Editing Sewage sludge (section)

==Contaminants==
The specific content of sewage sludge is affected by what enters the sewage stream, and how the sewage is treated and processed. As wastewater treatment policies are passed or amended to allow or regulate potential contaminants into the sewage stream, the content of the sewage sludge reflects those changes. For example, the EU's [[Urban Waste Water Treatment Directive]] shapes the types of contaminants that enter the EU's sewage treatment stream.<ref name=":26">{{Citation |title=COMMISSION STAFF WORKING DOCUMENT EXECUTIVE SUMMARY OF THE EVALUATION Council Directive 86/278/EEC of 12 June 1986 on the protection of the environment, and in particular of the soil, when sewage sludge is used in agriculture |date=2023 |url=https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=SWD:2023:158:FIN&qid=1684830815132 |access-date=2024-10-18 |language=en}}</ref>

=== Pathogens ===
Bacteria in treated sludge products can actually regrow under certain environmental conditions.<ref name="pmid16749313">{{cite journal |last1=Jolis |first1=Domènec |date=April 2006 |title=Regrowth of fecal coliforms in class A biosolids |journal=Water Environment Research |volume=78 |issue=4 |pages=442–5 |doi=10.2175/106143005X90074 |pmid=16749313 |bibcode=2006WaEnR..78..442J |s2cid=21071021}}</ref> Pathogens could easily remain undetected in untreated sewage sludge.<ref>{{cite journal |last1=Lewis |first1=David L. |last2=Gattie |first2=David K. |date=July 2002 |title=Pathogen Risks From Applying Sewage Sludge to Land |journal=[[Environmental Science & Technology]] |volume=36 |issue=13 |pages=286A–293A |doi=10.1021/es0223426 |pmid=12144261 |doi-access=}}

* {{cite press release |title=Researchers Link Increased Risk Of Illness To Sewage Sludge Used As Fertilizer |date=30 July 2002 |url=https://www.sciencedaily.com/releases/2002/07/020730075144.htm |website=ScienceDaily}}</ref> Pathogens are not a significant health issue if sewage sludge is properly treated and site-specific management practices are followed.<ref>{{cite journal |last1=Harrison |first1=Ellen Z. |last2=Oakes |first2=Summer Rayne |author-link2=Summer Rayne Oakes |year=2003 |title=Investigation of alleged health incidents associated with land application of sewage sludges |url=http://sludgenews.org/resources/documents/Harrison_NS.pdf |journal=New Solutions |volume=12 |issue=4 |pages=387–408 |doi=10.2190/0FJ0-T6HJ-08EM-HWW8 |pmid=17208785 |bibcode=2003NewSo..12..387H |s2cid=26931475 |access-date=30 May 2017 |hdl-access=free |hdl=1813/5319}}</ref>

=== Heavy metals ===
One of the main concerns in the treated sludge is the concentrated metals content ([[lead]], [[arsenic]], [[cadmium]], [[thallium]], etc.); certain metals are regulated while others are not.<ref>{{cite journal |last=McBride |first=Murray B. |date=October 2003 |title=Toxic metals in sewage sludge-amended soils: Has promotion of beneficial use discounted the risks? |url=https://www.researchgate.net/publication/222521560 |journal=Advances in Environmental Research |volume=8 |pages=5–19 |doi=10.1016/S1093-0191(02)00141-7 |access-date=30 May 2017}}</ref> Leaching methods can be used to reduce the metal content and meet the regulatory limit.<ref>{{cite journal |last1=Turek |first1=Marian |last2=Korolewicz |first2=Teofil |last3=Ciba |first3=Jerzy |year=2005 |title=Removal of Heavy Metals from Sewage Sludge Used as Soil Fertilizer |journal=Soil and Sediment Contamination |volume=14 |issue=2 |pages=143–54 |doi=10.1080/15320380590911797 |bibcode=2005SSCIJ..14..143T |s2cid=93258156}}</ref>

In 2009, the EPA released the [[Targeted National Sewage Sludge Study]], which reports on the level of [[metals]], [[chemicals]], [[hormones]], and other materials present in a statistical sample of sewage sludges.<ref name="TNSSS-SAR">{{cite web |date=January 2009 |title=Targeted National Sewage Sludge Survey Statistical Analysis Report |url=http://www.epa.gov/waterscience/biosolids/tnsss-stat.pdf |archive-url=https://web.archive.org/web/20090711032817/http://www.epa.gov/waterscience/biosolids/tnsss-stat.pdf |archive-date=11 July 2009 |access-date=6 August 2009 |publisher=[[United States Environmental Protection Agency|EPA]] |id=EPA-822-R-08-018}}</ref> Some highlights include:
* [[Lead]], [[arsenic]], [[chromium]], and [[cadmium]] are estimated by the EPA to be present in [[chemical analysis|detectable quantities]] in 100% of national sewage sludges in the US, while [[thallium]] is only estimated to be present in 94.1% of sludges.
* [[Silver]] is present to the degree of 20&nbsp;mg/kg of sludge, on average, while some sludges have up to 200 milligrams of silver per kilogram of sludge; one outlier demonstrated a silver [[lode]] of 800–900&nbsp;mg per kg of sludge.
* [[Barium]] is present at the rate of 500&nbsp;mg/kg, while [[manganese]] is present at the rate of 1&nbsp;g/kg sludge.
[[File:Plastic Atlas-SPREADING AROUND Microplastic sewage sludge spread fields per year tonnes Sweden Finland United Kingdom Estonia Germany Po.png|alt=Grey outline map of Europe with yellow circles for countries, sized to show the amount of microplastic sewage sludge spread on fields per year in tonnes in 2016. The amounts are: France 11653, United Kingdom 11455, Germany 9696, Spain 8394, Italy 5528, Poland 2253, Portugal 1579, Finland 1234, Austria 890, Sweden 655, Romania 244, Estonia 197.|thumb|Microplastic contamination from use of sewage sludge on agricultural land in Europe, 2016.]]

===Micro-pollutants===
Micro-pollutants are compounds which are normally found at concentrations up to microgram per liter and milligram per kilogram in the aquatic and terrestrial environment, respectively, and they are considered to be potential threats to environmental ecosystems. They can become concentrated in sewage sludge.<ref name="EPA822R08014">{{Cite web |date=January 2009 |title=Biosolids: Targeted National Sewage Sludge Survey Report&nbsp;— Overview |url=http://water.epa.gov/scitech/wastetech/biosolids/tnsss-overview.cfm |archive-url=https://web.archive.org/web/20150216032645/http://water.epa.gov/scitech/wastetech/biosolids/tnsss-overview.cfm |archive-date=16 February 2015 |access-date=12 January 2015 |website=[[United States Environmental Protection Agency|EPA]] |id=EPA 822-R-08-014}}</ref> Each of these disposal options comes with myriad potential—and in some cases proven—human health and environment impacts.<ref name="HarrisonMcBride2009" />
Several organic micro-pollutants such as endocrine disrupting compounds, pharmaceuticals and per-fluorinated compounds have been detected in sewage sludge samples around the world at concentrations ranging up to some hundreds mg/kg of dried sludge.<ref>Stasinakis et al., 2013. Contribution of primary and secondary treatment on the removal of benzothiazoles, benzotriazoles, endocrine disruptors, pharmaceuticals and perfluorinated compounds in a sewage treatment plant. Sci. Total Environ. vol.463-464, October 2013, p. 1067-1075. [https://www.sciencedirect.com/science/article/pii/S0048969713007390 Stasinakis et al., 2013]</ref><ref>Arvaniti and Stasinakis, 2015. Review on the occurrence, fate and removal of perfluorinated compounds during wastewater treatment. Sci. Total Environ. vol. 524-525, August 2015, p. 81-92. [https://www.sciencedirect.com/science/article/pii/S0048969715004593 Arvaniti and Stasinakis, 2015]</ref> 
[[Sterol]]s and other [[hormone]]s have also been detected.<ref name="TNSSS-SAR" />

=== Other hazardous substances ===
Sewage treatment plants receive various forms of hazardous waste from hospitals, nursing homes, industry and households. Low levels of constituents such as [[Polychlorinated biphenyl|PCBs]], [[Polychlorinated dibenzodioxins|dioxin]], and [[brominated]] [[flame retardant]]s, may remain in treated sludge.<ref name="Henry2005">{{cite web |last=Henry |first=Christopher |date=January 2005 |title=Understanding Biosolids |url=http://faculty.washington.edu/clh/understandingbiosolids/Ch7organics.pdf |archive-url=https://web.archive.org/web/20120221223427/http://faculty.washington.edu/clh/understandingbiosolids/Ch7organics.pdf |archive-date=21 February 2012 |access-date=1 June 2017 |website=[[University of Washington]]}}</ref><ref name="BiosolidsUSGS2016">{{cite web |date=16 November 2016 |title=Household Chemicals and Drugs Found in Biosolids from Wastewater Treatment Plants |url=http://toxics.usgs.gov/highlights/biosolids.html |access-date=1 June 2017 |website=[[United States Geological Survey]]}}</ref> There are potentially thousands of other components of sludge that remain untested/undetected disposed of from modern society that also end up in sludge (pharmaceuticals, nano particles, etc.) which have been proven to be hazardous to both human and ecological health.<ref name="EPA822R08014" />

In 2013, in South Carolina PCBs were discovered in very high levels in wastewater sludge. The problem was not discovered until thousands of acres of farm land in [[South Carolina]] were discovered to be contaminated by this [[hazardous]] material. SCDHEC issued emergency regulatory order banning all PCB laden sewage sludge from being land applied on farm fields or deposited into landfills in South Carolina.<ref name="SCDHECSep2013">{{cite web |last=Plowden |first=Mark |date=25 September 2013 |title=DHEC Issues Emergency Regulation, Expands Investigation into PCBs Found at Water Treatment Plants |url=http://www.scdhec.gov/administration/news/2013/nr20130925-01.htm |archive-url=https://web.archive.org/web/20130926153115/http://www.scdhec.gov/administration/news/2013/nr20130925-01.htm |archive-date=26 September 2013 |access-date=1 June 2017 |website=[[South Carolina Department of Health and Environmental Control|SCDHEC]]}}</ref><ref name="SCDHEC4413">{{cite web |date=25 October 2013 |title=Emergency Regulation for Management of Wastewater System Sludge |url=http://www.scdhec.gov/administration/news/docs/PCBEmergencyRegFINAL.pdf |access-date=1 June 2017 |website=[[South Carolina Department of Health and Environmental Control|SCDHEC]]}}</ref>

Also in 2013, after DHEC request, the city of Charlotte decided to stop land applying sewage sludge in South Carolina while authorities investigated the source of PCB contamination.<ref name="Henderson2014">{{cite web |last=Henderson |first=Bruce |date=14 April 2014 |title=Charlotte PCB cleanup costs to top $1.3 million |url=http://www.charlotteobserver.com/news/local/article9112850.html |access-date=1 June 2017 |website=[[The Charlotte Observer]]}}</ref> In February 2014, the city of Charlotte admitted PCBs have entered their sewage treatment centers as well.<ref name="HendersonLyttleBethea2014">{{cite web |last1=Henderson |first1=Bruce |last2=Lyttle |first2=Steve |last3=Bethea |first3=April |date=7 February 2014 |title=Task force named to probe chemical dumping |url=http://www.charlotteobserver.com/news/local/article9095525.html |access-date=1 June 2017 |website=[[The Charlotte Observer]]}}</ref>

Contaminants of concern in sewage sludge are plasticizers, PDBEs, [[PFASs]] ("forever chemicals"),<ref>{{cite web |date=26 February 2020 |title=Toxic 'Risk Assessment of Pollutants in Biosolids |url=https://www.epa.gov/biosolids/risk-assessment-pollutants-biosolids |access-date=28 March 2022 |website=EPA}}</ref> 
and others generated by human activities, including personal care products and medicines. Synthetic fibers from fabrics persist in treated sewage sludge as well as in biosolids-treated soils and may thus serve as an indicator of past biosolids application.<ref>{{cite journal |last1=Zubris |first1=Kimberly Ann V. |last2=Richards |first2=Brian K. |year=2005 |title=Synthetic fibers as an indicator of land application of sludge |journal=Environmental Pollution |volume=138 |issue=2 |pages=201–11 |doi=10.1016/j.envpol.2005.04.013 |pmid=15967553|bibcode=2005EPoll.138..201Z }}</ref>

=== Pollutant ceiling concentration ===
The term "pollutant" is defined as part of the EPA 503 rule. The components of sludge have pollutant limits defined by the EPA. "A Pollutant is an organic substance, an inorganic substance, a combination of organic and inorganic substances, or a pathogenic organism that, after discharge and upon exposure, ingestion, inhalation, or assimilation into an organism either directly from the environment or indirectly by ingestion through the food chain, could, on the basis of information available to the Administrator of EPA, cause [[death]], [[disease]], [[mental disorders|behavioral abnormalities]], [[cancer]], [[teratogens|genetic mutations]], [[physiological malfunctions]] (including malfunction in [[sexual reproduction|reproduction]]), or [[deformity|physical deformations]] in either organisms or [[birth defect|offspring of the organisms]]."<ref name="CFR2010">{{cite report |title=Code of Federal Regulations |issue=29 |volume=40 |access-date=1 June 2017 |chapter=503.9 |chapter-url=http://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol29/pdf/CFR-2010-title40-vol29-sec503-9.pdf |website=[[United States Government Publishing Office|GPO]]}}</ref>
The maximum component pollutant limits by the US EPA are:

{| class="wikitable"
|-
! Pollutant!! Ceiling concentration (mg per kg)
|-
|[[Cadmium]]||85
|-
|[[Copper]]||4300
|-
|[[Lead]]||840
|-
|[[Mercury (element)|Mercury]]||57
|-
|[[Molybdenum]]||75
|-
|[[Nickel]]||420
|-
|[[Selenium]]||100
|-
|[[Zinc]]||7500
|}