Circulation Within The Gas-lift Bioreactor Of Dynamic Parameters

The hydrodynamic parameters and mass transfer coefficient are studied In the internal loop airlift bioreactor used in treating wastewater. The hydrodynamic parameters consist of gas holdup, liquid velocity and axial dispersion coefficient. Some concentrate work has been done as following:1. An experimental apparatus is established. Some experiment without microorganism has been carried out to study dynamic properties of this equipment.2. According to the variation of reactor flow regimes among reactor parts, a more efficient model is built. A new algorithm (difference analysis) is used to analyze this model.3. In air-water system, the influence of gas superficial velocity on hydrodynamic parameters and volumetric mass transfer coefficient (k,,a) is investigated. In order to simulate microorganism, a series doses of solid particle are added into water. In such an air-water-solid particle system, the influence of solid concentration on hydrodynamic parameters and volumetric mass transfer coefficient are studied. To the same purpose, CMC solution is used to simulate the real liquid medium.4. The model built in this work is compared with CSTR model and PFR model. It is shown that the working model is more accurate.Through these work, some conclusion can be drawn:1. Gas holdup is a function of gas superficial velocity. And when the solid concentration (Cs) is 0.75%, the gas holdup in riser reaches the highest value.2. Liquid velocity increases when solid particles are added into the liquid phase. And the liquid velocity in riser can get to the highest value at Cs=0.5%.3. Axial dispersion coefficient increases with the increasing of gas superficial velocity. Adding solid phase makes the value of axial dispersion coefficient larger, what so ever, when Cs=0. 75%, axial dispersion coefficient arrive at the climax.4. In the air-water-solid system the value of volumetric mass transfer coefficient is larger than that in air-water system. And when Cs=1. 0%,the volumetric mass transfer coefficient get to the highest value. 5. The increasing of liquid phase viscosity undermines the volumetricmass transfer coefficient.According to the discussions above, an experiential equation is built. It agrees well with the experimental results at 0. 6%≤Cs≤2. 4%.