Enhanced algal CO 2 sequestration through calcite deposition by Chlorella sp. and Spirulina platensis in a mini-raceway pond

Abstract

Biological CO 2 sequestration using algal reactors is one of the most promising and environmentally benign technologies to sequester CO 2. This research study was taken up to alleviate certain limitations associated with the technology such as low CO 2 sequestration efficiency and low biomass yields. The study demonstrates an increase in CO 2 sequestration efficiency by maneuvering chemically aided biological sequestration of CO 2. Chlorella sp. and Spirulina platensis showed 46% and 39% mean fixation efficiency, respectively, at input CO 2 concentration of 10%. The effect of acetazolamide, a potent carbonic anhydrase inhibitor, on CO 2 sequestration efficiency was studied to demonstrate the role of carbonic anhydrase in calcite deposition. Calcite formed by both species was characterized by scanning electron microscopy coupled electron dispersive spectroscopy and X-ray diffraction. The overall scheme of calcite deposition coupled CO 2 fixation with commercially utilizable biomass as a product seems a viable option in the efforts to sequester increasing CO 2 emissions.