140
o. Pulz and K. Scheibenbogen
[119]. Watanabe and Hall [120] designed a cone-shaped helical tubular
structure and thus improved the PE of the top-illuminated photobioreactor in
contrast to standard geometry. Within the MELISSA-project, Binois et al. [36]
applied a tubular reactor with Spirulina and Rhodospirillaceae as a life-support
system for space equipment. The experimental work is continued with tubular
systems at outdoor conditions, high growth rates up to 2.7 gd.wt.1-1 d -1
(Phaeodactylum tricornutum) having been achieved [-121].
Thanks to the high technical level of cylindrical reactors of classical biotechnology, as offered by a number of known fermenter manufacturers, this type of
reactor is commonly applied for inoculation purposes and experimental cultivations in laboratory scale. In stirrer reactors, fully sterilizable 1-10 1 glass containers, surrounded by fluorescent lamps, well defined cultivation conditions
may be established. All the cylindrical reactors are characterized by a high
luminance at the surface, related to a large dark volume. Strong turbulences are
required in order to achieve sufficient productivities and to avoid photoinhibition [34, 122], which may lead to inhibitory growth effects by the corresponding
shear forces.
A reactor type, representing the various designs with internal illumination,
will be described which includes most of the typical features [,123]. The cylindrical reactors are made of stainless steel with diameters between 20 and 60 cm
and heights between 35 and 100 era, correponding to volumes of 20-2501. At
least four transparent pipes are inserted into the cylinder from the top through
holes in the lid, holding fluorescent tubes which can easily be removed during
sterilization without opening the reactor. A T-shaped multifunctional stirrer
agitates the suspension and supplies sterile air. Light supply was sufficient to
produce more than 10 mg exopolysaccharides from cyanobacteria on a daily
basis [124]. For the production of Spirulina biomass light input was found to be
insufficient though the concept of fluorescent tubes in combination with thin
layers was considered to be advantageous with regard to growth yield [-122]. The
idea to use internally fixed fluorescent lights was already set up in 1978, when
a 3 m 3 vessel was presented [125], but no data on algal growth are available.
For fully sterile operation, Schulze and Stahl [-126] presented a photobioreactor with a tumbler head equipped with plunger lamps. Due to the special
tumbling motion which ensures high gas exchange, troublesome glide ring seals
can be avoided.
Quite another concept is described by Semenenko et al. [61], the sterilizable
laboratory photobioreactor ~BP-10. The algal suspension is brought to rotation by a cylindrical insert and pressed by centrifugal force to the tempered wall
in defined layer thickness. Due to the special design of the rotor a high
turbulence within the suspension is generated which will result in a good
exchange of material without disturbing the limits of shear force sensibility. The
luminescent material is in the centre of the reactor, it is protected by a waterchilled quartz retort; a great part of the heat generated is absorbed and
discharged immediately. The growth rates of several microalgal species confirm the high efficiency of this concept. With Chlorella, a growth of
o. Pulz and K. Scheibenbogen
[119]. Watanabe and Hall [120] designed a cone-shaped helical tubular
structure and thus improved the PE of the top-illuminated photobioreactor in
contrast to standard geometry. Within the MELISSA-project, Binois et al. [36]
applied a tubular reactor with Spirulina and Rhodospirillaceae as a life-support
system for space equipment. The experimental work is continued with tubular
systems at outdoor conditions, high growth rates up to 2.7 gd.wt.1-1 d -1
(Phaeodactylum tricornutum) having been achieved [-121].
Thanks to the high technical level of cylindrical reactors of classical biotechnology, as offered by a number of known fermenter manufacturers, this type of
reactor is commonly applied for inoculation purposes and experimental cultivations in laboratory scale. In stirrer reactors, fully sterilizable 1-10 1 glass containers, surrounded by fluorescent lamps, well defined cultivation conditions
may be established. All the cylindrical reactors are characterized by a high
luminance at the surface, related to a large dark volume. Strong turbulences are
required in order to achieve sufficient productivities and to avoid photoinhibition [34, 122], which may lead to inhibitory growth effects by the corresponding
shear forces.
A reactor type, representing the various designs with internal illumination,
will be described which includes most of the typical features [,123]. The cylindrical reactors are made of stainless steel with diameters between 20 and 60 cm
and heights between 35 and 100 era, correponding to volumes of 20-2501. At
least four transparent pipes are inserted into the cylinder from the top through
holes in the lid, holding fluorescent tubes which can easily be removed during
sterilization without opening the reactor. A T-shaped multifunctional stirrer
agitates the suspension and supplies sterile air. Light supply was sufficient to
produce more than 10 mg exopolysaccharides from cyanobacteria on a daily
basis [124]. For the production of Spirulina biomass light input was found to be
insufficient though the concept of fluorescent tubes in combination with thin
layers was considered to be advantageous with regard to growth yield [-122]. The
idea to use internally fixed fluorescent lights was already set up in 1978, when
a 3 m 3 vessel was presented [125], but no data on algal growth are available.
For fully sterile operation, Schulze and Stahl [-126] presented a photobioreactor with a tumbler head equipped with plunger lamps. Due to the special
tumbling motion which ensures high gas exchange, troublesome glide ring seals
can be avoided.
Quite another concept is described by Semenenko et al. [61], the sterilizable
laboratory photobioreactor ~BP-10. The algal suspension is brought to rotation by a cylindrical insert and pressed by centrifugal force to the tempered wall
in defined layer thickness. Due to the special design of the rotor a high
turbulence within the suspension is generated which will result in a good
exchange of material without disturbing the limits of shear force sensibility. The
luminescent material is in the centre of the reactor, it is protected by a waterchilled quartz retort; a great part of the heat generated is absorbed and
discharged immediately. The growth rates of several microalgal species confirm the high efficiency of this concept. With Chlorella, a growth of