Small-scale solid particles (nanometals, fine particles, bacteria, viruses, asphaltenes..) also referred to as colloids are ubiquitous in geological porous media. The nature of the particles can vary significant and their presence in the soils and subsurface may be desired or on the contrary, avoided. They can be manufactured for engineering purposes or generated in situ. Such particles have an incredible potential to remobilize non-aqueous phase trapped by capillary forces in soils and the subsurface, and then to remediate contaminated groundwater or to enhance oil recovery. Their use in daily engineering, however, is still underexploited because the lack of knowledge regarding their transport mechanisms is an obstacle to precise control of two-phase flow. Importantly, the presence of colloidal particles flowing in the subsurface challenges the standard models of flow and transport in porous media. The objective of COCONUT is to decipher the mechanisms leading to the displacement of fluids trapped in an unsaturated porous media in the presence of colloids using pore-scale modelling and microfluidic experiments, and eventually proposes advanced remediation techniques.