Biofilm and colloidal biomass dynamics in a shallow sandy contaminated aquifer under in-situ remediation conditions

The overall objective of this investigation was to improve our current understanding of biofilm and colloidal biomass dynamics in shallow sandy aquifers, following consecutive accidental releases of phenols, which is a key step towards developing effective approaches to bioremediation of aquifers and risk management. The removal of phenol, 2-monochlorophenol, 2,4,6-trichlorophenol and pentachlorophenols was monitored in sand-bed columns. The results showed that the removal of these contaminants followed pseudo-first-order kinetics. Biofilm thickness was directly related to the hydrophobicity of the phenols, continuous in the sand-bed columns contaminated with less hydrophobic and discontinuous in the sand-bed columns contaminated with the more hydrophobic contaminants. Changes in size of biocolloids were observed following consecutive pulses of phenols in the sand-bed columns, but no relationship with any physicochemical property was encountered.