A Study on the Control of Attached Algae by Installing the Drainage Cover Device for the Final Sedimentation of Sewage Treatment Plant

Objectives : Adherent algae which are generated in the final sedimentation weir of the sewage treatment plant and the drainage channel, affect the quality of the final effluent water, and it has bad aesthetic effect due to fomation of flcok floating in the sedimentation tank. Therefore, the purpose of this study is prevention of the growth of adherent algae in advance by installing circular cover on the final sedimentation weir and drainage channels.Methods : In this study, we compared the growth pattern of adhered algae on weir and drainage channels before and after installation of circular cover at the final sedimentation weir and drainage channel of the sewage treatment plant. In addition, to identity species of attached algaem microscopic observation was applied, and ch-a concentration was analyzed to confirm the quality of the final effluent water.Results and Discussion : Then, we compared the results before and after installation of cover to check adhesion status of algae on the surface of final sedimentation drain. In case without cover, it was confirmed by observing the growth of attached algae under normal condition with air and photosynthetic reaction, and in case with cover, it was compared with opening after a certain period of time after installation of the drainage cover. As a result of the comparison, it was confirmed that a lot of attached algae occurred in the sedimentary weir and the drain. From the above results, the occurrence of final sedimentation algae is not only affected by the material and season of the drainage, but also after the formation a cluster by algae that have strong adhesion force, and then the microbial species contained in the effluent build secondary attachment and forms colony.Conclusions : In order to prevent the growth of adherent algae, a method of suppression of the growth of adherent algae by inhibition of photosynthesis was studied by installing a cover device on the weir and drain channels. As a result of installing a cover (34,000 thousand won) and reviewing economic feasibility, it can be recovered in 2.6 years, and stainless steel was selected in the view of mechanical stability and facility aging. The final sedimentation water quality increased 99.8% of Ch-a concentration treatment efficiency and 15% of SS sedimentation efficiency by installing a cover.