Treatment of wastewaters from dye industry

Abstract

The characteristics of a coagulation process for the removal of colour from the organic dye industry wastewaters by inorganic coagulant or polymeric flocculant has been studied. Flocculation/precipitation was carried out using three coagulation agents to wastewater samples: FeCl₃.6H₂O, Levafloc R and Colfloc 3915. The optimum pH range for decolourization with polymeric flocculants was found to be between 6 and 7 while with inorganic coagulant it was between 2.5 and 4. Acceptable efficiency of wastewater decolourization, low total organic carbon (TOC) and chemical oxygen demand (COD) were obtained with 0.1 M solution of Fe(III) as an inorganic flocculant. The addition of 1% of volume fraction of liquid Levafloc R and Colfloc 3915 removed the colour almost completely.