Polymer flotation and activated carbon adsorption treatment for in situ tar sand process water

Abstract

Process waters collected during a DepartmentThe first two of these efforts involved in situ combustion while the third used steam drive. During this last experiment 1150 barrels of oil and 6250 barrels of water were produced. These waters were characterized as having significant organic loads, primarily as emulsified bitumen. Inorganics, including trace metals were observed in apparently insignificant concentrations. Bench scale treatability experiments were initiated to determine appropriate technologies to remove this organic load. Two alternative approaches were found to be of equal effectiveness: metallic hydroxide coagulation, followed by flocculation and sedimentation and cationic polymer colloid destabilization followed by flotation. A series of experiments were undertaken to determine the most appropriate operating conditions for each of these respective approaches [ 4 , 5 , 6 , 71. This paper reviews some of the flotation configurations which were used to generate a large (350 L) volume of treated effluent as well as describing some toxicology and analytical chemistry protocols used to characterize these fluids. Additional emphasis is placed upon a series of activated carbon adsorption experiments undertaken to detoxify the flotation effluents. EXPERIMENTAL Materials and MethodsThe wastewater used in this effort was collected at the DOE tar sand field site near Vernal, Utah during the sum-154 August, 1986 mer of 1980. Collected waters were composited, placed in individual barrels and stored at 4°C. Aliquots of these materials were taken for the flotation experiments. Figure 1 is a schematic of the Induced Air Flotation apparatus used in this study. The process consisted of rapid and slow mix basins as well as a flotation column. Process water was rapid mixed with a predetermined concentration of polyelectrolyte, slow mixed to form flocs and injected into the flotation column. Resulting sludge layers were ejected from the top of the column while treated effluent exited at the bottom. Laboratory air was regulated at 10 psi and entered the column by way of a finely sintered (3 pm openings) stainless steel sparger. Air flowrate was controlled by a flowmeter. Other operating conditions included: polymer type = Betz 1195 polymer dose = 60 mg/L air flowrate = 1440 mL/min liquid residence time = 20 minutes Treated sample was wasted until the process reached steady state which was determined by Total Organic Carbon (TOC) analyses. The unit was operated continuously with periodic shutdowns for cleaning and adjustments until the 350 liter sample had been produced. Aliquots of the treated effluent were collected, preserved and analyzed for chemical and toxicological constituents and parameters.Toxicity testing was accomplished with a MICROTOX 2055 toxicity analyzer (Beckman Instruments). This instrument measures light output produced by Microtox Reagent, a lyophilized strain of marine luminescent bacteria, most closely resembling Photobacterium phosphoreum. This procedure is based upon an inverse relationship betwee...