Research On Factors Of Typical Halomethanes In Water

In recent years disinfection by-products(DBPs) in drinking water have draw attention due to their toxicity and occurrence. DBPs are formed during waterdisinfection process, which is the last step of drinking water treatment. As piping network acts as a connection between treatment plant and resident, degradation may happen during the transfer process; and It can af fect the stabilit y, occurrence, speciation and toxicity of DBPs. Meanwhile, More and more family purchase purification equipment to protect publich health from emerging environmentacccidents. So, removal of existing DBPs is currently necessary. Specifically, the DBPs’ s environmental behavior in the pipeline is not well understood now, reasons for the differences in behavior among different DBPs are not clear, and thetreatability for family under normal operating conditions is not clear.This research measures degradation behavior of three halogenated methane under a variety of network conditions, focusing on hydrolysis, oxidation and reduction processes of three halogenated methane; at the same time, discusss three kinds of halogenated methane removal for families in a variety of ways.Hydrolysis experiments show that the hydrolysis process are consistent wit h pseudo-first order kinetics and have a higher rate of degradation for alkaline hydrolysis. The rate of hydrolysis increases by increasing temper ature and p H, which is consistent with hydrolysis equation and Arrhenius equation. Hydrolysis rate: bromoform> chloroform> diiodomethane. Halide anions have little effect on the hydrolysis.hydrolysis rate is slightly different in different water bodys. Hydrolyzate of chloroform and bromoform is the corresponding halide ions.Oxidation experiments showed that chlorine and chloramine in oxidation haven’t contributed to the degradation rate of three types of halogenated methanes.Reduction experiment results showed that: zero valent iron can makes THMs degradate more quickly in acid conditions. In neutral and alkaline conditions, the degradation is slow; The best concentration of Fe0 is 2g/L; Fe2+ and humic acid will promot the reduction capacity zero pric e iron; sulfite root, Fe2+, and humic acid alone show no capacity to reduce THMs; in different waterbodyof degradation rate: seawater > Super water > tap water > lake.UV254nm photolysis experiment showed that: bromoform and diiodomethane in UV254 nm degradatequickly, chloroform cannot be photogradated by UV254nm; p H, chlorine ion, and bromide ion has nothing to do with reaction rates; iodine ion, and nitrate can promoting degradation; Fe3+ and humic acid can inhibit photolysis; in ultrapure water the degradation rates are faster than other water. Experimental results in the RO water purifier show that: Filter purification effect in removing three kinds of halogenated methanes: granular activated carbon>PP cotton> compressed activated carbon; the lowervelo cit y, higher is the removal efficiency.Removal rate of low concentrations of halogenated methanes is higher than high concentrations. RO membrane has a high removal efficiency(>99%)for three types of halogenated methanes. removal rate were irrelevant wit h concentration, p H and pressure. So household water purifiers for removal of halogenated methanes is feasible.The methods in house for halogenated methane removal include boiling water, fans, microwave, ultrasonic cleaning machine, soybean milk machine a nd other appliances. The theory is based on the DBPs volatilit y. Experimental results showed that temperature, wind velocit y, ultrasonic, rotary speed and microwave can contributed to their volatilization, with effectiveness ranked as: speed > ultrasonic > temperature > wind > microwaves. So using a family approach for emergency treatment of water in halogenated methane is feasible.In summary, this research explored different ways of removal of halogenated methanes, and the results of this project may prov ide theoretical guidance for further research on stability of disinfection by-products, orient engineering design in dealing with disinfection by-products at the point of entry location, and meanwhile, help protect common family in case of emergency by dis infection by-products.