Effect of nitrogen-mediated changes in alkalinity on ph control and CO/sub 2/ supply in intensive microalgal cultures

Journal Article · Mon Mar 01 04:00:00 EST 1982 · Biotechnol. Bioeng.; (United States)

DOI:https://doi.org/10.1002/bit.260240308· OSTI ID:5034665

Goldman, J C; Dennett, M R; Riley, C B

The freshwater alga Scenedesmus obliquus was grown in continuous culture at a fixed dilution rate of 0.5 per day, but at varying pH in the range 4.17-10.67. The pH was regulated in the range 4.17-7.67 by continuously bubbling 1% CO/sub 2/-enriched air into the cultures and by varying the source of nitrogen (NO/sub 3/-, NH/sub 4/+, or urea) in the growth medium, which, in turn, led to changes in culture alkalinity. Culture alkalinity and PCO/sub 2/ were the sole determinants of pH. A pH-stat system, together with NO/sub 3/- in the medium, was used to regulate the pH in the range 7.92-10.67. Maximum productivity, which occurred at pH 6.6, was dependent on N source only to the extent that culture alkalinity was a function of nitrogen uptake. The results demonstrate that the choice of N is a critical factor in controlling the pH+ large-scale algal cultures. NH/sub 4/+ is a poor source of N because it leads to destruction of culture alkalinity and concomitant growth-inhibiting reductions in pH, whereas NO/sub 3/- has an opposite effect, although pH is not so severely affected in this case. Urea is, by far, the most suitable N source for maximising algal yield when it is supplied in combination with the proper amounts of HCO/sub 3/- alkalinity in the growth medium and percent CO/sub 2/ in the bubbled gas that will lead to an equilibrium pH near the optimum pH. (Refs. 23).

• Research Organization: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
• OSTI ID: 5034665
• Journal Information: Biotechnol. Bioeng.; (United States), Journal Name: Biotechnol. Bioeng.; (United States) Vol. 24:3; ISSN BIBIA
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
550700* -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
ALGAE
AMIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONIC ACID DERIVATIVES
CHALCOGENIDES
COMPARATIVE EVALUATIONS
CONTINUOUS CULTURE
CULTURE MEDIA
ELEMENTS
MICROORGANISMS
NITROGEN
NONMETALS
NUTRIENTS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PLANTS
SCENEDESMUS
UNICELLULAR ALGAE
UREA