Microalgal Biomass Production 67
in motion by paddle wheels and some mixing can be accomplished by appropriately designed guides.
Raceway ponds are being in use in Israel, USA, China, India and other countries. Fertilizer is used for
mass cultivation and the culture is agitated gently by paddle wheel (Fig. 2d). The advantages of open
ponds are low costs and that they are easy to operate. However, they are sensitive to contamination
leading to introduction of unwanted fast growing organisms in the ponds. Especially heterotrophic
organisms will graze on the autotrophic biomass and lead to loss of productivity. Therefore, the present
commercial production of microalgae in open culture systems is restricted to only those organisms that
can grow under extreme conditions, i.e., high pH or salinity. Thus a limited range of microalgae can be
maintained as monoculture in open ponds in long-term operation. Currently there is lot of algae mass
cultured and marketed commercially they are Skeletonema sp., Chaetoceros sp., Dunaliella sp., Spirulina
in high alkalinity and Chlorella in high levels of nutrients have been successfully cultivated. Table 1
explains all the major differences between open pond and photobioreactor.
Fig. 2. (a) Seed culture scaling-up for open raceway ponds (b) A typical lab-scale photobioreactor (c) French press (side
view) (d) Open raceway pond (e) Flocculated culture shows algal clumping (f) CO 2 cylinder (g) Culture storage tank (h)
French press (front view) (i) Wet algal biomass collected from French press (j) Hot air dryer (Courtesy: Aquatic Energy LLC,
Louisiana).
in motion by paddle wheels and some mixing can be accomplished by appropriately designed guides.
Raceway ponds are being in use in Israel, USA, China, India and other countries. Fertilizer is used for
mass cultivation and the culture is agitated gently by paddle wheel (Fig. 2d). The advantages of open
ponds are low costs and that they are easy to operate. However, they are sensitive to contamination
leading to introduction of unwanted fast growing organisms in the ponds. Especially heterotrophic
organisms will graze on the autotrophic biomass and lead to loss of productivity. Therefore, the present
commercial production of microalgae in open culture systems is restricted to only those organisms that
can grow under extreme conditions, i.e., high pH or salinity. Thus a limited range of microalgae can be
maintained as monoculture in open ponds in long-term operation. Currently there is lot of algae mass
cultured and marketed commercially they are Skeletonema sp., Chaetoceros sp., Dunaliella sp., Spirulina
in high alkalinity and Chlorella in high levels of nutrients have been successfully cultivated. Table 1
explains all the major differences between open pond and photobioreactor.
Fig. 2. (a) Seed culture scaling-up for open raceway ponds (b) A typical lab-scale photobioreactor (c) French press (side
view) (d) Open raceway pond (e) Flocculated culture shows algal clumping (f) CO 2 cylinder (g) Culture storage tank (h)
French press (front view) (i) Wet algal biomass collected from French press (j) Hot air dryer (Courtesy: Aquatic Energy LLC,
Louisiana).