Bioreactor Case Study

Compared with model I, model II performs considerably better during simulation (Fig. 30.21). The manipulated variable i follows the measurements closely, which indicates that the closed loop dynamics of the simulation approximates the actual experimental setup. However, when the controller is switched on, the reflux fraction is increased and becomes larger than one, before it is decreased. This was found to be independent of controller tuning and is caused by the fuzzy model. The result is that there is a slight inverse response in the production curve the production first becomes negative before it increases, which is not possible in practice. The net effect is that the simulated production lags behind the measurements (Fig. 30.21c). Model III performs better than models I and II. Quality control is good and the simulation matches the measurements of i closely. The simulated production curve approximates the measured production well. 

In this case study, the bioreactor (Eqns. (30.I)-(30.8)) is simulated and the fuzzy relationship for ]U is determined. The simulation layout is shown in Fig. 30.22. 

The model for data generation block does not have an equation for and they are estimated using the so-called Pl-estimator that was discussed in section 30.2.4. If these values are estimated properly, the concentrations for cx and cp should follow there real values closely. This can be seen in Fig. 30.23 and Fig. 30.24. 

Since these concentrations do not deviate much from their actual values, the parameters j/ and rmust have appropriate values and they can now be estimated as a function of Cxand cg. This is shown in Fig. 30.25, where the real value of // is compared with the value from the fuzzy model. 

If necessary, a more accurate model could be developed when multiple runs are made under different conditions, i.e. when more data points are available. 

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There are a number of engineering variations of in situ bioremediation strategies potentially applicable for soil and/or groundwater contaminated by PAHs. Recent reviews of in situ bioremediation technologies by Norris et al. (1993) provide excellent sources of references and offer case studies for myriad in situ bioremediation applications. These include bioventing vadose zone soil, biosparging saturated zone soil, vacuum-vaporized well (UVB) technology, and in situ bioreactors. 

This case study presents the design of a biochemical process for NO removal from flue gases, where an absorber and a bioreactor are the main units. Based on a rough estimation of Hatta numbers, it was concluded that a spray tower offering a large G/L interfacial and a small liquid fraction is the best type of equipment, favoring the main chemical reaction. The bioreactor was chosen as a CSTR. 

Membrane technology may become essential if zero-discharge mills become a requirement or legislation on water use becomes very restrictive. The type of membrane fractionation required varies according to the use that is to be made of the treated water. This issue is addressed in Chapter 35, which describes the apphcation of membrane processes in the pulp and paper industry for treatment of the effluent generated. Chapter 36 focuses on the apphcation of membrane bioreactors in wastewater treatment. Chapter 37 describes the apphcations of hollow fiber contactors in membrane-assisted solvent extraction for the recovery of metallic pollutants. The apphcations of membrane contactors in the treatment of gaseous waste streams are presented in Chapter 38. Chapter 39 deals with an important development in the strip dispersion technique for actinide recovery/metal separation. Chapter 40 focuses on electrically enhanced membrane separation and catalysis. Chapter 41 contains important case studies on the treatment of effluent in the leather industry. The case studies cover the work carried out at pilot plant level with membrane bioreactors and reverse osmosis. Development in nanofiltration and a case study on the recovery of impurity-free sodium thiocyanate in the acrylic industry are described in Chapter 42. 

The case study is based on a tower-type bioreactor that uses S. cerevisiae immobilized in pellets with 4% of citric pectin, for production of bioethanol. The bioreactor is divided in four stages with gas separators between them to prevent the CO2 accumulation during the fennentation process because the CO2 release may eventually result in a drop in the fermentation yield. The experiments were performed at 30 °C, pH 4.0, initial substrate concentration of 161.4 g/L, feed flow rate of 40 mL/h, and residence time of 6.12 h. After 40 h of operation, the system has reached a steady state. A diagram of the system is shown in Fig. 1. 

This case study, by Tillman et aP°, shows that the PCL/collagen electrospun nanofibrous tubular scaffolds successfully supported cell attachment and growth under pulsatile flow conditions in a bioreactor and could maintain a high degree of structural integrity under normal physiological conditions without eliciting abnormal inflammatory response over a period of 1 month. 

Various chapters on membrane reactors (MR) consider different aspects of the integration of membranes with other conventional systems pervapo-ration, zeolite, bioreactors, fuel cells, wastewater treatment, systems for electrical energy, and so on. However, among the various possible examples not cited in these chapters, in the following, due to the lack of space, only seven, but very interesting, case studies are taken in consideration. 

In particular, techniqnes based on conpUng membrane processes and appropriate complexing agents, snpported Uqnid membranes (SLMs), pervaporation (PV) and membrane bioreactors (MBRs) are reviewed and discussed for their capacity to remove undesired componnds. Case studies referring to the treatment of ammoniacal etching solntion by SLM, complexation-nltrafiltration conpled with soil washing for soil remediation, volatile organic componnds removal by PV and treatment of tannery wastewaters by MBRs are also presented and discnssed. 

Abstract In this chapter, membrane bioreactors are described from an economic point of view. Economic analysis is a crucial stage in plant design, project and control and also requires an evaluation of the research, development and commercialization of the products and bioproducts. Such an analysis is focused here on membrane bioreactors and reactors, also taking into account the separation units such as micro-, ultra- and nano-flltration units that might be used as a downstream process or as pretreatment steps. The most important rules and parameters are first introduced. Some examples of application and case studies are also reported. 

The economic analysis reported in this chapter with the case studies already described will offer an idea of the methods that can be applied to the project and design of membrane reactors and bioreactors. New investments, as well as the introduction of bioreactors in existing plants, have been taken into account with the aim of offering a general view of their potentialities also from an economic point of view. 

Case Study Determining the Growth Rate in a Fed-batch Bioreactor... 

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