during oil sand extraction and upgrading. Thus a proper management of tailing
ponds is the main concern of oil sands operators.
Tailing ponds act as a good habitat for microbial growth and raise a major
environmental concern. SRB and methanogens are easily grown in tailing ponds
due to the availability of sulfate and anaerobic environment. Currently, oil sands
mining companies are operating under a zero effluent discharge policy to the
environment. In Canada alone, 1 billion m
3 tailings are stored in tailing ponds and
cover approx. 220 km
2 area (Foght et al. 2017). For reclamation of land, some
proposals related to placing tailing semi solids in the basin and capping with fresh
water (end pit-lake) ecosystem or wetlands have been proposed. Other options
available are placing de-watered tailing and covering with sand, soil, and vegetation
for the generation of the boreal forest.
Potential biotechnological approaches employed for the remediation of tailing
ponds are the aerobic treatment of froth treatment tailings. This leads to biodegradation of hydrocarbons prior to deposition in tailing ponds. This aerobic treatment also
decreases the toxicity of ponds and also decreases methane emission. Another
method employed is the in situ aerobic biological treatment of toxic organics (e.g.,
naphthenic acid). In this, partial oxidation of naphthenic acid is performed by
ozonation, followed by the biodegradation process. Other approaches involves use
of biofilm based bioreactors and algal based bio-treatment. Besides, microbial
sequestration of produced gases (e.g., CH 4 , CO 2 ) by methane oxidation is known
to occur by native tailing ponds methanotrophs. Currently, none of the approaches is
applied in pilot scale or in situ. While some of the approaches are in conceptual
stages such as improving bitumen recovery by pretreatment using mEOR methods
(uses of biosurfactant), uses of encapsulated microbes to remediate tailing ponds
water, electricity generation by the construction of microbial fuel cells (Foght et al.
2017).
Shale gas, on the other hand, is a natural gas trapped within shale formations/
rocks. Shale rocks are clastic sedimentary rocks and formed from the mud, clay, and
organic matter. Shale rocks porosity is very low (10–100 nanodarcies) and natural
gas are trapped in the tiny pores. Initially, shale gas production is economical, but
was not feasible due to the unviability of technology. At present, shale gas production is economically viable with the advancement of technology and improved
methods. Shale gas is produced through horizontal drilling and hydraulic fracturing
process. Major shale gas producing countries are China, USA, Canada, and
Argentina. Shale gas production has some issues like leakage of extraction
chemicals, high water requirement, and leakage of greenhouse gases during extraction and pollution due to the processing of natural gas. During the hydraulic
fracturing, water based fluid is injected in well at high pressure to create cracks in
shale rocks. This water based fluids contain water, diluted acids, biocides, breakers,
corrosion inhibitors, friction reducers, gels, oxygen scavengers, proppant, scale
inhibitors, and surfactant (Arthur and Layne 2008). Hydraulic fracturing fluid is
susceptible to microbial growth. These microbes can be injected through fluids
during drilling, drilling mud, and drilling water or indigenous to the shale gas
field. To reduce microbial growth biocides are added in hydraulic fracturing fluids.
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G. Prajapat et al.
ponds is the main concern of oil sands operators.
Tailing ponds act as a good habitat for microbial growth and raise a major
environmental concern. SRB and methanogens are easily grown in tailing ponds
due to the availability of sulfate and anaerobic environment. Currently, oil sands
mining companies are operating under a zero effluent discharge policy to the
environment. In Canada alone, 1 billion m
3 tailings are stored in tailing ponds and
cover approx. 220 km
2 area (Foght et al. 2017). For reclamation of land, some
proposals related to placing tailing semi solids in the basin and capping with fresh
water (end pit-lake) ecosystem or wetlands have been proposed. Other options
available are placing de-watered tailing and covering with sand, soil, and vegetation
for the generation of the boreal forest.
Potential biotechnological approaches employed for the remediation of tailing
ponds are the aerobic treatment of froth treatment tailings. This leads to biodegradation of hydrocarbons prior to deposition in tailing ponds. This aerobic treatment also
decreases the toxicity of ponds and also decreases methane emission. Another
method employed is the in situ aerobic biological treatment of toxic organics (e.g.,
naphthenic acid). In this, partial oxidation of naphthenic acid is performed by
ozonation, followed by the biodegradation process. Other approaches involves use
of biofilm based bioreactors and algal based bio-treatment. Besides, microbial
sequestration of produced gases (e.g., CH 4 , CO 2 ) by methane oxidation is known
to occur by native tailing ponds methanotrophs. Currently, none of the approaches is
applied in pilot scale or in situ. While some of the approaches are in conceptual
stages such as improving bitumen recovery by pretreatment using mEOR methods
(uses of biosurfactant), uses of encapsulated microbes to remediate tailing ponds
water, electricity generation by the construction of microbial fuel cells (Foght et al.
2017).
Shale gas, on the other hand, is a natural gas trapped within shale formations/
rocks. Shale rocks are clastic sedimentary rocks and formed from the mud, clay, and
organic matter. Shale rocks porosity is very low (10–100 nanodarcies) and natural
gas are trapped in the tiny pores. Initially, shale gas production is economical, but
was not feasible due to the unviability of technology. At present, shale gas production is economically viable with the advancement of technology and improved
methods. Shale gas is produced through horizontal drilling and hydraulic fracturing
process. Major shale gas producing countries are China, USA, Canada, and
Argentina. Shale gas production has some issues like leakage of extraction
chemicals, high water requirement, and leakage of greenhouse gases during extraction and pollution due to the processing of natural gas. During the hydraulic
fracturing, water based fluid is injected in well at high pressure to create cracks in
shale rocks. This water based fluids contain water, diluted acids, biocides, breakers,
corrosion inhibitors, friction reducers, gels, oxygen scavengers, proppant, scale
inhibitors, and surfactant (Arthur and Layne 2008). Hydraulic fracturing fluid is
susceptible to microbial growth. These microbes can be injected through fluids
during drilling, drilling mud, and drilling water or indigenous to the shale gas
field. To reduce microbial growth biocides are added in hydraulic fracturing fluids.
128
G. Prajapat et al.