Composting & Organics Recycling Flashcards

What does 'source separation' mean in the context of a municipal organics collection program?

Answer: Residents and businesses separating organic materials from other waste at the point of generation

Source separation means that generators (households or businesses) separate organic materials from trash and recyclables before collection, producing cleaner feedstocks and higher-quality compost.

Which type of screening equipment is most commonly used in composting facilities to separate finished compost by particle size?

Answer: Trommel screen

Trommel screens use rotating cylindrical drums with perforated surfaces to sort compost by particle size, separating fine finished product from oversized material and contaminants.

What are the two primary outputs of anaerobic digestion of organic waste?

Answer: Biogas and digestate

Anaerobic digestion produces biogas (primarily methane used for energy generation) and digestate (a nutrient-rich residue used as a soil amendment or further processed into compost).

What is the primary function of adding wood chips or other bulking agents to a food waste compost pile?

Answer: To improve pile porosity and support adequate oxygen flow for aerobic decomposition

Bulking agents such as wood chips create air pockets within dense organic material, improving porosity and ensuring oxygen can reach microorganisms throughout the pile for efficient aerobic decomposition.

What is 'digestate' in the context of an anaerobic digestion facility?

Answer: The solid and liquid residue remaining after anaerobic digestion is complete

Digestate is the nutrient-rich solid and liquid material that remains after organic matter has been processed in an anaerobic digester; it can serve as a fertilizer, soil conditioner, or feedstock for further composting.

According to the EPA Food Recovery Hierarchy, which action holds the highest priority for managing surplus food and food waste?

Answer: Source reduction — preventing food waste from being generated in the first place

The EPA Food Recovery Hierarchy places source reduction at the top because preventing waste generation entirely avoids all associated resource consumption and environmental impacts.

What is a major operational challenge commonly encountered in residential curbside organics collection programs?

Answer: High contamination rates from non-organic items placed in the organics bin

Residential organics programs frequently struggle with contamination from plastic bags, non-compostable packaging, and other non-organic items placed in the organics bin, compromising compost quality and increasing processing costs.