Using Resources

Question 1

What are the four main stages of a Life Cycle Assessment (LCA)?

Answer 1

The four main stages of an LCA are extracting and processing raw materials, manufacturing and packaging, using the product, and disposing of the product.

Question 2

How does extracting raw materials impact the environment?

Answer 2

Extracting raw materials often directly damages the local environment through activities like deforestation and mining.

Question 3

What are the indirect environmental damages associated with processing raw materials?

Answer 3

Processing raw materials can require significant energy and release pollutants, such as during the extraction of metals or the fractional distillation of crude oil.

Question 4

What are the three main problems associated with manufacturing and packaging?

Answer 4

The three main problems are energy use, the release of pollution (e.g., carbon monoxide, hydrogen chloride), and the production of waste products.

Question 5

What are the environmental consequences of disposing products in landfill?

Answer 5

Disposing products in landfill takes up space that could be used for nature and may lead to chemical seepage into surrounding ecosystems.

Question 5

What factors should be considered when evaluating the impact of using a product?

Answer 5

The evaluation should consider the damage caused during the product’s lifetime and the duration of its use.

Question 6

What are the environmental effects of burning waste products?

Answer 6

Burning waste products can release pollutants into the atmosphere

Question 7

What is the raw material for plastic bags, and what is its environmental impact?

Answer 7

Plastic bags are made from crude oil, a finite resource, which requires separation using energy-intensive fractional distillation.

Question 7

What are the disposal issues related to plastic bags?

Answer 7

Plastic bags are non-biodegradable, taking up space in landfills and posing risks to wildlife if they escape into the environment.

Question 8

How are paper bags produced, and what are the environmental implications?

Answer 8

Paper bags are made from wood, which reduces habitat for wildlife, and their production can require significant energy and generate waste.

Question 9

How does the usability of plastic bags compare to paper bags?

Answer 9

Plastic bags can be reused multiple times, while paper bags are typically designed for single use.

Question 10

How do paper bags compare to plastic bags in terms of disposal?

Answer 10

Paper bags are biodegradable and non-toxic, making them a more environmentally friendly disposal option than plastic bags.

Question 11

What challenges exist in quantifying the environmental impact of products in Life Cycle Assessments?

Answer 11

Quantifying the environmental impact is challenging due to the complexity of production processes and the difficulty in comparing different types of pollutants.

Question 12

What is potable water?

Answer 12

Potable water is water that is safe to drink but may contain dissolved substances.

Question 13

What are the three criteria for water to be considered potable?

Answer 13

Potable water must have low levels of dissolved substances, a pH between 6.5 and 8.5, and no microorganisms.

Question 14

What is the difference between surface water and groundwater?

Answer 14

Surface water is exposed at the surface (like lakes and rivers), while groundwater is found underground (like aquifers).

Question 15

What are the steps involved in treating fresh water to make it potable?

Answer 15

The treatment involves filtering out large particles, filtering smaller solids using sand and gravel, and sterilizing to kill harmful microbes.

Question 16

What methods can be used for sterilizing water?

Answer 16

Water can be sterilized by bubbling chlorine gas, exposing it to ozone, or using ultraviolet light.

Question 17

What are the two main techniques of desalination?

Answer 17

The two common techniques of desalination are distillation and reverse osmosis.

Question 18

What is desalination?

Answer 18

Desalination is the process of extracting potable water from seawater.

Question 19

How does the distillation process work in desalination?

Answer 19

Distillation involves boiling salty water and collecting the water vapor to obtain pure distilled water.

Question 20

What is reverse osmosis in desalination?

Answer 20

Reverse osmosis involves passing salty water through a membrane that allows only water molecules to pass, trapping ions and larger molecules.

Question 20

Why is desalination considered expensive and impractical for large quantities of water?

Answer 20

Desalination techniques require a lot of energy, making them costly and impractical for large-scale water production.

Question 21

What is the purpose of biological breakdown in sewage treatment?

Answer 21

Biological breakdown uses microorganisms to break down organic matter in wastewater.

Question 21

How does treating wastewater compare to desalinating saltwater?

Answer 21

Treating wastewater requires more effort than treating fresh water but is easier than desalinating salt water.

Question 22

What conditions are required for anaerobic digestion?

Answer 22

Anaerobic digestion occurs in the absence of oxygen, as maintained in a sealed tank for sludge.

Question 23

What is industrial wastewater?

Answer 23

Industrial wastewater comes from factories that make and use chemicals.

Question 24

What are the end products of aerobic digestion?

Answer 24

The end product of aerobic digestion is treated water that is safe for release into the environment.

Question 25

What is domestic wastewater?

Answer 25

Domestic wastewater refers to household waste, including water from showers, sinks, and toilets.

Question 26

Define sludge in wastewater treatment.

Answer 26

Sludge is the solids that precipitate out of a sewage mixture and accumulate at the bottom of a sedimentation tank.

Question 27

What is agricultural wastewater?

Answer 27

Agricultural wastewater is primarily nutrient runoff from fields and animal waste from farms.

Question 28

What conditions are required for aerobic digestion?

Answer 28

Aerobic digestion requires the presence of oxygen, typically provided by pumping air into the effluent tank.

Question 29

What are the three main sources of wastewater?

Answer 29

The three main sources of wastewater are domestic, agricultural, and industrial.

Question 30

What occurs during the sedimentation step of sewage treatment?

Answer 30

In sedimentation, sewage sits in a tank allowing heavier solids to sink and form sludge, while the lighter effluent remains on top.

Question 31

What additional treatments may be required for wastewater containing toxic substances?

Answer 31

Additional treatments may include adding chemicals to precipitate out metals and using ultraviolet radiation to break them down.

Question 32

What is the first step in the sewage treatment process?

Answer 32

The first step is screening, which removes large objects like twigs and plastic bottles from the sewage.

Question 33

What are the end products of anaerobic digestion?

Answer 33

Anaerobic digestion produces methane as an energy source and digested waste that can be used as fertilizer.

Question 34

Why do some countries rely on treating wastewater for drinking supplies?

Answer 34

Countries with limited water supply, such as Singapore, rely on treating wastewater to augment their drinking water sources.

Question 35

Define effluent in wastewater treatment.

Answer 35

Effluent is the liquid that emerges as output from a sewage treatment process after sedimentation.