Waste Treatment Technologies and Disposal Methods Flashcards

Plasma arc gasification differs from conventional gasification primarily in that it:

Answer: Uses electrically generated plasma reaching temperatures above 5,000°C to destroy virtually all waste constituents

Plasma arc gasification uses an electrically generated plasma torch at extremely high temperatures (>5,000°C) to fully decompose waste into syngas and vitrified slag.

What is the primary advantage of anaerobic digestion over aerobic composting for organic waste treatment?

Answer: Production of biogas (methane-rich) that can be used for energy recovery

Anaerobic digestion generates biogas (approximately 60% methane) as a recoverable energy product, unlike aerobic composting which releases heat to the atmosphere.

Which post-closure care requirement for Subtitle D landfills specifies the minimum duration of monitoring and maintenance obligations?

Answer: 30 years after closure

EPA Subtitle D regulations require a minimum 30-year post-closure care period, though regulators may adjust this period based on site-specific conditions.

Selective catalytic reduction (SCR) in waste-to-energy facilities is used to control emissions of:

Answer: Nitrogen oxides (NOₓ)

SCR systems inject ammonia or urea into flue gas over a catalyst bed to convert nitrogen oxides to harmless nitrogen gas and water.

Which waste treatment technology is classified as 'thermal desorption' and how does it work?

Answer: Heating contaminated soil or waste to volatilize contaminants for separate capture and treatment without destroying the soil matrix

Thermal desorption heats contaminated media to volatilize organic contaminants which are then captured and treated separately, leaving the soil matrix largely intact.

Under RCRA, what constitutes a 'contained-in' determination for contaminated environmental media such as soil and groundwater?

Answer: A regulatory agency determination that contaminated media no longer contains a listed hazardous waste and is exempt from hazardous waste regulations

A 'contained-in' determination is a state or EPA finding that contaminated soil or groundwater no longer contains listed hazardous waste, allowing management under non-hazardous waste rules.

When evaluating disposal alternatives for low-level radioactive waste (LLRW) mixed with hazardous waste (mixed waste), the applicable regulatory framework requires compliance with:

Answer: Both RCRA hazardous waste requirements and the Atomic Energy Act/NRC regulations simultaneously

Mixed waste containing both hazardous waste characteristics and radioactivity is subject to dual regulation under both RCRA and the Atomic Energy Act/NRC, requiring compliance with both simultaneously.