A carbon dioxide fixation system using microalgae on a filter membrane

There must be several problems to develop a CO_2fixation system with microalgae against the increase in atmospheric CO_2concentration：Water supply is one of the problems in some area such as a deseart where the large system can be placed.Some microalge such as Chlorella show a high photosynthetic activity even on a filter membrane.The photosynthetic characteristics was essentially the same as those obtained with the cells in liquid.The maximum rate of CO_2fixation on the membrane reached 1.2g CO_2·h^&lt；-1&gt；per sequare meter of the exposed area。The ratio of the increase in dry weight over the fixed amount of CO_2was 0.55 to 0.70 at various CO_2concentrations.The value can be comparable to 0.68 which is obtained as the assumption of starch as a final product of CO_2fixation。The photosynthetic activity decreased gradually to the half for 5days.If the cells was kept wet by an occasional spray，the activity continued for more than 3weeks。Most of the components which increased during the CO_2fixation was starch and protein.When nitorogen content was lowered in the culture medium，the increase in protein was suppressed。

There must be several problems to develop a CO_2 fixation system with microalgae against the increase in atmospheric CO_2 concentration : Water supply is one of the problems in some area such as a deseart where the large system can be placed. Some microalge such as Chlorella show a high photosynthetic activity even on a filter membrane. The photosynthetic characteristics was essentially the same as those obtained with the cells in liquid. The maximum rate of CO_2 fixation on the membrane reached 1.2g CO_2・h^<-1> per sequare meter of the exposed area. The ratio of the increase in dry weight over the fixed amount of CO_2 was 0.55 to 0.70 at various CO_2 concentrations. The value can be comparable to 0.68 which is obtained as the assumption of starch as a final product of CO_2 fixation. The photosynthetic activity decreased gradually to the half for 5 days. If the cells was kept wet by an occasional spray, the activity continued for more than 3 weeks. Most of the components which increased during the CO_2 fixation was starch and protein. When nitorogen content was lowered in the culture medium, the increase in protein was suppressed.