CARBON-DIOXIDE SUPPLY TO ALGAL CULTURES .2. EFFICIENCY OF CO2 ABSORPTION FROM A NATURAL-GAS SUPPLIED TO THE RECIRCULATION PIPE OF A CULTIVATION UNIT

Natural gas coming from an underground source, and containing 16.4-94.2 % vol. CO2, was fed into the recirculation pipe of the cultivation unit (225 m2) as the carbon source of an algal culture. It was found that 57.9 +/- 12.8 % of the delivered CO2 was absorbed by the culture. The cultivation unit contained a 5 m3 culture of the alga Scenedesmus incrassatulus strain R-83. Volumetric flow rate of the gas supplied to the recirculation pipe was in the range 2200-6600 l.h-1. The estimated average detention time of gas in the pipe was 26 s. The culture temperature was 21.0-37.7-degrees-C. For the calculation of the CO2 absorption efficiency mathematical models were used to describe the time course of pH in the culture after stopping and/or recontinuing the gas supply.