Treatment of coloured wastewater with the combination of Fenton process and ion exchange

Abstract

In this study, reuse of effluent obtained from the biological wastewater treatment plant of a textile dyeing facility has been investigated. Effluent has been further treated by Fenton process, chemical precipitation, adsorption and demineralisation, respectively. Optimum molar ratio of ferrous sulfate to hydrogen peroxide (FeSO4/H2O2) was determined to be 0.025 (0.25/10). Under these circumstances, colour limit values defined within EN ISO 7887 have been met and wastewater chemical oxygen demand (COD) has been decreased by 39%. Fe ion concentration in the wastewater was decreased to 0.08 mg/L by chemical precipitation using 30 mg/L polyaluminium chloride (PAC). At the adsorption step of the treatment scheme, 45% COD removal has been achieved. Various cation/anion exchanger ratios of 1/2, 1/1, 2/1 have been studied at the demineralisation step. However, pH of the tertiary treated wastewater was above 9 and the conductivity was measured to exceed 750 mu S/cm. These values verify that the effluent from the treatment plant of the textile facility can not be reused for irrigation after combined treatments.