Abstract: A process for preparing a granular composite adsorbent, that includes combining poly (diallyl dimethyl ammonium halide) and a clay mineral in water, maintaining the mixture under stirring, recovering a wet mass, forming the wet mass into granules and drying the granules to obtain the granular adsorbent having surface layer with positive zeta potential. The granular material and methods using the granular material in water treatment are also disclosed.