Studies of CO2 sequestration by Chlorella vulgaris in dairy waste water in stirred tank batch type photobioreactor

Abstract

Carbon dioxide, a Greenhouse Gas (GHG), is the one of the principle pollutant, warming earth. Enough carbon dioxide have pumped into the earth atmosphere raising its level to 400 ppm in the past 150 years because of anthropogenic activities, higher than they have been for hundreds of thousands of years. A number of CO2 capture technologies and storage technologies are being considered to tackle this climate change. The techniques to reduce the effects of Carbon dioxide are classified as chemical reaction based strategy (abiotic) and biological mitigation method (biotic). Abiotic method captures CO2 by reaction with chemical compounds before it is released into the atmosphere. But, the disadvantages of this method are that the chemical reactions are highly energy intensive and costly; and the problematic disposal of the wasted chemical compounds. On the other hand, biological mitigation is more favorable as it directly converts CO2 into biomass. Because of photosynthetic ability of microalgae, the potential microalgae such as Scenedesmus sp., Chlorella vulgaris, Chlamydomonas sp. And Chroococcus sp. have been actively used globally in open and closed photobioreactor for CO2 mitigation. Algae are also used as feed stocks for bio-energy diverse that include microalgae, macroalgae (seaweed) and cyanobacteria (blue-green algae). Algae occur in a variety of terrestrial habitats and natural aqueous in environment. Some microalgae also have the potential to store lipids under certain conditions. This dissertation describes the effectiveness of Chlorella vulgaris, used in a photobioreactor at different concentrations (0.04%, 5%, 10%, 15% and 20%) of CO2 in Fogg’s media with 10% (of total volume) inoculum. 10% is the CO2 concentration at which most of the kinetic parameters as well as total CO2 fixed and fixation rate is found to be maximum. The pH and CO2 concentration for this culture were also optimized.