CPWM CPWM Composting and Organic Waste Management Questions and Answers 1 — Questions and Answers
Question 1: What carbon-to-nitrogen (C:N) ratio is generally considered optimal for active composting?
- 10:1
- 25–30:1 (Correct answer)
- 60:1
- 5:1
Correct answer: 25–30:1
A C:N ratio of 25–30:1 provides the right balance of carbon for energy and nitrogen for microbial growth during composting.
Question 2: Which composting method uses earthworms to break down organic material?
- Windrow composting
- Aerated static pile
- Vermicomposting (Correct answer)
- In-vessel composting
Correct answer: Vermicomposting
Vermicomposting employs earthworms (typically red wigglers) to decompose organic matter into nutrient-rich castings.
Question 3: What is the primary purpose of turning a windrow compost pile?
- To add moisture
- To aerate the pile and redistribute heat (Correct answer)
- To compact the material
- To reduce the C:N ratio
Correct answer: To aerate the pile and redistribute heat
Turning a windrow introduces oxygen and redistributes heat so that all material reaches thermophilic temperatures needed to kill pathogens.
Question 4: Under the EPA's Part 503 biosolids rule, what minimum temperature must Class A compost reach to meet pathogen reduction standards?
- 45°C for 3 days
- 55°C for 15 days (Correct answer)
- 70°C for 30 minutes
- 80°C for 1 hour
Correct answer: 55°C for 15 days
EPA Part 503 requires windrow compost to be maintained at ≥55°C for at least 15 days (with five turnings) to achieve Class A pathogen reduction.
Question 5: Which gas produced during anaerobic decomposition of organic waste is a potent greenhouse gas?
- Carbon dioxide
- Methane (Correct answer)
- Nitrogen oxide
- Hydrogen sulfide
Correct answer: Methane
Methane (CH₄) generated during anaerobic decomposition has a global warming potential about 25 times greater than CO₂ over 100 years.
Question 6: What is 'food waste diversion' in the context of organic waste management?
- Shipping food scraps to another state
- Redirecting edible or compostable food from landfill to beneficial use (Correct answer)
- Separating food waste from recyclables at a MRF
- Burning food waste for energy
Correct answer: Redirecting edible or compostable food from landfill to beneficial use
Food waste diversion means redirecting organic food material away from landfill disposal toward uses such as composting, anaerobic digestion, or donation.
CPWM CPWM Composting and Organic Waste Management Questions and Answers 1
What carbon-to-nitrogen (C:N) ratio is generally considered optimal for active composting?