Secondary effects of implementing arsenic removal treatment—focus on corrosion and microbial regrowth

Strong‐base anion exchange, activated alumina, and granular ferric hydroxide/oxide media are technologies that small utilities will be using for arsenic removal to meet the new standards imposed by the US Environmental Protection Agency Arsenic Rule. Under at least some circumstances, however, these treatments can be predicted to cause severe adverse consequences. The removal of natural organic matter by column treatments can lead to an increase in copper pitting. Lower levels of bicarbonate in conjunction with higher concentrations of chloride can increase iron corrosion and cause red water complaints. Higher chloride‐to‐sulfate mass ratios can increase lead release from brass fittings and solder. Conversely, column treatments may remove phosphate or other trace inorganics creating nutrient limitations, which could reduce the potential for microbial regrowth in the distribution system.