Batch bioreactors

The fermentations were accomplished in a BioFlo lie bioreactor (Batch/Continuous Fermentor New Brunswick Scientific USA) with nominal capacity of 5.0 1 of volume. The useful volume used in the fermentations was 3.0 1, and the temperature was maintained at 30 °C and the agitation in 100 rpm, with a Rushton 6-blade impeller. The oxygenation was nondispersive with the use of pure oxygen [14]. The culture medium was composed by... 

Various bioreactors (batch stirred tank reactors, continuous packed bed, stirred tank, fluidized bed and membrane) have been used with varying efficiencies. Generally, stirred tank reactors are found to be less efficient than continuous ones (Macrae, 1985b Sawamura, 1988) due to... 

Activities associated with bioreactors include gas/hquid contacting, on-hne sensing of concentrations, mixing, heat transfer, foam control, and feed of nutrients or reagents such as those for pH control. The workhorse of the fermentation industry is the conventional batch fermenter shown in Fig. 24-3. Not shown are ladder rungs inside the vessel, antifoam probe, antifoam system, and sensors (pH, dissolved oxygen, temperature, and the like). Note that coils may lie between baffles and the tank wall or connect to the top to minimize openings... 

Subsequently, biological/physical treatment of leachate with an activated carbon-enhanced sequencing batch bioreactor (PAC-SBR) was analyzed to determine whether the improved treatment by simultaneous adsorption and biodegradation in the SBR would produce an acceptable effluent without post-treatment in the existing granular activated carbon adsorber (Ying et al., 1986). 

Ying, W.C., R.R. Bonk and S.A. Sojka. Treatment of Landfill Leachate in Powered Activated Carbon Enhanced Sequencing Batch Bioreactors. In Proc. of the 18th Mid-Atlantic Ind. Waste Conference, Technomic Publishing Company, Inc., Lancaster, Pennsylvania, 1986. 

Batch processing A processing technique in which a bioreactor is supplied with substrate and essential nutrients, sterilized and inoculated with microorganisms, and the process is run to completion followed by removal of products. 

Fed-batch culture A cell cultivation technique in which one or more nutrients are supplied to the bioreactor in a given sequence during the growth or bioconversion process while the products remain in the vessel until the end of the run. 

Bioreactors a) batch stirred tank b) continuous stirred tank c) continuous packed-bed i) downward flow, ii) upward flow and iii) recycle d) continuous fluidised-bed e) continuous ultrafiltration. Redrawn from Katchalski - Katzir E. (1993) Trends in Biotechnology II, 471-477. 

Item 1 is the major factor in choosing continuous systems rather than batch systems for improved SCP production. Economics are improved by lower capital cost for the bioreactor (a conomica major equipment cost, see Section 4.10) and by a higher output rate. Item 3 leads to greater control of product quality. 

The production-scale fermentation unit, with a projected annual capacity of over50,000 tonnes was fully commissioned in 1980. The bioreactor (Figure 4.8) is 60 m high, with a 7 m base diameter and working volume 1,500 m3. There are two downcomers and cooling bundles at the base. Initial sterilisation is with saturated steam at 140°C followed by displacement with heat sterilised water. Air and ammonia are filter sterilised as a mixture, methanol filter sterilised and other nutrients heat sterilised. Methanol is added through many nozzles, placed two per square metre. For start-up, 20 litres of inoculum is used and the system is operated as a batch culture for about 30 h. After this time the system is operated as a chemostat continuous culture, with methanol limitation, at 37°C and pH 6.7. Run lengths are normally 100 days, with contamination the usual cause of failure. 

A reasonable size of bioreactor, based on transport and handling considerations, is 200 m3, with a working volume of 150 m3. If file fermentation time is 48 hours and down time for reuse about 24 hours, then the total batch time is 72 hours. 

The culture can be used directly for the conversion of phenylpyruvic add to resting cells L-phenylalanine. Therefore, a batch process with resting cells can be carried out, with some glucose added for maintenance (fed-batch fermentation). Another approach is to harvest the cells from the fermentation broth and to use them in a separate bioreactor in higher concentrations than the ones obtained in the cell cultivation. An advantage of the last method can be that the concentration of compounds other than L-phenylalanine is lower, so that downstream processing may be cheaper. 

Batch. Fermentation run times are relatively short and the same bioreactor can be used for making several different products. 

A full set of bioreactors with pH and temperature controllers are shown in Figure 1.3. The complete set of a 25 litre fermenter with all the accessory controlling units creates a good opportunity to control suitable production of biochemical products with variation of process parameters. Pumping fresh nutrients and operating in batch, fed batch and continuous mode are easy and suitable for producing fine chemicals, amino acids, and even antibiotics. 

At unsteady-state conditions, the change of concentration with respect to time is detectable, ASIAt + 0 but for steady-state conditions the leaving substrate may be constant. For a plug flow bioreactor we can treat it like a batch system. 

Fig. 3.9. Growth simulation of C. ljungdahlii on synthesis gas in batch bioreactor, the experimental data are average...

The energy balance for the bioreactor is shown by the following equation. As the fermenter is used batch wise, the heat balance is mathematically expressed as stated in (4.4.1) ... 

Table E.10.1. Microbial growth in a batch fermentation bioreactor...

Fig. E.10.1. Plot of natural logarithm of the cell dry weight concentration versus time in the batch bioreactor...

Batch mixed reactor There are three principal modes of bioreactor operation (a) batch (b) fed batch (c) continuous. 

In a batch production of penicillin, 40 m3 capacity of the plant, sterile air is required to be supplied. The bioreactor requires 1 vvm (volume of air/volume of broth, min). The incoming air contains 3000cells/m3 of air, for 100 hours operation. Calculate the depth of filter, if the penetration of bacteria is 1 in 1 million. 

The actual fermentation process is known as the incubation phase and is just part of the batch cycle. A complete fermentation cycle can typically include the following steps, most likely depending on bioreactor design ... 

A batch production of penicillin of 40 m3 capacity is required to supply sterile ah through bioreactor at 1 volume of ah per volume of culture per min (1 win). Incoming ah contains... 

In a batch fermentation of ethanol, kinetic data were collected as product formed. The data are shown in Table E.5.1. The data will be used to design a continuous bioreactor (CSTR) with a 1001 working volume. 

The typical bioreactor is a two-phase stirred tank. It is a three-phase stirred tank if the cells are counted as a separate phase, but they are usually lumped with the aqueous phase that contains the microbes, dissolved nutrients, and soluble products. The gas phase supplies oxygen and removes by-product CO2. The most common operating mode is batch with respect to biomass, batch or fed-batch with respect to nutrients, and fed-batch with respect to oxygen. Reactor aeration is discussed in Chapter 11. This present section concentrates on reaction models for the liquid phase. 

Batch fermentation means the cultivation of microorganisms, where the sterile growth medium in desired volume is inoculated with the microorganisms into the bioreactor and no additional growth medium is added during the fermentation. The product will be harvested at the end of the process. Typically, PHA s production is performed using batch fermentation because of low cost for investment and no special control. In addition, sterilization of the feed stock is easier than other fermentation processes, and operation is flexible. 

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