Treatment of paper mill effluents in a batch-stirred electrochemical tank reactor

Electrochemical treatment of organic pollutants is a promising treatment technique for substances which are resistant to biodegradation. In this study an electrochemical treatment based on the principle of anodic oxidation was used to treat paper mill effluent from Rakta's Pulp and Paper Company where rice straw is used to produce paper pulp. Experiments were carried out in a cylindrical agitated vessel lined with lead sheet as anode while a concentric cylindrical stainless steel sheet screen was placed as a cathode. The effect of current density, pH, NaCl concentration, impeller rotational speed and temperature on the rate of color and COD removal was studied. The results showed that the use of electrochemical technique reduces the COD from an average value of 5500 to 160. The percentage color removal ranged from 53% to 100% depending on the operating conditions. Energy consumption calculation shows that energy consumption ranges from 4 to 29 kWh/m3 of effluent depending on the operating conditions. The experimental results proved that the electrochemical oxidation is a powerful tool for treating paper mill effluents where rice straw is used as a raw material.