Contribution of Main Pollutants in Oilfield Polymer-Flooding Wastewater to the Total Membrane Fouling Resistance

Polymer flooding technology has been used in the oilfield, but huge amounts of polymer-flooding wastewater are produced with oil extraction. Therefore, the treatment and recycle of this wastewater become very significant. In this study, the membrane technology was used to treat synthetic oilfield polymer-flooding wastewater in laboratory-scale dead-end/cross-flow test unit with flat polyvinylidene fluoride (PVDF) membrane (MW 100 kDa). We systematically inspected the membrane fouling mechanism, the variety of total fouling resistance, the dominant resistance, and the filtration proceeds in the filtration process. The orthogonal method and multivariate linear regression method were applied to analyze the influencing degree of main pollutants concentration which contains partially hydrolyzed polyacrylamide (HPAM), oil and suspended solid on the total membrane fouling resistance. According to a comparison of the average rates of change of total membrane fouling resistance for the HPAM concentration, oil concentration, and suspended solid (SS) concentration in single solute solution, double solute solution, synthetic oilfield polymer-flooding wastewater, and the value of pH, HPAM can decrease the average rate of change of total membrane fouling resistance for other two solutes and has the crucial effect on the total membrane fouling resistance. The sequence of influence degree on the total membrane fouling resistance is the HPAM concentration > oil concentration > suspended solid concentration. Moreover, the membrane cleaning effect was studied by using SEM images and the pure water flux.