Risk Management of Land Contamination

Question 1

What is bioremediation

Answer 1

The use of either naturally occurring or deliberately introduced microorganisms or other forms of life to consume and break down
environmental pollutants, in order to clean up a polluted site.

Question 2

How does bioremediation work

Answer 2

Bioremediation is merely the use of microbes to clean up contaminated soil and groundwater. Bioremediation stimulates the growth of
certain microbes that use contaminants as a source of food and energy.

Question 3

What are mercury toxicity symptoms

Answer 3

Concentration deficit & impaired motor
function.

Question 4

what are lead toxicity symptoms

Answer 4

Learning disability & mental retardation.

Question 5

what are Chromium toxicity symptoms

Answer 5

Damage to DNA & kidney damage.

Question 6

Why use bioremediation

Answer 6

– Bioremediation has the advantage of using natural processes to clean up sites. Because it may not require as much equipment, labour, or energy as some clean-up methods it can be cheaper. Another advantage is that contaminated soil and groundwater are treated onsite without having to dig, pump and transport them elsewhere for treatment.

Question 7

how does the microbes break down contaminants and what are the bi products.

Answer 7

Some types of microbes eat and digest contaminant, usually changing them
into small amounts of water and harmless gases like carbon dioxide and ethene. If soil does not have enough of the right microbes, they can be added in a process called bioaugmentation. For bioremediation to be effective, the right temperature, nutrients, and food also must be present. Proper conditions allow the right microbes to grow and multiply – and eat more contaminants. If conditions are not correct microbes grow to quickly or die and so contaminants are not cleaned up.

Question 8

what is Pseudomonas putida and what does it treat

Answer 8

It is a rod shaped soil bacterium. It demonstrates a very diverse metabolism,
including the ability to degrade organic solvents such as toluene.
Pseudomonas Putida breaks down organic solvents.

Question 9

What is Pseudomonas aeruginosa and what does it treat

Answer 9

This is a bacterium that is dangerous as it can cause disease in animals including humans. In animals the bacteria’s versatility enables it to infect damaged tissues or those with reduced immunity.
Pseudomonas aeruginosa breaks down oil

Question 10

what is Dehalococcoides ethenogenes and what does it treat

Answer 10

This bacteria has a very thick cell wall and ia single layer membrane. This bacteria can degrade halogenated hydrocarbons. It is the only known bacteria that can degrade PCE (Tetrachloroethylene) to ethene.
Dehalococcoides ethenogenes breaks down treat halogenated hydrocarbons

Question 11

Economic benefits of bioremediation technology compared to traditional treatment methods

Answer 11

1 – Costs are reduced drastically both in time, resources money and fighting
negative press.
2 – Clean up times are a fraction of alternative methods, going from months or years to days and weeks.

Question 12

Environmental benefits of bioremediation technology compared to traditional treatment methods

Answer 12

1 – Contaminants can be reduced to near zero.
2 – Contaminants are not recycled into some other form and put into the
atmosphere (as can happen with traditional methods).
3 – Clean up can be performed In Situ, thus not transferring the pollutants to
other areas (as can happen in traditional methods).
4 – Ex Situ methods can be untiled in certain sites to enhance the process of
the process and hence reduce the maximum amount of contaminants.
5 – Uses natural processes to remove the contaminants.

Question 13

What can bioengineering do

Answer 13

Genetic engineering has the potential to improve or redesign microorganisms, where the bacteria have a superior ability to absorb metals
and have superior resistance to environmental conditions.

Question 14

What are the risks concerned with bioengineering

Answer 14

• Genetically engineered micro-organisms may wipe out existing bacteria.
• They may affect the existing soil ecology with unknown consequences
• They may not behave the same way in the field as they do under
  laboratory conditions.

Question 15

what is the role of genetic engineering in modifying microorganisms for bioremediation.

Answer 15

Micro-organisms can be genetically engineered to;
* Decontaminate a site more rapidly than unmodified micro-organisms.
* Tolerate harsher conditions.
* Remove toxic materials (such as heavy metals)

Question 16

What does a bioreactor do

Answer 16

Bioreactor is a generic term used for a system that degrades contaminants
in groundwater and soil with micro-organisms. These reactors come in 2 forms;
 Open systems – such as constructed wetlands (no container)
 Enclosed chamber.

Question 17

What bioreactor do we use to treat contaminated soil

Answer 17

Enclosed chamber

Question 18

How does a bio reactor break down contaminated soil

Answer 18

In using this Bioreactor, the contaminated soil is excavated from the ground
and put into an enclosed chamber on the ground. In this vessel the soil will be
inoculated with the required bacteria, where;
 The temperature;
 pH;
 Aeration (the process by which air is circulated through, mixed with or
dissolved in a liquid or substance).
 Stirring conditions
Can all be controlled to give optimum rate of bacterial activity.

Question 19

what is phytoremediation

Answer 19

The direct use of green plants and their associated microorganisms to stabilise or reduce contamination in soils, sludge’s,
sediments, surface water or ground.

Question 20

How does a plant extract contaminants from ground

Answer 20

Transipation, with the same principle of up taking water lants also up take nutrients and minerals through there roots. These harmful contaminants in the ground.

Question 21

What plants can survive and absorb the contaminants

Answer 21

hyperaccumulators

Question 22

What is all the contaminants in the ground that plants can absorb

Answer 22

Copper - Alpine pennygrass / Indian Mustard
Cadium - Alpine pennygrass
Strontium - chinese cabbage
Rubidium -
Arsenic - Alpine pennygrass
Antimon -

Question 23

Advantages of using alphine pennygrass in phytoremediation

Answer 23

• The cost of phytoremediation is lower than that of traditional processes
  both on and off site.
• This can prove to be cost effective as the initial cost of Alpine
  Pennygrass is low whilst the potential for recovery of sale of contaminant
  metals is high.
• The plants can accumulate and tolerate high levels of toxic metal ions.

Question 24

disadvantages of using alphine pennygrass in phytoremediation

Answer 24

• Phytoremediation is limited to the surface area and depth occupied by
  the roots.
• The use of Alpine Pennygrass has low environmental impact although
  plants cannot absorb all contaminants and will eventually be killed by
  toxicity of the soil.
• There is a potential threat to the food chain by contaminated Alpine
  Pennygrass.

Question 25

what are the two plant species used in Phytoextraction and what metal do they extract

Answer 25

1- White mustard to extract copper
2- Sunflowers to extract gold

Question 26

How does phytoextraction work

Answer 26

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

Question 27

Define Biohydrometallurgy

Answer 27

Using bacteria to extract metal from low grade ores

Question 28

What is the issue with traditional metal smelting

Answer 28

1- highly pollutant causing CO2 and acid rain to be formed in the roasting and reducing stages
2 High energy intensive process due to metals having to be burned at 300 degrees

Question 29

what is Thiobacillus
ferrooxidans and what can it do

Answer 29

Thiobacillus ferrooxidans a bacteria capable of refining copper, zinc, lead and uranium.

Question 30

advantages of biorefining in relation to traditional metal extraction methods.

Answer 30

• 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
  – less necessity for expensive machinery / processes
• Much less environmental damage – bacteria grow naturally in mines and
  landscape is left untouched
• Bacteria can be harvested and recycled for use elsewhere

Question 31

disadvantages of biorefining in relation to traditional metal extraction methods.

Answer 31

• Bacterial ‘leaching’ process can be very slow compared to traditional
  smelting. This can cause cash flow problems
• In certain circumstances the bacterial ‘leaching’ process can lead to the
  production of toxic chemicals. Therefore the process need to be
  carefully planned
• If something goes wrong it cannot be stopped as the bioleaching process
  will continue with rainwater and natural bacterial action
• If ore concentrations are reasonably high it is uneconomical and very
  slow compared to traditional methods

Question 32

Describe how suitable sites are identified and prepared for biorefining in 6 steps

Answer 32

 Site is giving a suitable base with appropriate slope to allow desired fluid flow;
 Site may need impervious membrane or lining depending on the risk of
percolation to groundwater;
 Tailings material is excavated, possible broken up, and stacked in heaps, or lifts;
 Collection channel constructed to allow leachate collection;
 Associated pumping, reactor vessels and pipe work needs built to allow
circulation of leaching fluids and collection of leachate;
 The final electrowinning(electrolysis) process may also be carried out on site, so
these facilities would be built in advance