Treatment Of Domestic Swage By Three-dimensional Electrode Method

Three dimensional electrode method had been widely used in treatment of various sewage because of its high treatment efficiency, simple operation, easy control, broad range of application and little secondary pollution. It was a novel electrochemical technique. In recent years, the treatment can get better treatment for refractory organic wastewater and metal wastewater, and research about domestic wastewater rarely. In this paper, self-made three-dimensional electrode reactor was used in degradation of simulated domestic sewage with graphite as an anode, stainless steel as a cathode, and columnar activated carbon as particle electrodes. The experimental factors influencing removal rates of COD, NH3-N and TP were optimized, respectively, including electrolytic voltage and time, electrolyte type, electrolyte concentration and p H value under the condition of different activated carbon filling quantity, and the removal mechanism to be analyzed.The removal was better when particle electrode filling height was 500 mm. Voltage and electrolytic time had significant effects on removal efficiency. It improved removal rates to increase electrolytic time in the range of 0~50min, 50 min later the removal of each indicator to stabilize with the extension of time. Particle electrode filling height was 500 mm and powered 50 min, the removal of COD was 68%, while the removal of NH3-N and TP was 71.38% and 64%. Removal of COD and NH3-N had a peak when increased voltage, removal of COD and NH3-N was 68% and 71.38% at 9V. However, the removal was decreased with reaction voltage was further increased after 9V. Influence of voltage was different for TP and COD, NH3-N. The removal of TP was 64% at 5V, and the removal stabilized after 5V. Neutral initial water conducive the removal of COD and NH3-N. Na Cl and Na2SO4 were used as the electrolyte when particle electrode filling height was 100 mm, the results showed that removal of COD and NH3-N with Na Cl was higher than Na2SO4. Removal of COD and NH3-N rate can reach 46% and 58% used Na Cl electrolyte, but it was only about 32% and 44% by Na2SO4 under the same conditions.In the experiment of particle electrode filling height was 500 mm with Na Cl electrolyte. Removal of COD and NH3-N tended that first increased and then decreased. The removal of COD and NH3-N was 68% and 71.38%, and the effect was best when concentration of Na Cl was 0.02mol/L. Concentrations of Na Cl was greater than 0.02mol/L, but the lower removal efficiency. The concentration effect was not obvious on the TP removal. Removal was 70% for TP when concentration was 0.01mol/L and then decreased slightly with the concentration increasesed. Removal was 64% when concentration was 0.02mol/L. Comprehensive analysis with the reaction apparatus: the filling height with 500 mm, electrolytic voltage with 9V, electrolytic time with 50 min, neutral initial water, 0.02mol/LNa Cl as electrolyte, pollutant removal worked best, the removal of COD, NH3-N, TP was 68 %, 71%, 64%.The reaction mechanism of NH3-N and COD removal were similar, completed by direct oxidation of electrode and the indirect oxidation with intermediate product. Mechanism of TP removal was different with NH3-N and COD, it was mainly adhesion and interception by particle electrode layer.