Biodegradability and biodegradation kinetics of creosote compounds in a biofilm in a fractured clay flow model

If contaminated sites are situated in moraine clay areas, there may be a risk that the leachate is penetrating fractures to the underlying groundwater and thereby compromising the water quality. This study addresses the biodegradability and biodegradation kinetics of creosote compounds in a model fracture system. Eleven compounds typical of the water-soluble fraction of creosote were added to a mineral medium, each in a concentration of 0.5–1 mg/L: phenol, o-cresol, 2,4- and 3,5-dimethylphenol, naphthalene, 1-methylnaphthalene, 2,3-dimethylnaphthalene, indole, quinoline, benzothiophene, and dibenzofuran. The total concentration was around 7 mg/L. All the compounds were removed biologically by a biofilm in the model fracture under aerobic conditions. The compounds could be divided into readily biodegradable, moderately biodegradable and partly biodegradable compounds. The first order surface removal rates, k_1,a, were in the range 0.02–0.1 m/d.