A bird's-eye view on

contaminant leaching research at ECN

J.J. Dijkstra (ECN)

A. van Zomeren (ECN)

September 2014

ECN-L--14-048

www.ecn.nl

A bird’s-eye view on contaminant leaching research at ECN

Joris Dijkstra, Andre van Zomeren E&EE – Environmental Assessment

Rapperswil 10-11 September 2014

Outline

• About ECN • What is contaminant leaching? • Our approach and activities: highlights and examples

Important processes, findings Laboratory test development and standardization Model development to predict leaching in practice Applications of our research: tools and know-how for the industry and government

• Who are our clients • What makes the ECN approach unique compared to other institutes?

ECN R&D fields

Policy Studies

Energy Engineering

Environment Energy Efficiency

Wind Energy

Solar Energy

Biomass

Process & Energy Industry

~600 employees

Position

fundamental research

industrial development

• independent • connecting partners

Industrial partners Universities

applied research

Work field: contaminant emissions to soil and groundwater

Similar questions for different scenarios

SOURCE TERM

TRANSPORT

IMPACT

Road base

L/S

[con

c]

Point of compliance

SOURCE TERM

TRANSPORT

IMPACT

SOURCE TERM

TRANSPORT

IMPACTIMPACT

Road baseRoad baseRoad base

L/S

[con

c]

L/S

[con

c]

Point of compliancePoint of compliance

Examples of domain and regulations around leaching

• NL: Soil Quality Decree (“construction products” including recycled materials), dredged sediments (under development)

• EU: Landfill Directive (waste that cannot be re-used) • EU: Construction Products Directive / Regulation: (under development) • United States, wastes: leaching limit values • Many more examples

“Horizontal” development leaching tests • Testing can be seen as the first step in “source term” characterization • >1000 different products and scenarios, > 1000 tests? Inefficient! • Construction products, soil, waste: similar leaching mechanisms • Use that knowledge, group by mechanisms • Horizontal: -> “level playing field”, consistent regulation, cost-efficient

brick

Roof tiles

Waste materials in construction, e.g., bottom ash

Contaminated soil, sludge

brick

Roof tiles

Waste materials in construction, e.g., bottom ash

Contaminated soil, sludge

Importance of release mechanisms

Time

[conc] ?

diffusion

percolation

Release by percolation (granular) Water passes through material Equilibrium High concentration

Mass Transfer Release (monoliths) Water is around material Diffusion from material surface Lower concentration

“Tank test” CEN/TS-2, TS15863 and EPA 1315

1 Sample

n analytical samples

A1

L1

A2 An

L2 Ln

Δt1 Δtn

or Monolith

Compacted Granular

n Leaching Intervals

Δt2

Diffusion

Release fresh product during “intended use” Regulated test method in NL (NEN7375) Standardized in TC351 (“TS2”), TC 292, US-EPA

pH dependency of release

2 4 6 8 10 12pH

Soluble salts (Cl, Br)

2 4 6 8 10 12

pH2 4 6 8 10 12

pH

Anions (SO42-

AsO43-, MoO4

2-, CrO4

2-)

Cations (Ni2+, Cu2+, Zn2+)

Log release (mg/kg)

• Release is a function of physical and chemical processes. • pH is one of the dominant chemical influencing factors

• pH varies in different environments; • pH of products changes during “intended use” of products (ageing); • pH will be different during recycling and end-of-life

pH dependence test

ISO TS 21268-4, CEN TS14497, CEN TS14497, US-EPA 1313

ECN philosophy on contaminated materials

• Not the total content is relevant but potential and actual leaching!

• Leaching depends strongly on pH

• Predictions based on generic processes: chemical speciation (rather than empirical / ad hoc approaches)

0.01

0.1

1

10

100

1000

10000

0 2 4 6 8 10 12 14 pH

Con

tam

inan

t con

cent

ratio

n (m

g/kg

)

Total concentration

Potentially leachable (“availability”)

Actual leaching

Me 2+

-(OH) x Me

Enhanced leaching by DOC

Me -DOC

ECN philosophy on contaminated materials

0.01

0.1

1

10

100

1000

10000

0 2 4 6 8 10 12 14 pH

Con

tam

inan

t con

cent

ratio

n (m

g/kg

)

Total concentration

New Concrete (pH 13)

“Aged” concrete (pH 8)

Fresh waste incineration ash (pH 12)

Landfill pH 4-6

Natural soils (pH 5-7)

(1) Development and standardization of leaching tests

• Development of generic appliccable leaching tests

• Standardization of these tests

• Development of automated systems for the market and licensing (together with Rohasys)

Standardized leaching tests with ECN involvement

Test/Matrix

Soil, sediments, compost and sludge Waste Mining waste Construction products

pH dependence test ISO/TS21268-4 CEN/TS14429 CEN/TS14429 CEN/TS14429CEN/TS14497 CEN/TS14497

EPA 1313 * EPA 1313 EPA 1313 EPA 1313Percolation test ISO/TS21268-3 CEN/TS14405 CEN/TS14405 CEN/TC351/TS-3

EPA 1314 * EPA 1314 EPA 1314 EPA 1314Monolith test CEN/TS15683 CEN/TC351/TS-2

EPA 1315 * EPA 1315 EPA 1315 EPA 1315Compacted granular test NEN7347 CEN/TC351/TS-2

EPA 1315 EPA 1315 EPA 1315 EPA 1315Redox capacity NEN 7348 NEN 7348Acid rock drainage PrEN15875

Reactive surfacesISO/CD12782 parts 1-5

* EPA drafts in preparation for inclusion in SW846

(3) Model development

Experiment

database withstability constants

Geochemical speciationmodelling

computerprogram

assumptions

Cu2+??

?

CuOH+

Cu+

Cu2+

H+ (pH)Cu2+

Experiment

database withstability constants

Geochemical speciationmodelling

computerprogram

assumptions

Cu2+??

?

CuOH+

Cu+

Cu2+

H+ (pH)Cu2+

Modified after M. Gfeller & R. Schulin, ETH, Zürich

1

(ORCHESTRA)2

• Leaching (source term) and

reactive transport in soil/groundwater are governed by the same processes

• based on fundamental thermodynamic parameters

• Sorption models with generic parameters 3,4

• Implementation in Orchestra2

• no fitting!

1 NIST/MINTEQ 4.0; 2 Meeussen (2003); 3 Milne et al. (2003); 4 Dzombak & Morel (1990)

Dijkstra et al., Environmental Science and Technology (2004), 38, 4390-4395; & (2009), 43, 6196-6201

Cd

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

0 2 4 6 8 10 12

pH

conc

entr

atio

n (m

ol/L

)

Pb

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

0 2 4 6 8 10 12

pH

data soil Idata soil IVdata soil VIImodel soil Imodel soil IVmodel soil VIItotal soil Itotal soil IVtotal soil VII

Zn

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0 2 4 6 8 10 12

pH

Cu

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

0 2 4 6 8 10 12

pH

Ni

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

0 2 4 6 8 10 12

pH

conc

entr

atio

n (m

ol/L

) Ni(OH)2(s)

Pb(OH)2(s)

Zn(OH)2(s)

Guideline for modelling of leaching processes → New Work Item ISO/NP 19648 accepted

Experiment

database withstability constants

Geochemical speciationmodelling

computerprogram

assumptions

Cu2+??

?

CuOH+

Cu+

Cu2+

H+ (pH)Cu2+

Experiment

database withstability constants

Geochemical speciationmodelling

computerprogram

assumptions

Cu2+??

?

CuOH+

Cu+

Cu2+

H+ (pH)Cu2+

Modified after M. Gfeller & R. Schulin, ETH, Zürich

(ORCHESTRA)

“Available” concentrations: → Leaching at low pH (≈0.4) (ISO TS 21268-4)

Dissolved organic matter: → Humic and fulvic acids*

ISO DIS 12782-5

Reactive surfaces in the solid phase: → SOM (humic/fulvic acids)*

ISO DIS 12782-4

→ Fe/Al (hydr)oxide minerals

ISO DIS 12782-1 (Feam) ISO DIS 12782-2 (Fecryst) ISO DIS 12782-3 (Alam)

(3) Model parameterization

(3) Model development

Accessible model tools and applications

LeachXS: database expert system (ECN, Vanderbilt University, DHI) • LeachXS Lite (free license, developed mainly for US-EPA) • LeachXS Pro (License fee)

• Databases with > 10000 results of leaching tests, > 1000 materials • Tools for interpretation, regulations, statistics, plotting, reporting • Tools for modelling

(4) Applications (recent and ongoing)

• Development criteria for sustainable landfills, dredged sediments • Quality improvement steel slag • Quality improvement bottom ash • Dossiers on environmental quality of construction products • Measurement and modelling for several clients, quality improvement, ... • ....

(4) Applications (recent and ongoing)

• ECN calculated emission criteria for construction products in Soil Quality Decree; together with RIVM (national public health institute)

• First time a fundamental model approach was followed; • Approach is now being used for criteria for sustainable landfills, dredged

sediments, ...

Citation analysis (peer-reviewed) ECN leaching research*

*Search terms: leaching – waste – ash – slag (ISI Web of Science)

Results found: 3,816 Sum of the Times Cited: 33,688 Average Citations per Item: 8.83

Results found: 32 Sum of the Times Cited: 1,107 Average Citations per Item: 34.6

No.1 most cited institutes

2 papers in top-10 most cited

12 papers in top-100

All peer-reviewed papers

All peer-reviewed papers

Thank you for your attention!

Example: enhanced metal leaching in natural and waste materials

….MSWI bottom ash : copper leaching often > limit value (no recycling possible)

Waste incineration & use of ashes in construction is beneficial use

What causes enhanced metal leaching?

• Several ECN publications in high impact journals (van Zomeren, Comans et al.)

• Patent on quality improvement

using a technique based on this process

• Development and standardization of methods: ISO DIS 12782-4/5

fulvic acids (16.9%)

humic acids (0.3%)

hydrophilic acids (82.7%)

Types of models Simple empirical (fitting): “Kd” • Advantage: simple • Disadvantange: too simple, large uncertainty, no generic validity

Scientific (based on insights in processes, no fitting): • Processes on molecular scale are more general valid. Makes assessments for

specific soils possible. • Since years ECN has been co-developing these models and testing against

measurements

Empirical: lineair partitioning (Kd)

Cd 1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

0 2 4 6 8 10 12 pH

conc

entr

atio

n (m

ol/L

)

Kd Kd = [Me]soil/[Me]solution Aanname Kd = constant! [Me]solution = [Me]soil/Kd

Main sorption processes in soils

(2) Identification of fundamental leaching processes: chemical form (“speciation”)

CuOH+

Cu2+Cu2+ Cu

Cu+

–

pH

temperature ionic strengthcomposition

(“available” fractions) time

solid particles(reactive mineral andorganic surfaces)

organische ligands(humic- and fulvic acids)

transport in soiland groundwateruptake by plants and(micro)organisms

CuOH+

Cu2+Cu2+ Cu

Cu+

–

pH

temperature ionic strengthcomposition

(“available” fractions) time

solid particles(reactive mineral andorganic surfaces)

organische ligands(humic- and fulvic acids)

transport in soiland groundwateruptake by plants and(micro)organisms

0,0E+00

1,0E-02

2,0E-02

3,0E-02

4,0E-02

5,0E-02

6,0E-02

0 200 400 600 800 1000Tijd (Jaar)

Time (years)

Aver

age

GW

con

c. (m

g/l)

Risk limit value

Stationary (Fig. 1A), lower sat.

Dynamic (Fig. 1B)

Preferential flow 20% mobile (Fig. 2A)

Preferential flow mixed layer (Fig. 3)

Copper

Model sensitivity – hydrology

Bronte

0 m

-1.0 m

-2.0 m

Gemengde bovenlaag en onderla

Bronterm

0 m

-1.0 m

-2.0 m

Gemiddeldeconcentratiegrondwater

Gemiddeldeconcentratiebodem

Stationaire waterstroming

Bronter

0 m

-1.0 m

-2.0 m

Niet-stationaire waterstroming

Bronterm

0 m

-1.0 m

-2.0 m

Gemiddeldeconcentratiegrondwater

Gemiddeldeconcentratiebodem

Nietbeschikbaar

Preferente stroming

Non-available

Source term Source term

Source term Source term

1B. Non-stationary water flow 1A.Stationary water flow

2A. Preferential flow (20%) 3. Preferential flow (mixed layer)

Average Conc. soil

Average Conc. GW

Average Conc. soil

Average Conc. GW

Original

Mixed layer

Different transport velocity in the soil

“Old” experiment at school: The ink of a marker consists of a cocktail of color agents. Some are bound more strongly to the coffe- paper (the “soil”) than others. This becomes visible when water flows through the paper due to capillary forces.

Time

Dijkstra et al., Environmental Science and Technology 43, 6196–6201 (2009)

IAGC Hitchon award 2009 for best scientific paper in Applied Geochemistry 2006-2009

on the pH-dependence test Dijkstra, J.J., Van der Sloot, H.A., Comans, R.N.J. (2006), Applied Geochemistry, 21, 335-351

ECN-L--14-048 Fout! Geen tekst met de opgegeven stijl in het document. 3

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