Corrosion control in water supply systems: Effect of pH, alkalinity, and orthophosphate on lead and copper leaching from brass plumbing

Abstract

This study explored the potential of lead and copper leaching from brass plumbing in the Auckland region of New Zealand. A five-month field investigation, at six representative locations, indicated that Auckland's water can be characterized as soft and potentially corrosive, having low alkalinity and hardness levels and a moderately alkaline pH. More than 90% of the unflushed samples contained lead above the maximum acceptable value (MAV) of 10 microg/L (New Zealand Standards). In contrast, the copper level of unflushed samples remained consistently below the corresponding MAV of 2 mg/L. Flushing however reduced sharply metal concentrations, with lead values well below the MAV limit. Generally, metal leaching patterns showed a limited degree of correlation with the variations in temperature, dissolved oxygen and free chlorine residual at all sampling locations. Furthermore, a series of bench-scale experiments was conducted to evaluate the effectiveness of pH and alkalinity adjustment, as well as orthophosphate addition as corrosion control tools regarding lead and copper dissolution. Results demonstrated that lead and copper leaching was predominant during the first 24 hr of stagnation, but reached an equilibrium state afterwards. Since the soluble fraction of both metals was small (12% for lead, 29% for copper), it is apparent that the non-soluble compounds play a predominant role in the dissolution process. The degree of leaching however was largely affected by the variations in pH and alkalinity. At pH around neutrality, an increase in alkalinity promoted metal dissolution, while at pH 9.0 the effect of alkalinity on leaching was marginal. Lastly, addition of orthophosphate as a corrosion inhibitor was more effective at pH 7.5 or higher, resulting in approximately 70% reduction in both lead and copper concentrations.

Release of Metals from Different Sections of Domestic Drinking Water Installations

“…for copper pipes (Merkel et al 2002), fittings (Samuels and Méranger 1984;Tam and Elefsiniotis 2009;Triantafyllidou et al 2012) or tin-lead solder (Subramanian et al 1995). Metal releases of accepted alloys in Germany were extensively tested and are published in an official list (Umweltbundesamt 2013).…”

Correlation between total blood lead values and peripheral blood counts in workers occupationally exposed to urban stressors

“…For each worker blood sampling for the determination of total blood Pb and peripheral blood count was made at the end of the work shift after 4 working days. Each worker had been asked to refrain from eating vegetables, rice, cereals, mushrooms, milk and dairy products, [20][21][22] during the four days before the test.…”

“…and drinking water containing Pb. [20][21][22] Other studies have noticed variable amounts of Pb also in cigarettes smoke. [23,24] The development of diseases related to anemia due to decreased hematopoiesis, to partial or total inhibition of erythrocyte enzymes and to increased destruction of circulating red blood cells (RBC) have been documented as a result of chronic exposure to Pb.…”

“…[28,29] Other toxic effects due to exposure to Pb have been documented on the reproduction (including alterations in fetal development and abortion) with endocrine abnormalities of hypothalamic-pituitary-thyroid axis and Downloaded by [Umeå University Library] at 11:25 01 April 2015 hypothalamus-pituitary-gonadal axis. [30] These and other effects have been observed and explored by the scientific community mainly: (1) in groups of subjects non occupationally exposed to Pb and living near areas with high air pollution levels or near areas where Pb is produced, used or drained; [14,[31][32][33][34] (2) in subjects exposed to Pb through consumption of contaminated food or water; [22] and (3) in groups of subjects occupationally exposed to Pb like workers employed in mining facilities, in refineries, plastics industries, foundries, etc. [35][36][37][38][39] Occupational exposure to low doses of Pb and its possible effects on peripheral blood counts have not been well investigated.…”

An Unusual Case of Neurogenic Sexual Dysfunction Due to Lead Exposure

“…Lead is present in water [17], paint [18], brass plumbing fixtures [19], ayurvedic medicine [20,21], aphrodisiacs [22], alternative medications [23], etc. Lead is toxic to numerous organ systems, which include bone marrow, muscles, kidneys, endocrine glands, joints, and nervous system [24][25][26][27].…”