title: Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe.
abstract: Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity ε=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.
authors.affiliation: Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany. Electronic address: hacnor@gmail.com.
authors.forename: Norman
authors.initials: N
authors.lastname: Hack
authors.affiliation: Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Reinwand
authors.affiliation: Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Abbt-Braun
authors.affiliation: Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Horn
authors.affiliation: Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Fritz H
authors.initials: FH
authors.lastname: Frimmel
mesh_terms: D001557:Benzenesulfonates / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D060587:Groundwater / Q000382:microbiology; D062070:Hydrology / Q000379:methods; D007479:Iopamidol / Q000031:analogs & derivatives* / Q000378:metabolism; D019800:Phenol / Q000378:metabolism*; D016062:Porosity; D011551:Pseudomonas fluorescens / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D001557:Benzenesulfonates; D014874:Water Pollutants, Chemical; C057937:iomeprol; D019800:Phenol; C032365:benzenesulfonic acid; D007479:Iopamidol; D020156:Salicylic Acid
keywords: Biodegradation; Capillary fringe; Iomeprol; Phenol; Pseudomonas fluorescens; Salicylic acid