An Evaluation Of Household Methods For Haloacetic Acids Treatmen In Water

Haloacetic acids(HAAs) are the second largest disinfection byproducts(DBPs) detected in water behind trihalomethane. As they are hard to degrade and volatilize in water, the widespread occurrence of HAAs may increase the unsafe factors to drinking water quality, and therefore attracts considerable attention now. Currently, most approaches in controlling HAAs have been put on the removal of HAAs precursors or the optimization of disinfectants and dosing locations. The removing methods of HAAs, especially household method are not well-studied, which may hamper the further improvement of water quality for consumers. So, the treatability of household methods for HAAs becomes necessary.This study mainly covers the common household ways by using boiling kettle, microwave oven, RO water purifiers and UV d isinfector to treat seven types of HAAs, and furthermore assesses the influences of environmental and operational factors on the removal rates of HAAs. In addition to the kinetic study, we also investigate the reaction pathways in destruction of HAAs. This research hence may provide certain theoretical basis and practical advice for common people to improve drinking water safety.The RO water purifier experimental results show that the pretreatment filters can removal 16%~44% of HAAs. At low velocity, ultrapure water condition, the removal of halogenated acetic acid is better. The removal of halogenated acetic acid by RO membrane is generally significant, reaching more than 80% HAAs. At a relatively low pressure(but with in normal working pressure range), the removal of halogenated acetic acid is better.UV degradation experimental results show that the removal rate can reach 80% in the time scale of experiment. The removal decreases with the increases of molecular weight of halogen atom or the degree of halogenation. Humic acid can significantly inhibit the photolysis of all HAAs. At high p H condition, the photolysis rate of HAAs is smaller. Residual chlorine can promote HAAs photolysis. MHAAs and DHAAs undergo only dehalogenation during photolysis process, but THAA encounters both dehalogenation and decarboxylation processes.Household boiling pot experimental results show that the water boiling effect is poor to reduce HAAs(< 10%). With longer reaction time and a natural cooling process, trichloroacetic acid can achieve better removal effect( ?40%). Initial concentration and water components(such as ions and organics in tap water) do not significantly affect the removal of halogenated acetic acid. Such results were confirmed by microwave experiment results.Overall, this research has examined several different household treatment methods on the removal of HAAs. The results have found that reverse osmosis and UV lamp can efficiently remove HAAs in the tap water, the removal of HAAs is less than 50% by adsorbent column, and microwave and boiling are unhelpful to HAAs treatment.