Applications of activated carbon to reduce disinfection byproducts in small drinking water systems

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The addition of chlorine disinfectant to drinking water during the treatment process results in the formation of disinfection by-products (DBPs). The United States and several other nations regulate for DBPs in drinking water because studies have linked exposure to these compounds to increased incidence of cancers as well as birth and developmental defects. Incorporation of activated carbon(AC) into the drinking water treatment process may reduce the formation of DBPs through the adsorption of natural organic matter (NOM) precursors and formed DBPs. The goal of this research project is to investigate how AC can be better used by small-scale drinking water plants as a feasible option for reducing the DBPs formed in their systems, which would allow them to consistently achieve compliance with the Environmental Protection Agency's latest regulation Stage 2 D/DBP Rule. This research compared the factors of AC particle size, carbon source material, and concurrent coagulant addition in NOM sorption experiments. Although concurrent chemical addition and carbon source had no significant differences on AC performance, the performance of powdered activated carbon (PAC) was notably greater than granular activated carbon(GAC). Characterization of NOM in source water showed preferential adsorption of hydrophilic NOM compounds onto the AC. Finally, a pilot studied was designed to investigate the potential of granular activated carbon (GAC) to adsorb formed DBPs before entering the distribution system.