Printing ink wastewater treatment using electrocoagulation in lab- and pilot-scale

Packaging paper wastewaters, stemming mainly from the dyeing sector of the production process (where printing inks are utilized), are characterized by high concentrations of organic matter, intense color and almost zero biodegradability factor. These physicochemical characteristics, in combination with the presence of some toxic compounds (heavy metals, volatile organic compounds etc.) make further treatment necessary prior to wastewater discharge to prevent serious environmental problems. The present study deals with the treatment of these effluents in lab- and pilot-scale using electrocoagulation (EC). During the EC process, metallic species are electrochemically dissolved in the wastewater solution, resulting in coagulation, flocculation and subsequent separation of the pollutants via flotation or sedimentation. The efficiency of this method was evaluated by examining the organic matter removal and decolorization of the wastewater under a wide range of operating parameters (current density, initial pH and electrode material). It was observed that EC is efficient under most of the operating conditions used, as the chemical oxygen demand (COD) and color removal ranged between 72.03% to 85.81% and 98.7% to 100%, respectively. Finally, one set of experiments was performed in a local corrugated board packaging factory using a portable EC pilot-unit. The removal percentage of COD and color was comparable.