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.