From waste-to-energy: the process integration and intensification for bulk oil and biodiesel production by microalgae

The aim of this work was to evaluate the bulk oil and biodiesel production by cyanobacteria Phormidium sp. using cassava wastewater as culture medium. The study focused on optimization of the cultivation parameters (temperature and C/N ratio), on the evaluation of different operational modes of bioreactor (batch, fed-batch and continuous) and on the analysis of the biofuel quality. The results indicate that temperatures of 30 °C and C/N ratio of 68 improved the performance of system. Additionally, the continuous cultivation optimizes the rate of formation of product, reaching biomass productivities of 320.1 mg/L h in parallel to oil productivities of 43.8 mg/L h. Finally, the fuel properties of the biodiesel indicated an ester content of 99.98%, a cetane number of 57.28, an iodine value of 45.22 gl₂ 100 g−1, a degree of unsaturation of 49.27%, and a cold filter plugging point of 61.43 °C. The technological route developed indicates potential to sustainable production of bulk oil and biodiesel, through the minimization of water and chemicals demand needed to support such bioprocess.