Effects of Iron Particles on Chlorine Decay and DBP Removal during Boiling Drinking Water

Boiling has been widely used for sterilization; however, the chemical risks of boiling under drinking water conditions were not clear. Here, both clean tap water (TW) and discolored water from iron pipes (PW) were used to study the effects of iron particles on chlorine decay and DBP removal during boiling drinking water. When free chlorine was lower than 1 mg/L, boiling can completely eliminate free chlorine in PW and TW. With the increase in free chlorine, the removal effect of boiling on free chlorine gradually decreased. Under initial free chlorine of 5 mg/L, free chlorine removal in PW was 83.07% and that in TW was 71.96% after boiling. Under initial free chlorine of 3 mg/L, the dissolved organic matter (DOC) of PW increased with the increase of boiling time originating from iron particle release. After boiling, trihalomethanes (THMs) in TW decreased by 67.42%, while haloacetic acids (HAAs) increased by 29.81%, while for PW, the changes of THMs and HAAs were decreased by 48.00% and increased by 40.27%, respectively. Therefore, in the presence of iron particles, boiling decreased the removal effect of THMs and improved the promotion effect on HAAs, which revealed the risk of disinfection byproducts in the boiling process induced by iron particles.