Sustainable treatment of livestock effluents: use of biosorbents for heavy metal removal

Abstract

Livestock wastewater poses an environmental challenge because heavy metals are toxic and persistent. This issue can be mitigated through a previously investigated eco-friendly and low-cost alternative which is immobilized microalgae usage. This research evaluated heavy metal removal efficiency using two biosorbents: Chlorella vulgaris immobilized in calcium alginate beads and in Luffa cylindrica sponges. Tests were conducted under simulated multi-metal conditions representative of discharges from slaughterhouses and livestock facilities. Removal efficiency and equilibrium adsorption capacity were recorded for Zn, Cd, Cr, Pb, Cu and Mn, as well as metal desorption efficiency from biosorbents. Alginate-based biosorbent achieved removal rates exceeding 90 % for Pb, Mn and Cr, confirming its effectiveness for final purification stages requiring high metal removal rates. In contrast, L. cylindrica sponge showed moderate removal rates (17–66%) but stood out for its higher equilibrium adsorption capacity and superior desorption efficiency, particularly for Mn (91%) and Cu (70%). These results reinforce the potential of eco-friendly biosorbents as tools within green technologies aimed at sustainability and improved environmental management.