Numerical Simulation And Performance Analysis Of Ozone Contact Tank

CFD software was applied as a tool to optimize the design of the ozone contactorin this paper. The CFD-based model of ozone contactor,which included hydraulic model,ozone transfer and decomposition model, disinfection and byproducts model, oxidationmodel for nitrobenzene and lindane, was employed to simulate the front and rear ofozone tank’s hydraulic efficiency, disinfection, cnotrol of bromate generation andorganic pollutants removal efficiency. After that, experiments were performed based onthe simulation to select the optimal ozone contact tank. Lastly, based on the optimaltank, parameter optimization, as well as advanced oxidation process using O₃/H₂O₂toremove lindane referring to the problom that it was difficult to degrade lindane throughthe reace organochlorine, were researched. The following conclusions were obtained:（1） Simulation and experimental results are consistent. Based on the control ofdisinfection byproducts, hydraulic efficiency,disinfection and organic removalefficeency of the plug flow tank are superior to these of the traditional pool type.（2） Experimental parameters for the control of the refractory organics on the plugflow ozone contact tank （for instance: NB） were further optimized. Results showed thatthe higher NB substrate concentration, the faster the ozonation rate of NB. Appropriateamount of humus was in favor of stimulating the genneration of the dydroxyl radical.However, excessive amount of humus will cause the excessive consumption of ozone.pH ranging from8to9is conducive to generation of hydroxyl radicals, also, superlativepH value is not conductive to the removal of NB. Because the radicals can be easilyquenched through collision with faster ozone dacay. For the NB’s fast reaction, whenHRT>3min, it has no effect on the NB removel efficiency. So HRT=3min is selected tobe the optimal value, which can cut down processing time and increase the volune ofwater treatment.（3） Based on the plug flow ozone contact tank, comparison between O₃andH₂O₂/O₃advanced oxidation process to remove lindane was performed. It’s resulted thatthe removal efficiency of the latter is increased by66.67%from the former. In addition,the pilot scale verification experiments were conducted on the plug flow ozone contacttank. However, the verification results had some deviation with the results of the labstudy, which shows the optimal H₂O₂/O₃ratio is0.5, pH is about8, and H₂O₂is dosed in1.2min. Under this condition, the removal rate of lindane is apparently increased by137.04%, which is better than the result of the small expetiment.