Phosphorus Removal from Piggery Wastewater Using Alginate-like Exopolymers from Activated Sludge

The growing depletion of global phosphorus reserves underscores the urgent need for sustainable and circular nutrient recovery solutions. Rich in phosphorus, piggery wastewater represents not just a waste stream but a valuable resource. In this study, we explore an innovative approach by recovering alginate-like exopolymers (ALE) from activated sludge (AS) and utilizing them to produce biosorbent hydrogel beads capable of removing phosphorus directly from real piggery wastewater. The ALE extraction process yielded approximately 175 mg VSALE/gVSsludge, highlighting the potential of wastewater biomass as a source of functional biopolymers. Adsorption experiments revealed phosphorus removal efficiencies approaching 80%, with capacities ranging from 0.68 to 1.18 mgP/gVSALE. Structural and chemical characterizations confirmed both the successful adsorption of phosphorus and the stability of the biosorbent post-treatment. This work demonstrates a dual benefit: the recovery of critical nutrients and the transformation of wastewater-derived materials into value-added biosolids. By integrating phosphorus capture and biosorbent production, the approach offers a cost-effective and environmentally responsible pathway toward nutrient recycling and wastewater valorization.