CPWM CPWM Composting and Organic Waste Management Questions and Answers

Question 1

What carbon-to-nitrogen (C:N) ratio is generally considered optimal for active composting?

Accepted Answer

25–30:1

Answer

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?

Accepted Answer

Vermicomposting

Answer

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?

Accepted Answer

To aerate the pile and redistribute heat

Answer

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?

Accepted Answer

55°C for 15 days

Answer

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?

Accepted Answer

Methane

Answer

Methane (CH₄) generated during anaerobic decomposition has a global warming potential about 25 times greater than CO₂ over 100 years.

(CPWM) Certified Professional in Waste Management Practice Test