The aim of the present study is to evaluate the possibility of re-using the regenerated spent bleaching earth, subjected to acid and heat treatment, to decolourise and reduce the biological oxygen demand (BOD) of the final effluent discharged from palm oil mills. Different types of clays namely spent bleaching earth that has been regenerated using acid and heat treatment after de-oiling (RDSBE-AH), spent bleaching earth (SBE), de-oiled spent bleaching earth (DSBE) and new bleaching earth (NBE) were characterised for their surface area, pore volume and functional groups. RDSBE-AH was found to have the highest surface area and pore volume when compared to the other three types of clays with values of 122.3 m2 g-1 and 68 cm3 g-1, respectively. In terms of decolourisation, RDSBE-AH exhibited a higher efficiency than NBE. Higher BOD reduction efficiency was found for NBE as compared to RDSBE-AH. The adsorption kinetic models on colour and BOD for both RDSBE-AH and NBE were well described by the pseudo-second order equation with very good coefficient of determination (R2). The results demonstrated that the regenerated SBE, produced through the combined acid and heat treatments, had the potential to decolourise and reduce the BOD of the palm oil mill’s final effluent discharge.