Influence of Cleaning Time in Household Reservoirs on Trihalomethane Formation in Treated Water

Abstract

Chlorination is an efficient and low-cost technique in disinfecting water for public water supply. However, during the process, the formation of undesirable by-products called halogen compounds, such as trihalomethanes (THMs), occurs. Some of these compounds are proven to be carcinogenic to laboratory animals. The goal of this study was to investigate the occurrence of THMs in household reservoirs and the influence of cleaning time of these reservoirs on the formation of THMs. A total of 103 households were investigated in the city of Maringá, State of Paraná, Brazil. The residences were classified according to the cleaning time of the reservoir into: up to one year, one to two years and more than two years. Samples were taken from the reservoirs and total trihalomethanes (THMt) were analyzed by gas chromatography (GC-MS), total organic carbon (TOC) by means of a Hach kit for low concentrations and free residual chlorine (CLres) by means of a kit for in loco determination. According to the results, the highest concentrations of THMt were observed in the reservoirs with cleaning time of more than 2 years. However, no amount has exceeded the maximum limit allowed by law. In general, the longer the time for cleaning the reservoir, the greater the degradation of water quality in THMt.

Trihalomethanes and physicochemical quality of drinking water in Addis Ababa, Ethiopia

“…These findings are comparable with a related meta-analysis performed by Morris et al [ 49 ], which showed that chlorinated surface water has significantly more chlorination by products than chlorinated groundwater (medians of 50.7 and 0.8 ppb, respectively). Therefore, the consumption of surface water was found to be an indirect proxy of exposure to disinfection by products used in associated studies [ 50 , 51 ].…”