Treatment of produced water streams in SAGD processes using tubular ceramic membranes

The presence of fine solids and dissolved organics in produced water from Steam-Assisted Gravity Drainage (SAGD) process can potentially block pressure vessels and cause fouling and corrosion in steam boilers. Ceramic membranes in tubular configurations with pore sizes of 20 kDa, 50 nm and 100 nm were investigated for the removal of solids and dissolved organics from boiler feed water (BFW). The original BFW sample contained 125, 1300 and 20 mg/L of oil and grease (O&G), naphthenic acids (NAs) and total suspended solids (TSS), respectively. It was found that lowering the pH of the BFW to 4 prior to membrane treatment increased the permeate flux and also eliminated operating drawbacks such as foam formation. Among all the investigated membranes, the Al2O3 membrane with 100 nm pore size showed the best performance in terms of flux and removal efficiencies as no detection of total suspended solids was observed in the permeate streams while achieving a high removal efficiency of 80% and 95% for O&G and NA, respectively. © 2014 Elsevier B.V. All rights reserved.

Treatment of BFW samples was carried out using Al2O3 and ZrO2 ceramic membrane modules with different properties and monolith configurations. These modules consisted of 100 nm, 50 nm, and 20 kDa pore sizes. It was confirmed that treatment of the BFW by ultrafiltration mechanisms alone cannot remove all dissolved ions and organics in the feed. However, pretreatment of the feed by acid injection improved the permeate flux and eliminated operating drawbacks such as foam formation. Among all the investigated ceramic membrane modules, the membrane with 100 nm and 19 channels showed the best performance in terms of permeate flux and contaminant removal. On the other hand, pore clogging and blockage were observed for the membrane with the smallest pore size of 20 kDa, whereas the 50 nm membrane showed moderate performances while allowing the passage of very fine particles in the permeate streams. The 100 nm macroporous ceramic membrane was determined to be the best choice in this application due to the absence of any suspended solids in the permeate streams.