| The biological inactivation of ultraviolet light is widely applied,its characteristics of stable,safe,low-energy and high-efficiency in water treatment are generally accepeted.It has been applied in the prevention of aquatic outbreak and the prevention of biological invasion of ship ballast water in the marine field.However,how to efficiently,comprehensively and accurately calibrate the effective dose of UV instruments has been a technical bottleneck in this field.In this paper,based on the UV-parallel light dose calculation method,we screened the dose-validated microorganisms suitable for seawater and developed the UV biological combined dose verification method.With the CFD calculation,the actual UV dose of the device under 7 kinds of light transmittance was verified by a combination of organisms and the middle-sized spiral flow UV reactor was designed and optimized.The following results were obtained.The verified dose range of the UV reactor was determined to be 0-450 mJ/cm2 through the study on the UV inactivation effect of 6 challenge microorganisms suitable for seawater environment.Age differences and sensitivity range of the UV-dose calibration for single species are limited.In this study,the effect of UV-parallel light inactivation on six kinds of microorganisms suitable for seawater were investigated.The six challenge microorganisms were as follows:MS2 Phage,Aspergillus niger spores and Platymonas helgolandica,Platymonas subcordiformis,Dunaliella salina,and Isochrysis galbana.Challenge microorganism were inactivated at 0-200 mJ/cm2,0-500 mJ/cm2 and 0-450 mJ/cm2.The micro-biological survival rate was calculated by plaque count,spore germination,microscopic fluorescence and FCM number,the response curves of UV dose and 6 kinds of organisms were established.The results showed that there was a significant difference between the two concentrations of MS2 in the relationship between UV dose and inactivation rate(P<0.05).The high concentration of MS2 had a more effective inactivation rate curve,the UV dose required to achieve 4 log-level inactivation rates was 61.23 and 59.51 mJ/cm2 respectively when MS2 was 107 pfu/ml and 108 pfu/ml;the UV dose-response curve of MS2 phage at a concentration of 108pfu/ml was more than 95%confidence in the range of 0-160 mJ/cm2 and the curve showed a linear relationship within the dose range of 20-80 mJ/cm2.Aspergillus Niger spores showed a linear relationship within the dose range of 60-200 mJ/cm2.Microalgae was resistant to ultraviolet radiation and was sensitive to higher doses of ultraviolet radiation relative to MS2 and Aspergillus Niger.The inactivation rate of four species of algae was linear at 60-180 mJ/cm2,150-450 mJ/cm2 and 100-150 mJ/cm2,respectively.Combined with the equipment applicability,the linear range of UV dose-response curve of MS2,Isochrysis galbana,platymonas helgolandica,Aspergillus spores were selected 20-80mJ/cm2,60-180 mJ/cm2,120-200 mJ/cm2,150-450 mJ/cm2 as the validation range of effective dose of seawater ultraviolet disinfection equipment.So far,the UV dose verification was improved within the combined dose validation range of 0-450 mJ/cm2 for the four challenge microorganisms,providing a data basis for the dose calibration of the marine UV reactor.The spiral flow field formed by the impeller and the baffle closed vessel reactor was analyzed by CFD numerical simulation and the simulation value of UV dose was calculated,the spiral flow UV reactor was designed and installed.The spiral flow UV reactor was established from three aspects:light,intensity,flow distribution and particle dispersed dose.The optimized UV reacctor had a theoretical dose of 88 mJ/cm2 when UVT=95%water quality.Using Chrysophyceae and MS2 cooperative UV dose verification,adjusted the water flow rate UVT=65%-95%.The inactivation rate of microorganisms increased with the change of UVT.Finally,it was verified that the spiral flow UV reactor obtained the actual UV dose of 75.8 mJ/cm2 at a flow rate of 5 m3/h and UVT=95%,which was 14%deviation from the calculated value of CFD.The dose calculation of low-pressure ultraviolet parallel light was used to construct the UV-parallel light platform for 5.3W laboratory;optimize the microbial phase consistency and verify the ultraviolet inactivation experiment of variousmicroorganisms.A CFD calculation model in a seawater environment was established.An optimization scheme for the application of the spiral flow theory in the closed vessel reactor was presented,an ultraviolet disinfection equipment with a flow rate of 5m3 was designed and implemented to verify the actual dose of the closed vessel reactor by selected organism.Data analysis and application research were discussed on effectiveness in vivo testing methodology,combined dose calibration,and design of a closed vessel reactor for helical flow field. |
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