纯二氧化碳条件下小球藻固定CO2

微藻固碳已经成为消减温室气体排放的新的研究热点。利用静态吸收方法,考查了通人纯CO2对普通小球藻生长特点、固定CO2效率以及藻液pH值变异的影响。结果表明：通入纯CO2使小球藻生长延滞期显著延长,比普通培养延长10～12d,对其他生长阶段的影响不大;小球藻固定CO2速率可分为2个过程,即物理固碳过程和生物固碳过程,前者在藻细胞延滞期发生,峰值由CO。溶解于培养液造成,后者在藻细胞生长的指数期、稳定期和衰退期发生,峰值由藻细胞指数生长造成,2个过程中,固定CO2速率的变化趋势都是先增大后降低;纯CO2条件下,藻液pH值变化速率高,4d内,藻液即被酸化,随后藻液pH值变化速率逐渐降低,且pH值稳定在适宜水平。因此,采用小球藻固定高浓度CO2时,建议提高接种量并加强培养前期的pH值监测和调控,以保证藻液保持适宜的pH值,并缩短培养时间,提高生物固碳效率。

CO2 fixation by Chlorella vulgaris under purified CO2 conditions

CO₂ fixation by microalgae is a new hot issue for CO₂ reduction. Based on static CO₂ absorption method, experiment was designed to study the influence of CO₂ on growth of Chlorella vulgaris, CO₂ reduction and medium pH at the aeration of purified CO₂. The results showed that injection pure CO₂ significantly prolonged the lag phase of cell growth, prolonging 10~12 d, but it had no impact on other growth phases. Process of CO₂ fixation was divided into physical fixation process and biological fixation process, the former occurred in the cell lag phase and its peak value was caused by CO₂ dissolved in culture medium. The latter occurred in the exponential phase, stable phase and decline phases, its peak value was caused by exponential growth of C. vulgaris. All of efficiency of CO₂ fixation in two processes showed a trend of first increase and then decrease. Moreover, culture medium pH varied markedly and medium was sharply acidized in 4 days, then culture medium pH few changed and maintained at the suitable level. Therefore, it was suggested that high inoculum concentration and high-densitily monitoring and control of medium pH are necessary at the aeration of high concentration of CO₂, which will maintain appropriate medium pH, and shorten culture time in order to improve the efficiency of CO₂ fixation.