Bioprocess temperature

Temperature is a variable of paramount importance in any bioprocess. Temperature optimization of bioreactor operation is a complicated task since many variables and parameters are involved that are strongly dependent on temperature. Besides, temperature exerts opposite effects on enzyme activity and stability. Then, thermal optimization of enzyme reactor operation requires that temperature explicit functions for all parameters involved be determined and validated. Optimization wifi... 

Bioprocess Control An industrial fermenter is a fairly sophisticated device with control of temperature, aeration rate, and perhaps pH, concentration of dissolved oxygen, or some nutrient concentration. There has been a strong trend to automated data collection and analysis. Analog control is stiU very common, but when a computer is available for on-line data collec tion, it makes sense to use it for control as well. More elaborate measurements are performed with research bioreactors, but each new electrode or assay adds more work, additional costs, and potential headaches. Most of the functional relationships in biotechnology are nonlinear, but this may not hinder control when bioprocess operate over a narrow range of conditions. Furthermore, process control is far advanced beyond the days when the main tools for designing control systems were intended for linear systems. 

When compared to purely chemical synthesis, bioprocesses are operated under relatively mild conditions and in aqueous solvents they are essentially low temperature processes with operating temperatures usually below 40°C. The pH of most bioprocesses is between 6 and 8 and the pressure is usually one atmosphere. Under these conditions, substrates (eg oxygen) can be poorly soluble in water, which may limit productivity. Since reactions can generate considerable amounts of heat, waste heat generated during bioprocesses often has to be adequately dissipated to ensure high temperatures do not damage enzymes or cells. 

Other configurations are commercially available. PVDF has a use range from -40 to 302°F (150°C). PVDF has a high tensile strength, flex modulus, and heat deflection temperature. It is easily welded, resists permeation, and offers a high-purity smooth polymer surface. This is the polymer of choice for high-purity applications such as semiconductor, bioprocessing, and pharmaceutical industries. 

The reasons are elimination of HDS catalysts, such as Ni, Mo, etc., which result in hazardous transition metal waste, less use of energy for heating (since bioprocesses operate at room temperature or at the most 80°C), reduced green house gases such as C02, as well as less production of NOx, SOx, etc. 

In terms of the process, very little has been achieved. The mass transfer limitations still exist although emulsification has solved the problem partially, but not without creating another problem downstream in separation of the product from the rest of the stream and the issue still needs further work. The IP portfolio contains very few real process concepts. The patented material refers to a BDS process several times, but the process referred to, is no more than a simple description of the pH, temperature, etc., and the particular use of a given biocatalyst in an application. Some protected subject matter concerns the integration of a bioprocess into the flow sheet of the refinery, but again those are no more than theoretical scheme proposed for implementation, with no actual evidence with real feedstocks. 

Cull, S. G. Holbrey, J. D. Vargas-Mora, V. et al. Room-temperature ionic liquids as replacements for organic solvents in multiphase bioprocess operations, BiotechnoL Bioeng., 2000, 69(2), 227-233 Lau, R. M. van Rantwijk, F. Seddon, K. R. Sheldon, R. A. Lipase-catalyzed reactions in ionic liquids, Org. Lett., 2000, 2(26), 4189-4191. 

A key consideration in development of all multi-step bioprocesses is the type of bioreactor it may be necessary to accommodate a range of conditions including compartmentalization of the enzymes, cofactor recycle, adequate oxygen supply, variable temperature and pH requirements, and differential substrate feed rates. Examples described below include a range of different reactors, of which membrane bioreactors are clearly often particularly useful. 

Figure 2-2 Isomerization reaction that converts glucose into fiuctose. An enzyme causes this reaction to run selectively near room temperature. This process, the largest bioprocess in the chemical indus-hy, makes high-finctcse com synip for the beverage industry.

The BioView sensor (DELTA Light Optics, Denmark) was developed especially for industrial applications. It is capable of completely automatic optical measurement for monitoring and control of different bioprocesses. The instrument is conceived to withstand harsh industrial environments (e.g., high temperature, moisture) and electromagnetic interference. For data transfer a single-fiber asynchronous modem is used, which allows a distance between the computer and spectrometer of up to several hundred meters. 

Heat transfer (heat transmission) is an important unit operation in chemical and bioprocess plants. In general, heat is transferred by one of the three mechanisms, namely, conduction, convection, and radiation, or by their combinations. However, we need not consider radiation in bioprocess plants, which usually operate at relatively low temperatures. The heating and cooling of solids rarely become problematic in bioprocess plants. 

Temperature Ihe temperature in a bioreactor is an important parameter in any bioprocess, because all microorganisms and enzymes have an optimal temperature at which they function most efficiently. For example, optimal temperature for cell growth is 37 °C for Escherichia coli and 30 °C for Saccharomyces sp, respectively. Although there are many types of devices for temperature measurements, metal-resistance thermometers or thermistor thermometers are used most often for bioprocess instrumentation. The data of temperature is sufficiently reliable and mainly used for the temperature control of bioreactors and for the estimation of the heat generation in a large-scale aerobic fermentor such as in yeast production or in industrial beer fermentation. 

We know that the temperature control of the shower in a bathroom is not so easy. To have a comfortable shower, a hot water valve needs to be manipulated carefully (control action) however, we usually rely on a trial and error action until the proper temperature of a shower is achieved. How can we achieve the most comfortable shower temperature more quickly This is a common problem in the control action of many processes that are controlled by a feedback loop. The difficulty comes from a delay in the response, which naturally exists in any process - in other words, the dynamic characteristics of a process. Therefore, the control action should be determined based on the dynamics of the process. In particular, some bioprocesses are known to have serious delays in response. 

The on-off control is a simple and cheap algorithm for manipulating a control variable, and, therefore, it has been apphed to bioprocess controls such as temperature control and pH control. 

Temperature is one of the main factors affecting the feasibility and design of bioremediation processes. Bioprocesses slow down when the temperature decreases. 

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