Demonstrating the In Situ Biodegradation Potential of Phenol Using Bio-Sep super( registered ) Bio-Traps super( registered ) and Stable Isotope Probing

The effect of phenol concentration on phenol biodegradation at an industrial site in the south of Wales, United Kingdom, was investigated using standard Bio-Sep super( registered ) Bio-Traps super( registered ) and Bio-Traps super( registered ) coupled with stable isotope probing (SIP). Unlike many super(13)C-amendments used in SIP studies (such as hydrocarbons) that physically and reversibly adsorb to the activated carbon component of the Bio-Sep super( registered ) beads, phenol is known to irreversibly chemisorb to activated carbon. Bio-Traps super( registered ) were deployed for 32 days in nine site groundwater monitoring wells representing a wide range of phenol concentrations. Bio-Traps super( registered ) amended with super(13)C-phenol were deployed together with non-amended Bio-Traps registered in three wells. Quantitative polymerase chain reaction (qPCR) analysis of Bio-Traps super( registered ) post-deployment indicated an inhibitory effect of increasing phenol concentration on both total eubacteria and aerobic phenol-utilizing bacteria as represented by the concentration of phenol hydroxylase gene. Despite the chemisorption of phenol to the Bio-Sep super( registered ) beads, activated carbon stable isotope analysis showed incorporation of super(13)C into biomass and dissolved inorganic carbon (DIC) in each SIP Bio-Trap super( registered ) indicating that chemisorbed amendments are bioavailable. However, there was a clear effect of phenol concentration on super(13)C incorporation in both biomass and DIC confirming phenol inhibition. These results suggest that physical reductions of the phenol concentrations in some areas of the plume will be required before biodegradation of phenol can proceed at a reasonable rate.