Which of the following is NOT a common method of sludge disposal?

• A. Class A: application by public in parks, gardens, and golf courses
• B. Class B: land applied on agricultural lands (most common) and/or landfill disposal
• C. Class B: incineration at high temperature
• D. Class A: export to overseas sites

Answer: (D)

Disposal options for biosolids depend on how much treatment they’ve received, categorized as Class A or Class B. Class A biosolids are treated to meet strict pathogen-reduction standards and are commonly used on public sites such as parks, gardens, and golf courses because they’re considered safe for unrestricted use. Class B biosolids have higher pathogen levels and are typically land-applied on agricultural lands, with that land-application being the most widespread disposal path, or disposed of in landfills; incineration at high temperature is also a sanctioned disposal route, though it’s less common because of cost and energy requirements. Exporting sludge to overseas sites is not a common method due to regulatory hurdles, transport costs, and the need for compatible treatment and acceptance in another country. So the overseas export option doesn’t fit with typical domestic disposal or reuse practices.