Flow dynamics and physical treatment of suspended solids in wastewater drain

Most of the waterbodies are getting polluted due to wastewater discharges from the adjoining drains or channels. The present study focuses on flow dynamics and the physical separation of suspended solids in flowing wastewater drains. Two experimental setups were employed: a multi-tray sedimentation model without baffles and a modified model with vertical flow baffles. Laboratory experiments were conducted at flow rates of 60-240 mL min^-1, established through Froude-based dynamic similarity to represent typical urban drain hydraulics. Results demonstrated that the baffled model significantly outperformed the plain sedimentation model, achieving removal rates of total suspended solids (TSS) up to 88% and 70%, respectively. The staged baffle reduced turbulence, created quiescent zones, and facilitated the progressive settling of both larger and finer particles. Particle size analysis (1-2400 µm) further confirmed the system's efficiency, with median particle size (D₅₀) reduced from 1727 µm at the inlet to 1.35 µm at the outlet in the baffled system. The findings validate the hypothesis that engineered in situ sedimentation models can significantly improve TSS and organic removal in urban wastewater drains, offering a scalable solution for liquid waste management.