Kirk G. Scheckel Scheckel.Kirk@epa.gov

E. Lombi, E. Donner, K. Vasilev, B. Miller, C. Impellitteri, T. Luxton

Nanoparticles Down the Drain – Then What?

Office of Research and Development National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Waste Management Branch

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• Engineered materials • One dimension less than

100 nm

• Exhibits physical, chemical and biological properties that are particle size dependent

•  Increase in surface areas increases reactivity and enhances intrinsic toxicity

2  3 4 5 6 7 8 9 10

Diameter of the particle (nm)

CdSe Nanoparticles

What are Nanoparticles?

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Nanoparticles are in Consumer Products

3 Silver speciation and release in commercial antimicrobial textiles as influenced by washing. E. Lombi, E. Donner, K.G. Scheckel, R. Sekine, C. Lorenz, N. Von Goetz and B. Nowack. 2014. Chemosphere. 111: 352-358.

Nanoparticles are in Consumer Products

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Beneficial reuse of waste materials: •  Safely reducing or eliminating waste

streams is a global priority o  Preserve limited landfill space o  Reduce demand of virgin materials o  Conserve energy and GHG o  Materials re-purposed for other uses

Biosolids and biosolids-based products (compost) in the US results in nearly 7 million dry tons of material annually from about 16,500 MWTF ~55% of biosolids are land applied; remainder is incinerated/processed for energy recovery, composted or landfilled.

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HOME

In reality, nanoparticles are added here

Not here

Nanoparticles are in Consumer Products and Biosolids

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Scientific issues of adding nanoparticles at the end of the WWTP or directly to soil

Historical research on metals in biosolids demonstrated a “salt effect” Metals spiked into soils ≠ Metals in WWTP biosolids Metals spiked into processed biosolids ≠ Metals in WWTP biosolids

Why? pH and ionic strength changes Equilibrium perturbation Not the same reaction conditions Not the same reaction products Results are not comparable!

Anaerobic digestion Ø  30 day digestion

60% primary sludge + 40% thickened WAS

Treatments Ag 50mg/kg, Zn 400 mg/kg Ø  Zn and Ag salts Ø  ZnO-NP (naked and

trygiceride) Ø  Ag-NPs (3 coatings)

AgCl-NP

Bolivar WWTP, South Australia Sampling Ø  0, 3 hours Ø  1, 3, 10 and 30

days

Fresh biosolids separated by centrifugation

Ageing with wetting and drying cycles at 37 °C for up to 6 months

Experimental Design

  mg/kg     Min   Mean   Max   95th   50th  Silver   1.94   20   856   57   13  Zinc   216   ND   8550   ND   ND  

Targeted National Sewage Sludge Survey  

Energy (eV)

8980 9000 9020 9040 9060 9080

Inten

sity

k (A-1)

2 4 6 8 10

k3 X(k)

B6

B5

B4

B3

B2

B1

B6

B5

B4

B3B2

B1

Energy (eV)

8980 9000 9020 9040

Inte

nsity

k (A-1)

2 4 6 8 10

k3 X(k

)

Cu-humic acid

Cu-phosphate

Cu-substituted goethite

Covellite, CuS

Cubanite, CuFe2S3

Chalcocite, Cu2S

Cu-humic acid

Cu-phosphate

Cu-substituted goethite

Chalcocite, Cu2S

Covellite, CuS

Cubanite, CuFe2S3

Cu is transformed from Cu(I)sulfide to Cu(II) sorbed by HA during composting/stockpiling (Donner et al., 2011; 2012)

Why simulating stockpiling/composting?

Com

post

Agi

ng

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Ag NPs in a model WWTP

Transformation of Four Silver/Silver Chloride Nanoparticles during Anaerobic Treatment of Wastewater and Post-processing of Sewage Sludge. E. Lombi, E. Donner, S. Taheri, E. Tavakkoli, Å. Jamting, S. McClure, R. Naidu, B.W. Miller, K.G. Scheckel and K. Vasilev. 2013. Environ. Pollut. 176: 193-197.

Ag2S Ag-HA Ag-cystine

Ag-acetate Ag-ferrih.

Ag-NPs citrate Ag-NPs MSA Ag-NPs PVS Metallic Ag AgCl-NPs AgCl ‘bulk’

Nor

mal

ised

inte

nsity

Energy (eV) 25500 25520 25540 25560 25580 25600

Fate of Ag/AgCl-NPs during biosolid digestion: NPs disappearance is very rapid in all cases

Kim et al., 2010

25480 25500 25520 25540 25560 25580 25600

0 h 30 d 2 m 6 m Composting

Ag-NPs PVS

AgCl-NPs

Energy (eV)

Nor

mal

ised

inte

nsity

0 h 30 d

Composting 2 m 6 m

Ag salt 0 h 30 d

Composting 2 m 6 m

High stability of secondary Ag2S-NPs

11 Transformation of Silver Nanoparticles in Fresh, Aged, and Incinerated Biosolids. C.A. Impellitteri, S. Harmon, R.G. Silva, B.W. Miller, K.G. Scheckel, T.P. Luxton, D. Schupp, and S. Panguluri. 2013. Water Research. 47: 3878-3886.

Ag NPs in fresh, aged and incinerated biosolids

Ag NPs and AgNO3 via influent of a pilot-scale wastewater treatment system consisting of a primary clarifier (PC), aeration basin, and secondary clarifier (SC).

Solids were collected as ‘fresh’ (24hr from PC) and ‘aged’ (1mon from SC).

‘Fresh’ and ‘aged’ materials were incinerated at 850oC.

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25400 25500 25600 25700 25800

Ag2SO4-ref

Ag2S-refAg-Foil-refAgNP-refAgNP-ashAg2S-ash

Nor

mal

ized

µ (Ε

)

Energy (eV)

AgNO3-ash

Ag NPs in incinerated biosolids

Transformation of Silver Nanoparticles in Fresh, Aged, and Incinerated Biosolids. C.A. Impellitteri, S. Harmon, R.G. Silva, B.W. Miller, K.G. Scheckel, T.P. Luxton, D. Schupp, and S. Panguluri. 2013. Water Research. 47: 3878-3886.

Fate of ZnO-NPs during biosolid digestion: Different Zn species can be discriminated using XANES

Zn-sulfide Zn-cysteine

Zn-phosphate Zn-substitute ferrihydrite

Zn-citrate

ZnO-NP1 (OECD standard) ZnO-NP2 (as NP1 but in triglyceride) ZnO-NP3 (Co-doped)

Nor

mal

ised

inte

nsity

Energy (eV) 9660 9680 9700 9720 9740 9760

Lombi et al., 2012

ZnO NPs in a model WWTP

Fate of ZnO-NPs during biosolid digestion: NPs disappearance is a function of formulation

ZnO-NP1

ZnO-NP2

ZnO-NP3

Energy (eV)

9660 9680 9700 9720 9740 9760

Control

Zn salt

b

Nor

mal

ised

inte

nsity

Time 3h

ZnO-NP1

ZnO-NP2

ZnO-NP3

9660 9680 9700 9720 9740 9760

Control

Zn salt

c

Nor

mal

ised

inte

nsity

Time 1 day

ZnO-NP1

ZnO-NP2

ZnO-NP3

Energy (eV)

9660 9680 9700 9720 9740 9760

Control

Zn salt

d

Nor

mal

ised

inte

nsity

Time 3 days

ZnO-NP1

ZnO-NP2

ZnO-NP3

Energy (eV)

9660 9680 9700 9720 9740 9760

Control

Zn salt

e

Nor

mal

ised

inte

nsity

Time 10 days

ZnO-NP1

ZnO-NP2

ZnO-NP3

Energy (eV)

9660 9680 9700 9720 9740 9760

Control

Zn salt

f

Nor

mal

ised

inte

nsity

Time 30 days

ZnO-NP1 ZnO-NP2

ZnO-NP3

Energy (eV)

9660 9680 9700 9720 9740 9760

Control Zn salt

a

Nor

mal

ised

inte

nsity

Time 0

Zn sulfides are the final products

Fate of ZnO-NPs during biosolid digestion: NPs disappearance is very rapid in all cases

Biosolids are not used straight away: effect of composting/stockpiling on Zn

Zn Sulfide Zn-P Zn-FeOH

Wastewater Anaerobic digestion Sewage sludge 2 months simulated

composting

Fate of Zinc Oxide Nanoparticles during Anaerobic Digestion of Wastewater and Post-treatment Processing of Sewage Sludge. E. Lombi, E. Donner, E. Tavakkoli, T. Turney, R. Naidu, B.W. Miller and K.G. Scheckel. 2012. Environ. Sci. Technol. 46: 9089-9096.

ZnO NPs in a model WWTP

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Summary

•  Ag converts primarily to Ag sulfide during WWTP; present in PC, SC, and anaerobic digesters

•  ZnO converts to ZnS and then to Zn-phosphate and adsorbed phases upon aging/composting

•  Incineration of Ag containing biosolids converts Ag sulfide to metallic Ag and Ag sulfate

•  The environmental risk assessment of NPs for the waste water-biosolids-agriculture pathway can rely on the abundant information already available concerning metals in biosolids.

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Synchrotron needs of environmental scientists…. Faster detectors with lower detection limits/broader energy ranges/higher resolution/minimal deadtime – Not all issues are related to contamination – Use of relevant concentrations in experiments

Smaller, focused beams will aid in understanding the dynamics of biogeochemical reactions – Soils and environmental media are heterogeneous

Ability to explore biological samples (plants, animals, organisms) without damaging or causing artifacts

Better computing/read-out – No need to have fast detectors if computers cannot keep up – Balance between time and data quality, avoid under-sampling

All in one beamlines – Key advantages to conduct µ-XRF, µ-XAS, and µ-XRD in one sitting

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What environmental scientists need to consider…. Synchrotron time is precious, plan accordingly, communicate with beamline scientists to ensure success

More environmental scientists are coming to synchrotrons; more competition – write better, convincing proposals – publish your results

Get involved – participate on proposal review panels

Don’t start your research project at the synchrotron – Conduct bench studies and understand your experimental design/system

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We should get synchrotron time

to confirm it!

In some cases, a synchrotron may not be necessary!