Removal of Colour from Textile Wastewater Using Two- Step Coagulation Process

The waste water from the textile dyeing industry produces large amount of coloured water and this needs to be treated before discarding in the ecosystem. There are various treatment technologies to remove colour from this wastewater which includes the most primitive yet effective method of coagulation-flocculation. In this research, inorganic coagulants like Alum (trivalent) and ferrous sulphate (bivalent) were applied on commercial dyes Congo Red and Direct green 41 at different pH values of 8,9,10. Various parameters such as colour removal percentage, pH changes, TDS (Total Dissolved Solids), settled sludge volume has been evaluated. It has been estimated that though FeSO4 is the better coagulant for colour removal but somehow it produced an anesthetic colour to the residual water in comparison to Alum. Moreover Congo red being less complex in structure is removed more effectively than Direct green 41.