The ever‐increasing need for clean water is one of the most urgent sustainable development goals, which requires environmentally‐friendly strategies for water remediation against different types of pollutants. In this work, the possibility of using alginate, a biocompatible and natural polysaccharide, is explored for the preparation of both oxide (TiO2, Al2O3, and yttria‐stabilized ZrO2 (YSZ)) macrobeads and an active blend of rich carbon nanoparticles, depolymerized alginate, formic acid, and a complex mixture of other organic acids. In particular, the active blend is obtained through low‐energy‐demanding microwave assisted digestion of sodium alginate solution, and it is used to enhance the decontamination activity of oxide macrobeads in mild conditions (e.g., low temperature, no pH buffers, and visible illumination). It is demonstrated that the alginate‐derived active blend obtained without the addition of any other …