CAP Waste Management & Recycling 2 — Questions and Answers
Question 1: Which greenhouse gas is primarily produced during the anaerobic decomposition of organic waste in landfills?
- Carbon dioxide
- Methane (Correct answer)
- Nitrous oxide
- Hydrofluorocarbons
Correct answer: Methane
Anaerobic decomposition of organic matter in landfills produces methane (CH4), a potent GHG with a global warming potential 25–28 times that of CO2 over 100 years.
Question 2: Under the GHG Protocol, waste disposal emissions are typically assigned to which scope for the waste-generating organization?
- Scope 1
- Scope 2
- Scope 3 (Correct answer)
- Scope 4
Correct answer: Scope 3
Emissions from waste sent to third-party disposal facilities are indirect value chain emissions classified under Scope 3, Category 5 (Waste Generated in Operations).
Question 3: What is the primary environmental advantage of waste-to-energy (WtE) incineration over landfilling organic waste?
- It produces no CO2 emissions
- It eliminates the need for sorting
- It avoids methane generation from landfill decomposition (Correct answer)
- It recovers 100% of material value
Correct answer: It avoids methane generation from landfill decomposition
WtE incineration combusts waste at high temperatures, preventing the slow anaerobic decomposition that generates methane in landfills.
Question 4: The concept of 'circular economy' in waste management prioritizes which hierarchy of actions?
- Recycle → Reuse → Reduce → Recover
- Reduce → Reuse → Recycle → Recover → Dispose (Correct answer)
- Dispose → Recover → Recycle → Reduce
- Reuse → Reduce → Recover → Recycle → Dispose
Correct answer: Reduce → Reuse → Recycle → Recover → Dispose
The waste hierarchy places reduction at the top (most preferred), followed by reuse, recycling, recovery, and disposal as the least preferred option.
Question 5: When calculating Scope 3 Category 5 emissions, which emission factor source is most commonly recommended by the GHG Protocol for US companies?
- IPCC AR6 default factors
- EPA's Waste Reduction Model (WARM) (Correct answer)
- ISO 14064-1 country tables
- IEA electricity factors
Correct answer: EPA's Waste Reduction Model (WARM)
The EPA's WARM (Waste Reduction Model) provides material-specific emission factors for different waste management pathways commonly used by US organizations.
Question 6: Which metric best quantifies the carbon benefit of diverting waste from landfill to composting?
- Total waste weight diverted (tonnes)
- Avoided methane emissions minus process CO2 (tCO2e) (Correct answer)
- Compost nitrogen content (kg N)
- Landfill gate fee savings (USD)
Correct answer: Avoided methane emissions minus process CO2 (tCO2e)
The net carbon benefit of composting is measured as avoided methane emissions from landfill minus the CO2 emitted during the aerobic composting process, expressed in tCO2e.
Question 7: E-waste (electronic waste) is particularly significant in carbon accounting because it contains materials that, if improperly disposed of, release which type of potent GHGs?
- Perfluorocarbons and sulfur hexafluoride
- Hydrofluorocarbons from refrigerants and insulating foams (Correct answer)
- Biogenic CO2 from organic components
- Nitrous oxide from circuit board solvents
Correct answer: Hydrofluorocarbons from refrigerants and insulating foams
Electronic waste often contains refrigerants and foams with HFCs, which have extremely high global warming potentials (hundreds to thousands times CO2) if released during disposal.
CAP Waste Management & Recycling 2
Which greenhouse gas is primarily produced during the anaerobic decomposition of organic waste in landfills?