• Microbial characterization and biodegradation potential in novel filtration systems designed to remove sulfolane from potable water

      Janda, Sara C.; Leigh, Mary Beth; Barnes, David; Hueffer, Karsten (2016-05)
      Sulfolane is an emerging contaminant used as a solvent in natural gas refineries. In response to a sulfolane spill in North Pole, Alaska, that contaminated portions of the community water supply, a novel water filtration system utilizing granular activated carbon (GAC) was developed and installed in households affected by the contaminated water. While GAC is capable of adsorbing sulfolane, it is unclear whether microorganisms contribute to sulfolane removal in the filtration systems. We characterized the microbial community found within the filtration systems using quantitative PCR (qPCR) and 16S rRNA gene sequencing and assessed the aerobic sulfolane biodegradation potential of the microbial community adhered to the GAC by measuring sulfolane loss over time in incubations using gas chromatography mass spectrometry (GC-MS). Bacterial and archaeal DNA was detected in influent and effluent water as well as throughout the point-of-entry (POE) systems, but on average, influent water contained over 99% more bacterial and archaeal DNA compared to effluent samples. In addition, a difference in microbial biomass was also observed based on the location of the GAC in the filtering system. GAC located distally to the inlet contained more biomass than the GAC that was more proximal within a canister. This difference may be due to increased flow rates at the inlet preventing microbes from adhering to the GAC. The phylum Proteobacteria dominated the bacterial community on the GAC, with over 60% of the sequences assigned to this phylum. No significant biodegradation was observed when GAC used in a POE system was incubated aerobically with sulfolane for 10 weeks. This study provides the first known description of the microbial community in filtration systems used to remove sulfolane. The findings suggest that aerobic microbial processes do not contribute to sulfolane removal in these systems. Instead, processes such as sorption or UV-induced transformations may be responsible for sulfolane removal. Future research on the potential for anaerobic biodegradation and the production and release of sulfolane breakdown products by anaerobic or photooxidative processes would be warranted.