This study aims to determine the efficiency of reducing the phenol content (hence BOD/COD) of three agro-industrial wastes: olive mill effluent- olive mill wastewaters- OMW, brewery sludge – BS, and white wine lees – WWL by orange peel (OP) and dried brewer' spent grains (BSG). Orange peels and dried brewer’s spent grains are found to have absorbing properties to phenolic compounds. They can be characterized as absorption materials that use the mechanism of absorption (same as activated carbon- sorbent material/precursor mechanism) (Gayatri, 2010).