Distribution characteristics of poly-brominated diphenyl ethers between water and dissolved organic carbon from anaerobic digestate: Effects of digestion conditions

Abstract It is becoming increasingly urgent to investigate the partition coefficients (expressed as log K DOC values) of polybrominated diphenyl ethers (PBDEs) in dissolved organic carbon (DOC) present in wastewater. In the current study, after 72 h of equilibration, the concentrations of four common PBDEs were measured in the presence of four DOC solutions from two laboratories and two full-scale anaerobic digestion plants. Sixteen log K DOC s were determined by calculation and unit conversion. The results for the laboratory samples, such as log K DOC s for 2,2′,4,4′,5,5′-hexabromodiphenyl ether being 6.38 and 5.46 at different reaction temperatures during the cultivate procedure, suggest that a thermophilic environment promotes the solubility of PBDEs to a greater extent than mesophilic conditions. DOC composition directly influences the solubility of PBDEs, even at the same cultivating temperature: the highest log K DOC s for 2,2′,4,4′,5,6′-hexabromodiphenyl ether were 6.71 and 6.33 in different full-scale plant digestates. A linear regression with an R 2 of 0.9863 was used to construct a model describing the potential relationship between log K DOC and the composition of DOC, which includes proteins, polysaccharides and lipids, and which takes into account the positions of bromine atoms, for use in predicting the log K DOC values of PBDEs in different water systems.