Study On The Optimization Of Ozone Contact Tank Operation Parameters

This thesis summarized the designing and operating parameters of the ozone contacting tank by systematically investigated the existing advanced treatment of ozone-activated carbon technology,such as ozone dosage,ozone dosing ratio and ozone contact time.It was found that the operating parameters were mainly based on experience in domestic and overseas,lacking theoretical basis,especially raw water quality's influence.In order to solve these problems and offer theoretical foundation to waterworks'operation,the operating parameters in ozone contact tank,such as ozone dosage,ozone dosing ratio and ozone contact time,were optimized in this thesis by researching the relationship between water quality and ozonation kinetics.All the water samples were from different districts in China.The literature research found that the ozone dosage of current ozonation contact tank ranged from 1.0 to 3.5 mg/L,and can not be adjusted immediately once the water quality changed.Ozone contact tanks mainly use three-stage ozone dosing method nowadays.The distribution ratio was chiefly 2:1:1,1:1:1,3:1:1,basically meet the proposed requirement which the aeration rate of first stage accounted for about half of the total aeration rate.On-site research found that ozone dosing ratio was mainly 3:1:1and 3:2:2.Ozone contact time was generally between 10¹7 min.Moreover,the operating dosage of ozone is usually less than the design dosage.The water samples were taken from different sources.The ozone reaction kinetics experiment with different pH values,temperature and organic conditions showed that all the results conformed the reaction kinetics model_dt^d[O3]?28?-ae^-b?35?O3[O₃]based on ozone consumption.With the pH values,temperature,concentration of CODMn increased in the same water sample,a value increased.With the increase of CODMn,b value decreased.The quantitative relationship between water quality and ozone reaction kinetics coefficient a,b was established by BP neural network.The network structures were 3-10-10-1 and 3-11-11-1,and the training results?R²?were 0.997 and 0.995.The verification results?MSE?were 0.0019 and 0.0024,meaning a good prediction effect of this model.Building the operating optimization method of ozone contact tank based on water quality by using the effluent liquidoid ozone concentration?controlled in 0.05⁰.1mg/L?,off-gas ozone concentration and ozone use ratio as optimization target,we can obtain the optimum selecting range of ozone dosage,ozone dosaging ratio and ozone contact time in different water quality.With the pH values,temperature,concentration of COD_Mn increased,the optimal ozone dosage increased.With the concentration of COD_Mn increased,the optimal ozone dosaging ratio turned from uniform into the increase of the first stage.With the concentration of COD_Mn increased,the optimal ozone contact time prolonged,and with the pH values and temperature increased,it could get the opposite result.Compared with the operating working conditions of the existing waterworks,the model can guide the operation of waterworks well,thereby ensure the enough dosage of ozone and avoid wasting.In addition,the preliminary development of a visualization software based on the WEB interface in this thesis made the model more convenient to apply.