The Study On The Techniques For The Treatment Of Oil Wastewater By Pulse-electrolysis

With the development of petrochemical industry, the environment have been inevitably contaminating by the oil wastewater. Oil wastewater is degraded difficultly because of it having the similar density with water, high amount of organic content, low degradation rate with biological means. The current treatment methods, such as the physical treatment,chemical treatment,biological treatment and direct current electrolysis method, fail to extend in practical for the features of high treatment cost, complex technology, etc. To find a efficient, simple, no second-polluted method, is yet a important research object in environmental protecting.The paper, taking the oil wastewater as the research object, studied the removal efficiency of the pulse electrolysis by Ti, graphite, and Al electrode, analyzed the factors which affect the removal efficiency for electrolysis condition changes, and discussed the influence factors and action mechanism of pulse electrolysis. According to the electrolysis-coagulation principle, the author used electrolysis-coagulation technology to treat the oil wastewater. In this experiment, about 1050 data were collected with total duration of 10 months. Through these work, some results can be drawn:(1) Different kinds of electrodes have their own optimal parameter in the process of pulse-electrolysis treated oil wastewater: 1) using Ti electrode, 6v for electrolysis voltage, 4000Hz for frequency, 60% for duty cycle; 2) using graphite electrode, 10v for electrolysis voltage, 3750Hz for frequency, 70% for duty cycle; 3 ) using Al electrode, 7v for electrolysis voltage, 4000Hz for frequency, 70% for duty cycle.(2) The graphite electrode have better oil removing rate than Ti electrode and Al electrode for the oil wastewater in low salinity. The Al electrode has better oil removal rate than graphite electrode and Ti electrode for the oil wastewater in high salinity.(3) After 15 minutes, the petroleum removal rate of Ti, graphite and Al electrode in the oil wastewater in a Shanbei oil field is 54%, 56% and 84% differently.(4) The Pulse electrolysis-coagulation combination treatment process took the Al as the electrode, in simulating wastewater, the oil removal rate was about 82% after 15 minutes, After adding the PAM 50mg/L into the wastewater , the removal rate can reach 94%. Under the same condition, the removal rate is 93% to the oil wastewater in a Shanbei oil field.(5) The results of pulse electrolysis-coagulation in oil wastewater show that the Al electrode can degradate the oil by electro-oxidation and convert Al³⁺ into Al(OH)₃ in the process of electrolysis, and adding the PAM can improve the flocculation. It forms a high-performance model that the combination of electro-oxidation, Al(OH)₃ flocculation and PAM coagulation, supplying a theoretical basis to the method of oil wastewater disposal.