Study on the flocculation mechanism of diverging microporous curved surface Micro-Vortex flocculation magnetic stable bed reactor and its purification of Cr(VI)-containing wastewater

Abstract

In response to the contamination of water bodies by heavy metal pollution, particularly chromium (VI), this paper proposes a novel diverging microporous curved surface micro-vortex flocculation magnetic stable bed reactor for the treatment and purification of Cr(VI). The results show that under conditions of adding 0.0996 ∼ 1.373 mg/L FeSO₄, 70 mg/L polyaluminum chloride (PAC), and 1.5 mg/L polyacrylamide (NPAM) respectively, and with an inlet flow rate of 0.023–2.101 m3/h for the reactor’s opposed-flow water distribution with different elevations, the removal rates of Cr(VI) and turbidity reach over 97 % and 99 %, respectively. By analyzing the instantaneous velocity vectors, streamlines, and vorticity distributions within the reactor using Particle Image Velocimetry (PIV) instruments, it is found that various turbulent flow patterns such as swirling flow, annular flow pattern, spiral flow, and water tongue flow are formed within the reactor. These flow patterns correspond to the generation of vortexes, micro-vortices, and micro-holes, resulting in a cascade flocculation phenomenon with their respective solid–liquid separation mechanisms. This makes the reactor a promising candidate for the treatment of heavy metal wastewater.