Abatement techniques

Question 1

List some common abatement techniques

8

Answer 1

Wet Scrubbing - Air
Filtration - Air
Cyclonic Separation - Air
Catalytic Oxidation - Air
Air Stripping - Water
Carbon adsorption - Water
Chemical oxidation - Water
Bioremediation

Question 2

Describe the process of wet scrubbing

Answer 2

Gas enters at the bottom

Packed with Adsorbent to increase the surface for mass transfer

Question 3

What are the advantages of wet scrubbing

Answer 3

Simple technology
effective at removing pollutants
Highly scalable

Question 4

What are the disadvantages of wet scrubbing

Answer 4

No destruction of contaminant, just moved from one waste stream to another
Limited by constraints of vapour liquid equilibrium

Question 5

What are the advantages of air filtration

Answer 5

Most effective at removing small particles

Can be recharged by back flushing

Question 6

What are the disadvantages of air filtration

Answer 6

Creates a waste stream

Can cause high pressure drop

Question 7

What are the advantages of cyclonic separation

Answer 7

Low cost and mechanically simple
Low pressure drop
Small space requirement (for volume)

Question 8

What are the disadvantages of cyclonic separation

Answer 8

Poor separation efficiency

Can only handle dry streams

Question 9

What are the advantages of catalytic oxidation

Answer 9

Efficient and proven strategy to destroy VOCs

Requires less support fuel than thermal combustion

Question 10

What are the disadvantages of catalytic oxidation

Answer 10

Expensive

Does not abate non-flammable pollutants

Question 11

What are the advantages of air stripping

Answer 11

99% of pollutants can be removed
Operates at ambient temperatures
Highly scalable
No need for contaminated water

Question 12

What are the disadvantages of air stripping

Answer 12

No destruction of contaminant
only effective for water containing VOC
Equipment can be fouled with algae, fungi and bacteria

Question 13

What are the two forms of Carbon adsorption

Answer 13

Granular carbon or monoliths

Question 14

What are the advantages of granular carbon

Answer 14

Removes dissolved organics and chlorines effectively
Long operating life
Easy to maintain

Question 15

What are the disadvantages of granular carbon

Answer 15

Can produce carbon fines snd suffer from blockages
Risk of combustion in bed
Risk of polymerisation

Question 16

What are the advantages of monoliths

Answer 16

Low pressure drop
Contaminants can be recovered for further processing
Pore structure can be tailored to be specific to certain compounds
Once installed monoliths do not require replacement

Question 17

What are the disadvantages of monoliths

Answer 17

limited to organic compounds
fragile
Adsorption of long chain compounds can cause monoliths

Question 18

Explain what happens in chemical oxidation

Answer 18

Uses chemicals called oxidants to destroy organic and inorganic materials and remove them from waste water
Oxidants can change harmful chemicals into harmless ones

Question 19

What are the advantages of chemical oxidation

Answer 19

It destroys pollution underground
Often used to clean up pollution that other methods cant
Cleans up at the source

Question 20

What are the disadvantages of chemical oxidation

Answer 20

Oxidants are corrosive
Some oxidants can explode
High initial costs

Question 21

What is Bioremediation

Answer 21

The use of naturally occurring or synthesised micro organisms to breakdown environmental pollution

Question 22

What are 7 bioremediation technologies

Answer 22

Land farming - Solid phase treatment system for contaminated soils
Composting - Aerobic, thermophillic processes in which contaminated material is mixed with a bulking agent
Bioventing - drawing oxygen through soil to stimulate microbial activity
Bioaugmentation - Addition of bacteria cultures to a contaminated system
Biostimulation - Stimulation of indegenous microbial populations in soils or ground water by using necessary nutrients
Intrinsic bioremediation - Unassisted bioremediation of contaminant
Phytoremediation - Use of living green plants for in situ risk reduction and or removal of contaminants from contaminated soil

Question 23

What is bioremediation used for

Answer 23

Breaking down oil and petrochemical oil spills

Question 24

What are the advantages of bioremediation

Answer 24

Cost effective 
No need for removal of material 
Low maintenance 
Can be used to supplement other treatment technologies 
No solid waste materials

Question 25

What are the disadvantages of bioremediation

Answer 25

Slow
Cannot remove heavy metals and other
Can lead to assimilation of pollutants
Performance of some organisms is unpredictable