Study of the contribution of the main pollutants in the oilfield polymer-flooding wastewater to the critical flux

One of the major technical requirements of the crude oil exploitation industry is to minimize the concentration of hydrolyzed polyacrylamide (HPAM), crude oil and suspended solid (SS) in the oilfield polymer-flooding wastewater and realize the reuse of this wastewater. In this study, the membrane technology was used to achieve this goal in laboratory-scale dead-end test unit with flat polyvinylidene fluoride (PVDF) membrane (MW 100 kDa). We systematically inspected the membrane fouling mechanism, the variety of total membrane resistance, total fouling resistance, the dominant resistance, membrane fouling driving force and the filtration proceeds in the filtration process. The orthogonal method and multivariate linear regression method were applied to analyze the influencing degree of the main pollutant concentration on the critical flux. According to comparison of the average rates of change of the critical flux for the HPAM concentration, oil concentration and SS concentration in single solute solution, double solute solution and oilfield polymer-flooding wastewater, HPAM can decrease the average rate of change of the critical flux for other two solutes and has the crucial effect on the critical flux. The sequence of influence degree on the critical flux is the HPAM concentration (84.58%) > oil concentration (14.36%) > SS concentration (1.06%).

Research Highlights
► Inspecting the variation of the membrane fouling driving force.
► Quantitative analysis of the contribution of main pollutants to the critical flux.
► HPAM has the crucial effect on the critical flux.
► The sequence of influence degree on the critical flux is the HPAM > oil > SS.