Improvement of the quality of wastewater in a printing industry by physicochemical methods and Fenton treatment.

Abstract

Wastewater samples from flexographic printing machines, characterized by high coloration, low pH, high chemical oxygen demand, and low biodegradability, were subjected to primary physicochemical treatments and a subsequent Fenton process to decrease the chemical oxygen demand (COD). The primary treatment consisted of coagulation with aluminium polychloride or ferric chloride followed by filtration over activated carbon. The Fenton process was optimized by varying pH, and the iron and hydrogen peroxide concentrations. Upon primary treatment, aluminium polychloride was the better coagulation agent. After one hour of treatment with the Fenton process at pH: 4.0; 40 mgL -1 ferric chloride, 200 mgL -1 hydrogen peroxide, COD removal of up to 92% was achieved. Thus, coupling of physicochemical treatments with the Fenton process yields wastewater of low environmental impact.