<p>The pulp and paper industry plays a significant role in many countries, with substantial social, economic, and environmental impacts. The manufacturing process generates large amounts of effluents that undergo preliminary, primary, and secondary treatment. Despite these treatments, effluents often retain recalcitrant compounds. Studies have demonstrated that adding powdered activated carbon directly to activated sludge reactors enhances the treatment efficiency of pulp mill effluents without the need for new equipment and can be applied either continuously or intermittently. This study investigated the effects of three different activated carbon dosages in bench-scale sequencing batch reactors for simulating the treatment of bleached kraft pulp mill effluents. The reactors with activated carbon were compared to a reactor without activated carbon, evaluating the impact of continuous and intermittent activated carbon use on reactor performance, effluent quality, and biological sludge properties. Activated carbon addition reduced chemical oxygen demand and color in the treated effluents and did not affect biochemical oxygen demand, phosphorus, total suspended solids, or pH parameters. The reactor with an initial activated carbon dosage of 4&#xa0;g⋅L⁻¹ improved chemical oxygen demand removal from 77% to 84% and color removal from 14% to 47% compared to the control. The sludge volumetric index improved by 67% and the dewatering by 81% with the application of powdered activated carbon.</p> Graphical abstract <p></p>