Flocculation is the second step in separation process, where impurities in the water are collected to larger flocculated particles with the aid of flocculant. The flocculant in the water treatment is usually a charged polymer with very high molecular weight. In the flocculation the coagulated particles are bound together and even larger flocculated particles are formed with the aid of polymers. The large particles are then separated from the water with suitable separation process like clarification, flotation or filtration. See also “Coagulant.”