Coastal BioMarine Bioreactors

Photoautotrophic Applications

Coastal BioMarine's photoautotrophic photobioreactor is fabricated from a transparent, high stress film.  The device is produced by sealing together two or more layers of film to create an enclosure with pathways for internal flow. The design is proprietary.

Algae broth is circulated within the photobioreactor.  Broth is impelled upward by air introduced into a number of parallel pathways (risers) and returned to the bottom portion via a downcomer.  Liquid flow rates can be controlled in either turbulent or laminar mode.

The prototype photobioreactor is top supported, is 18 inches (47.5 cm) wide by 83 inches (210.8 cm) high.  There are eight risers of 0.75 inches (1.9 cm) in diameter and two downcomers of 2.0 inches (5.1 cm) indiameter.  The charge volume is 8 liters.  Liquids are introduced and withdrawn through fittings in the bottom section.  Air or treated flu gas is introduced at the bottom via a sparger designed to provide equal flow to all risers.  Carbon dioxide is also introduced at the bottom through two stainless steel microporous diffusers.  A circulating sample loop is connected between the bottom fittings for liquid.  Instrument probes are located in the sample loop.

Applications

The prototype photobioreactor is useful for laboratory and pilot plant applications:

• Study photobioreactor operating characteristics
• Study recombinant protein applications
• Therapeutics
• Industrial enzymes
• Study human and animal food from biomass
• Study fish meal from biomass
• Study biofuels from biomass

The laboratory photobioreactor will produce dense cultures.  The achievable cell density depends on the algae species, the degree of turbulence, radiation intensity, supplemental carbon dioxide, the quality of the instruments and the skill of the operator.  Tetraselmis species initiate growth inhibition at 4 to 5 grams per liter; nannochloropsis initiates growth inhibition at 7 grams per liter.

Commercial Applications

Commercial size photobioreactors are not presently offered.  Coastal BioMarine can provide designs and cost estimates for commercial and demonstration applications.

 Mixotrophic and Heterotrophic Applications

• Low Cost
• Designed for sterile applications
• Scalable to larger capacities
• Heat or gamma sterilizable
• Air lift mixer (low cell shear stress)
• Small foot print
• Sintered glass or microporous diffuser
• Settlement thwarting feature
• Custom designs available
• Engineered and provided by a company that operates bioreactors

Click to view larger image of bioreactor

Internal to the bioreactor is the diffuser for introduction of air or oxygen and the air lift mixing device.  Air lift is a more gentle mixer than rotating blades.

External to the bioreactor are two 0.2 micron gas filters, a sample loop that can be circulated with a peristaltic pump.  Instrument probes can be located in the sample loop.  At the top of the bioreactor is the vent line.

At Coastal BioMarine, 100-liter bioreactors have been operated in sterile mixotrophic mode.  A bioreactor of this capacity has a diameter of 10 inches (25.4 cm) and an overall length of 80 inches (203.2 cm).  For a capacity of 100 liters or more, a support tank is recommended to minimize film stress.  The tank diameter is 12 inches (30.5 cm) and height is 96 inches (243.8 cm).

Operating experience with this assembly is with a Tetraselmis strain in mixotrophic mode.  The carbon source was glucose.

Click to see Bioreactor Oxygen Absorption Rates.