Risk Management of Land Contamination

Question 1

What is bioremediation?

Answer 1

The use of microorganisms in the treatment of environmental pollution.

Question 2

What contaminants can be treated?

Answer 2

1. Waste Oils and Spills
2. Heavy Metals
3. Polychlorinated Biphenyls (PCBs)
4. Chlorinated Pesticides
5. Diesel Oil

Question 3

What microorganisms can be used

Answer 3

1. Pseudomonas putida
2. Pseudomonas aeruginosa
3. Dehalococcoides ethenogenes

(need to know how to spell each for the exam)

Question 4

What contaminants can Pseudomonas putida treat?

Answer 4

Organic Solvents

Question 5

What contaminants can Pseudomonas aeruginosa be used to treat?

Answer 5

Aromatic hydrocarbons

Question 6

What contaminants can Dehalococcoides ethenogenes be used to treat?

Answer 6

Used to degrade PCE to ethene
Also used to treat halogenated hydrocarbons

Question 7

What are the economic benefits of bioremediation?

Answer 7

1. Clean up time is significantly reduced
2. Contaminants reduced to effectively zero
3. Contaminants are not being recycled into another form or into the atmosphere
4. The clean up is done on the site itself. Without disturbing the surrounding environment.
5. Process requires less labour hours and costs

Question 8

Why are genetically modified microorganisms used in bioremediation?

Answer 8

There are instances that naturally occurring organisms cannot be used.

Question 9

How might bacterial genetic modification be used?

Answer 9

1. To remove a range of contaminants from a site
2. Survive in unfavourable conditions

Question 10

What are the ethical concerns surrounding Genetically Modified Microorganisms?

Answer 10

1. GMOs introduced to the environmental may have a negative or dangerous impact on native organisms
2. May mutate themselves into potentially dangerous organisms by gene transfer

Question 11

What is in-situ bioremediation?

Answer 11

Soil is treated on site where it sits

Question 13

What is Ex-Situ bioremediation?

Answer 13

Soil is taken off site to be treated then is returned to original site

Question 14

Is in-situ or ex-situ bioremediation more favourable?

Answer 14

In-Situ Bioremediation

Question 15

Why is in-situ bioremediation more favourable?

Answer 15

1. No expensive excavation or transport of vast quantities of soil
2. The excavation equipment releases polluting emissions

Question 16

What is bioventing?

Answer 16

Pumping air into the saturated zone in the soil where contaminants are more concentrated.

Question 17

How does bio-venting aid the process of bioremediation?

Answer 17

• Air assists aerobic respiration of the bacteria
• Aeration reduces level of waterlogged soil and increases the temperature of the soil. This increases the rate of respiration of the microorganisms

Question 18

What is land farming?

Answer 18

Uses liners on the ground. Contaminated soil is spread in order to control leaching of pollutants.
The soil is periodically tilled to aerate the waste

Question 19

What the conditions for bioremediation when land farming?
How are they maintained?

Answer 19

1. Moisture content (by irrigation or spraying)
2. natural aeration (tilling)
3. pH (buffered to neutral pH by adding limestone)
4. Nutrient content (Soil bulking agents added)

Question 20

Explain precisely how land farming works.

Answer 20

• Soil is treated in 18 inch piles
• When desired level of treatment is reached, the pile is removed
• Remove the top of the pile and add new soil (to inoculate new soil)

Question 21

What is a bioreactor system in bioremediation?

Answer 21

• Contaminated soil is moved into bioreactor vessel.
• The soil is inoculated with bacteria to maximise activity
• pH, temperature and aeration are controlled.

Question 22

What are the benefits of a bioreactor system in bioremediation?

Answer 22

The vessel is on the site of contaminated soil so transport costs are avoided.
There are excavation costs from digging up soil and tipping back.

Question 23

How is composting used in bioremediation?

Answer 23

Contaminated are metabolised and transformed into soil humus by microorganisms in a mature compost.

Question 24

What contaminants can be treated by composting?

Answer 24

• Hydrocarbons
• Wood chemicals
• Heavy metals
• Pesticides
• Petroleum
• Explosives

Question 25

What is a tailored compost in bioremediation?

Answer 25

compost that is specific to wastes.

Question 26

What is bioaugmentation?

Answer 26

Pro-biotic bacteria are isolated and mass produced to specific contaminations These microbes are added to contaminated areas to break down the contaminants. **(colony farming units)** These bacteria far exceed naturally occurring bacteria.

Question 27

What is biostimulation?

Answer 27

Bioremediation that has been enhanced by nutrients to increase population size of bacteria

Question 28

What it photoremediation?

Answer 28

The use of plants in the treatment of environmental pollution of metals.

Question 29

What metals can be extracted using phytoremediation?

Answer 29

Lead, Gold, Uranium, Cadmium, Zinc, Copper

Question 30

What plants are typically used in phytoremediation?

Answer 30

Indian Mustard Alpine Pennygrass

Question 31

What contaminants are removed by what plant?

Answer 31

Indian Mustard = lead, gold and uranium Alpine Pennygrass = cadmium, zinc and copper

Question 32

Describe the process of Alpine Pennygrass decontaminating a site.

Answer 32

1) Soil is tested and the contaminate is identified. The correct plant will be chosen for the contamination. 2) Plant extracts the contaminant through their roots and retain the metal in their tissues (roots/stems/leaves) 3. Once plant has grown and absorbed the metal pollutants they are harvested and carefully disposed of.

Question 33

What are the advantages of phytoremediation?

Answer 33

1. Ecologically friendly - using nature to cleanse nature. 2. Solar energy is used - less energy intensive than traditional decomposition methods 3. Positive public perception 4. Easy to implement

Question 34

What are the disadvantages of phytoremediation?

Answer 34

1. The depth of treatment is limited to the length of the roots 2. May be seasonal 3. Takes a longer time than traditional methods 4. It can transfer volatile pollutants across media (soil → air) 5. Ineffective for strongly absorbed or weakly absorbed pollutants. 6. Pollutants could bio-accumulate in animals / transfer to water if not narvested when grown.

Question 35

What is phytoextraction?

Answer 35

Using plants for the extraction of metals from contaminated soil for commercial use

Question 36

Essentially what is phytoextraction?

Answer 36

Using plant’s hyper-accumulation ability to ‘mine’ the metal

Question 37

Describe the process of phytoextraction.

Answer 37

1. Plant is grown on contaminated soil 2. Plant is harvested 3. Plant is dried, burnt and ash is collected 4. Metal is extracted from ash to produce a high grade commercially viable material.

Question 38

How can you increase the rate of extraction?

Answer 38

Adding **chelating agents** to make metals more **soluble** • This is dangerous as metal is more likely to enter ground water • But land farming techniques used to move solid to an impermeable area **Ploughing** to increase aeration before sowing improves plant grown rate

Question 39

What planet can be used in phytoextraction?

Answer 39

White mustard → copper Sunflower → gold

Question 40

What are the similarities between phytoremediation and phytoextraction?

Answer 40

• Both involve plants • Both involve uptake of a metal into a plant through root systems

Question 41

What are the differences between phytoremediation and phytoextraction?

Answer 41

Phytoremediation: • removes the metal • plant must be disposed of • plant is likely to contain a range of metals •alpine pennygrass and indian mustard are used Phytoextraction: • extracts the metal for commercial use • harvested and ashed • plant is more likely to only contain target metal • white mustard and sun slower are used

Question 42

What is biohydrometallurgy?

Answer 42

Using bacteria to extract a metal from low grade ore in sufficient amounts for it to be economically viable

Question 43

Why is traditional smelting bad for the environment?

Answer 43

1. Energy Intensive = requires high temperatures and significant fuel consumption 2. High Polluting = releases vast quantities of CO2 and CO into the atmosphere

Question 44

What bacteria is used in biohydrometallurgy?

Answer 44

*Thiobacillus ferrooxidans** (need to know how to spell!!)

Question 45

What metals can be refined by *Thiobacillus ferrooxidans*?

Answer 45

Copper Zinc Lead Uranium

Question 46

How is a suitable site identified for biohydrometallurgy?

Answer 46

1. Located close to mines or waterways 2. Located where soils are known to have high metal concentrations

Question 47

How can high metal concentrations in a site be identified?

Answer 47

Analytical techniques used to confirm this

Question 48

Describe the preparation of a site for biohydrometallurgy?

Answer 48

1. Conditions of soil need to be appropriate for microorganisms 2. Areas must be treated so other contaminants cannot interfere with the process or damage the bacteria