Characterization of biomass produced by Candida tropicalis ASY2 grown using sago processing wastewater for bioenergy applications and its fuel properties

Abstract

The cost of biodiesel production and the requirement of raw ingredients are the primary constraints that need to be addressed while searching for viable alternative fuels to petrol and diesel. Oleaginous yeasts are gaining wider acceptance as biofuel candidates among oil-rich crops/microbes. The present investigation aimed to integrate the agro-industrial wastewater stream as a nutrient source for the cultivation of oleaginous yeast and to use the resultant biomass and lipid as a feedstock for biofuel synthesis. The yeast biomass grown in sago processing\xa0wastewater contained 7.21% moisture content, 69.01% volatile matter, 12.61% fixed carbon, and 11.16% ash content. The ultimate analysis determined the contents of carbon (40.43%), nitrogen (5.14%), hydrogen (4.62%), sulfur (0.54%), and oxygen (49.27%). The heating value of yeast biomass was 16.54 MJ kg−1. The thermal behavior of yeast biomass also suggests its potential use as an energy source. The FTIR spectrum of biomass had major lipid (3030–2800 cm−1 and 1500–1350 cm−1) and carbohydrate (1250 cm−1 and 1000 cm−1) functional peaks. Further FAME profiling revealed that the yeast biomass is primarily composed of stearic, oleic, linoleic, and linolenic acids, similar to the vegetable oils. The fuel characteristics of yeast biodiesel (SV, 168.87 mg KOH\xa0g−1; IV, 120 mg I2 100 g−1; CN, 61.79; and KV, 3.16 mm2 s−1) are also within the ASTM standard limits, suggesting that yeast biomass could be a sustainable and economically viable feedstock for both solid and liquid biofuel production.