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Yields, photosynthetic efficiencies, and proximate chemical composition of dense cultures of marine microalgae. A subcontract report (open access)

Yields, photosynthetic efficiencies, and proximate chemical composition of dense cultures of marine microalgae. A subcontract report

The yields, photosynthetic efficiencies, and proximate composition of several microalgae were compared in dense cultures grown at light intensities up to 70% sunlight. Yields ranged from 3.4 to 21.7 g dry weight/m/sup 2/ day. The highest yield was obtained with Phaeodactylum; the lowest in Botryococcus cultures. The same species had the highest and lowest efficiencies of utilization of photosynthetically active radiation. In nitrogen-sufficient cells of all but one species, most of the dry weight consisted of protein. Lipid content of all species was 20 to 29%, and carbohydrate content 11 to 23%. Lipid content increased somewhat in N-deficient Phaeodactylum and Isochrysis cells, but decreased in deficient Monallanthus cells. Because the overall dry weight yield was reduced by deficiency, lipid yields did not increase. However, since the carbohydrate content increased to about 65% in N-deficient Dunaliella and Tetraselmis cells, the carbohydrate yield increased. In Phaeodactylum the optimum light intensity was about 40% of full sunlight. Most experimets with this alga included a CUSO/sub 4/ filter to decrease infrared irradiance. When this filter was removed, the yield increased because more red light in the photosynthetically active spectral range was included. These results should prove useful to workers attempting to maximize yields and …
Date: July 1, 1983
Creator: Thomas, W. H.; Seibert, D. L. R.; Alden, M.; Eldridge, P. & Neori, A.
System: The UNT Digital Library
Production of liquid fuels and chemicals by microalgae. Final subcontract report (open access)

Production of liquid fuels and chemicals by microalgae. Final subcontract report

An overall objective of the project was to conceptually determine if simple open pond systems have application for the production of fuels from microalgae. To demonstrate the overall objective, work concentrated on showing the potential microalgal yields that are possible from an open pond system on a sustained basis. Furthermore, problems associated with this experimental system were documented and reported so that future endeavors shall benefit. Finally, operational costs were documented to permit preliminary economic analysis of the system. The major conclusions of this project can be summarized as follows: (1) Using two wildtype species in northern California a yearly average productivity of 15 gm/m/sup 2//day, or 24 tons/acre/yr can be obtained in water with TDS = 4 to 8 ppt. (2) This can probably be increased to 20 to 25 gm/m/sup 2//day or 32 to 40 tons/acre/y in southern California. (3) Productivity can probably be further increased by using competitive strains screened for low respiration rates, tolerances to high levels of dissolved oxygen, broad temperature optima, and resistance to photoinhibition. (4) In systems with randomized, turbulent mixing, productivity is independent of channel velocity at least for productivities up to 25 to 30 gm/m/sup 2//day and velocities from 1 to …
Date: March 1, 1985
Creator: Weissman, J. C. & Goebel, R. P.
System: The UNT Digital Library
Research and development of shallow algal mass culture systems for the production of oils (open access)

Research and development of shallow algal mass culture systems for the production of oils

The major accomplishment of the past nine months' work was the identification of a microalgal species which can be grown in the system on a 12-month basis without temperature control. The most promising species identified to date is a strain of platymonas sp. This strain grows rapidly at temperatures from 20/sup 0/ to 34/sup 0/C, and at salinities from 1.5 to 3.5%. Neither the lower temperature limit nor the lower salinity limit of the strain are known at this time. A factorial experiment designed to determine optimum growth conditions indicated that the optimum culture depth was 10 cm, the optimum pH about 7.5, and the optimum flow rate about 30 cm/s. A major discovery was that diluting the culture every third day greatly enhanced production. In this dilution mode daily yields averaged 46 g/m/sup 2/ ash-free dry weight (AFDW) over a one-month period, and photosynthetic efficiencies averaged 11% (based on visible light energy). The former figure is over twice the best long-term yields achieved in microalgal mass culture systems grown exclusively on inorganic nutrients.
Date: October 1, 1984
Creator: Laws, E.A.
System: The UNT Digital Library