| Polyacrylamide(PAM)is a kind of linear water-soluble polymer,it has been widely used in oil field for enhanced oil recovery because of its comparative high molecular weight and high viscosity of low concentration aqueous solution. The oil wastewater with PAM is increasing year by year following with polymer flooding in oil field. As known to all, the polyacrylamide is non-toxicity and harmless, but the monomer acrylamide produced from polyacrylamide degradation is severely harmful to nervous system of human body and animal. What's more, most of PAM goes into surface water or subsurface water at last. The oil wastewater with PAM not only changes the physical and chemical property of water, but also PAM contributions to chemical oxygen demand (COD) and releases acrylamide because of depolymerization.The result of treatment is unsatisfactory by using traditional biochemical process, since the distinguishing features of oil wastewater with PAM, such as high viscosity, low biodegradability and hard degradability. So it has become a desirable subject to find an effective way to treat the oil wastewater containing polyacrylamide.The contents of this thesis were divided into six parts: the first part was literature summarization; the second part was improvement of biodegradability of oil wastewater contained PAM by Pretreatment with Fenton oxidation; the third part was treating oil wastewater contained PAM by biochemical processes; the fourth part was inside simulation of treating oil wastewater contained PAM by the combination pretreatment of Fenton oxidation with biochemical processes; the fifth part was conclusion.In this study, Shengtuo oil wastewater contained PAM was subject investigated. The result of treatment is unsatisfactory by using traditional biochemical process, since the distinguishing features of oil wastewater with PAM, such as the small value of BOD5/COD, low biodegradability and hard degradability. So physicochemical process as pretreatment process were combined with biological process to improve of biodegradability of oil wastewater contained PAM. Based on the experimental results presented, the following conclusions can be drawn:1. PAM of oil wastewater is pretreated by Fenton oxidation. The optimal conditions for Fenton reaction were obtained as follows: the initial solution pH was 4, the molar ratio of H2O2 and Fe2+ was 12 to 1, the mass ratio of H2O2 and CODcr was 1.25 to 1, the reaction temperature was 40oC, and the reaction time was 40 min, respectively. Under the above conditions, the removal ratios of PAM and CODcr were 83.8% and 77.1%. Treatment with Fenton's oxidation improved effectively the biodegradability of PAM. The ratio of BOD5 and CODcr increased from about 0.10 to above 0.40. In mix bacteria degradation process, the removal ratios of CODcr with Fenton oxidation pretreatment reached 62.5%, while that without Fenton oxidation pretreatment was only 2.13%. The result shows that Fenton oxidation is an effective pretreatment method for the non-biodegradable organics, which is favor of subsequent biological processes.2. In this paper, three strain bacteria which degraded polyacrylamide were screened from activated sludge of Shengli Oilfield. One of the three strains, which could degrade polyacrylamide efficiently, named AS-2. According to its physiological and biochemical characteristics and PCR-16S rDNA, AS-2 bacterium was identified as Paracoccus denitrificans sp. The optimal conditions for degradation of PAM by AS-2 were obtained as follows: the degradation time was 5 days, the initial pH value was 4, the temperature was 40℃, the carbon source was crude oil and its content was 2.5 g·L-1, the optimal nitrogen source was NaNO3 and its content was 1.4 g·L-1 . Under the above conditions, the removal ratio of PAM was 45.23 %.3. The inside simulation of treating oil wastewater contained PAM by the combination pretreatment of Fenton oxidation with biochemical processes at the best possible conditions. The removal ratios of PAM and CODcr were 93.63% and 90.50%. Through analyzing the IR spectra of PAM, partial PAM was oxidized to aldehyde and carboxylic acid by Fenton oxidation, The side chain of PAM was mainly degraded by AS-2. Amido in the side chain of PAM was degraded into carboxylic acid and free amino nitrogen. The acrylamide monomer was not detected in PAM solution after Fenton oxidation and biodegradation by high performance liquid chromatography (HPLC).
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