Characterization and Treatment of Oil Sands Blowdown Water
Abstract
The high concentrations of organic and inorganic impurities from the blowdown water of the Steam Assisted Gravity Drainage (SAGD) process in the oilsands operations cause significant operational and environmental issues. In this study the actual SAGD boiler and evaporator blowdown was investigated and found to contain complex mixtures of TSS, TOC and TDS. Further investigations were focused on SAGD boiler blowdown (BBD) water and included the screening of seven advanced oxidation processes (AOPs) which resulted in the selection of three O3/UV, H2O2/UV and O3/H2O2/UV AOP’s for testing TOC degradation in each sequence of the HCl-acidified, CaO-alkalized, CO2-neutralized and original BBD waters. O3/H2O2/UV irradiation showed effective degradation in the neutralized, alkalized, acidified and original BBD at 70%, 68.3%, 55.6% and 9.4% TOC removal. An unique, semi-batch treatment system was designed, integrated and evaluated using HCl-acidified, CaO-alkalized, CO2-neutralized BBD water in three stages; (1) Stage A; precipitation and centrifugation for TSS and TOC removal, (2) Stage B; O3/H2O2/UV for TOC degradation, and (3) Stage C; reverse osmosis filtration for the TDS and residual TOC removal. Stage A results showed that the HCl-acidified BBD at pH 4.2 achieved the highest TOC removal by 44.7% and TSS by 98.5% likely because the net reduction in the molecular electrical repulsion and neutralization of acid groups led to their aggregation and removal. Stage B results showed that the O3/H2O2/UV achieved the highest TOC removal of 68.0% in the CO2-neutralized BBD likely because interferences of the competing inorganic carbonate and bicarbonate species that scavenge hydroxyl radicals were minimized. Stage C results showed that reverse osmosis filtration purified all samples, but achieved the highest removal of 99.7% residual TOC and 98.8% TDS in the HCl-acidified BBD and the highest permeate recovery at 40.5% in the alkalized and neutralized BBD. Since there is a lack of published information on SAGD blowdown the result of this study is significant and a precursor to advancing future research solutions.
Description
Keywords
Engineering--Environmental
Citation
Martez, V. (2016). Characterization and Treatment of Oil Sands Blowdown Water (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25263