Performance of Freshly Generated Magnesium Hydroxide (FGMH) for Reactive Dye Removal

Abstract

Coagulation-flocculation (CF) is an essential process for water and wastewater treatment plants. Whilst compared with the conventional coagulants, the freshly generated magnesium hydroxide (FGMH) is environmental friendly within its coagulative and adsorptive jellied sediment. However, decoloration of dye wastewater using FGMH has not been well understood yet. In this paper, operating variables such as initial pH, coagulant dosage, agitation speed and duration were examined for efficient reactive dye removal. The flocs breakage and regrowth capacity after slow agitation of original CF phase were monitored for mechanism analysis. The mechanism analysis showed that the charge neutralization was the predominance during coagulation, and the precipitate enmeshment and adsorption bridging dominated the flocculation stage. In comparison with the initially formed flocs, though the regenerated flocs were considerably smaller after the second rapid agitation, the bridging interaction of loose flocs could absorb the small residual particles during the slow agitation stage.