Biosolids, sometimes referred to as sewage sludge, are the solid or semi-solid organic materials resulting from the treatment of wastewater carried through sewer lines from homes and businesses. Following treatment, the liquid effluent is typically discharged to a nearby receiving water (e.g., a stream or river), while the biosolids are removed from the treatment plant for beneficial use or disposal.
Recycling Biosolids
- Beneficial Use. Biosolids are nutrient-rich organic materials that can be recycled and utilized as a soil amendment here in New York State when properly treated and processed. Biosolids treatment and quality standards have been developed to promote the safe use of this material. Public health and the environment are protected by controlling pollutant limits and reducing the pathogenic content of the material that is beneficially used.
- Climate Impacts. Recycling biosolids keeps these organic materials out of landfills where they would create methane, a potent greenhouse gas, and contribute to climate change and potential odor nuisances at landfills.
Biosolids Recycling Regulations
The primary New York State regulations governing the beneficial use of biosolids are found in 6 NYCRR Part 361, Materials Recovery Facilities, in the following Subparts:
- 361-2 Land Application and Associated Storage Facilities
- 361-3 Composting and Other Organics Recycling Facilities
Prior to construction and operation, facilities recycling biosolids must apply for a Part 361 permit. Once operating, facilities are required to report annually to the department.
The primary federal regulations, implemented by the Environmental Protection Agency (link leaves DEC's website), governing the management practices and final use of biosolids are found in 40 CFR Part 503, Standards for the Use or Disposal of Sewage Sludge.
Ways to beneficially reuse biosolids
- Direct land application - The placement of biosolids on or in to the soil to benefit the crop grown and the soil present, and in some cases for land reclamation.
- Composting - The aerobic decomposition of biosolids using controlled temperature, moisture, and oxygen levels to achieve a humus-like material for landscaping or enhancing soil.
- Heat drying or pelletization - A treatment process in which almost all water is removed (typically to over 90% solids content) from the biosolids by exposure to a heat source. The product is typically used directly as a fertilizer or blended with another material.
- Chemical stabilization - A process in which chemicals are mixed with biosolids, which react, generate heat, and increase the pH of the material. The resultant product is often used as a lime substitute in agriculture.
Other biosolids management methods
- Landfilling - The disposal of biosolids at municipal waste landfills as well as monofills (sludge-only landfills). Engineered landfills are lined, have groundwater monitoring capabilities, and comply with other regulatory design and operational criteria.
- Incineration - The firing of biosolids at high temperatures in an enclosed device. The resultant ash must be properly disposed of.
- Long term storage - Storage in containers, tanks, lagoons, and treatment beds are common at smaller treatment plants.
DEC Actions to Address PFAS in Biosolids
DEC continues to take numerous actions to address and control PFAS in biosolids so that recycling remains safe and protective.
- Sampling & PFAs Standards for Biosolids Sources: DEC Policy DMM-7 requires sampling of all biosolids sources that are recycled and sets standards for PFAS in biosolids.
- SUNY ESF Partnership to Evaluate PFAS in Biosolids: DEC entered into a $500,000 contract with SUNY ESF to analyze biosolids.
- Mandatory PFAS testing for Water Resource Recovery Facilities: Requires each WRRF recycling biosolids to perform sampling of biosolids by a DEC-contracted laboratory.
- Scientific Review Group: Technical assessment group including scientists from DEC, DOH, and AGM.
- Upcoming Sampling & PFAs Standards for Biosolids Products: Forthcoming program, DMM-7A, that will require sampling of biosolids-derived products (compost, heat dried pellets etc.).
- Research Partnership with UAlbany: DEC entered into a $400,000 contract with the University at Albany to study on soils and crop uptake potential of PFAS on biosolids-amended soils.
- Regulations Requiring PFAS Treatment of Landfill Leachate: DEC will be proposing regulatory revisions that will require leachate to be treated to remove PFAS compounds prior to entering a WRRF.
- Restrictions on Consumer Products: DEC is implementing legislation restricting the use of PFAS in multiple consumer products which will reduce the amount of PFAS entering a WRRF.
- Evaluation of Soil PFAS Content at Agricultural Sites: DEC is developing a scope of work to fund engineering consultants that will sample soils at agricultural sites that have received biosolids.
- Upcoming Regulations: DEC is initiating a comprehensive rulemaking to address PFAS in biosolids recycling practices and products.
