Removal, partitioning, and fate of silver and other metals in wastewater treatment plants and effluent‐receiving streams

Shafer, Martin M.; Overdier, Joel T.; Armstong, David E.

doi:10.1002/etc.5620170416

Cited by 172 publications

(76 citation statements)

References 21 publications

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“…This is a wider range than that found by Li et al (2013) where 28-180 ng/L total was reported (Shafer et al, 1998;Adams and Kramer, 1999;Wen et al, 2002). With one exception (SB1) all the STPs, regardless of type, removed more than 93% of the particulate silver in the influent (table 2), confirming previous assessments made in the US in the late 1990s on the efficiency of silver removal in sewage treatment (Shafer et al, 1998).…”

Section: Particulate Silver (>450 Nm) In the Sewage Influents And Effsupporting

confidence: 82%

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Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants

et al. 2014

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Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. ABSTRACTDifferential filtration was used to measure silver (>2 nm) entering and leaving nine sewage treatment plants (STPs). The mean concentration of colloidal (2-450 nm) silver, which includes nanosilver, was found to be 12 ng/L in the influent and 6 ng/L in the effluent. For particulate silver (>450 nm) the mean values were 3.3 µg/L for influent and 0.08 µg/L for effluent. Thus, removal was around 50% and 98% for colloidal and particulate silver respectively. There was no significant difference in performance between the different types of STP investigated (three examples each of activated sludge, biological filter and biological filter with tertiary treatment located across England, UK). In addition, treated sewage sludge samples (biosolids) were taken from several STPs to measure the total silver likely to be discharged to soils. Total silver was 3-14 mg/kg DW in the sludge (median 3.6), which if the sludge were added at the recommended rate to soil, would add 11 µg/kg/yr to the top 20 cm soil layer. Predicted concentrations using the LF2000-WQX model for all the rivers of England and Wales for nanosilver were typically in the 0-1 ng/L range but levels up to 4 ng/L are possible in a high discharge and low flow scenario. Predicted concentrations for the total particulate forms were mostly below 50 ng/L except for a high discharge and low flow scenario where concentrations could reach 135 ng/L.

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Section: Particulate Silver (>450 Nm) In the Sewage Influents And Effsupporting

confidence: 82%

“…For the >450 nm particulate material collected on filters, the method used by Shafer et al (1998) was adopted. To get sufficient sample, three filters for the influent and 4-6 filters for effluent samples were used.…”

Section: Digestion Methods For Particulate and Colloidal Silvermentioning

confidence: 99%

Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants

et al. 2014

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“…4). Die Anreicherung im Schlamm be- (Shafer et al 1998), so sind im Ablauf einer realen Kläranlage mit rund 0,1 µg/L Ag zu rechnen.…”

Section: Pilotkläranlageunclassified

“…Beispielsweise resultiert auf Basis einer von Shafer et al (1998) berichteten mittleren Silberkonzentration von 4 µg/L Ag im Zulauf von Kläranlagen und einer durchschnittlichen Abwassermenge von jährlich 80 m einer mittleren Zulauffracht von 2,5 mg/Tag Ag pro Einwohner (Firk 1986). Diese Abschätzung führt, bei wiederum 10 Mio.…”

Section: Introductionunclassified

“…Wie gut Nanosilber in Kläranlagen aus dem Abwasser entfernt wird, lässt sich experimentell abgestützt nicht beurteilen, doch deutet die Gesamtsilberelimination von 94-99,9 % auf eine gute Reinigungsleistung hin (Shafer et al 1998;Howe und Dobson 2002;Benn und Westerhoff 2008). Die Silberkonzentrationen im gereinigten Abwasser von Kläranlagen (0,001-0,1 µg/L Ag) stehen im Einklang mit der hohen Eliminationsrate und erklären zudem die vergleichsweise geringe Sedimentbelastung in Fließgewäs-sern (Wen et al 1997;Warila et al 2001;Benn und Westerhoff 2008;Blaser et al 2008).…”

Section: Introductionunclassified

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Verhalten von Nanosilber in Kläranlagen und dessen Einfluss auf die Nitrifikationsleistung in Belebtschlamm

et al. 2010

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Zusammenfassung Hintergrund, Ziel und Zweck Die Anwendung von Nanosilber nimmt zwar stetig zu, doch die Kenntnisse zum Vorkommen nanoskaligen Silbers in Abwässern und zum Verhalten in Kläranlagen sind gering. Untersuchungen unter realen Betriebsbedingungen fehlen sogar vollständig. In der vorliegenden Studie wurde Nanosilber mit folgenden Zielen untersucht: 1) Hemmung der Nitrifikationsleistung im Belebtschlamm einer Kläranlage, 2) Erstellung einer Massenbilanz für Nanosilber in einer Pilotkläranlage und 3) Verifizierung der Bilanz durch eine Untersuchung in einer realen kommunalen Kläranlage, in die durch einen Indirekteinleiter partikuläres Silber eingetragen wird.Methoden Der Einfluss von vier marktüblichen Nanosilberadditiven auf die Ammoniumoxidation im Belebtschlamm wurde in Batchreaktoren bei zwei Konzentrationen (1, 100 mg/L Ag) und zwei Expositionszeiten (2 h, 6 Tage) untersucht. In einer Pilotkläranlage in der Größe von 70 Einwohnerwerten wurde partikuläres Silberchlorid und metallisches Nanosilber jeweils für die Dauer zweier Schlammalter (25 Tage) Schlüsselwörter Abwasserreinigung · Elimination · Kläranlage · Massenbilanz · Nanosilber · Nitrifikationsleistung · Silberionen · Trockensubstanz Fate of nanosilver in wastewater treatment plants and their impact on nitrification activity in sewage sludgeAbstract Background, aim and scope The application of nanosilver is increasing. Knowledge on the fate and behavior of nanosilver in wastewater and wastewater treatment plants is scarce. Studies under real world conditions are completely lacking. We studied (1) the impact of nanosilver on the nitrification of sewage sludge, (2) quantified the mass flow of nanosilver in a pilot-plant, and (3) verified the mass balance in a full-scale municipal wastewater treatment plant where nanosilver is introduced to the municipal plant by an indirect discharger.Materials and Methods The addition of four different nanosilver additives on ammonia oxidation in activated sludge has been studied in batch-reactors at two concentrations (1, 100 mg/L Ag) with two exposure times (2 h, 6 days). The pilot-plant treating 70 population equivalents of domestic wastewater is operated with a 12 day sludge age. Nanosilver was applied to the activated sludge tank within two sludge ages. The silver concentrations were measured in sludge and effluent samples during dosing and the following two sludge ages. The adsorption and speciation of silver particles has been analyzed using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Influent, effluent and sludge were sampled on a fullscale plant (60 000 equivalent inhabitants) and analyzed for silver.Results Silver nitrate, metallic nanosilver, nano-scaled silver chloride and microcomposite silver did not show any effect on ammonia oxidation after the addition of 1 mg/L Ag to the activated sludge (corresponding to 250 mg Ag per kg solids). In contrast, 100 mg/L Ag inhibited the nitrification process by 100 % after the addition of silver nitrate and 20-30...

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Silver and Gold

Juberg¹,

Hearne²

2001

Patty's Toxicology

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Silver, an element of the II(B) Group, is in the second transition series of the periodic table. It is a white, lustrous, relatively soft and very malleable metal. Silver has high thermal and electrical conductivity and resists oxidation in air that is devoid of hydrogen sulfide. Silver is insoluble in water although it can exist in an aqueous environment in three cationic forms, Ag(I), Ag(II), and Ag(III), in addition to its metallic state (AgO). Most silver compounds are made from silver nitrate, which is prepared from silver metal. The toxicological properties of many substances depend on the particular chemical species of that substance, and silver is no exception. Although silver exists in its elemental state and many references within the scientific literature are simply to “silver,” it is important to stress that speciation is critical to understanding the potential for toxicity and subsequent health effects. As with many substances, a discussion of each silver species' toxicological properties would appear rather incomplete due to the lack of information available. Given these factors, it is more logical to discuss silver based on specific target organs or endpoints of concern (i.e., irritation, carcinogenicity) and to provide information on relevant silver species within this context. An explanation for the apparent lack of toxicity information on numerous species of silver is that many of the commonly used forms are insoluble in aqueous media and therefore are not readily tested in laboratory animal species. This property of many silver species may, in part, also explain its apparent lack of acute or chronic toxicity in humans based on years of occupational and workplace experience. Gold is a dense, yet malleable, lustrous, yellow metal widely found in nature as elemental gold or in combination with sulfides in igneous rocks and ores. Gold is very stable and nonreactive and does not burn or oxidize in air. Other than in its atomic state, the metal does not react with oxygen, sulfur, or selenium at any temperature. Gold does react with various oxidizing agents at ambient temperatures provided a good ligand is present to lower the redox potential below that of water. Therefore, gold is not attacked by most acids under ordinary conditions and is stable in basic media. Early uses of gold were in medicinal, antibacterial, and dental applications dating back to the ancient Chinese and Egyptians. Gold salts have been used therapeutically, without notable success in treating several diseases, including asthma, leprosy, syphilis, and tuberculosis. Presently, gold salts have therapeutic usefulness (chrysotherapy) limited to treating rheumatoid arthritis of the peripheral joints and in certain rare skin diseases. Gold salts are most efficacious in the early stages of arthritic disease and reduce the inflammatory process but without inducting any repair process in the joints. Two generally recognized disadvantages to chrysotherapy include relapse following discontinuation of treatment and potential toxicity associated with gold salts. Because of its distribution in the body and short half‐life, colloidal radioactive gold, has been used as a radiation source in treating cancer. As noted for silver, a discussion of the toxicological properties for each gold compound is not practical from the standpoint of available information. Therefore, this discussion on gold and its toxicity potential centers on particular aspects of gold toxicology, and within this framework, where a particular gold compound has been evaluated, it are discussed.

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Removal, partitioning, and fate of silver and other metals in wastewater treatment plants and effluent‐receiving streams

Cited by 172 publications

References 21 publications

Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants

Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants

Verhalten von Nanosilber in Kläranlagen und dessen Einfluss auf die Nitrifikationsleistung in Belebtschlamm

Silver and Gold

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