The product, multifunctional silver-graphene sand composite was synthesised by using waste cooking oil as the low-cost and easily available feedstock for the graphene. The product showed high adsorption capability by removing a considerable amount of pollutants in water and wastewater. On top of that, the silver nanoparticles decorated on the graphene sand composite offered the antibacterial property to the adsorbent, prohibiting the growth of bacteria and preventing the microbes from contaminating the treated water. Our product alleviates the problem of water contamination by removing the pollutants. It also helps to reduce the size of the water treatment process as multiple processes (adsorption and disinfection) can be conducted in one compact system. In addition, the concept of waste-to-wealth helped to convert the waste cooking oil into valuable graphene adsorbent. This resolves the issues of Environmental Sciences pollution arouse from improper management of waste cooking oil too.