In this experimental study two methods of pretreatment of effluents from dyeing processes were investigated. The main objective was to reduce the colour strength of the effluents. The first method was chemical pretreatment using oxidation and reduction to destroy the conjugate double bonding system of the chromophore structure. The other method was the physical pretreatment using activated carbon to adsorb the colourant. The parameters studies were chemical auxiliaries, colour strength, conditions and types of dyestuff.