UCLA

Aims: The objective of this study is to develop kinetic models based on batch experiments describing the growth, CO2 consumption, and H2 production of Anabaena variabilis ATCC 29413-U as functions of irradiance and CO2 concentration.

Methods and Results: A parametric experimental study is performed for irradiances from 1120 to 16100 lux and for initial CO2 mole fractions from 0.03 to 0.20 in argon at pH 7.0 with nitrate in the medium. Kinetic models are successfully developed based on the Monod model and on a novel scaling analysis employing the CO2 consumption half-time as the time scale.

Conclusions: Monod models predict the growth, CO2 consumption, and O2 production within 30%. Moreover, the CO2 consumption half-time is an appropriate time scale for analyzing all experimental data. In addition, the optimum initial CO2 mole fraction is 0.05 for maximum growth and CO2 consumption rates. Finally, the saturation irradiance is determined to be 5,170 lux for CO2 consumption and growth whereas, the maximum H2 production rate occurs around 10,000 lux.

Significance and Impact: The study presents kinetic models predicting the growth, CO2 consumption,and H2 production of A.variabilis. The experimental and scaling analysis methods can be generalized to other microorganisms.