翻译英文版.doc

Treatment of tannery liming drum wastewater by electrocoagulation Abstract The removal of COD, suphide and oil–grease from tannery liming drum wastewater was experimentally investigated using direct current (DC) electrocoagulation (EC). In the EC of the wastewater, the effects of initial pH, electrolysis time and current density were examined. The COD, sulphide and oil–grease in the aqueous phase were effectively removed when mild steel electrodes were used as sacrificial anode. The optimum operating range for each operating variable was experimentally determined. The experimental results show that COD, sulphide and oil–grease was removed effectively. The overall COD, sulphide and oil–grease removal efficiencies reached 82%, 90% and 96%, respectively. The optimum current density for removal of COD, sulphide and oil–grease in the tannery liming drum wastewater were 35?mA/cm2, 35?mA/cm2 and 3.5?mA/cm2 at 10?min electrolysis time and pH 3, respectively. Mean energy consumptions were 5.768?kWh/m3 of COD, 0.524?kWh/m3 of sulphide and 0.00015?kWh/m3 of oil–grease. Results show that the pseudo-second-order rate equation provides the best correlation for the removal rate of the parameters. Keywords: Tannery wastewater; Liming drum wastewater; Electrocoagulation; Mild steel electrodes Article Outline 1. Introduction 2. Experimental 2.1. Wastewater samples 2.2. Experimental device 2.3. Experimental procedure 2.3.1. Iron electrodes 2.3.2. Aluminum electrodes 3. Results and discussion 3.1. Effect of electrode materials 3.2. Effect of initial pH 3.3. Effect of current density 3.4. Effect of electrolysis time 3.5. Electric Energy Consumption 4. Conclusions References 1. Introduction The leather industry is well known as a high consumer of water. Variety of chemicals at significant quantities are employed for leather processing. Major chemicals used for leather manufacturing are lime, sodium and ammonium salts, fatliquors, bacterial- and fungicides, tannins, dyes, etc.