Effect of Calcium on Lead in Soft-Water Distribution Systems

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

“…28 This relationship was not found in the current study, most likely due to different background water quality, although the large range of hardness to alkalinity ratios in the synthetic waters may also have played a role. Bisogni et al 31 found that at a concentration of 5 mg L −1 , calcium destabilized colloidal lead particles by altering the zeta potential. However, increasing the calcium concentration from 5 to 40 mg L −1 did not provide any additional benefit, 31 which may explain why this was not observed in the present study.…”

“…Bisogni et al 31 found that at a concentration of 5 mg L −1 , calcium destabilized colloidal lead particles by altering the zeta potential. However, increasing the calcium concentration from 5 to 40 mg L −1 did not provide any additional benefit, 31 which may explain why this was not observed in the present study.…”

“…12,[24][25][26][27] However, further research is still required as some studies have found that hardness can influence scale formation 19,[28][29][30] and that calcium can decrease the concentration of colloidal lead by altering the zeta potential of the colloids. 31 As well, divalent cations such as magnesium and calcium can adsorb to lead phosphate particles promoting their aggregation and lead immobilization. 32 To the authors' knowledge there have been no previous studies that have investigated hardness independently from DIC under parallel experimental systems.…”

Lead Particles in Potable Water

“…“Flaking lead” particles larger than 12 μm associated with scale detaching from a pipe were observed, along with colloidal lead fractions associated with iron oxides and humic acids (De Mora et al, 1987; Hulsmann, 1990). Particulate lead was clearly demonstrated to come from solder lead–tin joints in pipe rigs (Bisogni et al, 2000), and a small survey of lead in potable water from around the United States revealed numerous instances in which most of the lead was present as particulates (sometimes ≥ 1,000 μg/L Pb) in first‐draw tap samples (McNeill and Edwards, 2004).…”

Interactions of Pb(II)/Pb(IV) Solid Phases with Chlorine and Their Effects on Lead Release

“…However, given the practically universal coexistence of PbO 2 and Pb(II) minerals in corrosion scales , , it is unclear to what extent Pb(II) minerals need to be oxidized to effectively control lead release. On the other hand, a significant portion of Pb release, notably that during the Washington, DC event, is associated with colloidal particles with varying sizes − . Relative contributions of Pb(II) and Pb(IV) species in the structures of submicron particles that constitute particulate lead have not been ascertained.…”