Oxygen transfer rate bioreactors scaleup microbial processes gasliquid interface in aerobic bioprocesses, oxygen is a key substrate. Performances of bioreactors concentration productive bioreactors wastewater treatment 1050 aerobic anaerobic kgm3550 moulds bacteriayeast mixed culture viscosity high low low low oxygen consumption high high low absent mass transfer low high low absent heat production 315 315 0. Pdf oxygen transfer in production scale bioreactor researchgate. Oxygen transfer rate in a system is a function of the oxygen volumetric mass transfer coefficient kla and the oxygen solubility in the medium.
Techniques for oxygen transfer measurement in bioreactors. A new approach is proposed for the simultaneous determination of the volumetric oxygen transfer coefficient kla and the oxygen uptake rate our in bioreactors. Jan 07, 20 in stirred tank bioreactors the oxygen mass transfer is a function of many variables, such as the physical properties of the liquid viscosity, surface tension, etc. Mar 25, 2009 the microbial growth in a bioreactor depends upon the oxygen transfer rate otr. Membrane filtration allows a higher biomass concentration to be maintained, thereby allowing smaller bioreactors to be used. Applikon labscale bioreactors 500 ml, 3 l and 15 l were successfully used for scalingup k. Here, dcdt is the accumulation oxygen rate in the liquid phase, otr represents the oxygen transfer rate from the gas to the liquid, and our is the oxygen uptake rate by the microorganisms. The fundamental difference between oxygen mass transfer coefficient kla and. If high orp levels are present, lower dissolved oxygen levels are required. Providing sufficient oxygen and removing carbon dioxide are important in the design and operation of aerobic bioreactors.
This research closely examined the airtoliquid oxygen mass transfer coefficient. Aerobic processes demand a certain oxygen uptake rate our. Nevertheless, the oxygen mass transfer rate otr should be equal to or higher than the oxygen uptake rate our to prevent the culture from experiencing oxygen depletion. A new approach is proposed for the simultaneous determination of the volumetric oxygen transfer coefficient k l a and the oxygen uptake rate our in bioreactors. The methodology is based on modifications of the classical dynamic gassing in method and the steadystate mass balance method for obtaining the values kla and our, respectively. Pdf bioreactor scaleup and oxygen transfer rate in microbial. In the submerged configuration a coarse bubble diffuser is generally used. Oxygen transfer, mixing time and gas hold up characterization in a hybrid bioreactor 3 was 0. An overview of fermenter and the design considerations to enhance its productivity hitesh jagani, karteek hebbar, sagar s. Oxygen mass transfer characteristics for various twin and singleimpeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1. An overview of fermenter and the design considerations to. Nov 12, 2010 the intrinsic delay in dissolved oxygen do measurement was evaluated by shifting the bioreactor pressure and fitting a first. The membrane filtration system in effect can replace the secondary clarifier and sand filters in a typical activated sludge treatment system.
Scalability in laboratory bioreactors based on constant. Oxygen is a soluble substrate, but its solubility in aqueous media at ambient conditions is very low. The second term describes the oxygen consumption due to the biological activity. Analysis of distribution of oxygen transfer rate in stirred. Oxygen mass transfer rate in a pressurized labscale stirred bioreactor oxygen mass transfer from air to the liquid phase in bioreactors with aerobic cultureshaslongbeena serious impairmentto theproductivityofvarious bioprocesses. A novel method of simulating oxygen mass transfer in two. The fundamental difference between oxygen mass transfer coefficient kla and oxygen transfer rate. The oxygen transfer rate otr is influenced by the physical properties of the gas and liquid, operational conditions, geometric parameters, and the consumption rate by the cells. Start with the peak oxygenuptakerate our requirement and assume that the otr must match it. The intrinsic delay in dissolved oxygen do measurement was evaluated by shifting the bioreactor pressure and fitting a first. If oxygen is limited, cell growth and product formation can be affected. Oxygen mass transfer in a stirred tank bioreactor using.
But, although the oxygen transfer is directly related to the processes studied and modeled by cfd, there are no information concerning the distribution of oxygen transfer rate inside the stirred bioreactors with multiple impellers and real fermentation broths, probably due to the number and complexity of the involved factors. Calculated values of the oxygen transfer rate are compared with. Simultaneous determination of oxygen consumption rate. The last term can be expressed by the product q o 2.
The process of energy generation utilizes the use of substrate. An increase of the oxygen mass transfer rate otr can be the key to overcome oxygen limitation. Improved scaleup strategies of bioreactors springerlink. In an aerobic process, optimal oxygen transfer is sometimes the rate limiting step. The mass transfer coefficient k l a determines the magnitude of the otr. Mar 01, 2012 here, dcdt is the accumulation oxygen rate in the liquid phase, otr represents the oxygen transfer rate from the gas to the liquid, and our is the oxygen uptake rate by the microorganisms. However, realizing conditions that reflect the largescale process accurately can be challenging. This system does not offer very efficient oxygen transfer but the rising bubbles provide a. The effect of antifoam agents on mass transfer in bioreactors. Analysis of distribution of oxygen transfer rate in. Biochemical oxygen demand bod the amount of oxygen consumed by these. A bioreactor system based on a novel oxygen transfer. The mass transfer of oxygen transfer is often a limiting factor in bioreactors.
Under optimum conditions of gas air, oxygen, nitrogen, and carbon dioxide flow rates, temperature, ph, dissolved oxygen level, and agitation speed, the microorganisms or cells will reproduce at a rapid rate. Scope scaleup in bioreactors volumetric oxygen transfer coefficient eq. Chisti department of chemical engineering, university of almer. Extensive literature on the oxygen transfer rate in bioreactors is nowadays available and a considerable part of it has been published in the last years arrua et al. There is a lack of studies that examine the oxygen mass transfer in fungal fermentation. Nitrification rates vary significantly based on the residual oxygen levels. The otr is widely used to study the growth behavior of microbial and plant cell cultures. Enhancement of oxygen mass transfer and gas holdup using palm. Simultaneous determination of oxygen consumption rate and volumetric oxygen transfer coefficient in pneumatically agitated bioreactors j. With an increasing organic fraction, the mass transfer coefficient decreases, whereas. Bioprocess development upstream and downstream technologies monica chuong, phd. In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene.
This is based on the authors experience that the lowest total power consumption agitator plus compressor occurs roughly at this condition. Bioreactor scaleup and oxygen transfer rate in microbial processes. Pdf a twocompartment model is presented to calculate the oxygen. The volumetric mass transfer coefficient k l a describes the efficiency with which oxygen can be delivered to a bioreactor culture for a given set of parameter conditions. Gasliquid mass transfer in bioreactors is characterized in terms of the overall volumetric oxygen transfer coefficient kla and the oxygen uptake rate our. Oxygen mass transfer rate in a pressurized labscale. Oxygen transfer can be described by the mass transfer model for a sparingly soluble gas into a liquid, where the driving force for oxygen transfer is the oxygen concentration that would be in equilibrium with the sparger gas, o 2, minus the dissolved oxygen concentration, o 2. Taking again the example of oxygen in aerobic cultures, if mass transfer of oxygen from the bubbles is slow, the rate of cell metabolism will become dependent on the rate of oxygen supply from the gas phase. Traditional methods for mixing use an impellor, and the classical o2 transfer method features a sparging stone that expels air bubbles to increase the o2 transfer surface area in contact. The oxygen transfer rate otr must be known, and if possible predicted to achieve an optimum design operation and scaleup of bioreactors. Applications of gasliquid transport with reaction gasliquid mass transfer in bioreactors microbial cells often grown aerobically in stirred tank reactors oxygen supply is often limiting x d. Cx, with q o 2 being the specific oxygen uptake rate of the microorganism used and cx is the biomass.
The oxygen transfer rate otr must be known, and if. While it is desirable to keep as many operating parameters constant as possible during the scaleup, the number of constant parameters realizable is limited by the degrees of freedom in designing the largescale operation. An industrial perspective on scaledown challenges using. Oxygen transfer, mixing time and gas holdup characterization. The latter is an important factor for aerobic cultures. Bioreactor scaleup and oxygen transfer rate in microbial.
Apr 11, 2017 oxygen is typically considered the limitation. Bioprocess development upstream and downstream technologies. Enhancement of oxygen mass transfer and gas holdup using. The dynamic method was coupled with the do lag results to determine the oxygen transfer rate in water for injection wfi and a complete culture medium. Effective scaleup is essential for successful bioprocessing. Scaleup of aerobic fermentations is often carried out on the basis of a constant. Oxygen transfer and scaleup in bioreactors using hydroejectors for.
For productionscale bioreactors, a better representation of oxygen transfer may be achieved using a twocompartment model of the vessel, with different. In this work, palm oil was chosen as the organic phase to study the oxygen transfer characteristics such as effect of viscosity, gas holdup, and mass transfer coefficient on the xanthan gum solution by varying the agitation rate and aeration rate in a stirred tank bioreactor. This article highlights common challenges of using msbrs for scaledown. The residence time of the gas in dispersion tr, and average bubble rising velocity ub in the riser,were calculated using eqs.
Measuring kla for better bioreactor performance bioprocess. In aerobic fermentations, the bioreactor performance greatly depends on its oxygen transfer capacities. The oxygen transfer rate otr must be known, and if possible predicted to. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these. Jun 01, 2008 bioreactor technologies for mammalian cell culture may seem quite sophisticated 1. Miniaturized stirred bioreactors msbrs are gaining popularity as a costeffective approach to scaledown experimentation.
The methodology is based on modifications of the classical dynamic gassingin method and the steadystate mass balance method for obtaining the values k l a and our, respectively. Other key differences between chemical reactors and bioreactors are selectivity and rate. Cell culture scaleup in stirredtank singleuse bioreactors. To eliminate oxygen limitations and allow cell metabolism to function at its fastest, the dissolved oxygen concentration has to be above a critical level at any point of the bioreactor.
Although our varies throughout the process, engineers must design for the peak rate. In combination with the liquid jet momentum, which characterizes the hydroejector, a scaleup correlation with the oxygen transfer rate as scaleup. Thus, actively growing cells can consume all the dissolved oxygen quickly and, hence, oxygen has to be supplied continuously by mass transfer from air to. Oxygen mass transfer rate in a pressurized labscale stirred. In this work, a critical distinction is made between the oxygen mass transfer coefficient, k l a, and the oxygen mass transfer rate. In aerobic bioprocesses, oxygen is a key substrate. Bioreactor technologies for mammalian cell culture may seem quite sophisticated 1. Traditional methods for mixing use an impellor, and the classical o2 transfer method features a sparging stone that expels air bubbles to increase the o2. This bibliography was generated on cite this for me on tuesday, march 10, 2015.
For a specific bioreactor and medium, it is possible to increase kla using higher aeration rates. Classification of bioreactors there are numerous types of bioreactors batch, sequence, continuously stirred tanks, anaerobic contact processes, anaerobic filters, etc. A polarographic dissolved oxygen electrode is used to. The rate of oxygen transfer from gas to liquid is therefore of prime importance, where the demand for dissolved oxygen is high. Under quasi steadystate conditions, this equals the oxygen transfer rate otr. In fact, efficient mammalian cell culture is simple and requires just two major elements. Oxygen transfer, mixing time and gas hold up characterization in a hybrid bioreactor 5 d d l h h. The microbial growth in a bioreactor depends upon the oxygen transfer rate. There are many techniques for measuring oxygen concentration and otr in bioreactors. A bioreactor system based on a novel oxygen transfer method. Simultaneous determination of oxygen consumption rate and. Aeration within the bioreactor provides the required oxygen transfer for growth of the biomass and mixing of the reactor. Oxygen transfer rate an overview sciencedirect topics.
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