Pilot‐scale evaluation of blending desalinated seawater into a distribution system

Abstract

A pilot‐scale pipe loop test was conducted to evaluate the effects of desalinated seawater on corrosion, lead release, disinfectant decay, and formation of disinfection by‐products in the distribution system. Results indicated that the desalinated blend water did not increase corrosion of unlined cast‐iron pipes, coated cement‐lined pipes, or copper pipes. However, aluminum release from uncoated cement‐lined pipes was increased. The blend water also increased lead release from leaded solder. These results agreed with the predictions from corrosion indexes and earlier bench‐scale testing. Orthophosphate (1 mg/L) added to mitigate lead release was ineffective. Adding phosphate increased bacterial growth in unlined cast‐iron pipes and solder. Although chloramine decay was increased by desalinated water, this effect can be managed by controlling bromide levels and either reboosting or preforming chloramine. Desalinated blend water did not increase biological activity. In addition, the blend water decreased the formation of total trihalomethanes and haloacetic acids as expected but increased nitrosodimethylamine for unknown reasons.

A literature review of bench top and pilot lead corrosion assessment studies

“…Pipe loops have generally used new lead pipes (Figure 5a) (Bae et al, 2019;Kirmeyer et al, 1994;Nguyen et al, 2010;Welter et al, 2015) or lead pipes harvested from drinking water systems (Bae et al, 2020) with standard inner diameters of 12.7 or 19 mm (0.5 or 0.75 in.). Some studies also used other plumbing materials, such as new bronze and copper pipes with lead solder (Nguyen et al, 2010;Zhang et al, 2012), aged lined and unlined cast iron pipes, and aged galvanized steel pipes excavated from drinking water systems (Tang et al, 2006). Pipes were conditioned for studies that used new pipes (Bae et al, 2020) as well as harvested pipes (Bae et al, 2020;Tang et al, 2006).…”