This research aims to study the effect of activated carbon particles in adsorption of the methylene blue as a replacement of wastewater treatment when coated on a high density polyethylene (HDPE) substrate (e.g. flat sheet and cosmo ball substrates). Prior to coating, the activated carbon has been cleaned using tab water to remove ashes which blocks the activated carbon pores. Coating was done by applying epoxy material using brushing technique, and then sprayed the activated carbon on epoxy either manually or using spray machine. The thickness and morphological of the coatings were characterized using Scanning Electron Microscopy (SEM). Analyses conducted have confirmed that granuler activated carbon coating layers ranged between 100 to 500 μm have been successfully deposited on different shapes of HDPE substrates. The coatings deposited on HDPE substrate produced high surface roughness of around 7 μm. The ability of the coated samples in removing the colour of methylene blue is believed due to the high porosity of the activated carbon(AC). The surface area has been increased dramatically if compared with uncoated substrate since the BET of activated carbon is 426 m2/g .