Research On Control Strategies Of Bromochloracetonitrile,Disinfection By-product In Drinking Water

It is well known that the disinfection by-products in drinking water cause great harm to human health due to the carcinogenesis, genetic toxicity and mutagenicity. Therefore, it is of great practical significance to probe and research on the disinfection by-products in drinking water.In this study, the quantitative analysis of bromochloracetonitrile (BCAN), one kind of nitrogen disinfection by-product in drinking water by gas chromatography/mass spectrometry (GC/MS) on the extracting agent of methyl tertiary butyl ether (MTBE) and using1,2-dibromopropane as internal standard, was introduced. Based on this analytical method, the formation process of BCAN and its influencing factors were evaluated with methylamine as the precursor. In addition, the technologies, such as activated carbon adsorption, iron reduction and advanced oxidation technologies were applies to control the BCAN, and then its degradation mechanism and dynamic behaviors were also discussed.According to the spiked recovery and accuracy, the measurement method for BCAN was highly accurate and the recovery rate was between103.9%and109.2%with relative standard deviation of 5.06-11.95%and limit of detection less than1μg/L.The addition of iron scraps enhanced the removal efficiency of BCAN in low concentration, and when the initial concentration of BCAN was20μg/L, after reaction time of180min, removal of BCAN was71.8%with iron scraps of15g/L. The degradation rate can be improved as the addition of iron scraps and the increase of the temperature. However, BCAN removal did not change a lot with the variation of initial concentration of BCAN when it was in a low level.Meanwhile, Fe/Cu catalytic reduction could effectively romove BCAN of drinking water. The Fe/Cu mass ratio was of great impact on BCAN removal and the optimum Fe/Cu mass ratio is10:1. The Fe/Cu dosage was of great impact on BCAN removal and the removal increased with the increase of Fe/Cu dosage. When the initial concentration was set at20μg/L, after reaction time of150min, removal of BCAN was improved from51.1%to89.5%with the increase of Fe/Cu dosage addition from5g/L to10g/L. The temperature was also of great impact on BCAN removal and the removal increased with the increase of the temperature. When the initial concentration of BCAN was20μg/L, after reaction time of180min, removal of BCAN with Fe/Cu dosage of lOg/L was improved from86.15%to92.5%with the increase of temperature from20℃to40℃.In the UV-H2O2process, when the UV light intensity was set at 31μw/cm2, after reaction time of120min, removal of BCAN with the initial concentration of20μg/L was improved from62.35%to77.5%with the increase of H2O2addition from10mg/L to40mg/L.The enhancement of UV light intensity also contributed to the BCAN removal. When the H2O2addition was set at40mg/L, after reaction time of120min, removal of BCAN with the initial concentration of20μg/L was improved from77.5%to88.6%with the increase of UV light intensity from31μw/cm2to64μw/cm2.In the UV-H2O2-O3process, removal of BCAN with the initial concentration of20μg/L was94.05%, when the UV light intensity, O3addition and H2O2addition were only31μw/cm2,7.9mg/L and40mg/L, respectively due to the more hydroxyl radical generated in this process. The BCAN degradation by UV-H2O2-O3process accorded with the first-order kinetics model. The H2O2addition was of great impact on BCAN removal and the removal increased with the increase of H2O2addition. The enhancement of UV light intensity also contributed to the BCAN removal.