Multiphase Bioreactor Design

concept. In this case, pulsation is the result of the liquid entering the columns,

through the pulsation chamber. Once the pressure in the chamber is high enough,

the membrane covering the feeding tube injects the liquid into the column; the

membrane then closes the inlet tube again, which creates a cyclical feed system.

In contrast with the previous pulsators, in this system, the motion of the liquid in

the column is always upwards (Baltar, 1972).

Uses of Pulsing Systems

Pulsation was firstly used in several separation processes in order to enhance the contact
between the phases and, consequently mass transfer rate improved. Pulsation has been
applied to a number of systems, including chemical and biochemical reactors. Table 11.1
shows a summary of the different pulsators coupled to several types of unit operations
and processes.

Separation processes

One of the most extended and useful applications of pulsation is to liquid-liquid
extraction. In this process, pulsation generates higher degrees of turbulence, which
increases the interfacial area and, accordingly, enhances mass transfer rate (Bailes et al.,
1976). An electric motor connected, via an acentrical and a crank-rod to the central rod,

Table 11.1 Some equipment and process to which

different pulsing systems have been applied.

Equipment of
pulsation

Unit type Process Reference

Pulsing plates
column

Column of perforated plates Absortion Skala and

Veljkovic 1988

Packed-bed column with
perforated plates

Anaerobic treatment of

waste-water

Brauer and Sucker

1979

Membrane pulsator Column of perforated plates L-L Extraction Golding and Lee
1981

Anaerobic filter Anaerobic treatment of
waste-waters

Etzold and

Stadlbauer 1990

Alternating motion
pumps

Packed-bed column S-L Extraction Göebel and Fortuin

1986

Pulsing pump Ultrafiltration unit Clarification of juices Finnigan and
Howell 1989

Plug pulsator Column of perforated plates Obtention of SCP Serieys et al. 1978

Batch bioreactor Production of
biodegradable plastic

Harrison and

Mackley 1992

Pneumatic pulsator Packed-bed column with Alcoholic fermentation Navarro and Goma

Multiphase bioreactor design 330