The efficiency of an automated sludge dewatering system depends on both the impeller parameters and the discharge pipe design, especially for long-distance transport. These systems transport sludge from the bottom of the pond to onshore facilities, with minimal vertical lift but significant challenges in terms of horizontal distance. The choice of pipe diameter is critical: too large will increase the weight and cost of the float, while too small will cause pressure loss and reduced efficiency. This study focuses on finding the optimal pipe diameter to lift sludge to a height of 5 m vertically and 200 m horizontally. CFD simulations with a k-epsilon turbulence model and a Lagrangian two-phase flow model are applied to evaluate the performance. The results provide a practical and cost-effective solution to improve the performance and cost-effectiveness of the sludge dewatering system.