AN EVALUATION OF AUTOTROPHIC MICROBES FOR THE REMOVAL OF CARBON-DIOXIDE FROM COMBUSTION GAS STREAMS

Carbon dioxide is a greenhouse gas that is believed to be a major cont ributor to global warming. Studies have shown that significant amounts of CO2 are released into the atmosphere as a result of fossil fuels c ombustion. Therefore, considerable interest exists in effective and ec onomical technologies for the removal of CO2 from fossil fuel combusti on gas streams. This work evaluated the use of autotrophic microbes fo r the removal of CO2 from coal fired power plant combustion gas stream s. The CO2 removal rates of the following autotrophic microbes were de termined: Chlorella pyrenoidosa, Euglena gracilis, Thiobacillus ferroo xidans, Aphanocapsa delicatissima, Isochrysis galbana, Phaodactylum tr icornutum, Navicula tripunctata schizonemoids, Gomphonema parvulum, Su rirella ovata ovata, and four algal consortia. Of those tested, Chlore lla pyrenzoidosa exhibited the highest removal rate with 2.6 g CO, per day per g dry weight of biomass being removed under optimized conditi ons. Extrapolation of these data indicated that to remove CO2 from the combustion gases of a coal fired power plant burning 2.4 x 10(4) metr ic tons of coal per day would require a bioreactor 386 km(2) x 1 m dee p and would result in the production of 2.13 x 10(5) metric tons (wet weight) of biomass per day. Based on these calculations, it was conclu ded that autotrophic CO2 removal would not be feasible at most locatio ns, and as a result, alternate technologies for CO2 removal should be explored.