REMEDIATION AND REUSE OF CONTAMINATED ...cement08.in2p3.fr/Presentation Workshop pour site...

REMEDIATION AND REUSE OF CONTAMINATED SEDIMENTS: A NEW PHYSICAL-CHEMICAL PROCESS TO THE POINT

2nd International Workshop: Mechanism and Modelling of Waste/Cement InteractionsLe Croisic, October 12-16, 2008 october 2008

G. Ferrari, A. Careghini, S. Dastoli, L.Bonomo,L.DePropris, M.Gabellini, S.Saponaro

VOLUME OF SEDIMENT TO BE REMEDIATED 6.000.000 m3

Remediation and Reuse of Contaminated Sediment: a new physical-chemical

process to the point

VOLUME OF SEDIMENT TO BE DREDGED 13.000.000 m3

Analytical results of most contaminated sediment selected for this work (600.000 m3)

Compound Concentration (mg/kg d.w.)

ISPRAintervention

values

D. Lgs. 152/06

column B

HazardousSubstances

limitsChromium (total) 91 150 800 1000

Copper 210 75 600 250 000

Nickel 22 63 500 10 000

Lead 51 80 1 000 5 000

Zinc 314 165 1 500 1 000

Arsenic 18 32 50 1 000

Cadmium 1 1 15 1 000

Mercury 200 1 5 500

PCB (total) 3 0,2 5 50

>C12 petroleum hydrocarbons 5 000 - 750 1 000

HCB 0,003 0,005 5 1 000

PAH (total) 5 4 100 1 000

PCDD/F 2,8· 10–4 0,3 · 10–4 1 · 10–4 1 · 10–2

TBT 0,003 0.07 - 2 500



THE OBJECTIVE OF THIS STUDY IS TO EVALUATE THE EFFICIENCY OF A NEW PHYSICAL-CHEMICAL PROCESS FOR THE TREATMENT OF LARGE VOLUME OF CONTAMINATED SEDIMENTS FROM AUGUSTA BAY

REUSE OF RESULTING S/S MATERIAL



Ordinary Solidification/Stabilization (S/S) processes aims at encapsulating wastes into a solid cement matrix (Solidification) and decreasing mobility and toxicity of inorganic contaminants (Stabilization)

Poor attention has been paid in the past to impart to S/S materials good mechanical properties in a form which could allow their reuse. The reason for this is that, in Italy, S/S process has been normally used to reduce leaching before landfill disposal.



first step: production of a cementitious granular material, based on principles of high performance concrete (HPC)

use of superplasticizers and hydrophobic additive to reduce W/C and to improve watertightness

Environmental aspectService life Mechanical properties

MAPEI HPSS SYSTEMHigh Performance Solidification/Stabilization2 STEPS


process for the purpose

LOWER W/C AND HIGHER WATERTIGHTNESS MEANS

Lower leaching of contaminants

HIGHER ENVIRONMENTAL COMPATIBILITY

Lower permeability

HIGHER DURABILITY

Stronger bonds

HIGHER MECHANICAL STRENGTH

First step: granulation

Formulation:• Augusta harbour sediment (60%, dry basis) • Cement (CEM I, 52.5) (21%)• Additives: Mapeplast ECO 1-A e ECO 1-B (2 %)• Water (17%)

High shear mixer Rotating plate



W/C = 0.8

W/C+S = 0.2



0

5

10

15

20

25

30

35

40

<1 1 2 4 5,6 >8

RET

AIN

ED F

RA

CTI

ON

(%)

MESH SIZE (mm)

TYPICAL PARTICLE SIZE DISTRIBUTION OF GRANULAR MATERIAL FROM STEP 1

First step: granulation



INDUSTRIAL PLANT CAPACITY 4m3/h



Second step: thermal vacuum distillation (TDV) of the granular materialsfrom step 1. It is necessary when soil or sediments containorganic/volatile/semivolatile contaminants.

Low temperature distillation (max 250 °C) under high vacuum (≤20 mm Hg)

No degradation of cement matrixNo gas emissions because the process is operating in high vacuum conditionsNo dust problems because the process is operated on the granular materials

MAPEI HPSS SYSTEMHigh Performance Solidification/Stabilization2 STEPS



THERMAL VACUUM DISTILLATION EQUIPEMENTS

LAB SCALE (LEFT) – PILOT SCALE (RIGHT)

XRD after 24 hours XRD after 28 days

FISRST STEP - CEMENT HYDRATION



• no negative effect of sediment on set and hydration rate• portlandite consumption• monocarbonate formation

Fine quartz sand mortar

W/C = 0.8

ESEM images after 24 hours of hydration



Sediment based granular material

W/C = 0.8




ESEM images after 7 days of hydration


W/C = 0.8


W/C = 0.8




ESEM images after 28 days of hydration


W/C = 0.8


W/C = 0.8


SECOND STEP: THERMAL VACUUM DISTILLATION TVD

Evaluation of three different conditions

1. Temperature = 150 °C and tresidence = 16 hours;2. Temperature = 200 °C and tresidence = 6 hours;

development process parameters

3. Temperature = 250 °C and tresidence = 4 hours.



0

50

100

150

200

250

300

0 2 4 6 8 10 12

TIME (HOURS)

TEM

PER

ATU

RE

(°C

)

SELECTED CONDITIONS: 250 °C FOR 4 HOURS

250 °C, 4 hours

150 °C, 16 hours

Results of morphological analysis




Results of chemical analysis (1/3)Mercury

0

50

100

150

200

250

300

Sediment Step one 150 °C x16 h

200 °C x6 h

250 °C x4 h

gravel 1 gravel 2

mg

/ kg

d.w

.

C > 12 petroleum hydrocarbons

0

1000

2000

3000

4000

5000

6000

7000

Sediment Step one 150 °C x16 h

200 °C x6 h

250 °C x4 h

gravel 1 gravel 2m

g / k

g d.

w.




Results of chemical analysis (2/3)

PAHs (total)

0

1

2

3

4

5

6

7

8

9

10

Sediment Step one 150 °C x 16 h 200 °C x 6 h 250 °C x 4 h

mg

/ kg

d.w

.

PCBs (total)

0

1

2

3

4

5

6


mg

/ kg

d.w

.




PCDD/Fs ( WHO-TE index)

0

50

100

150

200

250

300

350

400


ng /

kg d

.w.

Results of chemical analysis (3/3)




Results of leaching test (EN 12457-2)

Mercury

0

0.2

0.4

0.6

0.8

1

1.2

Step one 150 °C x 16h

200 °C x 6 h 250 °C x 4 h gravel 1 gravel 2

μg /

L

Lead

0

10

20

30

40

50

60

Step one 150 °C x 16h

200 °C x 6 h 250 °C x 4 h gravel 1 gravel 2

μg /

L






Results of leaching test (EN 12457-2)


Copper

0

50

100

150

200

250

Step 1 150 °C x 16h 200 °C x 6h 250 °C x 4h

μg/L

Nickel

0

10

20

30

40

50

60

Step 1 150 °C x 16h 200 °C x 6h 250 °C x 4h

μg/

L

• pH value too high (13) – conditioning step in water

• Chlorides

• Selenium

Identified problems:



BEFORE VTD

AFTER VTD (250 °CFOR 4 HOURS)

AFTER REHYDRATION

CONDITIONING STEP IN WATER FOR 7 DAYS



0

5

10

15

20

25

30

35

40

EFFUSIVEROCKS

LIMESTONE MIXEDAGGREGATE

SILTYLIMESTONE

BLAST FURNACESLAG

AC

V (%

)

TYPE OF AGGREGATE

MAPEI HPSS SYSTEM

CONCLUSIONS (1/2)



MAPEI HPSS TREATMENT WAS EFFECTIVE IN STABILIZING INORGANIC AND REMOVING VOC AND SVOC WHEN APPLIED TO MARINE SEDIMENT OF THE AUGUSTA HARBOUR (SICILY)

1.

HYDRATION RATE WAS NOT AFFECTED BY THE SEDIMENT, BUT CHEMICAL INTERACTION BETWEEN CEMENT AND SEDIMENT WERE EVIDENT (PORTLANDITE CONSUMPTION, MONOCARBONATE FORMATION AND MORPHOLOGICAL MODIFICATION OF THE HYDRATED MATRIX)

2.

THERMAL TREATMENT OF HYDRATED GRANULAR PRODUCTS HAD A POSITIVE EFFECT IN REDUCING THE LEACHING OF COPPER, NICKEL AND COBALT

3.

4. THERMAL TREATMENT OF HYDRATED GRANULAR PRODUCTS DECOMPOSED AFt AND AFm PHASES BUT REHYDRATION IN WATER PROMOTE THEIR REFORMATION



5.

CONCLUSIONS (2/2)

Pollutants mass balancea.

FUTURE DEVELOPMENTS

More complete tests for physical and mechanical properties and durability (total porosity, Los Angeles, Micro-Devall, alkali-silicareaction, freezing-thawing) will be performed

b.

pH dependent leaching tests and leaching column test c.

Speciation of mercuryd.

THERMAL TREATMENT OF HYDRATED GRANULAR PRODUCTS AT 250 °C DID NOT CAUSE THE DEGRADATION OF THE CEMENT MATRIX AND THE RESULTING PRODUCTS SHOWED GOOD MECHANICAL PROPERTIES FOR REUSE OPTION

Thank you for your attention!!!



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