Effects of household handling on disinfection by- products

Abstract

KeywordsChlorinated water samples were used to determine the effect of handling modes on disinfection byproducts (DBPs). The DBPs studied were trihalomethanes (THMs), haloacetonitriles (HANs), chloral hydrate (CH), chloropicrin (CP) and 1,1,1-trichloropropanone (TCP). Tap water samples were collected from the distribution system in Damanhour City (Egypt). The investigated strategies included storing water in covered and uncovered bottles in a refrigerator up to 9 hours, with and without previous short boiling. Water quality parameters were not affected by storage or boiling except for electrical conductivity (EC), which decreased after boiling. 90% of THMs were removed by boiling and storage for 9hrs.HANs, including dichloroacetonitrile (DCAN), dibromoacetonitrile (DBAN) and trichloroacetonitrile (TCAN), were not affected by storage, but they were not detected after boiling for 30 seconds. CH and TCP, like the HANs, were affected by boiling rather than storage.Chlorine is currently the most reliable chemical disinfectant used for water disinfection. However, chlorine also reacts with natural organic matter (NOM) present in water, leading to the formation of trihalomethanes (THMs), haloacetic acids (HAAs), halonitromethanes (HNMs) . The most abundant HANs after water chlorination are dichloroacetonitrile and its brominated analogs, bromochloroacetonitrile and dibromoacetonitrile. Data available on trichloroacetonitrileis insufficient to serve as a basis for defining a guideline value for trichloroacetonitrile. The previous provisional guideline value of 1μg/L was based on developmental toxicity studies. Dichloroacetonitrile induced decreases in body weight and increases in relative liver weight in short-term studies. Despite the potential health effects, there is no US regulatory limit for these compounds, but WHO has suggested guideline values of 20μg/L for DCAN and 70μg/L for DBAN [9].Indoor handling,such as boiling, refrigerating and storing of drinking water, can greatly impact DBP concentrations.Krasner and Wright [10] studied the impact of boiling water on different DBPs. The boiling experiments were conducted on water samples from the Weymouth water treatment plant (California) in the winter of 2000. They found that from 68% to 98% of THMs were removed when chlorinated water was boiled for 1-5 minutes. Complete removal of 1,1,1-trichloropropanone (TCP) was observed after boiling for 1 minute. Chloral hydrate (CH) concentration was reduced by at least 97% following a 1-minute boil of water and was not detected after 2 min. 94-98% removal of the HANs occurred upon boiling the chlorinated samples for 1 minute, and no HANs were detected in the chlorinated water after 2 minutes. 57% removal was observed for CP in water boiled for 1 min, and was not detected after2 minutes of boiling. Battermanet al.[11] examined thermal effects on THM concentrations by heating chlorine-free distilled water in an electric kettle. Average removal reported for chloroform and bromodichloromethane at 100˚C were 81% and 73% respect...