Evaluating Total Organic Carbon Derived Algae Biomass Productivity Compared with Ash Free Dry Weight Measurement

Abstract

Algae are the third generation feedstock for production of biofuels, high value chemicals, and antioxidants. Considering gradual depletion of fossil fuel, biofuel production from algae could be an attractive proposition. In recent years, biofuel production from algae has fascinated many researchers worldwide. Sustainability of this effort directly depends on daily areal productivity of biomass from cultivation, measured by dry weight (DW) or ash free dry weight (AFDW) basis. This method is based on the quantification of total suspended solids and volatile suspended solids using filtration, washing, drying and ashing of algal samples. However, AFDW method is time consuming, laborious, and expensive. Hence, an automated approach of using total organic carbon of centrifuged algae pellet (TOC-P) for calculating algal biomass productivity is evaluated. Accurate species specific conversion factors were determined to derive AFDW from TOC-P values using two different analytical methods, TOC-P and carbon per cent. A linear correlation was obtained between TOC-P and AFDW, carbon per cent of algae pellets was analysed by CHNS analyser for Picochlorum sp. and Chlorella sp. to establish species specific conversion factor. Once the TOC-P is measured in an algal sample, the AFDW can be calculated using the species specific conversion factors. The total organic carbon of algae pellets (TOC-P) estimation was found to be more than 11 times economical as compared to conventional gravimetric method (AFDW). The time and manpower required for AFDW measurement were estimated more than two times higher as compared to TOC-P. Thus, TOC-P is much more economic, quicker and convenient alternative method as compared to conventional AFDW for biomass productivity measurement.