The process is called filtration. It involves passing a mixture through a filter medium that lets the fluid (liquid or gas) pass through freely while blocking solid particles or unwanted components from passing.Filtration is the process of separating solid particles from a liquid or gas by passing the mixture through a filter medium.The filter medium has tiny pores that allow the fluid to pass freely but block larger solid particles.The liquid or gas that passes through is called the filtrate, while the trapped solid particles form the residue.