Study On Oxidation Removal Technology Of Aldehyde Characteristic Odorants In Drinking Water

The issue of smell of drinking water is a common problem in current water treatment.Conventional treatment methods such as coagulation,sedimentation and filtration in waterworks have limited effects on the removal of taste and odor compounds in water.On the basis of conventional treatment processes,appropriate pretreatment or advanced treatment is extremely necessary.For this issue,five aldehydes including trans-,trans-2,4-heptadienal,trans-2-octenal,trans-,trans-2,4-octadienal,trans-,trans-2,4-decadienal and ?-cyclocitral were studied in this research given the current situation of taste and odor issue in drinking water in China.The treatability evaluation based on different oxidation treatment processes of the selected taste and odor compounds was conducted that contained the specific technical parameters,application conditions and influence factors.The study can provide a basis for dealing with the taste and odor issue caused by such substances.This research found that:(1)Comparing the kinds of oxidation processes,the removal rates of each of mentioned aldehyde odorants when using potassium permanganate were higher than that when using other oxidation processes,which were all more than 50%.In particular,the removal rates of trans-2-octenal,trans-,trans-2,4-octadienal and ?-cyclocitral were all over 90%.The other five oxidation processes had a limited effect on the removal the above five aldehyde odorants.the removal rates of the above aldehydes by sodium hypochlorite,chlorine dioxide and hydrogen peroxide respectively were all less than 30%.The removal rate of trans-,trans-2,4-heptadienal by 2 mg/L Ozone was 43.7%.When ozone combined with hydrogen peroxide was used,the removal rate of trans-,trans-2,4-decadienal was more than 50%.In addition,In the experiments of removing trans-2-octenal,trans-,trans-2,4-decadienal and ?-cyclocitral,the oxidant combination had an obvious effect on the removal of those odorants compared with ozone alone.The removal rates of those odorants by the former were approximately 2 times of that by the latter.(2)Through regression analysis of the experimental data,it was found that the reaction of potassium permanganate to oxidize all the above aldehyde odorant substances was in accordance with the second-order kinetic model,and to potassium permanganate or the odorant substances,it was a first-order reaction.Under the condition of pH 7 and reaction temperature of 20?,the second-order kinetic constants of the reaction of potassium permanganate with each odorant were obtained in the experiment.They were 5.082 × 10 M ? s in the reaction of potassium permanganate and trans-,trans-2,4-heptadienal,2.175 × 10 M ? s in the reaction of potassium permanganate and trans-2-octenal,,and,3.204 × 10 M ? s in the reaction of potassium permanganate and trans-,trans-2,4-octadienal,2.598 × 10 M ?s in the reaction of potassium permanganate and trans-,trans-2,4-decadienal,5.077 ×10 M ? s in the reaction of potassium permanganate and ?-cyclocitral.(3)The empirical reaction curve could be well fitted to the reactions of potassium permanganate oxidizing trans-,trans-2,4-heptadienal,trans-,trans-2,4-octadienal,trans-,trans-2,4-decadienal and ?-cyclocitral in the source water.However,for the reaction of potassium permanganate oxidizing trans-2-octenal,the empirical reaction curve could not fit well.It is necessary to further study the factors affecting the reaction and enrich the variable parameters of the empirical reaction curve in order to play its guiding role.According to the reaction kinetics study of the oxidation of the above-mentioned aldehyde odorants by potassium permanganate,Tables about the removal rate of the above-mentioned aldehyde odorants by potassium permanganate at different reaction time and oxidant dosage were obtained.They can help find the appropriate dosage of oxidant potassium permanganate quickly.