Abstract In this study aimed at enhancing energy efficiency and pulp quality in recycled paper production, the structural optimization of a pulper system was investigated with respect to its effects on the process. Key modifications, including the reduction of rotor blade count, redesign of the screen perforations into a conical geometry, and narrowing of the rotor-to-screen clearance, were implemented to evaluate system performance. Following these improvements, energy consumption was reduced by 8.32 %, the Schopper-Riegler (°SR) degree increased from 20 to 25, and retention time decreased from 7 to 5 min. Significant enhancements were observed in fiber morphology and the mechanical properties of the paper. The revised pulping system yielded a more homogeneous and denser pulp structure, which contributed to increased production capacity and a more sustainable manufacturing process. The results demonstrate that simultaneous improvements in both energy savings and product quality are achievable in recycled paper production.