2.2. PEP reactor setup and procedure
The batch experimental setup is schematically shown in Fig. 1. Electrochemical oxidation of wastewater was conducted in an undivided cell reactor equipped with a magnetic stirrer using a constant speed of 200 rpm in order to get a correct homogenization of the wastewater – flocs mixture. The reactor consisted of an EC cell, a D.C power supply and monopolar electrodes in parallel connection. All experiments were run under isoperibolic conditions, at a temperature of 20 °C. The D.C source was used to power supply the system (GW, GPR-25H30D) with 0–20 mA. The reaction was timed starting when the D.C power supply was switched on. Two plates flat with a smooth surface were connected as cathodes and two as anodes and the electrodes dipped in a 1.5 dm3 electrochemical reactor. Each electrode was 4 cm × 3 cm and the distance between iron electrodes was 20 mm. The total area submerged into the solution of the anode and the cathode was 48 cm2. To eliminate the influence on the removal efficiency of mass transfer rate of pollutants to the electrodes (iron salts produce electrode passivation and it causes a 50% increase in treatment time and power requirements), high mixing was assured by a magnetic stirrer. To obtain same experimental conditions, the Fe electrodes were polished after each experiment using grinding papers and then rinsed with soap water and deionized water before electrolysis.