Harnessing Nordic microalgae for arsenate biosorption from industrial wastewater

Abstract

Microalgae-based biosorption represents a promising yet underexplored strategy for arsenic removal from industrial effluents. Here, two Nordic freshwater strains, Chlorella vulgaris 13-1 and Coelastrella sp. 3-4, were assessed for arsenate [As(V)] biosorption from industrial wastewater. Both strains demonstrated remarkable tolerance to As(V) as their ultrastructural integrity under arsenate stress was preserved. Coelastrella sp. 3-4 demonstrated higher arsenate removal efficiency compared to Chlorella vulgaris 13-1 across all tested conditions, including varying As(V) concentrations and realistic industrial wastewater scenarios. Elevating wet biomass loading from 4% to 8% substantially enhanced As(V) removal, highlighting the critical role of biomass loading in process optimization. Kinetic modeling indicated that a pseudo-second order model best describes the biosorption process for both strains, with R 2 values of 0.99. Desorption experiments using 0.1 M EDTA and 0.1 M citric acid yielded comparable arsenate release efficiencies, with citric acid emerging as the environmentally preferable desorbing agent owing to its biodegradability. These findings establish Chlorella vulgaris 13-1 and Coelastrella sp. 3-4 as effective, scalable, and sustainable biosorbents for arsenate remediation in industrial wastewater treatment applications.