Concentrating emulsified oily wastewater by integrated membrane technology

Abstract

The effects of operating pressure, feed temperature, oil content of feed solution, and membrane surface flow rate on membrane flux, concentration multiple, and average particle size of oil droplets in the concentrated solution during the single-stage membrane concentration process were investigated. The experimental results show that within a certain operating range, the membrane flux increases with the increase of operating pressure, feed temperature, and membrane surface flow rate, while it decreases continuously with the increase of feed oil content. Optimal conditions for single stage concentration based on membrane flux, concentration factor, and average particle size of oil droplets in the concentrated solution were determined. Then, on the basis of single-stage membrane concentration conditions, three different pore size separation membranes are combined in different ways. After concentration through multi-stage membranes, the particle size of the oil droplets in the concentrate is greater than 20 μm, which is beyond the particle size range of the emulsified oil, and the concentration of the oil in the concentrate is 20–30 times that of the original oil. The method can realize the recovery of oil resources in the emulsified oil-containing wastewater. HIGHLIGHTS Under the optimal membrane separation conditions, the concentration rate reaches the highest.; An integrated membrane can effectively concentrate oily wastewater.; The oil in the concentrated wastewater can be better recovered.;

Keywords

• concentration multiple
• emulsifying oily wastewater
• integrated membrane
• membrane flux
• oil droplet size