Research Of The Micro-algae Absorption And Fixation CO₂ In The Flue Gas

There are much enormous economic, social and environmental benefits in the Micro-algae CO₂ fixation technology. Although there are still many technical problems to overcome, but many researchers in the world focus on a growing number of applications of micro-algae fixed CO₂ from flue-gas, wastewater treatment and high value-added products. Through combinning with other new technologies, the micro-algae CO₂ fixation technology, micro algae waste water's processing and micro-algae high added value product's production these three kinds of technologies can be integrated. There are sufficient reasons to believe that micro algae CO₂ fixation for the humanity facing the energy, the health, the environment and the food these four major problems could provide new, economical and effective carbon fixation pattern.The paper focuses on the ability of absorption carbon dioxide for chlorella and spirulina, through the self-made photo bioreactor at different experimental conditions. The ability of CO₂ absorption for chlorella and spirulina was investigated by controlling the various conditions in photo bioreactor, and then through the use of gas chromatography and visible light spectrophotometer to analyze gas compositions and algous density with time, the optimal conditions for growth of Chlorella and Spirulina could be determinated, there are useful conditions as follows:(1) The growth of Spirulina and Chlorella in their respective growth medium is corresponded with Logistic growth curve; the pH value of medium is a steady upward trend after short-term adjustment, at the range of suitable pH value of context; the two kinds of algaes can be grown in the medium in a suitable growth condition. They can absorb and fix CO₂ effectively through photosynthesis.(2) Through investigating the effect of the growth of Chlorella at experimental conditions, it is concluded that when the environment temperature is nearly 25℃or so, the best growth conditions for chlorella, is gas velocity 500ml/min, light incubator pH value of about 5.5, and CO₂ concentration in gas of 10%. Chlorella can grow fastly to absorb and fix CO₂ gas, through sufficient photosynthesis, by the greatest extent.(3) By investigating the effect of the growth of Spirulina at experimental conditions, it is concluded that when the environment temperature is nearly 30℃, Spirulina optimal growth conditions is gas velocity about 500ml/min, the pH value about 9.0 to ensure the rapid algae growth, through adequate photosynthesis, Spirulina can achieve fast growth to absorb and fix CO₂ gas, through sufficient photosynthesis by the greatest extent.(4)The results of CO₂ fixation by two kinds of algae show that chlorella growth environment is weak acid environment (pH=5⁶) to adapt to high concentration of CO₂ gas, chlorella absorbs and fixes CO₂ in the flue gas effectively. The growth of Spirulina can adapt to weak alkaline environment (pH=9¹0), a higher concentration of CO₂ gas will inhibit the normal growth of algae. Spirulina is not is suitable algae to absorb CO₂ gas species.The paper uses the algaes to absorb and fix flue gas CO₂ in order to achieve reduction CO₂ concentration in flue gas for energy conservstion and emission reduction. The harvested algae can be used to product bio-diesel by pyrolysis and other new energy sources. It not only can reduce the cost of dealing with smoke in the exhaust gas, but also has energy-saving environmental protection significance.