Batch mode of operation

Advantages of the continuous mode over the batch mode of operation include ... 

In many cases, problems cannot be overcome by biological means. This is especially true for those related to inhibition by substrate or product. There may, however, be technical solutions to these problems. Nowadays, complicated feed strategies with different substrates can be achieved through the use of flow injection analysis, on-line sensors, mass flow meters and sophisticated computer control. Such control coupled to a fed-batch mode of operation (Figure 2.5) can often eleviate problems caused by substrate inhibition. For some processes, continuous product removal can avoid the problems associated with product inhibition the various options include ... 

In fed-batch mode residual substrate concentration may be maintained at very low levels. Ibis would reduce substrate costs, may remove catabolic repressive effects and may avoid possible toxic effects of the substrate. The fed-batch mode of operation may also avoid oxygen depletion of the culture during rapid growth. 

Fig. E.5.1. Ethanol concentration profile with respect to fermentation time in batch mode of operation.

Also, 1,3-dioxolane was obtained from the reaction of ethylene glycol (EG) and aqueous formaldehyde in high yield using an ion-exchange resin catalyst. In a batch mode of operation, with 50% excess EG, the conversion of formaldehyde is limited to 50% due to equilibrium limitation, whereas in batch reactive distillation, formaldehyde conversion greater than 99%... 

In most arrangements used for AAS, the batch mode of operation is preferred (Fig. 7.2a). The acidified s. is transported into a stirred glass cell containing 1% w/v aqueous sodium borohydride. The contents are i and the liberated hydrides flushed with an inert gas into either... 

Using it in the semi-batch mode of operation this reactor type has been used in the determination of the reaction rate constants of fast direct reactions of ozone with certain waste water pollutants, e. g. phenol or azo-dyes (Beltran and Alvarez, 1996). Beltran and coworkers have also successfully studied the reaction kinetics of various fast reacting substances using semi-batch mode STRs (see further references of Beltran, Benitez or Sotelo et al. in Chapters B 3 and B 4). 

The value of catalyst testing is enhanced by reporting the results in a professional way. It is important to describe the following procedures Was a batch mode of operation or continuous, steady-state operation used What was the reactor configuration How were the catalysts prepared Was activation or pretreatment required ... 

At low water flow rates, a batch mode of operation can be used for greater treatment efficiency. 

The term development is used to describe the process by which chemical solutes are transported through the stationary phase. For batch modes of operation, solute development is done by elution or displacement processes. For continuous modes of operation, solute development is accomplished by the process of frontal analysis. 

Fed-batch bioreactors—This method begins as a batch mode of operation as cells undergo their initial growth phase. However, run time, cell mass, and product titer are increased with the addition of supplemental nutrients, or feeds, to the bioreactor. These reactors are cost effective to run because higher product titers can be achieved from a single extended reactor run, increasing volumetric productivity. However, volumetric output is fundamentally restricted by the size of the vessel, and formation of toxic cellular metabolites can limit the duration of each reactor run. 

The reactor was loaded with 75 ml granular carrier material [14], and finally, the entire reactor system, including tubing and recirculation reservoir, was autoclaved at 120°C for 30 min. Before use, the reactor system was gassed for 15 min with N2/CO2 (4 1) to ensure anaerobic conditions and filled with BA medium with an initial xylose concentration of 10 g/1. The reactor was started up in batch mode by inoculation with 80 ml of cell suspension with an optical density (OD578) of 0.9-1. The batch mode of operation was maintained for 24 h to allow cells to attach and to immobilize on the carrier matrix. After the batch run, the system was switched to continuous mode, applying a hydraulic retention time (HRT the volume of the reactor divided by the influent flowrate) of 8 h and up-flow velocity of 1 m/h. To achieve operational stability, the reactor was run for 7 days under... 

The batch mode of operation (Figure 1.16) brings several advantages as it allows us to monitor the progress of the reaction over time and thus to acquire the whole kinetic curve in one experiment. 

In general, two different modes of operation are possible for distillation columns, no matter whether reactive or non-reactive. The first is the continuous and the second is the batch mode of operation. Focus in this section is on control of continuously operated RD columns. For optimal operation and control of batch columns we refer to the literature [4, 20, 75, 101, 110]. 

The associated disadvantages include (1) requirements for large quantities of nutrients (growth medium) relative to batch and fed batch modes of operation (2) high material costs associated with purchase and preparation/sterilization of the growth medium (3) elevated waste treatment costs and (4) fouling of the surfaces of permselective membranes or conventional or membrane microfiltration devices, which can lead to marked decreases in the flux of... 

One way of expressing the material balance on the total mass of snbsirate present in the reactor during the fed batch mode of operation is... 

During the batch mode of operation, input and output (dVjdt = So = 0). Thus the first term on the RHS of each vanishes. For example, for species B, flows are both absent of the above equations... 

The total number of moles of a particular species (say B, again) that is formed is the sum of the moles formed during the semibatch and batch modes of operation. This may be written as ... 

It often becomes necessary in biochemical reactions to continuously add one (or more) substrate(s), a nutrient, or any regulating compound to a batch reactor, from which there is no continuous removal of product. A reactor in which this is accomplished is conventionally termed the semibatch reactor (Chapter 4) but is referred to as a fed-batch reactor in biochemical language. The fed-batch mode of operation is very useful when an optimum concentration of the substrate (or one of the substrates in a multisubstrate system) or of a particular nutrient is desirable. This can be achieved by imposing an optimal feed policy. 

In batch mode of operation, airless drying has three distinct stages. These... 

---