Development of the UMBR/Oxic process model using the biological settling model and assessment of process characteristics

Abstract

The Upflow Multilayer Bio-Reactor (UMBR)/Oxic process was developed to remove nutrients from wastewater. The UMBR having multiple functions of denitrification, anaerobic reaction, and sludge thickening is an upflow and plug-flow reactor which could maintain high concentration of biomass in the UMBR could be maintained. This process train was the same as the conventional activated sludge process except replacing a primary settling tank with the UMBR. Since the primary settling tank in a conventional process can be easily retrofitted to the UMBR, the UMBR/Oxic process could be a viable alternative to conventional BNR processes. The main objective of this study was to develop and to verify the UMBR/Oxic process model applying a biological settling model, and to evalute the characteristics of the process with the process model. As results, the biological settling model was developed by combining one-dimensional layer model with ASM No. 3 $+$ bio-P module and verified with opearating result of the lab-scale and semi-pilot UMBR/Oxic process. This model could simulate the all components in the UMBR and the clarifier according to their depth and confirm the characteristics of the UMBR/Oxic process. And the UMBR/Oxic process has high potential to remove nitrogen in low COD/N ratio in the experimental results. This high TN removal efficiency was due to high biomass concentration in the UMBR. TN removal was mainly affected by TCOD/TN ratio of influent but became better after the process acclimimated. On the other hand, TP removal was not stable and generally dependent of the amount of wasted sludge. Enhanced biological phosphorus removal was not active in the UMBR/Oxic process. And the UMBR could play a role of a sludge thickening. MLSS of wasted sludge from the bottom of the UMBR was very high. Sensitivity analysis was conducted by the `single parameter method (SPM)`. As results, sensitivity of parameters and components about heterotrophic organisms was dependen...