MODELING OF THE BEHAVIOR OF EFFLUENT SUSP ENDED MATTER IN LAMINAR PRIMARY SETTLING

Process modelling can prove a useful tool for the control of wastewate r treatment plants. The objective of this research was to verify that a primary settling model developped for a conventional process is appl icable to a process using lamellar settling. The lumped-parameter mode l examines the hydraulics of a system composed of stirred tank reactor s in series and simulates suspended solid concentration of the effluen t under various flow regimes. The model has been validated using data collected from a pilot lamella settler of a capacity of 15 m3 and oper ated over a wide range of flows (Hazen velocity between 0,43 and 2,59 m . h-1). The prediction of the model was in agreement with the observ ed values both in terms of concentration and hydraulic behavior of eff luent suspended solids (average relative error of 17%). However, less satisfactory was the model performance tested with the concentration d ata on settleable solids. Research is under way to study the different mechanisms of sedimentation going on in the settler.