Editing Sewage sludge (section)

=== 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.]]