Effect of spray aeration on unregulated drinking water disinfection byproducts

Spray aeration is a comparatively low-cost option to reduce trihalomethane (THM) concentrations in distribution system storage. The effect of spray aeration on unregulated, toxic disinfection by-products was investigated in a bench-scale apparatus in closed-tank and open-tank experiments. In the closed-tank experiments, initially over 90% of THMs, trichloroacetonitrile, and chloropicrin were removed, while 36% of dihaloacetonitriles were removed. However, due to the buildup of concentrations in the tank headspace, removal rates for all compounds decreased significantly with time, falling to 44% removal of THMs, 76% removal of trichloroacetonitrile, and 58% removal of chloropicrin. Removal of dihaloacetonitriles decreased to zero. In the open-tank experiments, THM removal rates were high and did not decrease with time. Considering the results with open and closed tanks as approximate bounds for performance expected under real-world conditions in storage tanks, the findings suggest that spray aeration may not significantly reduce haloacetonitrile-related toxicity while halonitromethane-related toxicity may be reduced.