Microalgae Isolation for Nutrient Removal Assessment and Biodiesel Production

Abstract

This study was designed to isolate microalgal species which can tolerate severe environmental stresses and can be used for wastewater treatment and biofuel generation. Three different microalgal strains (including Chlorella sorokiniana GEEL-01, Parachlorella kessleri GEEL-02, and Parachlorella kessleri GEEL-03) were isolated from a wastewater treatment plant and Waterwheel Park. The highest growth rate (1.61 OD680nm) was observed for C. sorokiniana GEEL-01 with highest removal of total nitrogen (1.5 mg L−1 day−1) and total phosphorus (1.82 mg L−1 day−1). The biocomponents of the isolated species ranged from 19.47–29.64%, 39.39–52.51%, and 15.08–22.75% for carbohydrate, protein, and lipid, respectively, based on the dry cell weight (DCW). The function groups in microalgal biocompounds were also confirmed by Fourier-transform infrared radiation (FT-IR) spectra, indicated their ability for biofuel generation. Ultimate and proximate analyses of C. sorokiniana GEEL-01 showed high carbon (54.24% DCW) and volatile content (92.69% DCW), compare to other strains. Moreover, it exhibited a significant accumulation of lipid with an increase in the fractions of saturated fatty acids (64.5%), and the major fatty acids were palmitic acid (11.17%), stearic acid (33.86%), oleic acid (9.84%), and linoleic acid (11.56%). Biodiesel derived from the major fatty acids had optimum engine efficiency properties including iodine value (77.34 g I2/100 g oil) and cetane number (54.83). Cultivation of C. sorokiniana GEEL-01 can serve as a dual function of biodiesel feedstock generation and nutrients removal.