Experimental Study On Microwave-assisted Processing Polymer-bearing Wastewater

Now the oilfield is entering into exploitation later stage and widely using polymer flooding technology. However, the changing of oilfield wastewater component makes the viscosity of oil-bearing wastewater increase and difficulty to treat by flocculant technology. Treatment of oil-bearing wastewater from Daqing oilfield by microwave-flocculant was dicussed in this paper and polyacrylamide(PAM) was the target object. The experimental study designed to examine the feasibility of new technology, and to explore the best mode of operating parameter, and to analysis the reaction mechanism, which provide technical reference and theoretical basis for practical engineering applications.1. The influencing factors on the dynamic viscosity of polyacrylamide were studied including different metal cation, temprerature, pH value, microwave irradiation. The visbreaking effect on polyacrylamide is enhanced by three kinds of metal cation cooperative microwave. It is shown that pH value affect viscosity of polyacrylamide apparently. Based on the comparison of metal cation cooperative microwave and single treatment, it is shown that microwave cooperative Fe3+ has the best effect of viscosity of polyacrylamide.2. It is proved that the removal PAM efficiency of flocculant cooperative microwave is better than single treatment and microwave cooperative Fe2(SO4)3 has the best effect by experiment. It is shown that aspects with maximal average deviation of each factor are flocculant dose, microwave radiation time, microwave power. Meanwhile, it is proved that it is feasible to treat polymer-bearing wastewater combined microwave to flocculation process and ferric salt that has a good absorption for microwave should be used as the first choice in the treatment technique of the microwave purifying oil-bearing wastewater. 3. The results of microwave-flocculant treating oil-bearing wastewater show that the removal efficiency of PAM and TOC is enhanced certain by microwave; however, the flocculation efficiency is enhanced significantly and the turbidity value of water after microwave treatment is lower. The optimum conditions are pH value of 5, microwave power of 400 W, microwave radiation time of 90 s, flocculant dose of 320mg·L-1. Under these conditions, the removal efficiency of PAM reaches to 98.17%, TOC decrease to 11.59mg·L-1, the turbidity value decrease to 24.60 NTU, petroleum type substances are not detected,COD decrease to 69.41mg·L-1. Finally, the oil content and COD are up to the One-class standard of《Integrated wastewater discharge standard》. The synergistic effect of H+ and flocculant makes the zeta value of oil-bearing wastewater within the range of colloid condensation rapidly; microwave irradiating oil-bearing wastewater makes the temperature of the solution increase and brownian motion accelerate. So the main role of microwave in the reaction system are thermal effect.