Influence Of Solution Chemistry On The Inactivation Of Particle-associated Viruses By Simulated Sunlight Irradiation

In our study, bacteriophage MS2, kaolinite and Microcystis aeruginosawere chosen as model materials of human enteric viruses, inorganic particle and organic particle, respectively. The effect of kaolinite and Microcystis aeruginosaparticles on the inactivation of MS2 coliphage by simulated sunlight irradiation under different experimental conditions（particles concentration, p H, ionic strength, SRNOM） were investigated. And the XDLVO theory was used to studythe interacrion between MS2 and particles, futher verify experimental results. The results were concluded as followed:（1） In the XDLVO interaction energy profiles calculation, lower p H, Na⁺ and Ca²⁺ all could decrease the energy barrier between MS2 and particles. And Ca²⁺ advances decrease of energy barrier better than Na⁺. Under the same conditions, the energy barrier between MS2 and kaolinite was lower than that between MS2 and Microcystis aeruginosa.（2） In the simulated sunlight inactivation experiments, the log inactivation of MS2 was increased with the light intensities. In particle-free solution, when the p H=3 or in Ca²⁺ condition, MS2 would aggregate and cause lower log10 inactivation. In kaolinite solution, the main influence of particle under p H or Na⁺ conditions was that kaolinite particles reflect and shield simulated sunlight to protect MS2. Ca²⁺ appeared to promote part of MS2 to adsorb on kaolinite and log10 inactivation was increased. In Microcystis aeruginosasolution, MS2 would adsorb on algae particle under lower p H and Ca²⁺ conditions and a lot of components in the Microcystis aeruginosacells could act as photosensitizers and sensitize the production of.Hence, the log inactivation of MS2 was increased.（3） In UVA and visible light inactivation experiments, we found that MS2 aggregated at lower p H and indirect endogenousinactivation was the main mechanisms. And the log10 inactivation of MS2 was increased because of the aggregation.The appearance of Microcysti aeruginosalower the log10 inactivation compared with particle-free conditions may because of its main action spectrum was UVB which was blocked and indirect exogenous mechanisms didn’t work. Under Ca²⁺ conditions, the log10 inctivation of MS2 was constant because of the mechanism of Ca²⁺ promoted aggregation was that the changes on the capsid of MS2, and which was also the main photosensitizers. For the particle solution, the appearance of Ca²⁺ promoted MS2 to adsorb on kaolinite and Microcysti aeruginosa particles. And these two particles were sensitized to produce ROS to inactivate the absorbed MS2 as exogenous photosensitizers. SRNOM would produce with the irradiation of UVA and visible light and the log10 inactivation of MS2 was increased with the increasing SRNOM concentration. In kaonilite solution, the log10 inactivation of MS2 was greater than particle-free solution because of the sensitization of kaolinite. And in Microcysti aeruginosa solution, algae had a negative effect on the inactivation because of the shield of algal particles.