Impact of wastewater cultivation on pollutant removal, biomass production, metabolite biosynthesis, and carbon dioxide fixation of newly isolated cyanobacteria in a multiproduct biorefinery paradigm

The impact of wastewater cultivation was studied on pollutant removal, biomass production, and biosynthesis of high-value metabolites by newly isolated cyanobacteria namely Acaryochloris marina BERC03, Oscillatoria sp. BERC04, and Pleurocapsa sp. BERC06. During cultivation in urabn wastewater, its pH used to adjust from pH 8.0 to 11, offering contamination-free cultivation, and flotation-based easy harvesting. Besides, wastewater cultivation improved biomass production by 1.3-fold when compared to control along with 3.54-4.2 gL^-1 of CO₂ fixation, concomitantly removing suspended organic matter, total nitrogen, and phosphorus by 100%, 53%, and 88%, respectively. Biomass accumulated 26-36% carbohydrates, 15-28% proteins, 38-43% lipids, and 6.3-9.5% phycobilins, where phycobilin yield was improved by 1.6-fold when compared to control. Lipids extracted from the pigment-free biomass were trans-esterified to biodiesel where pigment extraction showed no negative impact on quality of the biodiesel. These strains demonstrated the potential to become feedstock of an integrated biorefinery using urban wastewater as low-cost growth media.