Removal of residual carcinogenic dyes from industrial wastewater using flocculation technique

Abstract

Due to inefficient dyeing procedures in a typical dye industry, a large quantity of dye spills out into the wastewater, polluting it and causing serious harm to the environment. Consequently, special attention was focused on the use of a novel combination of a coagulant and a flocculant. As potato starch has already proved its strength as a bioflocculant, a combination of potato starch with iron(III) chloride as a coagulant was tested in order to achieve favorable results of dye reduction in simulated wastewater. The effect of various parameters on dye removal was investigated, like dosage of flocculant, temperature of treatment and flocculation time. Batch experimentation mode was adopted for the flocculation process, using a jar test apparatus. A mixed level parametric design (L16) was employed for experimentation. The orthogonal tests revealed that the best operating parameters were: 2% of potato starch, 60?C and 20 min of flocculation time. Furthermore, the significant factor test was performed using Minitab-17 from where the dosage of potato starch was proven to be the most significant factor. The study successfully raised dye removal efficiency up to 85% using a novel coagulant-flocculant combination. Finally, the results were compared with existing literature.