| The tertiary oil recovery technologies have be carried out in most of oil fields in our country. Among which the polymer flooding technology is an effective method for improving the crude oil recovery. The years' accumulation of experiences in laboratory, the succeed of pilot scale tests in oilfield and the wide application in oil field indicated the polymer flooding come to the most advance technology in the world. Accompany with the application of polymer flooding, the treatment of wastewater containing hydrated polyacrylamide (HPAM) comes to be a problem. The wastewater can't achieve the criteria for reinjection or discharge with tradition wastewater treatment technology, especially with the extension using polymer flooding and fast increasing the wastewater. New technology for wastewater treatment is an urgent task. Advanced Oxidation Processes (AOPs), which is the free radicals with strong oxidation degradation of organic contaminations, is a new technology for wastewater treatment. According to its' degradation rate, AOPs have good application foreground. They can also be used for the treatment of wastewater containing polymer. In the paper, the wastewater containing polymer was treated by Advanced Oxidation Processes such as Fenton, UV/TiO2 and Fe(VI) system, the degradation rate of HPAM was compared and the mechanism of degradation was also discussed.(1) The Microscopic images show that the wastewater containing polymer is highly emulsified. The adsorption of polymer on the oil/water interface increases the stability of the emulsion and film evidently.(2) With the analytical results of existing position and action of oil and HPAM, the emulsifying mechanism was discussed and the solution for demulsifying was suggested. By the evidences, a breaking of HPAM and emulsifier is proposed for destructing the film on oil/water interface.(3) Nano-TiO2 photocatalyst was prepared by Sol-Gel method and doped technique. Influence of deposing condition on the grain size, crystal structure and surface properties of nano-TiO2 was investigated; the existing position and action of TiO2 in oil/water system was also studied. Results of photographs show that nano-TiO2 can enter the oil/water interface and well dispersed, a solid film is formed and well stability. The results support our anticipation of photo catalytic.(4) The activity and affecting factors of nano-TiO2 was investigated. Photocatalyst activities show that the particle size of nano-TiO2 and the calcinations temperature play a chief role on the activity. Results of HPAM degradation show that with 0.5%～l% photocatalyst, wastewater with low HPAM concentration can be well degraded. The adding of Fe3+ (3.70×10-3mol/L) or H2O2 (5×10-3mol/L) can promote degradation. The degradation rate of HPAM reaches 80% with solar radiation in 4 hours.(5) The presence of HPAM causing the wastewater become viscously which increasing the difficulty in treatment. In the paper, the photocatalytic visbreaking for HPAM wastewater was investigated. The conception "photocatalytic visbreaking" was proposed. Results shows photocatalyst is a feasible technique with notable efficiency for viscosity-reduction of HPAM wastewater. The light source, catalyst type and amount, addition of oxidizer have different effects on photocatalytic visbreaking of the HPAM wastewater. With 1% photocatalyst, small amount of Fe3+ (about 10-3 mol/L) and H2O2 (about 10-3 mol/L), the wastewater with HPAM 200 mol/L can reach viscosity of pure water in 5 minutes. With solar radiation the viscosity of HPAM wastewater can also reach the value of pure water in 3 hours. The solar for photocatalytic visbreaking of aqueous HPMA is feasible.(6) The systematical investigation results of photocatalytic degradation and visbreaking of HPAM wastewater shows that the degradation rate of wastewater containing polymer from polymer flooding can reach 70% in 2 hours and the prolong of expose time or the adding of small amount of oxidizer can enhance the effect. It is rapid for photocatalytic visbreaking. The viscosity of wastewater with 370 mg/L HPAM can reduce more than 90% in 5 minutes when exposed to the light, the same as pure water in 10 minutes; with 520 mg/L HPAM the viscosity can down to pure water in 30 minutes. With 1% photocatalyst, 5×10-3 mol/L H2O2 and expose to solar for 5 hours, the HPAM in wastewater with 370mg/L HPAM can be degraded by more than 95%, the concentration of HPAM is low than 15 mg/L. The solar energy for the degradation of wastewater containing polymer from polymer flooding is feasible.(7) Results of light-Fenton reagent for HPAM degradation show that with only Fenton reagent the degradation of HPAM is hard, but light-Fenton reagent (UV/Fenton/C4H4O62-) the degradation of HPAM is efficient. The pH of solution has a distinct influence on the degradation, weak acid plays a positive role. For certain reaction system, the H2O2 for HPAM degradation has a optimum concentration.(8) A series of Fe (Ⅵ) compound was synthesized. The oxidation ability and capacity were adjusted in a certain oxidizing potential for HPAM degradation of wastewater from polymer flooding. The results show that with conditions of Fe(NO3)3 as iron resource of 85%-95%, the concentration of KOH solution of 10.5mol/L, 0 ～ 5 ℃ and recrystallization technique, the pure Fe (Ⅵ) compound can be gained in high yield. The optimum condition of Fe (Ⅵ) oxidation for wastewater containing polymer is 40-60℃ and pH=3, and the initial concentration has little effect on oxidation ability. The Fe (Ⅵ) solution is strong oxidation ability. CODcr of Wastewater from tertiary oil recovery can reduce more than 60%. With high HPAM concentration the reducing rate is even higher (more than 70%). That Fe (Ⅵ) plays as both oxidizer and flocculant makes it be superior in treatment of wastewater containing polymer and oil. Fe (Ⅵ) is a high efficient reagent of wastewater treatment.It can be conclude that three type of oxidation method for HPAM degradation are feasible, innovative and valuable for application in oilfields. This study provides science and technique for the wastewater treatment in oilfields.
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