Post on 28-Mar-2018
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!