Degradation of disinfection byproducts in the presence of Fe(0) and iron corrosion products

Cast iron and ductile iron pipes are in use in water distribution systems throughout the U.S. and in Europe. Iron metal (Fe(0)) and the Fe(II) produced during corrosion of iron are potent reductants that have been shown to promote the reduction of a wide variety of halogenated organic chemicals. Thus, batch experiments were performed to investigate the degradation of a wide variety of disinfection byproducts (DBPs) in the presence of Fe(0), iron minerals containing Fe(II), and Fe(II) sorbed onto iron oxide surfaces. Most DBPs tested were completely dehalogenated in the presence of Fe(0) to non-toxic endproducts. As expected, degradation rates in the presence of Fe(II) minerals (e.g., magnetite) and sorbed Fe(II) were slower than with Fe(0). The effects of a competing oxidant such as dissolved oxygen were mixed, as the degradation rates of rapidly degraded (i.e. mass transfer limited degradation) compounds were unaffected while a lag phase was observed for slower reacting (i.e. surface reaction limited) compounds. The results of this research suggest that abiotic degradation may play a role in the fate of DBPs in distribution systems and also suggests a possible treatment strategy for DBP removal from water supplies.