Which regulation number is associated with the definitions for sewage sludge and biosolids?

• A. 40 CFR 122
• B. 40 CFR 503
• C. 40 CFR 260
• D. 40 CFR 141

Answer: (B)

Defining what counts as biosolids and sewage sludge comes from the EPA’s biosolids regulation, 40 CFR 503. This rule provides the formal definitions and the overarching framework for how these materials may be used or disposed of, including requirements for land application and disposal. In this regulation, biosolids are the treated sewage sludge that meets pollutant and pathogen limits, while sewage sludge refers to the solids produced during wastewater treatment that may be processed to meet those standards. The other regulation numbers cover different topics: one governs permit requirements for discharges from facilities (NPDES), another handles hazardous waste management, and another sets drinking water standards. So the regulation number that includes the definitions for sewage sludge and biosolids is 40 CFR 503.