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Abstract
Enantiospecific wastewater and environmental fates of chiral synthetic polycyclic musks (PCMs) including galaxolide (HHCB), tonalide (AHTN), phantolide (AHDI), traseolide (ATII) and cashmeran (DBMI) were investigated. These PCMs are commonly used ingredients in personal care products (PCPs) and household detergents.
A sensitive and robust enantioselective analytical method based on gas chromatography with tandem mass spectrometry (GC–MS/MS) was developed to facilitate enantiospecific measurement of PCMs. The analysis of individual PCM enantiomers enabled the calculation and comparison of enantiomeric fractions (EFs) among various sample matrices.
PCM concentrations and EFs were determined in a range of household products in order to assess source water compositions to sewage treatment plants. PCM concentrations and EFs were then monitored in wastewater treatment plant (WWTP) influent and effluent, and a range of landfill leachates. No significant changes in EF were observed in WWTP samples or leachate samples. This indicated that any biodegradative processes were not significantly enantioselective.
The enantiospecific fate of PCMs was further assessed in a laboratory scale anaerobic membrane bioreactor (AnMBR). While the AnMBR was observed to be effective for the removal of PCMs by a combination of biodegradation and biosorption, negligible change in EF was observed. Again, this indicated that the dominant biodegradation pathways were not appreciably enantioselective.
Finally, alternative means of biodegradation/transformation were investigated using fungi and the enzymes that they produce. Experiments were undertaken with fungal batch reactions, as well as semi-continuous treatment with a sequencing batch fungal reactor. In both cases, some significant changes to EF were observed. Monitoring of EF in both cases provided insights to the mechanisms of removal of PCMs, which would otherwise not have been available. Observed changes in EF confirmed a role for biotransformation among the removal mechanisms and facilitated the diagnosis of reducing sequencing batch reactor performance over time.
This work has enhanced our understanding of the fate of chiral PCMs in various matrices. Observed changes in EFs revealed the potential for using EF as a powerful tool to distinguish between biological and physical processes in some wastewater treatment processes, which in turn offer opportunities to improve the operation and management of these systems.