Small-scale performance of a novel arsenic sorbent from contaminated groundwater
Date Issued
2006
Abstract
Several arsenic (As) treatment technologies exist for arsenic-contaminated groundwater,
but the majority of them are cost-prohibitive for rural communities and small municipalities
around the world. Our proposed technology relies on a packed bed reactor (PBR) system,
utilizing a novel, low-cost, As filter medium, i.e., the drinking-water treatment residuals
(WTRs). The drinking-water treatment process generates a by-product, the WTRs, which
are available, free of charge from the drinking water treatment facilities in the U.S. Earlier
batch experiments have shown the tremendous affinity of WTRs for soluble As(V) and
As(III). A small-scale (30 x 5 cm) PBR system containing the WTRs were tested for its
effectiveness in treating As-contaminated, synthetic groundwater. Influent groundwater
composition was 150 µgL-1 As added either as As(V) or As(III) mixed with 2 mg Fe++ at a
pH of 6.5. Influent solution was constantly purged with N2 to simulate typical anaerobic
conditions in groundwater, and it was delivered to the PBR filter medium consisted of
either an Al-, or Fe-based WTRs (<1-mm). The total bed volumes processed varied
between the WTR type (Fe-, or Al-based), and the As oxidation state (III vs. V). The AlWTR
was superior to the Fe-WTR effectiveness in treating both As(V) and As(III)-
contaminated groundwater, processing > 18,000 bed volumes before exceeding the current
MCL value for As in the U.S. and Europe (10 µgL-1) for As in India and other developing
countries that are being poisoned by their drinking water. Continuous monitoring of
several metals (Al, Fe, Cr, Cu, Zn, Pb, and Mn) did not show that WTRs leached metals to
the effluent solution to any measure of significance.
but the majority of them are cost-prohibitive for rural communities and small municipalities
around the world. Our proposed technology relies on a packed bed reactor (PBR) system,
utilizing a novel, low-cost, As filter medium, i.e., the drinking-water treatment residuals
(WTRs). The drinking-water treatment process generates a by-product, the WTRs, which
are available, free of charge from the drinking water treatment facilities in the U.S. Earlier
batch experiments have shown the tremendous affinity of WTRs for soluble As(V) and
As(III). A small-scale (30 x 5 cm) PBR system containing the WTRs were tested for its
effectiveness in treating As-contaminated, synthetic groundwater. Influent groundwater
composition was 150 µgL-1 As added either as As(V) or As(III) mixed with 2 mg Fe++ at a
pH of 6.5. Influent solution was constantly purged with N2 to simulate typical anaerobic
conditions in groundwater, and it was delivered to the PBR filter medium consisted of
either an Al-, or Fe-based WTRs (<1-mm). The total bed volumes processed varied
between the WTR type (Fe-, or Al-based), and the As oxidation state (III vs. V). The AlWTR
was superior to the Fe-WTR effectiveness in treating both As(V) and As(III)-
contaminated groundwater, processing > 18,000 bed volumes before exceeding the current
MCL value for As in the U.S. and Europe (10 µgL-1) for As in India and other developing
countries that are being poisoned by their drinking water. Continuous monitoring of
several metals (Al, Fe, Cr, Cu, Zn, Pb, and Mn) did not show that WTRs leached metals to
the effluent solution to any measure of significance.