**8. Acknowledgments**

The study was carried out within the frames of the grant W-10/1/2011/Dz. St.

### **9. References**

616 Mass Transfer - Advanced Aspects

close to the one obtained on the basis of determination of the number of living cells. In the case of high suspension concentrations the decrease of the intracellular compound release rate was not so significant as in the case of results obtained by the direct measuring method. The sequence of events: cell wall disruption – release of intracellular compounds, was used by Melendres et al. (1993) to describe nonlinear release of enzymes. This theory can be used in the description of total protein release. Eq. (35) can be written in the form of Eq. (51).

<sup>0</sup> (1 ) *kt NN e <sup>d</sup>*

If protein release rate is proportional to that which can be released from disrupted cells, the

( ) *dR k R R d* = *II D* −

Protein can be released only from disrupted cells. The maximum amount of protein RD that

Upon substitution of Eq. (53) and Eq. (51) to Eq. (52) we obtain Eq. (54) for protein release in

(1 ) *<sup>k</sup> dR k R e R II m*

Results illustrated in Fig. 4 show that differences in the process rates increase with an increase of the concentration of microorganism suspension. Character of changes of the rate constants determined on the basis of absorbance measurements is in agreement with that revealed on the basis of computer-aided analysis of microscopic images and Bradford's

Disintegration of microorganisms in bead mills is the process of random transformation of organic matter dispersed in limited space. The general theory can be used to formulate a phenomenological model of the disintegration process and its mathematical description. They allow us to illustrate fundamental phenomena and mechanisms of the tested process. The presented method of modeling allows us to analyze many factors that have an influence on the kinetics of transformations, for instance such as different sizes, strength and

The disintegration of microorganisms covers the process of cell disruption and subsequent release of intracellular compounds contained in the cells. The discussed results of experiments proved that the size of cells of microorganisms of the same species had an effect on microorganism disintegration rate. A subsequent loss of the biggest size fractions during the process causes nonlinearity of cell disruption kinetics. The probability of decay of the biggest cell size fractions at a very low concentration of microorganisms is very high. It

In the packing of the mill working chamber, with an increase of the suspension concentration increases also intensity of intercellular relations due to filtering of

decreases with an increase of the concentration of microbial suspensions.

= −− <sup>⎡</sup> <sup>⎤</sup> <sup>⎣</sup> <sup>⎦</sup>

*D m <sup>N</sup> R R* τ

0 *d*

− τ

*N* ⎛ ⎞ <sup>=</sup> ⎜ ⎟ ⎝ ⎠

increment of protein released in time dτ is described by Eq. (52).

can be released from cells disrupted in time τ is specified by Eq. (53).

the process of microbial cell disruption.

method (1976).

**7. Conclusions** 

morphological forms of cells.

<sup>−</sup> = − (51)

(52)

(53)

(54)


**27** 

*Italy* 

Carlo Gostoli

**Recovery of Biosynthetic Products** 

GAS or

"2"

WETTING LIQUID

*Department of Chemical Engineering, Alma Mater Studiorum – University of Bologna* 

Membrane Contactors (MC) make possible to accomplish gas-liquid or liquid-liquid mass transfer operations without dispersion of one phase within another. The membrane acts as a mere physical support for the interface and does not contribute to the separation through its selectivity, the separation being primarily based on the principle of phase equilibrium. Porous membranes with narrow pore size (typically in the range 0.02-0.2 μm) are used. One of the two phases enters the membrane pores and contacts the other phase at the pore mouth on the opposite side. Generally MC operations involve an aqueous phase and the membrane has hydrophobic character, however hydrophilic membranes can be used too [Kosaraju & Sirkar, 2007]. The key factor is that one of the two phases enters the pores whereas the other phase is kept outside. In the case of hydrophobic materials (Fig. 1), the membrane pores are filled by the non-polar phase or by the gas while the aqueous phase can

Fig. 1. The membrane contactor concept based on porous hydrophobic membrane in contact with an aqueous (non wetting) liquid at one side and a gas or organic (wetting) liquid at the

**1. Introduction** 

not penetrate into the pores.

other side

NON WETTING

 LIQUID "1"

**Using Membrane Contactors** 

