CRP Composting & Organics Recycling 2 — Questions and Answers
Question 1: What is vermicomposting?
- High-temperature composting using enclosed vessels
- The use of worms to decompose organic waste into nutrient-rich castings (Correct answer)
- Anaerobic digestion of food waste in sealed tanks
- Composting performed outdoors in wind-exposed rows
Correct answer: The use of worms to decompose organic waste into nutrient-rich castings
Vermicomposting uses worms (typically red wigglers, Eisenia fetida) to consume and process organic waste, producing nutrient-rich worm castings as the primary end product.
Question 2: What is the primary greenhouse gas concern associated with organic waste disposed in landfills?
- Carbon dioxide from aerobic surface decomposition
- Nitrous oxide from nitrogen-rich food waste
- Methane generated from anaerobic decomposition (Correct answer)
- Hydrogen sulfide from protein-containing materials
Correct answer: Methane generated from anaerobic decomposition
Organic waste in landfills decomposes anaerobically, generating methane, a potent greenhouse gas with approximately 28–36 times the global warming potential of CO₂ over a 100-year period.
Question 3: How does an 'aerated static pile' (ASP) composting system supply oxygen to the composting mass?
- A mechanical turner regularly mixes and aerates the pile
- Perforated pipes connected to blowers force or draw air through a stationary pile (Correct answer)
- Workers manually insert aeration probes into the pile daily
- A sealed tarp with vented holes allows passive air exchange
Correct answer: Perforated pipes connected to blowers force or draw air through a stationary pile
Aerated static pile composting supplies oxygen via perforated pipes connected to blowers that either force air into or draw air through the pile, eliminating the need for mechanical turning.
Question 4: Which of the following is a common contaminant found in residential curbside organics collection programs?
- Coffee grounds and paper filters
- Vegetable peels and fruit cores
- Plastic bags used to line collection containers (Correct answer)
- Yard trimmings with woody stems
Correct answer: Plastic bags used to line collection containers
Plastic bags—even those marketed as 'compostable'—are a major contaminant in residential organics streams because they frequently fail to break down in commercial facilities and must be removed.
Question 5: What is the primary purpose of the 'curing' phase at the conclusion of the active composting process?
- To raise temperature one final time for additional pathogen kill
- To allow continued stabilization and maturation of the compost product (Correct answer)
- To add nutrients and soil amendments to enhance product quality
- To reduce moisture content to a target level before screening
Correct answer: To allow continued stabilization and maturation of the compost product
The curing phase allows remaining unstable organic compounds to decompose further, reduces phytotoxic compounds, and ensures the compost is biologically stable and safe for plant application.
Question 6: What does the US Composting Council's Seal of Testing Assurance (STA) program provide to compost producers?
- Certification that facilities comply with all EPA permitting requirements
- Verification that compost products meet quality standards through independent laboratory testing (Correct answer)
- A federal government endorsement for commercial compost sales
- Liability insurance coverage for compost facility operators
Correct answer: Verification that compost products meet quality standards through independent laboratory testing
The STA program requires compost producers to have products tested by approved independent laboratories against minimum quality standards for stability, maturity, metals, pathogens, and other parameters.
Question 7: According to EPA estimates, approximately what percentage of the US municipal solid waste (MSW) stream consists of organic material that could be composted?
- 10–15%
- 20–25%
- 30–35% (Correct answer)
- 45–50%
Correct answer: 30–35%
EPA data shows that food waste (approximately 24%) and yard trimmings (approximately 12%) together constitute roughly 30–35% of the US MSW stream, representing significant composting potential.
