Utilization of carbon dioxide by Chlorella kessleri in outdoor open thin-layer culture units
Lívanský, Karel; Doucha, Jiří
published: Jul 1, 2005
ArtNo. ESP142015700011, Price: 29.00 €
Measured profiles of partial pressure of dissolved carbon dioxide (pCO2) in suspension of the microalga Chlorella kessleri and measured flow rate of CO2 gas (food grade) supplied into the culture unit were used in mass balance considerations concerning CO2. The microalga was grown outdoors in a 224 m2 culture unit with sloped cultivation surface (inclination 1.7%). The velocity of suspension flow down the cultivation surface was about 50 cm.s-1, thickness of suspension layer 6-7 mm. An amount of 1.115 g CO2 was consumed by the alga per 1 g of evolved O2. About 80% of supplied carbon dioxide was absorbed in the suspension during saturation. Considerable part of supplied CO2 in the suspension was converted via carbonic acid into bicarbonate ions which buffered the pCO2 gradient along the flow path of the suspension on the cultivation surface. The logarithm of pCO2 in suspension decreased linearly with increasing pH. For a 28 m long suspension flow path the pH increased about 0.4 units. Net rate of CO2 consumption by the alga referred to 1 m2 of cultivation area was proportional to solar irradiance. About 64% of supplied CO2 was utilized by the alga and the rest (about 36%) was lost as a result of incomplete CO2 absorption in the process of saturation, and escape of CO2 from the suspension into the atmosphere. About 2.73 kg CO2 was needed for production of 1 kg (dry matter) Chlorella biomass.