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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/1760

Title: Performance of polypropylene geosynthetic filters under pressurized hydraulic flow conditions: headloss and iron oxide coating retention
Authors: Blackwood, Jade Mitchell
Keywords: Civil Engineering;Polypropylene;Filters and filtration
Issue Date: 4-Sep-2007
Abstract: Fibers present favorable physical, hydraulic and specific surface area properties for use as a substrate in developing a novel media for the adsorption of heavy metals from drinking water. Specifically the high surface area of the fibers is able to achieve a significantly higher iron-oxide density than reported results for sand under similar coating conditions; the high porosity and high permeability can result in lower headloss in column treatment than traditional materials; and the chemical inertness of the surface can only achieve loosely attached, physically associated coatings making simple, physical regeneration a possibility. The coating procedures for iron-oxide coated sand from previously reported studies were considered as a model. Previous studies included abrasion tests to remove loosely attached iron-oxide after coating at unspecified or very high Reynolds numbers. This study was conducted to determine the ability of polypropylene fiber to retain a high iron-oxide coating under reasonable flow rates, typical of those used in water treatment, through column studies. In the column studies, the material was tested under two different packing schemes, and headloss, an important parameter to consider in choosing filter media for practical application, was also measured. Additional experiments were included to characterize the coated media, illustrate the removal effectiveness of a representative heavy metal (arsenic), and determine its ability to be regenerated. The polypropylene mat achieved an iron density of up to 99.8 mg Fe/g of material and retained 72% of this coating after being subjected to hydraulic flows several times the reasonable rate, while maintaining an acceptable headloss. However, even after washing at 100 bed volumes, the suspended iron concentration of the effluent water was consistently above the secondary MCL for iron in drinking water, 0.3 mg/L. While the samples showed a substantial reduction from the initial concentrations, the result, while promising is unreliable. Further investigation should include maximizing the coating conditions, minimizing iron loss in effluent water and evaluating the effective lifetime of the media.
URI: http://hdl.handle.net/1860/1760
Appears in Collections:Drexel Theses and Dissertations

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