Removal of some reactive dyes from synthetic wastewater by combined Al(III) coagulation/carbon adsorption process

This study was designed to investigate the removal of reactive dyes, C.I. Reactive Red 45 and C.I. Reactive Green 8, from wastewater using a two-step, Al(III) coagulation/activated carbon adsorption method. The effect of pH and coagulant dosage as well as the effects of contact time and a powdered activated carbon dosage on dye removal have been studied. The process was optimized with reasonable consumption of coagulant and quantity of obtained sludge. Coagulation as a main treatment process followed by adsorption achieved almost the total elimination of both dyes from wastewater with significant reduction (90%) of chemical oxygen demand (COD), total organic carbon (TOC) and adsorbable organic halide (AOX). Besides high efficiency of dye removal, the combined treatment process offers many advantages for potential application such as coagulant savings, minimal amount of sludge formation and also a economic feasibility since it does not require high costs for chemicals and equipment. (C) 2004 Elsevier Ltd. All rights reserved.