Suppression Performance Of Typical Algae Under UV-C Irradiation

This thesis explored the suppression effectiveness of UV-C irradiation（0²00mJ/cm²ï¼‰ on the growth and photosynthesis activity of bloom-formingcyanobacteria species, including Microcystis aeruginosa, Oscillatoria planctonica,and Anabaena flos-aquae, as well as typical green algal species, Chlorella vulgarisand Scenedesmus obliqnus, and diatom species Synedra sp.. The enhancement on UV-induced suppression effects by repeated UV-C exposure and H₂O₂addition were alsoinvestigated.The results indicate that UV-C doses at50²00mJ/cm²can effectively suppressthe growth of M. aeruginosa and A. flos-aquae in both lag phase and logarithmicphase for1¹0d. However, only UV-C dose at200mJ/cm²can suppress the growth ofO. planctonica in logarithmic phase for2d.The results show that UV-C dose at100mJ/cm²can suppress the growth of C.vulgaris and S. obliqnus in lag phase for1³d. For the algae species in logarithmicphase, UV-C doses at50²00mJ/cm²can suppress the growth of S. obliqnus for2⁷dand S. sp. for2⁹d, however, only200mJ/cm²can suppress the growth of C. vulgarisfor3d. The sensitivities of both growth and photosynthetic activities of S. sp., M.aeruginosa, O. planctonica, and S. obliqnus to50¹00mJ/cm²UV-C irradiation weresignificantly higher than that of C. vulgaris and A. flos-aquae.For the co-culture solution of M. aeruginosa and C. vulgaris, UV-C doses at50²00mJ/cm²can effectively suppress M. aeruginosa growth for10¹4d, andsignificantly promote the competition ability C. vulgaris against M. aeruginosa. Forthe co-culture solution of M. aeruginosa and S. obliqnus, UV-C doses at100²00mJ/cm²can effectively suppress M. aeruginosa growth for10d, andsignificantly promote the competition ability S. obliqnus against M. aeruginosa.The results show that the repeated UV-C treatment at50¹00mJ/cm²after onesuppression period can induce the prolonged suppression effects on M. aeruginosagrowth for4⁷d. But the sensitivity of both growth and photosynthetic activities ofM. aeruginosa upon the repeated UV-C treatment were lower than that of the initialUV-C treatment. The suppression effect of50mJ/cm²UV-C on M. aeruginosa growthcan be effectively enhanced by adding0.5².0mg/L H₂O₂before UV-C treatment.