Hydrodynamic modelling and performance assessment of continuous-flow single-channel reactor for river water turbidity removal using electrocoagulation process

Abstract

A hydrodynamic modelling of a continuous-flow single-channel (CFSC) reactor was highlighted by means of Residence Time Distribution (RTD) experimental approach using stimulus response technique and three inlet flowrates (43.66, 79.40 and 115.10 L.h−1). Axial dispersion model (ADM) was applied for approximating the RTD experimental curves in order to check the flow patterns homogeneity and identify the possible flow deviations. The CFSC reactor was then evaluated for river water treatment by electrocoagulation process. At 43.66 L.h−1, dead zones were diagnosed within the CFSC reactor and corresponding experimental RTD curve deviated from ADM. At high inlet flowrates, the hydrodynamic behaviour was highly plug-flow (Pe > 100) without flow malfunctions and a satisfactory agreement was obtained between RTD experimental curves and ADM. In contrast, at 43.66 L.h−1, the CFSC reactor exhibited higher turbidity removal (of about 91.7%) compared to high inlet flowrates, indicating that the treatment efficiency depends mainly on coagulant dose electro-dissolved per unit of time rather hydrodynamic condition. However, the associated operating cost was relatively high at 43.66 L.h−1. As for the effect of initial water quality, it was observed that, for the same coagulant dose electro-dissolved, the treatment efficiency dropped as the initial turbidity of water decreased.