Environmental Engineering Reference
In-Depth Information
ZVI systems such as Ni/Fe and Pd/Fe is believed to be one of the promising technolo-
gies for remediation of chlorinated hydrocarbons and other priority pollutants, and their
conversion to environmentally friendly end products. In spite of the high reactivity of
nZVI for the effective reduction of many priority pollutants under anaerobic condition,
the environmental application of nZVI still faces many uncertainties. The rapid aggrega-
tion of nZVI into microscale ZVI under various environmental conditions may hinder the
transport of nanomaterials in soil and groundwater, which results in the change in long-
term stability of nZVI during the remediation of priority pollutants. The use of adsorbed
polyelectrolyte to modify the surface characteristics of nZVI or on the development of
immobilization of nZVI in microiltration membranes to minimize the aggregation and
improve mobility will be an important subject requiring further research.
Close to 60 nZVI ield application studies worldwide indicate that the mobility and
transport of nZVI is greatly inluenced by aquifer geochemistry and groundwater hydro-
geology. A detailed and accurate site assessment is highly recommended to assure the
cost-effectiveness of nZVI application. Polymeric stabilization remains to be the most com-
mon way to stabilize nZVI and retard its aggregation in the aquifer. Furthermore, to help
better design and implement ield remediation, there appears to be a need to develop a
working guideline on parameters such as nZVI dose, contaminant removal capacity, and
speciic throughput. In addition to gauging geochemical variables such as ORP, DO, and
pH, the authors suggest that iron-based suspended solids may serve as a relatively reliable
indicator to monitor the effective zone and the mobility of nZVI.
Acknowledgment
The authors thank the National Science Council, Taiwan, for inancial support under grant
no. NSC 98-2221-E-007-030-MY3.
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