Study On The Electrolytic Pretreatment Of Refractory Organic Wastewater

Refractory organic wastewater is harmful and it is hardly treated directly by the conventional wastewater treatment methods. Consider from economy and technology, new pretreatment techniques should be developed to improve biodegradability of that wastewater, and then it is treated by the conventional methods. Electrolytic method was studied for the refractory organic wastewater pretreatment to reduce COD value and improve biodegradability of wastewater in this paper.Preparation technology of PbO₂ anode was studied, and optimal condition was determined. PbO₂ anode was modified by oxides of Ni or by La or by Bi respectively in order to improve efficiency of electrolysis. The result of experiment shows that Ni-doped electrode is better than others.Preparation technology of gas diffusion cathode was studied, and optimal condition was determined. Polarization curves and scanning electron microscope show that large quantities of gas cavities formed by pore-forming material and enough dissolved oxygen formed by aeration can create H₂O₂, which is the main reason that improvement of electrode performance.Applying Ni-doped PbO₂ anode and gas diffusion cathode work together to pretreat acidic light yellow, dyeing and coking wastewater. The result of experiment shows that the COD value of three wastewaters reduced and at the same time the biodegradability increased after the electrolytic pretreatment which create a well condition for latter biological process. Using modified PbO₂ anode and gas diffusion cathode to pretreat refractory organic wastewater provided a new way to treat that wastewater.