WA1 Biorestoration Strategies for Contaminated Sediments
256 Portland Ballroom
8:00 AM - 12:00 PM, Wednesday
() Scaling of Sediment Bioremediation Efficacy Assessment Using Microbial Sensing and Geostatistical Analysis.
Adriaens, P1, Towey, T1, Li, M-Y1, Gruden, C2, McCulloch, R3, Baraba, N3, Wolfe, J3, 1 University of Michigan, Ann Arbor, Michigan, USA2 University of Toledo, Toledo, Ohio, USA3 LimnoTech, Inc., Ann Arbor, Michigan, USA
ABSTRACT- Contaminated sediments are characterized by large volumes, heterogeneous matrices and low levels of contamination. The in situ microbial ecology is extremely diverse, and the total respiratory competence and in situ expressed activity is largely unknown. The hydrogeological and microbial limitations argue for a stochastic bioengineering approach aimed at increasing and interpreting microbial activity in large areas. The overarching goal is to develop a sediment bioremediation technology, using hydrogen as a catalyst for microbial dechlorination of highly halogenated compounds, using the following objectives: (i) development and validation of a rapid throughput microbial sensing approach to evaluate causal relationships; (ii) scaling of hydrogen infusion approaches to field sites (Pearl Harbor, Passaic River, San Diego Harbor, Anacostia River). Dual-stain flow cytometry using PicoGreen and redox dyes (CTC) were used for microbial enumeration and respiratory competence assessment, respectively. Ecological assessment was based on terminal Restriction Fragment Length Polymorphism (tRFLP). The experimental set-up is comprised of cell elutions, sediment slurries, and intact sediment columns. All three sets of studies use hexachlorobenzene (HCB) as a surrogate contaminant, but differ in terms of matrix, degree of mixing, scale, complexity, and expected speed of system response. Hydrogen amendments (0.5-3.6 microM) in elutions resulted in a 2-3 fold increase in activity over baseline activity. Hydrogen amendments in columns by upward diffusive transport through the column at a rate of about 15 cm/mo. was depleted across a 15 cm distance. In elution studies, HCB degradation rates were approximately 50% greater with hydrogen enhancement than with below-threshold enhancement. For both enhanced and unenhanced slurries, statistically-significant results are consistent with HCB degradation in response to treatment. Geostatistical and fractal approaches are being explored to determine the appropriate spatial microbial abundance and activity distribution structure and to scale the technology to the field.
Key words: biostimulation, fractal analysis, dehydrogenase