User talk:Joeho604: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
{{Uncurated}} | {{Uncurated}} | ||
=Introduction= | |||
The oil sands in Alberta, Canada, covering over 100000 km2, produce over 1.3 million barrels of bitumen per day [1]. Extraction of bitumen by surface mining of oil sands requires large amount of water and hydrocarbon solvents. The resulting byproduct creates large volumes of water, sands, clays, residual hydrocarbons, heavy metals, naphtha diluents, and naphthenic acids, which are termed as tailings. Due to operational policies preventing zero discharge of any liquids into the environment, these fine tailings are collected and confined into settling basins to create tailings ponds [1]. Despite the toxicity of tailings, microbial communities exist in tailings pond, which aid to accelerate tailings sedimentation while being able to degrade certain compounds in the tailings. | The oil sands in Alberta, Canada, covering over 100000 km2, produce over 1.3 million barrels of bitumen per day [1]. Extraction of bitumen by surface mining of oil sands requires large amount of water and hydrocarbon solvents. The resulting byproduct creates large volumes of water, sands, clays, residual hydrocarbons, heavy metals, naphtha diluents, and naphthenic acids, which are termed as tailings. Due to operational policies preventing zero discharge of any liquids into the environment, these fine tailings are collected and confined into settling basins to create tailings ponds [1]. Despite the toxicity of tailings, microbial communities exist in tailings pond, which aid to accelerate tailings sedimentation while being able to degrade certain compounds in the tailings. | ||
=Physical & Chemical Environment= | |||
==Composition of tailings pond== | |||
Along with the 20-30 wt% of solids (sands and clays) and slightly alkaline water (pH>7.5), mature tailings consist of 1-3 wt% of residual bitumen and naphtha, comprising of a mixture paraffins (n-alkanes), iso-paraffins (branched alkanes), olefins (alkenes), naphthenes (cycloalkanes), naphthenic acids (cyclopentyl and cyclohexyl carboxylic acids), and monoaromatics (benzene, toluene, ethylbenzene, and xylenes, or BTEX) [2][3]. Other minor elements include trace metals (Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Mo, Ba), and ions (HCO3-, PO43-, NO3-, SO42-, Na+, K+, Mg2+, Ca2+, Cl-) [4]. | |||
Toxicity of tailings ponds to aquatic organisms is often associated with naphthenic acids, which have surfactant properties that penetrate the cell membrane [5]. | |||
Revision as of 04:18, 13 December 2012
Introduction
The oil sands in Alberta, Canada, covering over 100000 km2, produce over 1.3 million barrels of bitumen per day [1]. Extraction of bitumen by surface mining of oil sands requires large amount of water and hydrocarbon solvents. The resulting byproduct creates large volumes of water, sands, clays, residual hydrocarbons, heavy metals, naphtha diluents, and naphthenic acids, which are termed as tailings. Due to operational policies preventing zero discharge of any liquids into the environment, these fine tailings are collected and confined into settling basins to create tailings ponds [1]. Despite the toxicity of tailings, microbial communities exist in tailings pond, which aid to accelerate tailings sedimentation while being able to degrade certain compounds in the tailings.
Physical & Chemical Environment
Composition of tailings pond
Along with the 20-30 wt% of solids (sands and clays) and slightly alkaline water (pH>7.5), mature tailings consist of 1-3 wt% of residual bitumen and naphtha, comprising of a mixture paraffins (n-alkanes), iso-paraffins (branched alkanes), olefins (alkenes), naphthenes (cycloalkanes), naphthenic acids (cyclopentyl and cyclohexyl carboxylic acids), and monoaromatics (benzene, toluene, ethylbenzene, and xylenes, or BTEX) [2][3]. Other minor elements include trace metals (Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Mo, Ba), and ions (HCO3-, PO43-, NO3-, SO42-, Na+, K+, Mg2+, Ca2+, Cl-) [4]. Toxicity of tailings ponds to aquatic organisms is often associated with naphthenic acids, which have surfactant properties that penetrate the cell membrane [5].
