Study On Photocatalytic Inactivation And Rapid Detection Technology Of Ship Ballast Water

In recent years,ship ballast water discharge has become the important cause of marine invasion and ecological environmental damage,and we focus on the efficient inactivation and rapid detection of ship ballast water in this field.Based on what we have learned,we had prepared the ultraviolet catalytic modified loaded nano-titanium dioxide?TiO₂?,and investigated its inactivation effect and mechanism on ballast water microorganisms.In order to quickly test the inactivation effect,in the aspect of rapid detection of ballast water,we also had investigated the detection effect of two fast detectors on simulating ship ballast water in laboratory.Firstly,the preparation conditions of Sol-gel method for modified catalysts were optimized by the methed of response surface,and then we could obtain the better conditions:load times with 15 times,calcination temperature at 445°C,calcination time at 2h.And we had further prepared the modified catalysts doped with different content of Ag,Fe and Gd.SEM showed that the modified catalyst had better surface morphology and improved agglomeration after modification,and the EDS showed that the improved catalyst realized better the doping of Ag,Fe and Gd elements respectively,and XRD showed that the modified catalyst appeared sharp titanium ore phase,and the particle size was smaller.The inactivation was carried out by using modified catalysts of Ag,Fe and Gd with different contents?0.4%,0.7%and 1%?,and the final results showed that the TiO₂ catalyst achieved optimal results when it was doped with 1%Ag.Secondly,the inactivation effect and mechanism of ultraviolet photocatalytic modified nano-TiO2 on Escherichia coli,Enterococcus and Scenedesmus dimorphus were investigated by using the optimal catalyst.The results showed that ultraviolet photocatalytic modified nano-TiO₂ could accelerate the inactivation rate by at least 8 s compared with pure ultraviolet inactivation,and the content of MDA increased more,and the activity of SOD decreased more obviously,and chlorophyll a was reduced more,which indicated that ultraviolet photocatalytic modified nano-TiO₂ significantly improved the damage effect to microbial cells.The effects of temperature?12?,22?and 32??,salinity?fresh water,15‰and 30‰?and ultraviolet wavelength on inactivation effect were investigated.The results showed that the system had the best inactivation effect on ballast water microorganisms with the condition of 12?,fresh water and long wave ultraviolet rays.On the basis of the ballast water inactivation experiment,in order to further investigate and test the inactivation effect,quickly and accurately determine whether the system was up to standard,and determined the number of algae cells,the presence of dead algae,salinity and turbidity,etc.And the results showed that the rapid detection effect of comprehensive fluorescence method performed better.The rapid detection process of simulated ballast water in laboratory was simulated by BP neural network,and got the importance of each factor:comprehensive fluorescence method:algal cell concentration>the presence of dead algae>salinity>turbidity,and modulated chlorophyll fluorescence method:the number of dead algae cells>algal cell concentration>turbidity>salinity.