Leaching of Metals from Aquifer Soils during Infiltration of Low-Ionic-Strength Reclaimed Water: Determination of Kinetics and Potential Mitigation Strategies
Principal Investigator and Project Manager
Qilin Li, Ph.D., Rice University
Reclaimed water recharged into aquifers represents a significant source of potable water. Among the high-priority research initiatives surrounding this source of water is the association of metals of public health concern with soil particles during aquifer transportation and storage. These metals are influenced by the aqueous milieu, including ionic strength, pH, and redox potential of the surrounding groundwater.
Observations from aquifer storage and recovery (ASR) sites have indicated the potential for metal mobilization in response to shifts in introduced water chemistry. Introduction of reclaimed water with TDS levels significantly lower than those in groundwater may significantly disturb chemical equilibria, possibly resulting in dissociation of some of these metals and subsequent mobilization into the groundwater. Depending on the kinetics of desorption, leached metals may produce regions of unacceptable water quality.
The overall research objective of the proposed study is to evaluate the potential for release of metals of public health concern from surface infiltration operations when reclaimed water of low TDS is used for recharge. Specific goals of the project included the following:
- Evaluate the effects of solution chemistry, for example, ionic strength, pH, and redox potential, on trace metal immobilization;
- Compare the potentials for metal leaching of different soil types and identify key soil characteristics related to metal leaching;
- Obtain trace metal desorption kinetics data for batch and continuous-flow systems; and
- Develop metal transport models for evaluation of contamination mitigation strategies.
(2009, 137 pages, 06-005-1)
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