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

The disinfection by-products produced in the process of drinking water disinfection cause great harm to human health due to the carcinogenesis, genetic toxicity and mutagenicity. Therefore, it is great significance to research on the control technology of disinfection by-products.In this study, the quantitative analysis of bromonitromethane(BNM), 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 using 1, 2-dibromopropane as internal standard, was introduced. Based on this analytical method, the technologies, such as hydrotalcite adsorption, activated carbon adsorptionand advanced oxidation technologies were applies to control the BNM, and then its degradation mechanism and dynamic behaviors were also discussed.According to the spiked recovery and accuracy, the measurement method for BNM was highly accurate and the recovery rate was between 100.7%and 105.6% with relative standard deviation of 3.86-6.11% and limit of detection less than 3μg/L.When the initial concentration of BNM was 100.0μg/L, after reaction time of 90 min, removal of BNM by Mg/Fe hydrotalcite compounds(Mg/Fe-LDH) was 92.46%,while the removal by Mg/Al hydrotalcite compounds(Mg/Al-LDH) was 82.49%,with them both of 0.10g/L, which the Mg/Fe-LDH was 1.12 times higher than the Mg/Al-LDH.The degradation rate can be affected by the dosing quantity and the mole ratio of magnesium and iron. The BNM adsorption by Mg/Fe-LDH followed the pseudo second-order kinetics model.30% sodium hydroxide was used to modified the granule activated carbon(NaOH-GAC) to enhance the removal efficiency and adsorption capacity of BNM in this experiment. The results indicated that when the initial concentration of BNM was 100.0μg/L, removal of BNM by NaOH-GAC was 90.25%,while the removal by GAC was70.68%, the NaOH-GAC was 1.28 times higher than the GAC. The adsorption process of BNM by the modified GAC could be divided into three phases, which were rapid phase, slow phase and dynamic equilibrium phase. The time of equilibrium adsorption of BNM by NaOH-GAC was 60 min earlier than GAC. The BNM adsorption by NaOH-GAC and GAC accorded with the Freundlich adsorption isotherm model and followed the pseudo second-order kinetics model.The UV-O3 process was applied to remove BNM, which performed with better higher BNM removal than the individual process of UV and O3. When the UV light intensity was set at 31μw/cm2 and the O3 addition was 7.88mg/L, after reaction time of 210 min, degradation rate of BNM with the initial concentration of 100μg/L was 30.09 %、34.36 % 、 71.39 % by O3 alone, UV alone and UV-O3 process respectively. The O3 addition and enhancement of UV light intensity was both of great impact on BNM removed by UV-O3 process. The BNM degradation by UV-O3 process accorded with the first-order kinetics model.