Satellite-Guided Biomass Harvesting and Valorization of Cyanobacterial Blooms: A Circular Bioeconomy Perspective in a Brazilian River

Satellite-guided valorization of harmful cyanobacterial blooms represents a transformative approach to mitigate environmental risks while fostering sustainable bioeconomy. In this study, we integrated Sentinel-2 remote sensing with targeted in situ sampling to efficiently harvest cyanobacterial biomass from eutrophic waters of the Tietê River (São Paulo, Brazil), during peak bloom conditions. The spatial chlorophyll-a mapping enabled precise identification of high-biomass zones, streamlining collection efforts and minimizing resource use. Following biomass concentration by multilayer nylon filtration, we evaluated innovative drying protocols, including ethanol-assisted greenhouse drying, which accelerated processing without compromising biomass quality. Physicochemical characterization revealed a rich profile of essential nutrients, including phosphorus, nitrogen, potassium, calcium, magnesium, and iron. The biomass exhibited high carbon content (47%) and a favorable C/N ratio (4.3), underscoring its potential for carbon sequestration and biobased applications. Crucially, cyanotoxins (microcystins, 491 μg/L) were present, emphasizing the need for controlled processing, while heavy metals remained within Brazilian regulatory limits, confirming the safety of biomass for specific nonedible uses. These findings position cyanobacterial biomass as a viable resource for biofertilizers and reforestation inputs, transforming an ecological liability into a valuable asset aligned with the United Nations Sustainable Development Goals (SDGs 3, 6, 9, and 15).