PENGARUH SIMULASI PENGARUH KONSENTRASI SOLID DAN GEOMETRI BIOREAKTOR MEMBRAN TERENDAM TERHADAP PERPINDAHAN MASSA GAS-LIQUID DAN FLUKS MELALUI MEMBRAN

Abstract

Abstract: Hydrodynamics characteristic for the mixing of gas-solid-liquid in membrane bioreactor submerged (MBRs) and its influence on mass transfer was studied computationally at various solid concentration, incoming gas rate, and the baffle distance. Computational method was conducted by using software GAMBIT 2.1.6. for the making of the grid which represents the calculation domain and conduct the simulation using CFD software FLUENT commercial code 6.2.16. Multiphase flow in reactor was simulated with mixture model, while to model the turbulence characteristic of the flow standard k-ε model was used. The geometrical system investigate is bioreactor in the form of box with flat bottom, 2 baffles, submerged membrane and air passage through the reactor bottom. The membrane type used is hollow fiber, the liquid used is water, and the solid is activated sludge, and air acts as gas phase. The result indicates that closer the baffle to the membrane, the liquid dispersion process goes faster, so that fluid in tank can be mixed perfectly and it can increase the gas-liquid mass transfer rate and the flux at MBRs. The increase of the solid concentration does not significantly affect the change of gas-liquid mass transfer rate and flux through the membrane, but the increase of air flow rate can accelerate the gas-liquid mass transfer and the flux. The position of baffle 9 cm from tank wall is the best position among the others because the amount of air flow is balanced with the circulating fluid flow. Consider from the solid distribution, double inlet MBRs is better compared to that of single inlet. Flux obtained does not show significant difference. From the both approach of the membrane model, membrane model as porous media give the simulation results closer to the experimental data.