Soil con & rem > Presentations > Flashcards

Presentations Flashcards

(54 cards)

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1
Q

Burning methods?

A

Ex-situ incineration

in situ combustion

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2
Q

Advantages of burning?

A
  • contaminants are converted
  • relatively quick remediation
  • high temperature good for sandy soil, desert, beach
  • very high (+1600C) temperatures effective for inorganic contaminants
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3
Q

Disadvantages of burning?

A
  • energy intensive
  • destroys everything organic
  • emits pollutants to the atmosphere
  • cost
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4
Q

What is remediation by volatilization?

A

Heating the contaminated soil to volatilize the contaminants

-> released to the atmosphere or collected

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5
Q

Advantages of volatilization?

A
  • less destructive than incineration

- both ex- and in situ

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6
Q

Disadvantages of volatilization?

A
  • applications mainly volatile organic compounds (VOC), semi-volatile organic compounds (SVOC) and heavier hydrocarbons
  • not effective for most inorganic contaminants
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7
Q

Capping and encapsulation in a nutshell?

A
  • Contaminants from the soil are not removed nor somehow treated.
  • The methods prevent people and wildlife from coming in contact with contaminants.
  • After executing any of the methods, soil is not used for agriculture.
  • The methods are chosen when other cost-effective remediation technologies are not available
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8
Q

How does capping work?

A

Soil is covered on top or also with additional tools in the ground (like monitoring well) that prevent the spreading of the pollutants in the soil.

Layers could be:
• Asphalt or concrete
• Vegetative layer
• Geomembrane
• Clay
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9
Q

When to use capping?

A
  • Volume of polluted soil is big
  • Concentration and the hazard of the pollutants are low enough
  • No groundwater under the contaminated site
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10
Q

How does encapsulation work?

A

1) Excavation phase to remove the contaminated soil
2) Creation of the storage cell formed by geomembrane
3) Putting the soil in the cell
4) Creating a layer on top with geomembrane and ventilation if needed

The encapsulation can take place on the site or
in waste storage place specialized for hazardous
waste

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11
Q

When to use encapsulation?

A
  • Quantity of soil is small enough to excavate it
  • Concentration and the hazard of the pollutants is high
  • Groundwater can possibly be contaminated
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12
Q

What is natural attenuation?

A

Natural attenuation means physical, chemical and biological processes (or combinations of these processes) that occur naturally and reduce concentration or mass of contaminants

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13
Q

What is the primary mechanism for natural attenuation?

A

Biodegradation

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14
Q

What are monitored natural attenuation’s essential aspects?

A

Source control

Long-tern performance monitoring

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15
Q

Natural attenuation involves aerobic and anaerobic degradation of the pollutants, these processes can be assessed by?

A

Measuring microbial activity and using molecular biology methods in combination with chemical
analyses

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16
Q

Where does monitored natural attenuation work best?

A

Where source of pollution has been removed

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17
Q

What are the two types of natural attenuation?

A

Destructive and non-destructive

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18
Q

Advantages of natural attenuation?

A
  • Cost-effective
  • Can be applied partly or on all contaminated areas
  • Less intrusive
  • Less generation and transfer of waste
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19
Q

Disadvantages of natural attenuation?

A

• Slow process
• NA is not a desirable remedial alternative for certain sites
• For long-term situations, performance monitoring is required
– Costs more

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20
Q

What is excavation?

A

Excavating, digging is mostly done when something specific is aimed to be removed.
Excavation of contaminated sediment basically involves taking off the sediment from the water and this can be achieved by relocating the
water body permanently or re-routing the water body temporarily using pipes, dams or sheet piling.

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21
Q

Positives of excavation?

A

Excavation enables visual observation of the sediment removal process.

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22
Q

What happens after the contaminated soils are excavated from the area?

Study These Flashcards
A

Clean soils obtained from other locations are used to fill in the excavated area.

23
Q

How long does excavation takes?

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A

Excavating contaminated soils may take as little as a couple hours or as long as a few years.

24
Q

What is dredging?

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A

Removal of sediment from the banks or the bottom of bodies of water, such as canals, lakes or rivers.

25
How does dredging work?
The operator of the dredge lowers the boom to the bottom of the water body. Teeth cutter used to loosen the settled material, pump removes the sediment form the bottom of the waterway. Silt and debris are transported away for final processing.
26
Reasons for dredging?
* Improving water quality * Preserving wildlife and ecosystems * Remediates eutrophication (excess of nutrients in water due to runoff) * Reduces excess growth of plant life, which can cause oxygen deprivation in the body of water * Keeping waterways clean * Reduce flood risk
27
Two types of dredgers?
Mechanical dredgers | Hydraulic dredgers
28
What is electrokinetic remediation?
The use of direct electric current to remove organic, inorganic and heavy metal particles from the soil by electric potential. This has the effect of remediating the soil and recovering minerals to be used for other purposes.
29
For what purpose is electrokinetic remediation applied?
Applied to many contaminants that dissolve in groundwater
30
How does electrokinetic remediation works?
An electrokinetic system is set up by inserting electrodes into the contaminated soil. These electrodes are split into two categories; positively charged 'anodes' and negatively charged 'cathodes'.
31
How does electrokinetic remediation works? An electric current then....
An electric current then passes through the electrodes to create an electrical field, which moves the contaminants using electromigration and electro-osmosis. * Electromigration: the process of charged dissolved ions moving through liquid medium * Electro-osmosis: water being transported through porous material
32
With electrokinetic remediation, the removal of contaminants depends on what?
The removal of contaminants depends on their solubility. If they are non-soluble, co-solvents are used to make them more soluble.
33
Benefits of electrokinetic remediation?
* They are proven to be the fastest form of remediation available, making it cost efficient and time saving. * The method also requires little energy, which can even be provided via solar panels and wind turbines. * No pollution comes from the machinery. It also does not harm any plants, wildlife, or habitats, making it environmentally friendly
34
Limitations of electrokinetic remediation?
* The addition of liquids to aid in the extraction of difficult to extract contaminants * Prolonged use may alter the pH of the soil. * Large metal objects underground can lead to short circuits and change the voltage gradient, decreasing or stopping the flow * VOC (volatile organic compound) removal can result in increased soil vapor concentration * Decrease in electrical potential of system depending on polarization effect
35
What is composting?
Composting is a managed system in which organic materials naturally decompose and convert into nutrient-dense output called compost
36
What has to be in place to make composting succesful?
Nutrients, moisture, warm temperature and oxygen.
37
When composting can be used?
Soil that has been contaminated with harmful organic substances, for instance pesticides and solvents. Or, inorganic substances like toxic metals can be remediated.
38
Positives of composting?
Inexpensive | Elimination of diseases and improvement in water-holding ability, structure and soil tilt.
39
How does composting works?
Contaminated soil is excavated and placed in long composting piles. Then it is mixed with ''airy'' substances such as wood bark or straw.
40
Disadvantages of composting?
Not for inorganic contaminants or organic compounds that are not biodegradable. Not suitable for volatile compounds. A lot of space and care needed.
41
What is phytoremediation?
Phytoremediation is an in-situ remediation technique for contaminated soils and groundwater that uses living plants to contain, extract, or degrade pollutants.
42
What has to be taken into consideration to make phytoremediation succesful?
To succeed, plants should be chosen carefully: non-edible, able to produce biomass quickly, tolerant to contaminants in question, resistant to diseases. To be a sustainable remediation method, disposable and utilization techniques for the produced hazardous biowaste should be applied.
43
Advantages of phytoremediation?
• Cost-effective; • Suitable for the treatment of a wide range of organic and inorganic contaminants; • Can be applied over large territories; • Able to restore quality and functionality of the soil that positively affects the ecosystem in general; • Biomass grown during phytoremediation processes can be used to produce biofuels reduced need to use croplands for production of renewable energy sources; • Aesthetically attractive approach.
44
Disadvantages of phytoremediation?
* Phytoremediation generates huge amounts of contaminated biomass * In many cases, phytoremediation does not eliminate pollutants from the environment but relocates or immobilizes them; * Lengthy procedure: it takes time to see the results of phytoremediation; * Effectiveness of the technique can be limited by the length of plant roots; * Can be not so effective in case there is a mix of pollutants.
45
Types of phytoremediation?
``` Phytoextraction Phytodegredation Phytostabilization Phytovolatilization Phytostimulation Rhizofiltration ```
46
Methods to dispose plants in phytoremediation?
Incineration Pyrolysis Gasification Composting
47
What is bioaugmentation?
Bioaugmentation is a form of soil remediation through the microorganism cultures of the soil or groundwater
48
When is bioaugmentation usually used?
It is usually used to remediate soils that have undergone a previous bioremediation method that has proven to be unsuccessful.
49
Bioaugmentation optimization?
In the bioaugmentation process pre-grown microbes are added to the existing culture ensuring that the degradation becomes more optimal and efficient.
50
Advantages and dis of bioaugmentation?
Diat
51
To what substances bioaugmentation is suitable?
– Organic contaminants: diesel oil, gasoline, oil, creosote oil, PAHs and chlorinated hydrocarbons – Inorganic contaminants: not suitable
52
To what soil types bioaugmentation is suitable?
Can be used in sand, silt, till and organic soil areas (topsoil, peat). Not suitable for areas with very dense soil and clay
53
Limitations of bioaugmentation?
* Low soil and groundwater temperatures in Finland often slow down decomposition * Poor bioavailability of contaminants, such as binding to soil particles, can slow down disintegration activities * Added microbes can convert contaminants into a more harmful form or attack the original microorganisms * Contaminants may be present in concentrations that are toxic to microorganisms * Injection of nutrient solutions and recycling of groundwater may flush out contaminants to a larger area
54
Process of bioaugmentation?
Feeding of nutrients and other substances into the soil can take place by injection wells or by recirculating contaminated groundwater.
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