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Intention, Goal and Background Contaminated sediments represent a significant, worldwide environmental problem since they contain a mixture of different
xenobiotics and heavy metals. The presence of mixed contamination presents a unique set of obstacles for remediation efforts.
Often sediment remediation occurs as an ex-situ application (i.e., after dredging) in an attempt to minimize some of the problems.
However, dredging poses it’s own issues. It does not address contaminated water and often material is not completely removed
thereby leaving a long-term residual contamination source in the waterway.
Objective The potential of bio remediation to treat sediments contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated
biphenyls, and heavy metals was addressed. The primary objective was to assess two delivery mechanisms for microbial inoculation
to facilitate in-situ remediation of PAH contaminated sediments.
Methods Simulated river beds were constructed to mimic the Mahoning River. Contaminated sediment from the river was added to each
reactor at a uniform depth, followed by the addition of river water. Fifteen inoculation points were used in each simulated
river bed to ensure adequate microbial populations. One tank was inoculated with an acclimated bacteria solution as a free
suspension. The other tank was inoculated with an attached growth biofilm system. Sediment samples were taken throughout the
experiment and the percent PAH degradation determined. Water characteristics (DO, pH, bacterial activity, etc.) were also
tracked as corroborating evidence.
Results and Discussion The monitoring sites indicated that an attached growth system was more effective, and achieved a 99% PAH degradation efficiency
at some of the sampling sites. Tracking individual PAH compounds also indicated a higher overall microbial activity with the
attached growth system. This activity was evident by the formation and subsequent biodegradation of lower molecular weight
degradation byproducts. However, more of the sediment area was treated by the free suspension inoculum due to the ease of
microbial migration.
Conclusions The applicability of using an aerobic microbial consortium composed ofMycobacterium sp., Pseudomonas aeruginosa, andPseudomonas flourescens to treat contaminated sediment was demonstrated. In addition, it was found that introducing the consortium as an attached
growth was more effective than when delivered as a free suspension.
Recommendation and Outlook The results demonstrated that the consortium was effective at treating the PAHs present in the contaminated soil. An additional
study to evaluate the consortium’s effectiveness at remediating the PCB present in the sediment is warranted. Optimization
of the consortium-nutrient combination could enable a treatment approach to effective for all the organic contaminants present.
Although this would not address the heavy metals present in the sediment, it would afford a great opportunity at remediating
a severely contaminated sediment system. 相似文献
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