Fermentor chemostat

Reaction times of fermentation range from a few hours to several days. Batch processes are common, but continuous stirred tanks also are used either singly or in stages. A continuous stirred tank reactor (CSTR) also is called a chemostat. Figure 8.4 is a schematic of a fermentor with representative dimensions from the literature. 

There are two different ways of operating continuous stirred-tank fermentors (CSTFs), namely chemostat and turbidostal. In the chemostat, the flow rate of the... 

Tros, M T. N. P. Bosma, G. Schraa, and A. J. B. Zehnder, Measurement of minimum substrate concentration (Smin) in a recycling fermentor and its prediction from the kinetic parameters of Pseudomonas sp. strain B13 from batch and chemostat cultures , Appl. Environ. Microbiol., 62,3655-3661 (1996). 

The term fermentation is used to describe the biological transformation of chemicals. In its most generic application, a fermentor may be batch, continuous-stirred tank (chemostat), or continuous plug flow (immobilized cell). Most industrial fermentors are batch. Several configurations exist for these batch reactors to facilitate aeration. These include sparged tanks, horizontal fermentors, and biological towers. 

The chemostat vessel was a modified 500-mL Virtis fermentor with a teflon impeller. The medium consisted of 350 mL MSM containing alachlor (100 mg/L), glucose (100 mg/L), and yeast extract (50 mg/L). The chemostat was inoculated with 20 mL of soil perfusate, the inoculum was allowed to grow to stationary phase as a batch culture,... 

There are two different ways of operating a continuous stirred-tank fermentor, namely chemostat and turbidostat. In the chemostat, the flow rate of the feed medium and the liquid volume in the fermentor are kept constant. The rate of cell growth will then adjusts itself to the substrate concentration, which depends on the feed rate and substrate consumption by the growing cells. In the turbidostat the liquid volume in the fermentor and the liquid turbidity, which varies with the cell concentration, are kept constant by adjusting the liquid flow rate. Whereas, turbidostat operation requires a device to monitor the cell concentration (e.g., an optical sensor) and a control system for the flow rate, chemostat is much simpler to operate and hence is far more commonly used for continuous fermentation. The characteristics of the continuous stirred-tank fermentor (CSTF), when operated as a chemostat, is discussed in Chapter 12. 

---