In the mean time, attention to recycling, clean up and the removal of smaller debris via wastewater treatment plants (WWTPs) are a critical point source for microplastics in marine ecosystems. As for different emergent pollutants, WWTPs are not yet set up to remove them effectively. For microplastics, this is primarily due to a lack of viability of filtering devices. Furthermore, studies suggest that WWTPs can act as a formation source of microand nano-plastics across the different treatment stages. Microplastics undergo mechanical crashes in the primary stage, biodegradation in the secondary stage and chemical oxidation processes in the tertiary stage. Alternative removal strategies involve for example the silanization of contaminated water to foster the coagulation of microplastics, using organosilane-based precursors, which have a high affinity to microplastics and high reactivity in water. Then, adding hybrid silica gels induces a sol-gel process, resulting in the fixation of microplastics into a three-dimensional networked hybrid silica gel form, which is subsequently removed from the system. The principle of assembling microplastics to separate them has also been investigated with selfpropelling Au@TiO 2 microparticles, which exhibit rafts or clusters when interacting with passive particles (like SiO 2 or polystyrene microparticles). This rafting behaviour not only gave a physical understanding of the interactions between an active and passive particle but allowed the capture and removal of microplastics of different sizes and geometry. Other micro/nanomotor-based strategies have been efficiently used in the removal of microplastics. Apart from the separation of microplastic from aquatic systems, another intensely researched approach is to degrade plastic to either recover the monomers and recycle them, or to mineralize the materials, which can be initiated through biological and non-biological processes. Using microorganisms to produce enzymatic reactions is a biological process that can lead to the degradation of microplastics. In this process, the enzyme attaches to the polymer structure of microplastics and degrades it into its monomer, which is later used by the microorganism for energy production. On the other hand, photocatalysis is a non-biological process in which a photocatalytic material absorbs a light source's energy, producing an excited electron/hole pair that triggers a series of chemical reactions. Depending on the conditions of the process, different oxidant species are formed, which interact with the microplastics and degrade them until, ideally, their mineralization occurs. Figure 1: Schematic illustration of photocatalytic micromotor-based approach (with inherent asymmetry) combining the principles of motion and phoretic interaction for dual action strategy of collection and degradation of microplastics. The colorful translucent spheres represent polystyrene microparticles, and the transparent ones close to the photocatalyst (right and center) are the degraded ones due to the photocatalytic action.