Photoautotrophic Cultivation, Lipid Enhancement, and Dry Biomass Characterization of Microalgae Scenedesmus dimorphus for Bioenergy Application

Microalgae have been recognized as promising competitors for bioenergy production, because of their high lipid content and quick biomass development. In this work, freshwater microalgae Scenedesmus dimorphus was cultivated in a synthetic wastewater media with the object of investigating the bioenergy potential by physicochemical characterization. Batch experiments were performed photoautotrophically for biomass generation supplemented with different levels of CO2 concentration. Maximum biomass production was in the limit of 373 mg/L to 587 mg/L under different CO2 feed concentrations. Cultivation of microalgae along with CO2 supplementation found a substantial impact on buildup of lipid in microalgae biomass. Maximum 29% and 32% lipid content were achieved for 2% and 6% CO2 enrichment respectively, under nitrogen-depleted conditions. Fourier transform infrared spectroscopy, thermogravimetric analysis, and carbon, hydrogen, nitrogen, sulfur elemental analyzer instrumental tools were used to perform physicochemical characterization on biomass in order to determine its proximate analysis, ultimate analysis, higher heating value (HHV), and macromolecular composition, The higher heating value (HHV) of Scenedesmus dimorphus biomass achieved 33.26 MJ/kg with almost zero sulfur content. This HHV value is significantly higher than that of other microalgae sp. Moreover, this HHV value is also even higher than that of bituminous coal (24.3 MJ/kg) and other types of lignocellulosic biomass. Scenedesmus dimorphus biomass indicates that it can be a potential fuel feedstock for environmentally friendly bioenergy production.

Automated summary

Microalgae Scenedesmus dimorphus was cultivated in synthetic wastewater media to investigate its bioenergy potential. Batch experiments with different CO2 concentrations were performed for biomass generation. The highest biomass production was achieved under different CO2 feed concentrations. Cultivation of microalgae with CO2 supplementation significantly impacted lipid buildup in the biomass. Physicochemical characterization revealed that the biomass had a high heating value and low sulfur content, making it a potential fuel feedstock for environmentally friendly bioenergy production.