A Model for Estimating the Impact of Orthophosphate on Copper in Water
Citation:
Lytle, D., M. Schock, J. Leo, AND B. Barnes. A Model for Estimating the Impact of Orthophosphate on Copper in Water. JOURNAL OF THE AMERICAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, 110(10):E1-E15, (2018). https://doi.org/10.1002/awwa.1109
Impact/Purpose:
The nature of copper-phosphate minerals in drinking water distribution systems has remained largely unsolved despite being an important link to reducing cuprosolvency. Important copper-phosphate solids associated with drinking water tend to be amorphous and form very fine layers on copper pipes. Also, geochemical modelling based on fundamental thermodynamic principles has largely failed to accurately predict soluble copper levels in the presence of orthophosphate due to uncertainties surrounding equilibrium and formation constants, and the identity of the copper-phosphate solids. The objective of this work was to develop and validate an empirical copper solubility model that considered pH, DIC and orthophosphate from a series of bench-scale copper precipitation experiments. An empirical model was constructed that allows for the determination of copper levels in a system given pH, DIC and orthophosphate data. The predictive reliability of this model was assessed by evaluating a collection of cuprosolvency data from two decades of bench-scale tests, field observations and water treatment reports. The tests yielded a firm correlation between predicted and observed copper levels attested by a regression coefficient of 0.92 for a total of 851 observations
Description:
The nature of copper-phosphate minerals in drinking water distribution systems has remained largely unsolved despite being an important link to reducing cuprosolvency. Important copper-phosphate solids associated with drinking water tend to be amorphous and form very fine layers on copper pipes. Also, geochemical modelling based on fundamental thermodynamic principles has largely failed to accurately predict soluble copper levels in the presence of orthophosphate due to uncertainties surrounding equilibrium and formation constants, and the identity of the copper-phosphate solids. The objective of this work was to develop and validate an empirical copper solubility model that considered pH, DIC and orthophosphate from a series of bench-scale copper precipitation experiments. An empirical model was constructed that allows for the determination of copper levels in a system given pH, DIC and orthophosphate data. The predictive reliability of this model was assessed by evaluating a collection of cuprosolvency data from two decades of bench-scale tests, field observations and water treatment reports. The tests yielded a firm correlation between predicted and observed copper levels attested by a regression coefficient of 0.92 for a total of 851 observations.
URLs/Downloads:
DOI: A Model for Estimating the Impact of Orthophosphate on Copper in Water
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