Effects Of Electrolytic Oxidation On Treating Dye Simulated Wastewater By Nanofiltration

The wastewater produced by dye industrial has been one of main pollution sources. Because of its great quantity, high chromaticity and low biological degradability, dyeing wastewater is hard to deal with. Electrolytic oxidation technology can remove organics and chromaticity remarkably, but the energy consumption is very large. Therefore, it's unsuitable to treat so much wastewater. While nanofiltration (NF) can treat dyeing wastewater at low power consumption, but its application was limited by concentration polarization and membrane fouling. If couple this two methods together, membrane concentration could be reduced by electro-chemical oxidation. Concentration polarization and membrane fouling would be controlled and separation performance improved.Acid scarlet dye wastewater was used as processing object. Positive electrode was Ti/SnO₂+Sb₂O₃ electrode and negative electrode was stainless steel wire. DL and DK membrane were used to study the improvement of separation by coupling. To change operational condition, that permeate flux and objective rejection rate varies with voltage, feed concentration, transmembrane pressure, velocity of flux, temperature were all studied. And the effect of electrophoresis, electroosmosis and electro-chemical oxidation on permeate flux were also observed.The results showed that electroosmosis flux was linear with voltage, temperature transmembrane pressure. Electrophoresis and electro-chemical oxidation were very useful in controlling the reduction by polarization and membrane fouling. When voltage was 2.2V, acid scarlet began decomposition. The pore of membrane choked by decomposition product, so permeate flux reduced acutely. The coupling was helpful to get high permeate flux at low circulative flux, which showed its advantages. Higher temperature made more permeate flux. Meantime, the effect of electrophoresis, electro-osmosis and electro-chemical oxidation were more obviously. Consider all the condition, 35℃would be appropriate.In summary, the coupling of electrolytic oxidation and NF membrane could, to a great extent, weaken polarization and membrane fouling. Therefore, the service life of membrane may be extended, expenses of cleaning would lower, and operation cost reduced.