Characterization and application of different ceramic membranes for the oil-field produced water treatment

The characterization and application of cross-flow microfiltration (MF) process as a pre-treatment step and, partly in combination, with cross-flow ultra- (UF), and nanofiltration (NF) systems as final-treatment techniques for efficient treatment of oilfield produced water and different prepared model solutions using ceramic membranes are issued here. Generally, surface fossil water, “produced water”, arises through the production of crude oil and natural gas. This water is always to be cleaned to some extent and the level of cleaning is determined by the intended use and/or current discharge regulations. Technologies that recently exist are not usually capable of reaching the new levels of required cleanliness. Therefore, innovative technologies are required to cope with the regulations of produced water treatment. Thus, aiming at the investigation of the average flux rates and oil and total organic hydrocarbon (TOC) removal efficiency, the cross-flow velocities through membranes were in the range of 0.6–1.3 m/s. Permeate flux varied from 3.4 to 3300 L/(h m2 bar) at a trans-membrane pressure of 1 bar and a feed water temperature of 60°C. Using a MF membrane (0.1 µm) and a solution modeling produced water, the permeate flux declined from initially 1150 to 200 L/(h m2) after 5 h. Utilizing an UF membrane (0.05 µm), oil removal up to 99% and TOC removal up to 39% were achieved.

Rest oil [ppm] Generally, the removal of oil and TOC depends on the condition of the oil–water mixture. The investigated ceramic membrane systems under micro-, ultra-, and nanofiltration conditions 0.5 0.05 µm 0.1 µm Rest oil 1.5 2.5 3.5 4.5 5 5.5 Time [h] 1 kD Flux 6.5 7.5 8.5 9.5 Flux [l/m2*h*bar] Membrane Cut-off Fig. 6. Average flux rates, flux degradation and oil removal efficiency for different ceramic membranes – MF followed by UF/NF. Model solution (f) was used in a membrane-assisted continuous reactor, experimental conditions were TMP, 1 bar; temperature, 60°C.