BIOFOULING OF CONTAMINATED GROUNDWATER RECOVERY WELLS - CHARACTERIZATION OF MICROORGANISMS

The taxonomy and physiology of microorganisms isolated from contaminat ed ground-water recovery wells prone to biofouling are characterized f or an industrial site in Rochester, New York. Principal aquifer contam inants include acetone, cyclohexane, dichloroethane, dichloromethane, 1,4-dioxane, isopropanol, methanol, and toluene. These contaminants re present a significant fraction (up to 95%) of the total organic carbon in the ground water. Ground-water samples from 12 recovery wells were used to isolate, quantity, and identity aerobic and anaerobic bacteri al populations. Samples from selected wells were also characterized ge ochemically to assess redox conditions and availability of essential a nd trace nutrients. Dominant bacteria, listed in order of descending n umbers, including sulfate-reducers (Desulfovibrio desulfuricans), anae robic heterotrophs (Actinomyces, Bacteriodes, Bacillus, Agrobacterium) , aerobic heterotrophs (Pseudomonas, Flavobacterium, Nocardia, Citroba cter), iron-oxidizers (Gallionella ferruginea, Crenothrix polyspora), iron-reducers (Shewanella), and sulfur-oxidizers (Thiobacillus ferroox idans). Fungi were also recovered in low numbers. Both aerobic and ana erobic heterotrophs were able to utilize all principal contaminants as sole carbon and energy sources except 1,4-dioxane. The prevalence of heterotrophic bacteria and their ability to use the available anthropo genic carbon suggests that aerobic and anaerobic heterotrophs contribu te to the biofouling of wells at this site, in addition to the often c ited fouling due to iron-oxidizing bacteria and sulfate-reducing bacte ria.