastewater treatment plants (WWTPs) is of concern for the environment and human health. Alternative halogenated flame retardants (HFRs) are a group of potentially harmful organic contaminants in the environment. In this study, a nationwide survey was carried out to identify the occurrence of HFRs and their potential dehalogenated products in sewage sludge from 62 WWTPs in China. Of all 20 target chemicals analyzed, decabromodiphenyl ethane (DBDPE), hexabromocyclododecane (HBCD) and 1, 2-bis (2,4,6-tribromophenoxy)-ethane (BTBPE) were detected in all sludge samples, and the concentrations were in the range of 0.82−215, 0.09−65.8, and 0.10−2.26 ng g −1 d.w., respectively. Dechlorane Plus (DP) was found in 60 of 62 samples, and the concentration ranged from nd−298 ng g −1 with a mean of 18.9 ng g −1 d.w. The anti-DP fractional abundance f anti (0.79) in the samples was much higher than the commercial DP composition (f anti = 0.59), indicating a stereoselective degradation. Comparison with global sludge concentrations of HFRs indicate that China is at the medium pollution level in the world. Principal components analysis revealed that strong correlations existed between ln-transformed concentrations (natural logarithm) of the dominant BFRs and total organic carbon (TOC) as well as industrial wastewater proportion, influent volume and serving population. Significant linear relationships (R = 0.360−0.893, p < 0.01) were found among emerging brominated flame retardants (BFRs), suggesting their common commercial applications and release sources to the environment. Two kinds of dehalogenated products, pentabromocyclododecane (PBCD) and undecachloropentacyclooctadecadiene (Cl 11 -DP), derived from HBCD and DP, were also identified in sewage sludge for the first time.

Sources and environmental behaviors of Dechlorane Plus and related compounds — A review

“…De la Torre et al (2011) reported higher levels of DP in sewage sludge from 31 urban Spanish wastewater treatment plants (WWTP), and a significant positive correlation (r = 0.619, p b 0.05) was found between DP concentrations with the contribution of industrial input to waste streams. Zeng et al (2014) also found relatively higher levels of DP in sewage sludge from the eastern China, especially in coastal areas where the urbanization and industrialization level is higher. In the residential indoor dust in the city of Ottawa, DP levels ranged from 2.3 to 5683 ng g −1 , which were comparable to the levels in dust from Stockholm (b 0.19-4800 ng g − 1 ) (Newton et al, 2015), but were several times higher than those in the sediment of the Great Lakes (Zhu et al, 2007).…”

“…Chromatographic separation was usually achieved using capillary gas chromatography (GC) columns with a non-polar stationary phase, such as DB-5MS (De la Hoh et al, 2006;Jia et al, 2011;Ren et al, 2008;Zeng et al, 2014;Zhang et al, 2013;Zheng et al, 2015a), DB-5HT (Muñoz-Arnanz et al, 2011), DB-XLB (Chen et al, 2013a(Chen et al, , 2013bMo et al, 2013;Yan et al, 2012;Zhang et al, 2011b), CP-Sil 13 CB , VF-5MS (Peng et al, , 2014, Rxi-5MS (Qiu and Hites, 2008) and Rtx-1614 (Ben et al, 2013;Peverly et al, 2015). The 15 m and 30 m columns were generally selected.…”

“…The GC to mass spectrometry (MS) transfer line was generally held at the similar temperature as the injection port. Different GC-MS approaches, including electron capture negative ion (ECNI)-MS, negative chemical ionization (NCI)-MS, NCI-MS/MS and electron impact-high resolution mass spectrometry (EI-HRMS), were generally applied for DP analysis and quantification (Barón et al, 2012(Barón et al, , 2014a(Barón et al, , 2014bDe la Torre et al, 2010a;Hoh et al, 2006;Kang et al, 2010;Möller et al, 2010;Muñoz-Arnanz et al, 2011;Qiu and Hites, 2008;Xiao et al, 2012;Zeng et al, 2014). Molecular ion fragments at m/z 651.8/653.8 were generally selected for DP monitoring in ECNI-MS and NCI-MS, while the selected ion and transition at 654 N 35/ 654 N 37 were monitored in NCI-MS/MS (Barón et al, 2012).…”

“…Molecular ion fragments at m/z 651.8/653.8 were generally selected for DP monitoring in ECNI-MS and NCI-MS, while the selected ion and transition at 654 N 35/ 654 N 37 were monitored in NCI-MS/MS (Barón et al, 2012). In order to obtain relatively high intensity of ion response, lower temperatures such as 150°C Hoh et al, 2006;Möller et al, 2010;Zeng et al, 2014) and 200°C (Qiu and Hites, 2008) were recommended in ECNI (or NCI) mode. In EI mode, fragmentation process was much more extensive and therefore the two most abundant ions of a fragment cluster (m/z: 271.8102/273.8072) were selected for DP monitoring when using HRMS (Feo et al, 2012;Shen et al, 2011a,b).…”

“…Two dechlorinated breakdown products of DP were generally reported including undecachloropentacyclooctadecadiene (anti-Cl 11 -DP) and decachloropentacyclooctadecadiene (anti-Cl 10 -DP). The concentrations in air, dust and sediment were generally low or even undetectable in most cases, especially for anti-Cl 10 -DP (Chen et al, 2011;Peng et al, 2014;Zeng et al, 2014;Zhao et al, 2011;Zheng et al, 2010). The exception was that relatively higher levels of anti-Cl 11 -DP were observed in ewaste recycling areas in South China, such as in air (3.68-671 pg m −3 , Chen et al, 2011), indoor dust (nd-20.2 ng g − 1 , Zheng et al, 2010) and sediment (6.32-25.0 ng g −1 dw, Zhang et al, 2011b).…”