Evaluation of the efficiency of rotating bio-disk system in domestic wastewater treatment

Document Type : Research Article

Authors

1 Department of Civil Engineering-Environment-Faculty of Engineering-Birjand University-Birjand-Iran

2 Associate Professor, Faculty of Engineering, Civil-Environmental Department of Birjand University

3 Assistant Professor, Faculty of Engineering, Department of Civil Engineering, Environment, Birjand University, Birjand, Iran

Abstract

Due to the water shortage crisis, the importance of wastewater treatment and wastewater reuse, today the application of advanced wastewater treatment methods has been considered. Therefore, in the present study, a rotating bio-disk system has been used to treat municipal wastewater. To conduct the research, a laboratory-scale reactor unit made of Plexiglas with 35 disks was used, and initially the system used a 20-liter tank in a completely anaerobic manner to increase the reactor efficiency. The aerobic sludge of the wastewater treatment plant (activated sludge method) of the slaughterhouse has been used for the initial inoculation of the reactor and sugar, urea and potash fertilizer have been used to feed the reactor. The study lasted 96 days in three periods. During the study, the organic load increased 575 to 1250 mg/ l.d. The reactor temperature is in the mesophilic and psychrophilic temperature range for two periods. The results showed that the thickness of the biofilm on the surface of the disks is 2 mm and the pH changes are in the range of 9 to 7. COD removal efficiency during the second period is between 19.48% and during the third period is between 50-92%. During the study of the hydraulic retention time factor and the change in the rotation speed of the disk, the highest efficiency was obtained at 24% in 24 hours and 92% at 12 rpm, respectively. Experiment with real wastewater has an efficiency of 80%, which is 12% different from the efficiency of laboratory wastewater.

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