In this paper, a 3 L membrane-photobioreactor was first prepared to study the CO2 removal capability using Chlorella pyrenoidosa. The CO2 was efficiently removed from the airstream when the following operating conditions were set: the inlet airflow of 0.6 L/min, the aeration gas containing 1% CO2, light intensity of 3500 Lx, at 25~30°C and pH at 8.5~9.5. It showed that CO2 concentration in the discharged gas decreased 50% compared to that in the aeration gas, and the removal capacity of the experimental photobioreactor was 0.118 g CO2/(L-medium·h).
The medium composition of C. pyrenoidosa for CO2 removal from air was also studied in a 10 L enclosed photobioreactor, in which the proper values of temperature, pH and dissolved oxygen (DO) were controlled on-line. In order to alleviate the influence of DO on the growth of microalgae, N2 was also used to form mixed aeration gas instead of condensed air. Based on the ascertainment of the mode of inorganic carbon (Ci) uptake, the concentration changes of HCO3−, CO32−, NH4+, PO43−, NO2− and NO3− were analyzed during the process of high-density photoautotrophic microalgal culture.
Consequently, the optimization performance of CO2 removal by the high-density photoautotrophic microalgal culture will be carried out in this lab under optimum operating conditions.