Role of natural organic matter and hardness on lead release from galvanic corrosion

King, Patrick W.; Peldszus, Sigrid; Mishrra, Anushka; Trueman, Benjamin F.; Aghasadeghi, Kimia; Gagnon, Graham A.; Giammar, Daniel E.; Huck, Peter M.

doi:10.1039/d1ew00903f

Cited by 5 publications

(7 citation statements)

References 55 publications

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“…For example, hydroxylpyromorphite (Pb 5 (PO 4 ) 3 (OH)), chloropyromorphite (Pb 5 (PO 4 ) 3 Cl), and phosphohedyphane (Ca 2 Pb 3 (PO 4 ) 3 Cl) have been reported as the potential lead phosphate solids. ,,, The composition of the phosphate-based inhibitors as well as the water chemistry can be the main factors determining the speciation of the lead phosphate solids. The lead phosphate scale formed in this experiment was identified as phosphohedyphane (Ca 2 Pb 3 (PO 4 ) 3 Cl) or a structurally similar phase, which has been reported in other LSLs. ,,, By removing the polyphosphate during treatment stage 2, more lead phosphate solids formed in the bottom layer of the scale. Our study revealed that 0.2 mg/L PO 4 orthophosphate as part of a blend phosphate could thermodynamically promote lead phosphate solid, but the small amount of lead phosphate solid exerted a limited influence on lead release.…”

Section: Resultssupporting

confidence: 70%

Improved Control of Lead Release from Boosting Orthophosphate and Removing Polyphosphate from a Blended Phosphate Corrosion Inhibitor

Ma,

Mishrra,

Giammar

et al. 2023

ACS EST Eng.

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Orthophosphate addition can be an effective lead corrosion control method. Commercial phosphate-based inhibitors used in water treatment are often a blend of orthophosphate and polyphosphate. Orthophosphate (PO 4 ) can limit lead release from pipes by forming low-solubility lead phosphate compounds on the inner surfaces. In contrast, polyphosphate can increase lead release by forming soluble lead phosphate complexes. In a controlled laboratory study using recirculating pipe loops, the effects of boosting the orthophosphate concentration and removing polyphosphate on lead release were investigated. The study began with conditioning of six harvested lead service lines from locations in the service area of Buffalo Water with artificial Buffalo water that received a 70%/30% poly/ortho-blended phosphate chemical (orthophosphate concentration: 0.2 mg/L of PO 4 ). Three of the pipes were tested in two treatment stages, while the other three remained as controls. During treatment stage 1, the orthophosphate concentration in the test pipes was boosted to 1.5 mg/L for PO 4 while maintaining the original blended phosphate concentration. Both the total and dissolved lead concentrations decreased and became more stable during this treatment stage. During treatment stage 2, blended phosphate was no longer added to the test pipes, and the test pipes received only orthophosphate (1.5 mg/L of PO 4 ). During treatment stage 2, the total and dissolved lead concentrations continued to decrease from their values at the end of treatment stage 1. Scale analysis revealed that the phosphorus content of the scales on the test pipes increased during treatment. A crystalline lead/calcium phosphate was observed that was phosphohedyphane (Ca 2 Pb 3 (PO 4 ) 3 Cl) or a similar solid. The lead phosphate increased in abundance in moving from treatment stage 1 to treatment stage 2.

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Section: Resultssupporting

confidence: 70%

Improved Control of Lead Release from Boosting Orthophosphate and Removing Polyphosphate from a Blended Phosphate Corrosion Inhibitor

Ma,

Mishrra,

Giammar

et al. 2023

ACS EST Eng.

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“…And while the seasonal component of the model (Figure b) is described as a function of time (ordinal day), this is a proxy for the physical and chemical inputs that are expected to have caused it. The true seasonal relationship is probably complex and difficult to determine from the study data, but temperature and influent iron concentration are plausible drivers: both varied seasonally and have been shown to impact lead release (Figure b,c). − And although dissolved organic carbon has also been shown to increase lead solubility, ,, true colora proxy for dissolved organic carbonwas not strongly seasonal (Figure S9).…”

Section: Resultsmentioning

confidence: 99%

“…Time series representing lead release to drinking water tend to feature extreme values caused by particulate or colloidal lead. Even in 0.45 μm filtrate (i.e., dissolved lead), small colloids can sometimes elevate lead concentrations well above solubility limits . These “outliers” can severely bias parameter estimates unless they are accounted for.…”

Section: Methodsmentioning

confidence: 99%

Comparing Corrosion Control Treatments for Drinking Water Using a Robust Bayesian Generalized Additive Model

Trueman

James²,

Shu³

et al. 2022

ACS EST Eng.

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Pipe loop studies are used to evaluate corrosion control treatment, and updated regulatory guidance will ensure that they remain important for drinking water quality management. But the data they generate are difficult to analyze: nonlinear time trends, nondetects, extreme values, and autocorrelation are common attributes that make popular methods, such as the t- or rank-sum tests, poor descriptive models. Here, we propose a framework for describing pipe loop data that accommodates all of these challenging attributes: a robust Bayesian generalized additive model with continuous-time autoregressive errors. Our approach facilitates corrosion control treatment comparisons without the need for imputing nondetects or special handling of outliers. It is well suited to describing nonlinear trends without overfitting, and it accounts for the reduced information content in autocorrelated time series. We demonstrate it using a 4-year pipe loop study, with multiple pipe configurations and orthophosphate dosing protocols, finding that an initially high dose of orthophosphate (2 mg P L–1) that is subsequently lowered (0.75 mg P L–1) can yield lower lead release than an intermediate dose (1 mg P L–1) in the long term. Water utilities face difficult trade-offs in applying orthophosphate for corrosion control, and better models of pipe loop data can help inform the decision-making process.

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“…Even in 0.45 µm filtrate (i.e., dissolved lead), small colloids can sometimes elevate lead concentrations well above solubility limits. 48 These "outliers" can severely bias parameter estimates unless they are accounted for.…”

Section: Model Descriptionmentioning

confidence: 99%

“…The true seasonal relationship is probably complex and difficult to determine from the study data, but temperature and influent iron concentration are plausible drivers: both varied seasonally and have been shown to impact lead release (Figure 8b-c). [58][59][60][61] And although dissolved organic carbon has also been shown to increase lead solubility, 48,62,63 true colour-a proxy for dissolved organic carbon 64 -was not strongly seasonal (Figure S9).…”

Section: Identifying Stabilitymentioning

confidence: 99%

Comparing corrosion control treatments for drinking water using a robust Bayesian generalized additive model

Trueman

James

Shu

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Pipe loop studies are used to evaluate corrosion control treatment, and updated regulatory guidance will ensure that they remain important for water quality management. But the data they generate are difficult to analyze: non-linear time-trends, non-detects, extreme values, and autocorrelation are common attributes that make popular methods, such as the t- or rank-sum tests, poor descriptive models. Here, we propose a model for pipe loop data that accommodates many of these difficult-to-model attributes: a robust Bayesian generalized additive model with continuous-time autoregressive errors. Our approach facilitates corrosion control treatment comparisons without the need for imputing non-detects or special handling of outliers. It is well-suited to describing nonlinear trends without overfitting, and it accounts for the reduced information content in autocorrelated time series. We demonstrate it using a four-year pipe loop study, with multiple pipe configurations and orthophosphate dosing protocols, finding that an initially high dose of orthophosphate (2 mg P L-1) that is subsequently lowered (0.75 mg P L-1) can yield lower lead release than an intermediate dose (1 mg P L-1) in the long term. Water utilities face difficult tradeoffs in applying orthophosphate for corrosion control, and better models of pipe loop data can help inform the decision-making process.

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Role of natural organic matter and hardness on lead release from galvanic corrosion

Abstract: Suwannee river natural organic matter greatly increased dissolved lead release from galvanic corrosion due to complexation with humic acid-like substances.

Cited by 5 publications

References 55 publications

Improved Control of Lead Release from Boosting Orthophosphate and Removing Polyphosphate from a Blended Phosphate Corrosion Inhibitor

Improved Control of Lead Release from Boosting Orthophosphate and Removing Polyphosphate from a Blended Phosphate Corrosion Inhibitor

Comparing Corrosion Control Treatments for Drinking Water Using a Robust Bayesian Generalized Additive Model

Comparing corrosion control treatments for drinking water using a robust Bayesian generalized additive model

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