Definitions

Alternative Daily Cover (ADC): biosolids or other material that is spread over the top of solid waste at a landfill at the end of each working day to reduce odors and access by birds and animals… For the purposes of this survey, ADC is not considered a “beneficial use of biosolids.”

APLR (Annual Pollutant Loading Rate): If a biosolids does not meet the higher quality standards for pollutants (e.g. metals) in Table 3 of Part 503 and is sold for public use (e.g. bagged products), then the APLR applies and is the maximum amount of regulated pollutants in biosolids that can be applied to a site in one year. This is rare with modern biosolids.

Biosolids: domestic (municipal) sewage sludge that has been treated and tested and meets standards for beneficial use as a soil amendment or fertilizer.

Beneficial use of biosolids (as a soil amendment and/or fertilizer): biosolids applied in bulk to farm or other soils or made into compost and fertilizer products or otherwise treated and used in some way that results in their ultimate application to soils or soil-like products (e.g. potting mixes) – for this survey, does not include biosolids incinerated or landfilled, even if these involve energy recovery. And Alternative Daily Cover (ADC at landfills is not included in the definition of beneficial use. (However, final vegetative cover as part of an engineered soil mix for post-landfill closure reclamation is beneficial use.)

Ceiling limit: refers to the numerical standards in federal and state regulations which, if exceeded by any pollutant (e.g. heavy metal), means a biosolids cannot be land applied or used beneficially; in the federal regulations (Part 503), the ceiling limits are listed in Table 1.

CHP: Combined heat and power (CHP) systems are energy-efficient systems that capture usable heat from engines, turbines, generators, boilers, and other machines that are generating electricity or driving machinery. CHP systems capture a much higher percentage of the total energy from a fuel source than do conventional energy generation systems. CHP systems are commonly used when anaerobic digestion biogas is used to generate electricity; the heat is captured and used for heating digesting solids and/or buildings. CHP is also commonly used to capture heat from conventional fossil fuel systems.

Class A biosolids: domestic sewage sludge that has been treated to meet the requirements of 40 CFR Part 503.32(a), which includes options for advanced, or further, pathogen reduction (e.g. PFRP).

Class B biosolids: domestic sewage sludge that has been treated to meet the requirements of 40 CFR Part 503.32(b), which includes options for significantly reducing pathogens (e.g. PSRP).

Contractor or private contractor: a company or individual who performs a service, under contract, for a WWTP… in the biosolids & septage professions, this includes haulers/transporters of biosolids and/or septage, companies that manage biosoilds (or septage) treatment and use or disposal, and companies or individuals who provide consulting services for biosolids and/or septage management.

CPLR (Cumulative Pollutant Loading Rate): If a biosolids does not meet the higher quality standards for pollutants (e.g. metals) in Table 3 of Part 503, then the CPLR applies. CPLR is the maximum amount of regulated pollutants in biosolids that can be applied to a site considering all biosolids applications since July 20, 1993.

EQ biosolids: bulk or bagged biosolids that meet a) Part 503, Table 3 (and Table 1) pollutant concentrations, b) one of the Class A pathogen reduction standards in Part 503, and c) specific vector attraction reduction processes in Part 503 (options 1 through 8). There are Class A biosolids that are not EQ because they don’t meet the Table 3 pollutant standards, but these are rare with modern biosolids and pretreatment programs.

High quality limit: refers to the numerical standards in federal (and some state regulations) which, if exceeded by any pollutant (e.g. heavy metal), means a biosolids cannot be generally distributed to the public without restrictions; in the federal regulations (Part 503), the ceiling limits are listed in Table 1 and the “high quality limits” are lower numerical standards (lower concentrations of pollutants) in Table 3.

Industrial pretreatment program (IPP): a formal program, as required by federal regulations, conducted by a WWTP, for permitting, controlling, and monitoring industrial discharges to a sewer system to protect against WWTP process interference, pass-through of pollutants in effluent, and interference with use or disposal of wastewater solids (sewage sludge).

Lagoon, sludge lagoon: For the purposes of this survey, we are seeking data on the number of WWTPs with sludge lagoons, whether they are for treating sludge and/or just storing sludge. Include both kinds in your count. Do not include wastewater treatment lagoon systems.

Land application: Generally, and for this survey, this term is used when biosolids are applied in bulk to soils in large-scale settings such as on farms, in forestry, and/or at reclamation sites. Smaller-scale uses of Class A EQ biosolids are called “distribution” or “product distribution” or “marketed and distributed;” they too end up on soils. The term “applied to soils” includes all biosolids used as fertilizers and soil amendments, both land applied and marketed and distributed biosolids.

MGD: million gallons per day, the standard for measuring wastewater flow.

MSW: municipal solid waste.

NPK: abbreviations for nitrogen, phosphorus, and potassium, the major plant nutrients.

Organic chemical compounds: chemical compounds containing carbon that are present in sewage sludge and biosolids, including polychlorinated biphenyls (PCBs), dioxins/furans, volatile organic compounds (VOCs), pesticides, herbicides, polybrominated diphenyl ethers (PDBEs), PFAS, etc. and including compounds found in pharmaceuticals and personal care products (PPCPs).

Part 503: refers to the federal U. S. EPA 40 CFR Part 503 regulations - the EPA biosolids/sewage sludge regulations adopted in 1993. These include tables of pollutant limits, shown on this page.

Pasteurization & Heat Drying - in the State’s spreadsheet, please include these two treatment options in the heat drying line.

Pollutant: the term used (including officially by EPA) for the variety of contaminants in sewage sludge or biosolids, including nutrients, trace elements (e.g. heavy metals), and organic chemical compounds.

POTW: publicly owned treatment works; includes public municipal wastewater treatment facilities, lagoons, ponds, etc. This survey uses the more common term “WWTP” to include POTWs and private facilities treating domestic sewage.

Quality, biosolids quality: This refers to the class of biosolids - EQ, Class A, or Class B, as defined under the U.S. EPA regulations 40 CFR Part 503.

Separate preparer (or Preparer): sludge/biosolids/septage management facilities that take in sewage sludge from one or more WWTPs – and/or septage - and treat it – changing its quality – to create biosolids that may go to any of the end use or disposal options (application to soils, landfilling, or incineration). We mean “preparer” as defined in 40 CFR Part 503: a facility or operation that is not part of a WWTP, that changes the quality of the sewage sludge and/or septage. In the state survey, if a separate preparer treats mostly sewage sludge, count it in the state spreadsheet as a sludge/biosolids separate preparer. If the separate preparer treats mostly septage, count it in the state online survey, in the septage section.

Septage: the solids that collect at the bottom of a septic tank. To ensure proper function, most septic tanks should be pumped out every 3 - 5 years. The resulting septage must be properly managed, either by delivery to a wastewater treatment facility or by treatment and land application.

Septic system: also called “onsite system” - a wastewater treatment system for a house, business, or other structure where a relatively small amount of wastewater is treated on site, typically consisting of piping from sinks, washers, and toilets to a septic tank and additional piping to an in-ground leach field. Heavier solids settle in the septic tank and clearer effluent flows to the leach field where it is distributed into the soil for final treatment by soil microorganisms.

Sludge, sewage sludge, solids: terms used interchangeably for the material removed from the bottom of wastewater clarifiers that may be further treated and tested to become biosolids. Some sludge/sewage sludge/solids are not further treated and are landfilled or incinerated; these are covered by this survey also, counted as they leave the gate of a WRRF/WWTP.

Treatment Works Treating Domestic Sewage (TWTDS): includes POTWs and privately-owned wastewater treatment facilities, of all sizes, that treat domestic sewage (does not include industrial wastewater treatment facilities such as at paper mills). TWTDS is a term used in 40 CFR Part 503 and was the term used in the first national biosolids survey (NEBRA et al., 2007). Sewage sludge from TWTDS must generally be managed in accordance with Part 503 (503 applies to the sludge from POTWs and private facilities treating domestic sewage). This survey uses the more common term “WWTP” to include POTWs and private facilities treating domestic sewage.

WRRF - water resource recovery facility or
WWTP - wastewater treatment plant: For this survey, “WWTP” means public and private wastewater treatment facilities that treat domestic sewage. Often used interchangeably with “wastewater treatment facility” (“WWTF”) or “water resource recovery facility” (“WRRF”). Also commonly called a POTW, although we include in “WWTPs” – and in this survey – private facilities treating domestic sewage. This includes mechanical treatment plants and wastewater lagoon treatment systems. But this does not include septic systems (also called “onsite” systems), which are in-ground systems consisting of septic tanks and leach fields.