Effects of blending on total copper release in distribution systems

The effects of water quality on total copper release in drinking water distribution systems were investigated in a field study using pilot distribution systems (PDSs) that distributed different finished waters produced from groundwater, surface water, and saline sources. Finished groundwater was produced by conventional treatment (i.e., aeration, disinfection, and stabilization), softening, and nanofiltration. Finished surface water was produced by enhanced coagulation–ozone–biological granular activated carbon and nanofiltration. Finished desalinated water was simulated by reverse osmosis filtration of groundwater and sea salt addition. PDS water quality was varied quarterly over one year by blending different finished waters. Total copper release was found to be dependent on blended water quality, increasing as alkalinity, sulfate levels, and temperature increased and decreasing as pH and silica increased. Calcium, chloride, dissolved oxygen, total dissolved solids, and ultraviolet absorbance at 254 nm did not affect total copper release in these investigations. Total copper release was accurately described by nonlinear regression models as a function of water quality.