Experimental and simulation study of rectangular and circular primary clarifier for wastewater treatment

Abstract

Clarification is an essential process in wastewater treatment which removes suspended solids using flocculants The efficiency of the primary clarifier is important as it affects the performance of the subsequent processes. The modeling of clarifiers are carried out using one-dimensional flux theory or two dimensional computational fluid dynamics. In this paper one-dimensional modeling of sedimentation process based on flux theory applied to lab-scale circular and rectangular primary clarifiers is reported. The experiments were carried out for three operating conditions i.e. low, medium and high solid concentrations using lab-scale setup. The one-dimensional sedimentation process model was implemented on MATLAB platform and simulation was carried out. The model simulation is able to predict effluent total suspended solids as well as TSS present along the height of the lab-scale primary clarifiers. The average R 2 value 0.97 was observed between measured and simulated total suspended solids present along the height of circular clarifier for the three operating conditions whereas average R 2 value 0.96 was found in the case of rectangular clarifier for identical conditions. Based on the simulation and experimental results the removal of suspended solids is found better in circular clarifier as compared to rectangular clarifier for the influent flow rate of 134 mL/min with influent total suspended solids from 300 to 600 mg/L. • One-dimensional sedimentation process model applied to the two primary clarifiers. • Experiments were performed using lab scale setup of the two primary clarifiers. • Simulation was carried out to generate profiles of the Total Suspended Solids (TSS). • TSS removal is found better in circular as compared to the rectangular design.