Solids generated in the treatment of sanitary wastewater are known as biosolids. Solids generated in the treatment of wastewater without a sanitary component are known as non-hazardous waste residuals. These solid products may be permitted for land application as a fertilizer and for other end uses.
These uses are governed by the Guidance and Regulations Governing the Land Treatment of Wastes (7 DE Admin. Code 7103).
Sewage sludges that are solid, semisolid, or liquid residues generated during primary, secondary, or advanced treatment of sanitary sewage. Treated sewage sludge that has undergone an approved process to reduce pathogens, reduce the attractiveness of the material to disease vectors (flies, birds, rodents), and that meets limits for certain pollutants are known as biosolids. Biosolids are typically used as a fertilizer, as soil amendment, made into compost, or are disposed of in a landfill.
EPA regulations (40 CFR Part 503) establish the minimum national standards for the use and disposal of biosolids. EPA’s standards are incorporated into Delaware’s regulations. The state’s rules include additional requirements and safeguards that are more stringent than EPA standards.
DNREC publishes data showing locations where the use of biosolids is permitted or monitored by the state.
Non-hazardous residual materials from wastewater treatment that do not contain a sanitary waste component can be permitted for agricultural use under Delaware’s Guidance and Regulations Governing the Land Treatment of Wastes (7 DE Admin. Code 7103).
Wastes must meet regulatory limits for certain pollutants and must be suitable for use as a fertilizer substitute or as a soil amendment.
Biosolids Application (relative to Part III of the regulations)
Waste and Residuals Application (relative to Part V of the regulations)