Chapter 4 - Risk Management Of Land Contamination

Question 1

Define what is meant by bioremediation

Answer 1

The use of microorganisms in the treatment of environmental pollution

Question 2

State 4 pollutants that can be treated using bioremediation

Answer 2

Oil spills
Heavy metals
Diesel oils
Chlorinated pesticides

Question 3

Describe the process of bioremediation

Answer 3

The use of microorganisms added to soils to consume and break down environmental pollution to clean a site

Question 4

What pollutant is treated using pseudomonas putida

Answer 4

Organic solvents

Question 5

What pollutant is treated using pseudomonas aeruginosa

Answer 5

Oil contamination

Question 6

What pollutant is treated using Dehalococcooides ethenogenes

Answer 6

Halogenated hydrocarbons

Question 7

Economic benefits of using bioremediation technology compared to traditional treatment methods

Answer 7

Traditional treatment is expensive due to high energy costs

Bioremediation does not require large energy inputs making it cheaper

For traditional treatment soil may need to be treated off site which costs more

Question 8

Environmental benefits of using bioremediation technology compared to traditional treatment methods

Answer 8

Bioremediation produces almost zero contaminants

Bioremediation using bacteria that occurs naturally in the soil so better for the ecosystem

Byproducts of bioremediation are non toxic so water and air pollution is reduced

Question 9

What are two benefits of associated with contaminated land treatment named bioremediation

Answer 9

Clean up time reduced significantly which can reduce costs

Less energy is required because the micro organisms work at atmospheric temperatures

Question 10

Name a method used to modify microorganisms to enhance their bioremediation process

Answer 10

Genetic engineering

Question 11

What is the role of genetic engineering in modifying microorganisms for bioremediation

Answer 11

Decontaminate a site more rapidly than unmodified microorganisms

Tolerate harsher conditions

Question 12

Explain how in situ bioreactors are used to treat contaminated soil

Answer 12

The bioreactors will be placed below ground,
Contaminants will then be pumped around the bioreactor
Where microorganisms in the bioreactors will break down the contaminants

Question 13

What is the process of phytoremdiation

Answer 13

It is the direct use of green plants and their associated microorganisms to stabilise or reduce contamination in soils, sludge sediments,surface water or ground

Question 14

What plant is used to remove copper contaminants

Answer 14

Alpine pennygrass

Question 15

What plant is used to remove cadmium

Answer 15

Alpine pennygrass

Question 16

What plant is used to remove arsenic

Answer 16

Alpine pennygrass

Question 17

Advantages of using alpine pennygrass in the decontamination of ground

Answer 17

It brings the cost of phytoremediation down

Any metal recovered from the use of alpine pennygrass can be sold for a high price

It can accumulate and tolerate high levels of toxic metal ions

The contaminants are absorbed into the plant so the plant can be harvested and disposed of without causing water contamination

Question 18

Disadvantages of using alpine pennygrass for the decontamination of ground

Answer 18

The phytoremediation process will be limited to the surface area and depth occupied by the roots

Plant can not absorb all contaminants and will eventually be killed by toxicity of the soil

Potential threat to the food chain by contaminated Alpine pennygrass

Question 19

Describe the process of phytoextraction

Answer 19

Plants uptake metals from contaminated soil and concentrate them in above ground plant tissue/biomass. This is then harvested for disposal or metal recovery

Question 20

What are the plant species for phytoextraction and what metal can they recover

Answer 20

White mustard - copper
Sunflower - gold

Question 21

What are the similarities between phytoremediation and phytoextraction

Answer 21

Both involve plants
Both involve uptake of metal into the plant tissue through the roots

Question 22

What are the differences between phytoremediation and phytoextraction

Answer 22

Phytoremediation involves the extraction of copper contaminant. Phytoextraction involves the removal of copper for commercial use

The plant for phytoremediation must be disposed of carefully. The metal containing plant used for phytoextraction is harvested and ashes to aid with metal extraction

Phytoremediation plant will contain more than one metal whereas phytoextraction plant is used on soil contain ore mine tailings meaning it will have large sums of target metal

Alpine pennygrass/ Indian mustard can be used for copper phytoremediation. White mustard can be used for copper phytoextraction

Question 23

Name and describe the process which uses plant species to extract metal from ore mine tailings

Answer 23

Phytoextraction

Phytoextraction makes use of a plants ability to hyper-accumulate a metal. The site should be tested to see what metals are present in the soil and then the appropriate plant should be grown on the contaminated site. When the plant has grown and absorbed all the metal through its roots it will be harvested and burned in a controlled environment and the metal will be extracted from the ash

Question 24

What is biogydrometallurgy

Answer 24

The use of bacteria to extract metals from low grade ore

Question 25

What is the main problem with traditional smelting process

Answer 25

It’s is very energy intensive and highly polluting

Question 26

What is the name of the bacteria used to extract copper lead zinc and uranium

Answer 26

Thiobacillus ferroxidans

Question 27

Describe how suitable site and identified and prepared for biorefining

Answer 27

Identified by using land close to mines or waterways. Located where soils are known to have metals in them, this is confirmed using analytical techniques.

Prepared by making the area appropriate for the microorganism that will be used, this is done by treating the area to make other metal contaminants that may interfere with the biorefining process or damage the microorganisms

Question 28

What are the advantages of biohydrometallurgy in relation to traditional metal extraction method

Answer 28

Bacteria can operate successfully in low ore concentration environments such as mine tailings that would not otherwise be economical

Simpler and cheaper to operate than traditional metal extraction methods

Much less environmental damage

Bacteria can be harvested and recycled for use elsewhere

Question 29

What are the disadvantages of biohydrometallurgy in relation to traditional metal extraction methods

Answer 29

Length process compared to traditional smelting

Can lead to production of toxic chemicals

If something goes wrong the process cannot be stopped as rainwater will continue the process

If ore concentrations are very high it is uneconomical and very slow compared to traditional methods