Photobiohydrogen production and high-performance photobioreactor - Solar Energy Sciences and Engineering Applications - page 356

Figure 11.4.4 Flat panel photobioreactor with rocking motion (Gilbert et al., 2011).

11.4.1.3 Tubular photobioreactor

A tubular photobioreactor is usually constructed with either a glass or plastic tube,
in which the culture liquid is pumped by mechanical or airlift pumps. In terms of the
configuration, tubular photobioreactors can be divided into two major categories: hor-
izontal and helical tubular photobioreactor, as shown in Figures 11.4.1c and 11.4.1d.
The most significant feature of tubular photobioreactors is large illumination surface
area so that it is particularly suitable for outdoor mass cultures of photosynthetic
microorganisms (Posten, 2009; Ugwa et al., 2008). However, tubular photobioreac-
tors also face some problems of poor mass transfer, gas accumulation and wall growth
(Dutta et al., 2008). Hence a lot of modifications to the tubular photobioreactor config-
uration have been proposed to improve the performance of photobioreactors. Tredici
and Zittelli (1998) designed a near horizontal tubular photobioreactor which was laid
on a wooden framework with an angle of 5 degrees horizontally. The elevation reduced
the gas holdup and improved the oxygen removal, resulting in a higher volumetric
productivity and photosynthetic efficiency with Arthrospira platensis . Gebicki et al.
(2009) also devised a near horizontal tubular photobioreactor with an inclination of
below 10 degrees (Figure 11.4.5a) and found that a photobiohydrogen production rate
of 3.3 mL/L/h with R. capsulatus was achieved. In addition to horizontal photobiore-
actors, investigations on the helical photobioreactor have also been widely performed.
Morita et al. (2000) used PVC tube to be coiled in a conical framework, forming a
conical helical photobioreactor with a cone angle of 60 degrees (Figure 11.4.5b) and
examined the effect of the cone angle. It was shown that this photobioreactor had the
maximal photosynthetic efficiency of 6.84% among all cone angle tested because 60
degrees gave the highest light harvesting efficiency with the same basal area. Lee et al.
(1995) designed an -shape tubular photobioreactor (Figure 11.4.5c), in which the

algal culture was lifted by air to a receiver tank, and then flowed down through paral-
leled tubes with a horizontal angle of 25 degrees to reach another set of air riser tubes.
Again the culture was lifted to another receiver tank and then flowed down through

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