Graphene sand composite (GSC), sand media coated with graphene, possess higher adsorption capacity for wastewater treatment compared to conventional activated carbon (AC). However, large-scale synthesis of GSC due to costly carbonaceous source appears as a great challenge towards commercial application. Palm oil mill effluent (POME), which abundantly discharged from the palm oil industry, appears to be a potentially low cost carbonaceous source for the synthesis of GSC. This study presented a green chemistry approach by utilizing the POME as carbonaceous source coated on the different particle size of river sand in synthesizing POME-based GSC (P-GSC). Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX), and X-ray Diffraction (XRD) analysis indicated the successful graphinization of POME coated onto the river sand surface. Adsorption studies – batch column study and batch equilibrium study showed that small size P-GSC (0.30 – 0.60 mm) had the best performance in removing chemical oxygen demand (COD), colour, turbidity, and total dissolved solids (TDS) from diluted aerobic POME up to 94.7%, 92.3%, 83.3%, and 51.5%, respectively. This could be attributed to its larger surface area that provides more active sites for adsorption. Equilibrium sorption data of small size P-GSC was wellfitted to the Freundlich model and its associated adsorption kinetic could be described by Pseudo First Order model. The concept of sustainable waste-to-treat-waste has been proven throughout this study, where POME can be utilized to produce high performance P-GSC that can be used to treat aerobic POME.