Surface Water Discharges Section
Land Treatment of Waste (Biosolids and Residuals)

Biosolids are defined as solid, semisolid, or liquid residues generated during primary, secondary, or advanced treatment of domestic sanitary sewage through one or more controlled processes that reduce pathogens and attractiveness to vectors (flies, birds, rodents).

These processes include, among others, anaerobic digestion, aerobic digestion, and lime stabilization. The term "Biosolids" is related to the definition of sewage sludge found in Part 31, Water Resources Protection of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended; however biosolids are only that portion of sewage sludge that has undergone adequate treatment to permit its application to land.

Regulations: 

• Guidance and Regulations Governing the Land Treatment of Wastes (regulation in full)
        Part III, specific to biosolids starts on page 86, Section 100.0
        Part V, specific to waste starts on page 142, Section 161.0  

Applications:

• Biosolids Application - relative to Part III, starts on page 86, Section 100.0 of the regulations
• Waste and Residuals Application - relative to Part V, starts on page 142, Section 161.0 of the regulations

Related links: 

• EPA Guide to Field Storage of Biosolids and Other Organic By-Products Used in Agriculture and for Soil Resource Management 
• EPA Biosolids Frequently Asked Questions
• A Plain English Guide to the EPA Part 503 Biosolids Rule
• National Biosolids Partnership
• EPA Composting Guide
• EPA Process Design Manual: Sludge Treatment and Disposal (Chapter 12)

For more information about Land Treatment of Waste, please call Brian Churchill, 302-739-9946, or via email:  brian.churchill@state.de.us