Treatment of printing ink wastewater using electrocoagulation.

The present study investigates the treatment of real printing ink wastewater by using the electrocoagulation (EC) process. Effects of initial chemical oxygen demand (COD) concentrations, electrode materials and current densities were examined to determine the maximum COD and color removal from the wastewater. In parallel, raw and treated printing ink wastewater toxic potential was further estimated via the application of toxicity tests using the freshwater crustacean Thamnocephalus platyurus for assessing EC process efficiency. According to the results, it was observed that the EC is efficient under most of the operating conditions used, as COD and color removal ranged between 72.03 to 85.81% and 98.7-100%, respectively. The total cost of the EC process, considering the treatment time, applied current, applied voltage and the total anode electrode mass consumption was also estimated. The Fe electrode proved to be of lower cost than the Al electrode, however the use of Al electrode produced better decolorization results in the solutions. Moreover, toxicity tests currently performed with the use of larvae of the fairy shrimp Thamnocephalus platyurus revealed a substantial decrease in the toxic potential of printing ink wastewater, thus indicating the efficiency of the proposed EC process.