Sodium Bicarbonate as Inorganic Carbon Source for Higher Biomass and Lipid Production Integrated Carbon Capture in Chlorella vulgaris

Abstract

Chlorella vulgaris was isolated from sewerage treatment plant and grown in the presence of sodium bicarbonate as carbon source at 0.25, 0.5 and 1.0gL−1. Highest specific growth rate (0.653μd−1) was obtained with 1gL−1 bicarbonate followed by 0.5gL−1 (0.641d−1) on 15th day culturing. Total chlorophyll content of microalgae has increased in a dose dependent fashion with bicarbonate addition and maximum level recorded in 1gL−1 (0.769±0.09gL−1). The biomass productivity was in the range of 0.237–0.996gd−1L−1. Rate of CO2 fixation and carbon content, in terms of quantity was estimated. Results showed that at 1gL−1 sodium bicarbonate concentration, maximum CO2 fixation (0.497g/dry weight) and carbon content (0.69gmL−1day−1) was found. Biomass concentration was significantly higher (p<0.05) in cultures (1.54gL−1) supplemented with 1gL−1 bicarbonate whereas there was no much difference in cellular lipid concentration (16mgmL−1). GC–MS analysis of fatty acids showed highest amounts of palmitic acid, myristic and stearic acid. In summary, the addition of sodium bicarbonate increases cellular abundance, chlorophyll content and to some extent in the case of lipid content in C. vulgaris integrated with CO2 sequestration.