The disinfection effects of the ozone molecule alone and that of ozone decomposition products when inactivating Giardia muris cysts were investigated at bench-scale using two different ozone demand-free laboratory buffer systems. The first water was a 0.05 M phosphate buffer with hydrogen peroxide added at a 10:1 weight ratio. The second water was a 0.05 M phosphate – 0.01 M bicarbonate buffer which quickly scavenged radical species from ozone decomposition. The C3H/HeN mouse model was used to assess the infectivity of ozone treated cysts.
The phosphate-bicarbonate buffer system had significantly greater (P ≤ 0.05) inactivation of G. muris cysts than that observed in the phosphate buffer – peroxide system where ozone was completely decomposed in less than 120 s. Consequently, the design of ozone disinfection processes should maintain ozone residual for disinfection prior to the addition of hydrogen peroxide for the oxidation of other compounds. 相似文献
The destruction of methyl-tert-butyl ether (MTBE) in contaminated waters by O3/H202 process was studied and the influence background COD, alkalinity, and hydrogen peroxide and MTBE concentrations on process treatment efficiency and ozone dosage was investigated. The treatment efficiency was evaluated by an Efficiency Index, which is based on electrical energy requirement for ozone production. It was found that the treatment efficiency decreases linearly with increasing concentrations of MTBE at constant background COD and with background COD at constant MTBE concentration. A simplified kinetic scheme was presented to account for these observations. 相似文献
Kinetics of competition between the ozone direct reaction with compounds in water, ozone-hydroperoxide ion reaction leading to free radicals in the O3/H2O2 process, and the photolysis of ozone in the O3/UV process are discussed in terms of diffusion and reaction times to establish conditions for these reactions to be competitive. Film theory and chemical kinetic concepts then are applied to estimate initial rates of ozone absorption and consumption, removal rates of compounds present in water, and the importance of the radical oxidation path versus direct ozone and/or photolysis reactions. 相似文献
The coupling reaction of melt linear low density polyethylene (LLDPE) initiated by dicumyl peroxide (DCP) in steady shear flow field was investigated. The conversion of DCP was measured by electron spin resonance (ESR) and chemical titration. An absolute method was proposed to calculate the actual conversion of DCP from rheological data. The coupling efficiency of DCP was obtained from those analyses, which was shown to increase at first, reach a maximum and then decrease in the end stage. A linear relationship between the coupling efficiency of DCP and the concentration of macroradicals was also found in the experiments. 相似文献
The present study investigates the decomposition of N-Methyl-2-Pyrolidone (NMP) using conventional ozonation (O3), ozonation in the presence of UV light (UV/O3), hydrogen peroxide (O3/H2O2), and UV/H2O2 processes under various experimental conditions. The influence of solution pH, ozone gas flow dosage, and H2O2 dosage on the degradation of NMP was studied. All ozone-based advanced oxidation processes (AOPs) were efficient in alkaline medium, whereas the UV/H2O2 process was efficient in acidic medium. Increasing ozone gas flow dosage would accelerate the degradation of NMP up to certain level beyond which no positive effect was observed in ozonation as well as UV light enhanced ozonation processes. Hydrogen peroxide dosage strongly influenced the degradation of NMP and a hydrogen peroxide dosage of 0.75 g/L and 0.5 g/L was found to be the optimum dosage in UV/H2O2 and O3/H2O2 processes, respectively. The UV/O3 process was most efficient in TOC removal. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of NMP in wastewater. 相似文献
Advanced oxidation processes are defined as those which involve the generation of hydroxyl radicals in sufficient quantity to affect water purification. The theoretical and (practical yield of OH from O3 at high pH, 03/H202, O3/UV and H2O2/UV systems is reviewed. New data is presented which illustrates the importance of direct photolysis in the O3/UV process, the effect of the H202:03 ratio in the O3/H2O2 process, and the impact of the low extinction coefficient of H2O2 in the H202/UV process. 相似文献
CATAZONE is a new process of heterogeneous catalytic ozonation in which water is ozonated in the presence of a solid catalyst composed of titanium dioxide. The efficiency of this O3/TiO2 system has been compared to the two well-known oxidant systems: ozone alone and ozone combined with hydrogen peroxide.
This comparison was undertaken on three models of natural organic compounds : an aquatic fulvic acid, a protein and a disaccharide. The first results showed the following order of relative efficiency: O3/TiO2 > O3/H2O2 > O3 as far as Total Organic Carbon (TOC) removal was concerned. 相似文献