TY - GEN
T1 - The influence of water chemistry on lead release rates of lead(II) carbonate solids found in water distribution systems
AU - Noel, James D.
AU - Nading, Tyler M.
AU - Pasteris, Jill D.
AU - Shah, Vivek
AU - Suresh, Akkihebbal K.
AU - Giammar, Daniel E.
PY - 2009
Y1 - 2009
N2 - Lead is a toxic heavy metal and the adverse effects of lead consumption are a public health concern. Internal corrosion of lead-containing pipe, fittings, and solder in water distribution systems is currently the most significant source of lead to drinking water. While new construction does not use lead pipe, many older buildings retain the original lead service lines and internal plumbing. Lead concentrations in drinking water are affected by chemical reactions that occur within the water distribution system, and previous studies have investigated the equilibrium solubility of lead corrosion products. The current project focuses on the dissolution and transformation rates of lead carbonate corrosion products. Hydrocerussite, Pb3(CO 3)2(OH)2, is a widely observed lead corrosion product, and its dissolution in response to changes in water chemistry can greatly affect the dissolved lead concentration in water distribution systems. The dissolution rate of hydrocerussite was investigated as a function of pH and the concentrations of dissolved inorganic carbon, orthophosphate, and chloramine. The rates and rate constants of synthetic hydrocerussite dissolution were measured as a function of water chemistry using completely-mixed continuous-flow reactors. Lead release rates from lead service lines that had been used in water distribution for 80-100 years were investigated as a function of water chemistry, recirculation flow rates, and stagnation times. The lead pipe scale was also characterized for molecular structure, morphology, and mineralogy before and after each experiment. The experimentally measured dissolution rates were used to generate a model for lead release rates as a function of water chemistry and then compared to the lead release rate from lead pipe extracted from a water distribution system. Such a model will allow water treatment facilities to determine lead concentrations as a function of measurable bulk water properties. Utilities are implementing lead corrosion control strategies, such as the addition of phosphate, to control lead concentrations in their distribution systems. The transformation of hydrocerussite to lower solubility lead phosphates was monitored in real-time using Raman spectroscopy. The data was then used to develop conceptual models for the specific processes governing the transformation of hydrocerussite to lead phosphates. A numerical solution to the system of equations will then be used to simulate the transformation process with time. The data were evaluated to determine whether the transformation occurs via dissolution of one phase and subsequent precipitation of the second phase or by direct transformation of the solid. Models for each approach were tested and provide insight into the transformation process. 2009
AB - Lead is a toxic heavy metal and the adverse effects of lead consumption are a public health concern. Internal corrosion of lead-containing pipe, fittings, and solder in water distribution systems is currently the most significant source of lead to drinking water. While new construction does not use lead pipe, many older buildings retain the original lead service lines and internal plumbing. Lead concentrations in drinking water are affected by chemical reactions that occur within the water distribution system, and previous studies have investigated the equilibrium solubility of lead corrosion products. The current project focuses on the dissolution and transformation rates of lead carbonate corrosion products. Hydrocerussite, Pb3(CO 3)2(OH)2, is a widely observed lead corrosion product, and its dissolution in response to changes in water chemistry can greatly affect the dissolved lead concentration in water distribution systems. The dissolution rate of hydrocerussite was investigated as a function of pH and the concentrations of dissolved inorganic carbon, orthophosphate, and chloramine. The rates and rate constants of synthetic hydrocerussite dissolution were measured as a function of water chemistry using completely-mixed continuous-flow reactors. Lead release rates from lead service lines that had been used in water distribution for 80-100 years were investigated as a function of water chemistry, recirculation flow rates, and stagnation times. The lead pipe scale was also characterized for molecular structure, morphology, and mineralogy before and after each experiment. The experimentally measured dissolution rates were used to generate a model for lead release rates as a function of water chemistry and then compared to the lead release rate from lead pipe extracted from a water distribution system. Such a model will allow water treatment facilities to determine lead concentrations as a function of measurable bulk water properties. Utilities are implementing lead corrosion control strategies, such as the addition of phosphate, to control lead concentrations in their distribution systems. The transformation of hydrocerussite to lower solubility lead phosphates was monitored in real-time using Raman spectroscopy. The data was then used to develop conceptual models for the specific processes governing the transformation of hydrocerussite to lead phosphates. A numerical solution to the system of equations will then be used to simulate the transformation process with time. The data were evaluated to determine whether the transformation occurs via dissolution of one phase and subsequent precipitation of the second phase or by direct transformation of the solid. Models for each approach were tested and provide insight into the transformation process. 2009
UR - https://www.scopus.com/pages/publications/84873486490
M3 - Conference contribution
AN - SCOPUS:84873486490
SN - 9781615679591
T3 - Water Quality Technology Conference and Exposition 2009
SP - 2428
EP - 2442
BT - Water Quality Technology Conference and Exposition 2009
T2 - Water Quality Technology Conference and Exposition 2009
Y2 - 15 November 2009 through 19 November 2009
ER -