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Permeable reactive barriers (PRBs) are a well-known technique for groundwater remediation using industrialized reactive media such as zero-valent iron and activated carbon. Permeable reactive concrete (PRC) is an alternative reactive medium composed of relatively inexpensive materials such as cement and aggregate. A variety of multimodal, simultaneous processes drive remediation of metals from contaminated groundwater within PRC systems due to the complex heterogeneous matrix formed during cement hydration. This research investigated the influence coarse aggregate, portland cement, fly ash, and various combinations had on the removal of lead, cadmium, and zinc in solution. Absorption, adsorption, precipitation, co-precipitation, and internal diffusion of the metals are common mechanisms of removal in the hydrated cement matrix and independent of the aggregate. Local aggregates can be used as the permeable structure also possessing high metal removal capabilities, however calcareous sources of aggregate are preferred due to improved removal with low leachability. Individual adsorption isotherms were linear or curvilinear up, indicating a preferred removal process. For PRC samples, metal saturation was not reached over the range of concentrations tested. Results were then used to compare removal against activated carbon and aggregate-based PRBs by estimating material costs for the remediation of an example heavy metal contaminated Superfund site located in the Midwestern United States, Joplin, Missouri.
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Heavy Metals Sorption by Drinking Water Treatment Byproducts in Jar Tests
Heavy metals contaminants include lead, chromium, arsenic, zinc, cadmium, copper, and mercury all of which can cause significant damage to human health and the environment as a result of their mobility and solubility within groundwater. In the Midwest portion of the United States, soil and groundwater based lead, zinc, and cadmium are the prominent pollutants of concern. While remedial technologies exist for heavy metals pollution, the majority of these solutions are expensive to design, maintain, and install. Drinking water treatment waste (DWTW) is a currently landfilled, relatively pure, industrial waste byproduct composed almost entirely of calcium oxide produced during water purification processes. Measured doses of drinking water treatment waste were submerged in synthetic groundwater solutions containing 0.01, 0.1, and 1.0 millimolar concentrations of lead, cadmium and zinc in order to determine if this material could provide remedial measures for heavy metals. In addition, the geomechanical properties and chemical composition of the material were determined. Removal rates varied based upon internal and external water content as well as flocculant formation. However, all tests verify that the material is capable of heavy metals removal at relatively rapid rates. This data suggests that when entrained in a previous matrix, the reactive nature of the byproduct sorbs ions in solution passing through the matrix.
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- Award ID(s):
- 1439378
- PAR ID:
- 10063165
- Date Published:
- Journal Name:
- Geo-Chicago 2016
- Page Range / eLocation ID:
- 32 to 41
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1061/9780784480168.004
