A Simulation And Experiment Study On Process Of Mass Transportin Internal Loop Biofilm Reactor

Study on substrate nutrition mass transfer from liquid to biofilm in bioreactor is significant to bioreactor design, The development of computational fluid dynamics and computer hardware constantly push such study to go further and further.This paper amend and develop the previous one-dimensional numerical model based on the substrate diffusion-reaction equation to make it more interoperable and accurate. Through the observation of the reactor within the biofilm surface, several complex surface structures of biofilm are calculated by using spline interpolation function. Meanwhile, it found that Sh would increase with the increases of Re while the decrease of Ae by the redefinition of the Sherwood number and a Sh-Re and Sh-Ae curve.This paper establish an experimental installation with the capacity of 14 L internal loop biofilm reactor. It changed the hydrodynamic residence time (HRT) and COD in the entrance in the observation effects of COD degradation. It found that the removal rate of COD increased with HRT increase; the removal rate of COD increased with the increase of COD at entrance when HRT was longer than 1 Oh. However, the removal rate of COD would icrease at first and then decrease with the increase of COD at entrance when HRT was smaller than 10h.It is the first time to apply a 3D model that based on the substrate diffusion-reaction equation to internal loop biofilm reactor and study on two-phase mass transfer between liquid-solid. Substrate biological reaction kinetics coefficient is figured out by using nonlinear regression method with the experimental data, which meant that the largest oxygen consumption rate was 0.012 g/L.min, half-saturation concentration was 1.84 mg/L; Glucose maximum degradation rate was 0.56 g/L.min and half-saturation concentration of 594.56 mg/L. The error between the simulated and experimental values is from 5% to 15%. Through the substrate consumption rate analysis, it found that in small HRT, the removal rate of COD increased and then descreased with the increase of entrance COD concentration is because that the biofilm substrate concentration is larger more than the half-saturation concentration and substrate consumption rate was close to the largest biofilm substrate consumption rate.