Control of drinking water lead contamination from brass plumbing fixtures by aqueous copper(II) treatment
Abstract
Lead contamination in drinking water is a major environmental problem in the United States. Lead can cause irreversible adverse impacts on public health particularly on young children and pregnant women. Low levels lead are usually found in natural waters, however, relatively high lead concentrations are frequently observed "at-the-tap". Major contributors to lead contamination in drinking water include lead pipes, lead based solder, and brass plumbing fixtures. Lead pipe and lead based solder were banned under Safe Drinking Water Act amendment in 1986. Brass plumbing fixtures, mostly household faucets, still allowed to contain 8% lead become the potential lead contamination sources. The main objective of this research is to develop one step, effective and considerable cheap chemical process to reduce lead contamination contributed from brass plumbing fixture. The process consists of exposing brass fixtures internal surface to a Cu(II) treatment solution at low pH for a short period of times. The introduced oxidation-reduction reaction results in "deleadification", an selective leaching of lead. Lead leaching that would otherwise take months to years to occur, can be accomplished in the practical period of times. Different Cu(II) salts as treatment solutions were selected. Lead leaching kinetics in contact with Cu(II) treatment solution were studied under static condition and dynamic condition for both closed loop and single pass test. Various factors affecting the treatment process efficiency including Cu(II) concentration, pH, dissolved oxygen and accumulating lead in treatment solution were investigated. All lead pockets and surface lead origin from the "lead sweating" distributed on surface grain boundary were oxidized and dissolved after treatment. The treated surface examined by X-ray microanalysis shows low lead residual was left with similar composition of bulk brass. The total leachable lead for selective treatment components, faucet fixture bodies, was estimated to be about 300 mg, or 1.3% total mass of lead in single brass fixture studied. Lead contamination assessment of treated and untreated fixture following National Sanitary Foundation test protocol confirmed that the Cu(II) treatment is an effective method to remove lead contamination from brass plumbing alloys in drinking water.
Degree
Ph.D.
Advisors
Marinas, Purdue University.
Subject Area
Civil engineering|Environmental science|Toxicology
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