Waste Cleaning Waste: Combining Alginate with Biowaste-Derived Substances in Hydrogels and Films for Water Clean-up.

Biowaste-derived substances isolated from green compost (BBS-GC) are environmental-friendly reactants similar to humic substances, which bring multiple functionalities, suitable to adsorb different kinds of pollutants in wastewater. Here we propose sodium alginate (derived from brown algae) crosslinked with both Ca 2+ ions and BBS-GC in the form hydrogels and dried films as green, easy-to-form and handleable materials for tertiary water treatments. Our results show that both hydrogels and films are mechanically stable and can effectively remove differently charged dyes through an adsorption mechanism describable by the Freundlich model. BBS-GC-containing gels always performed better than samples prepared without BBS-GC, revealing that such unconventional materials can integrate waste valorization and water decontamination, potentially providing social and environmental benefits.