Duckweed as a multifunctional industrial biomass: Advances in cultivation, processing, valorization, and circular bioeconomy potential

Duckweed (Lemnaceae) is increasingly recognized as a multifunctional industrial biomass that can link wastewater-based nutrient recovery with feed production and downstream valorization. Recent studies have moved beyond basic biomass cultivation to evaluate duckweed in resource-recovery systems, where nitrogen- and phosphorus-rich effluents are converted into protein-rich biomass while reducing wastewater pollutant loads. The harvested biomass has potential applications in animal feed, bio-based products, nutrient recycling, and integrated biorefinery schemes, thereby supporting circular bioeconomy models that connect waste treatment, biomass generation, and product development. However, industrial deployment remains constrained by variability in biomass composition, contaminant accumulation during wastewater cultivation, inefficient harvesting and drying technologies, uncertain cost performance, and incomplete regulatory frameworks for feed-grade use. This review synthesizes recent advances in duckweed cultivation, biomass processing, nutritional and functional attributes, wastewater-based production, environmental performance, and techno-economic feasibility. Unlike previous reviews focused mainly on controlled cultivation, food-oriented applications, bioactive nutrient extraction, or general biorefinery potential, this review provides a feed-oriented circular-biomass framework that integrates wastewater-to-feed resource recovery, biomass safety, animal-feed deployment, processing requirements, life-cycle implications, and techno-economic feasibility.