[Flocculation of wastewater produced in polymer flooding].

The particle size distribution, flocculation index, Zeta potential and oil content in water were tested during flocculation of wastewater produced in polymer flooding of oil field. CHP-03, a mixture of a modified pluronic demulsifer and a weak-cationic flocculant, was used to improve the efficiency of oil droplet collision. The effects of polyacrylamide, temperature, and mixing speed on flocculation dynamics are discussed. Polyacrylamide affects the oil-water separation by obstructing the aggregation of small oil droplets, but electrostatic repulsion is not a major factor in preventing flocculation. The local temperature has a limited effect on flocculation. Fast mixing favors the growth of flocs, while slow mixing is suitable for the coalescence of oil droplets. Addition of 250 mg/L CHP-03 can enhance the oil-water separation and remove 92% of the oil content.