Remediation of Soils Contaminated with Remediation of Soils - - PowerPoint PPT Presentation

V.

• V. Schifano

Schifano, C. MacLeod , C. MacLeod Arcadis Arcadis Geraghty Geraghty & Miller International Inc. (UK) & Miller International Inc. (UK) A.W.L. A.W.L. Dudeney Dudeney, R. , R. Dudeney Dudeney Imperial College, London (UK) Imperial College, London (UK)

Remediation of Soils Contaminated with Remediation of Soils Contaminated with Petroleum Hydrocarbons Petroleum Hydrocarbons Using Quicklime Mixing Using Quicklime Mixing

Outline of Presentation Outline of Presentation

• Introduction
• Objectives
• Experimental Study
• Results
• Conclusions

Introduction Introduction

• Why Quicklime?
• Mechanisms of Stabilisation/Solidification
• Adsorption on (CaOH)2 and other precipitates
• Encapsulation into the CSH/CAH cementitious matrix
• Physical entrapment within the soil macro-aggregates voids
• Thermal Effects
• Volatilisation
• Degradation in alkaline, O2 rich environment
• Drying of soils and improvement of mechanical properties

Objectives Objectives

• To examine the effects of Quicklime mixing on

the a) concentration and b) leachability of petroleum hydrocarbons compounds in clayey soils

• To evaluate the effects of variables such as soil

type, moisture content and quicklime content

• n a) and b).

Experimental Study Experimental Study

Materials

• Natural contaminated samples of London clay

(45% sand; 35% silt; 20% clay; w = 27 – 36%; wl= 43 – 61%; wp = 17 –22%) from Petrol Filling Station in Hampshire.

• Artificial samples of Sand and Kaolinite to

which Petrol and Diesel were added.

• Quicklime (Limbase 60, Buxton Lime Industries

Ltd).

Experimental Study Experimental Study

Methods

• BS methods for Moisture Content, Atterberg

Limits, pH

• Chemical Analyses on TPH working group
• GRO by GC-FID
• EPH Accelerated Solvent Extraction in + GC-FID
• Leachates by DIN 34-414 (CO2 saturated water

at pH 5.6; water to solid 10:1).

Experimental Study Experimental Study

Preparation of Samples

• Dry mixed Sand and kaolinite
• Added Distilled Water and Petrol (3g/kg) and

Diesel (3g/kg)

• Homogeneise by hand-mixing (stainless steel

spatula/rod on glass plate or plastic dish)

Experimental Study Experimental Study

Preparation of Samples

• Stored in Refrigerator for one week during

which samples were periodically mixed

• Quicklime added and hand-mixed
• Samples stored in sealed plastic containers at

room temperature

Experimental Study Experimental Study

Preparation of Samples: a) London Clay

____________________________ Sample w CaO pH ____________________________ LC1U 32 7.71 LC1A 32 5* 11.37 LC1B 64* 5* 11.51 LC2U 32 7.75 LC2A 32 5* 11.35 LC2B 32 10* 11.67 LC2C 32 20* 12.72 LC2D 64* 5* 11.34 ____________________________________ Note: w=moisture content; * estimated value

Experimental Study Experimental Study

Preparation of Samples: b) Sand/Kaolinite Samples

Sample Sand Kaol. w CaO G/D % % % % mg/kg O 90 10 24 6000 P 75 25 29 6000 Q 50 50 40 6000 R 50 50 60 6000 S 50 50 20 6000 A 90 10 24 5 6000 B 90 10 24 10 6000 C 90 10 24 20 6000 D 75 25 29 10 6000 E 50 50 40 10 6000 F 50 50 60 10 6000 G 50 50 20 10 6000 Note: G/D = Gasoline/Diesel.

Experimental Study Experimental Study

Upon Mixing with Quicklime

• Temperature, pH, moisture content, Atterberg Limits
• Concentrations of Petroleum Hydrocarbons in Soils
• Concentrations of Petroleum Hydrocarbons in Leachates

Results Results

Temperature Changes during quicklime mixing: Sand Samples

20 40 60 80 100 120 140 160 5 10 15 20 25 30 35 40 45 50 55 60 65

Time (minutes) Temperature (ºC)

Beaker w=5%, CaO= 15% Beaker w=10%, CaO 30% Open Tray w=15%, CaO 45%

Table 4. Pre- and Post-Treatment pH of K/S Mixtures ______________________________________________________ SAMPLE A B C D E F G Time (days) ______________________________________________________ t=0 5.5 5.5 5.5 5.6 5.5 5.4 5.3 t=1 12.3 12.3 12.3

• t=3
• 12.3

12.1 12.8 12.2 t=7 12.3 12.3 12.5 12.6 12.5 12.5 12.5 t=15 12.6 12.5 12.5 12.2 12.4 12.4 12.6 t=30 12.6 12.6 12.7 12.6 12.6 12.6 12.7 _______________________________________________________

Results Results

Results Results

Table 4. Pre- and Post-Treatment Moisture Content, w (%),

• f Kaolinite / Sand Mixtures

__________________________________________________________ SAMPLE A B C D E F G Time (days) __________________________________________________________ t=0 24 24 24 29 40 60 20 t=1 20 13 7

• t=15

19 13 8 18 29 48 12 t=30 19 13 8 18 28 45 12 ___________________________________________________________

Table 4. Post-Treatment Liquid Limit, wl (%),

• f Kaolinite / Sand Mixtures

______________________________________________________ SAMPLE A B C D E F G Time (days) ______________________________________________________ t=0 23 23 23 23 34 34 34 t=1 24 27 29

• t=3
• 36

52 57

• t=7

26 28 29 37 52 51 47 t=15 26 29 30 38 52 60 48 t=30 26 28 29 36 52 61 44 ______________________________________________________

Results Results

Results Results

Table 4. Pre- and Post-Treatment Plastic Limit, wp (%), of Kaolinite / Sand Mixtures ______________________________________________________ SAMPLE A B C D E F G Time (days) ______________________________________________________ t=0 18 18 18 16 23 23 23 t=1 19 21 21

• t=3
• 25

31 34 28 t=7 22 22 22 22 30 32 28 t=15 21 20 20 23 31 34 28 t=30 18 20 19 24 31 35 28 ______________________________________________________

Results Results

• Changes in moisture content, liquid limit, plastic limit and pH of

the treated sample A-G, occurred rapidly upon quicklime mixing (first determination after 1 day), then continued at a much lower rate.

• The largest changes in liquid and plastic limit occurred in the

sample with the largest initial moisture content (sample F).

_______________________________________________________ COMPOUND LC1U LC1A LC1B CaO 5 5 W 32 32 64 Concentrations (mg/kg) Benzene 0.03 <0.01 <0.01 Toluene 0.03 <0.01 <0.01 Ethylbenzene 0.03 <0.01 <0.01 Xylenes 0.08 <0.01 <0.01 MTBE 0.22 <0.01 <0.01 Aliphatics C5-C6 0.02 <0.01 <0.01 C6-C8 1.08 <0.01 <0.01 C8-C10 0.84 0.03 0.23 C10-C12 2.01 0.39 0.66 C12-C16 172.5 35.2 25.5 C16-C21 20.1 13.2 10.2 C21-C35 46.1 25.5 25.9 Aromatics EC8-EC10 1.38 0.04 0.35 EC10-EC12 3.01 0.59 0.99 EC12-EC16 1.7 <0.1 1.7 EC16-EC21 1.4 <0.1 <0.1 EC21-EC35 0.9 <0.1 <0.1_ TPH 250.98 74.96 65.56

London Clay Samples Concentrations (mg/kg)

_________________________________________________________________________________ COMPOUND LC2U LC2A LC2B LC2C LC2D CaO 5 10 20 5 W 32 32 32 32 64 _________________________________________________________ Benzene 0.02 <0.01 <0.01 <0.01 <0.01 Toluene 0.03 <0.01 <0.01 <0.01 <0.01 Ethylbenzene 0.03 <0.01 <0.01 <0.01 0.03 Xylenes 0.07 <0.01 <0.01 <0.01 <0.01 MTBE 0.23 <0.01 <0.01 <0.01 0.05 Aliphatics C5-C6 0.06 0.04 <0.01 <0.01 0.02 C6-C8 1.28 0.05 <0.01 <0.01 0.08 C8-C10 0.94 0.01 0.06 0.14 0.50 C10-C12 1.78 0.10 0.51 0.63 1.13 C12-C16 93.9 21.8 33.4 25.6 24.1 C16-C21 7.9 3.5 3.9 3.2 3.9 C21-C35 13.2 12.0 <0.1 <0.1 8.6 Aromatics EC8-EC10 1.52 0.02 0.09 0.21 0.86 EC10-EC12 2.68 0.14 0.76 0.94 1.69 EC12-EC16 6.4 3.2 <0.1 <0.1 1.2 EC16-EC21 9.1 3.1 <0.1 <0.1 <0.1 EC21-EC35 2.5 1.9 <0.1 <0.1 <0.1 TPH 141.26 45.88 38.69 31.69 42.08

London Clay Samples Concentrations (mg/kg)

London Clay Samples Concentrations (mg/kg)

Results Results

Hydrocarbon content in London Clay samples LC2U (without quicklime) and LC2B (with 10% quicklime)

0.01 0.1 1 10 100 B e n z e n e T

• l

u e n e E t h y l b e n z e n e X y l e n e s M T B E A l i p h a t i c s C 5

• C

6 C 6

• C

8 C 8

• C

1 C 1

• C

1 2 C 1 2

• C

1 6 C 1 6

• C

2 1 C 2 1

• C

3 5 A r

• m

a t i c s E c 8

• E

c 1 E c 1

• E

c 1 2 E c 1 2

• E

c 1 6 E c 1 6

• E

c 2 1 E c 2 1

• E

c 3 5

Concentration (mg/Kg)

LC2U LC2B

K/S Samples Concentrations (mg/kg)

_________________________________________________________________ O(t=0-30) A(t=1) A(t=17) A(t=30) Benzene 0.33-0.02 <0.01 <0.01 <0.01 Toluene 11.64-0.65 <0.01 0.05 0.03 Ethylbenzene 2.98-0.81 0.15 0.04 0.03 Xylenes 17.07-4.98 1.16 0.28 0.26 MTBE 2.42-1.07 0.05 <0.01 <0.01 Aliphatics C5-C6 1.30-0.26 0.04 <0.01 0.09 C6-C8 6.54-12.41 1.64 0.70 0.77 C8-C10 2.76-9.30 1.47 1.00 1.66 C10-C12 2.39-6.62 1.88 1.29 1.61 C12-C16 367.3-471.5 165.7 570.7 136.6 C16-C21 952.3-749.1 431.5 1121.7 379.3 C21-C35 302.6-205.4 158.6 328.1 120.9 EC8-EC102 4.19-19.74 3.51 1.81 2.79 EC10-EC12 3.59-9.93 2.82 1.94 2.42 EC12-EC16 0.6-68.7 0.3 3.4 3.6 EC16-EC21 4.3-139.1 0.3 12.8 7.0 EC21-EC35 0.2-60.5 0.3 4.6 11.9 TPH 1679.96-1753.22 768.07 2048.12 668.63

K/S Samples Concentrations (mg/kg)

________________________________________________________________ SAMPLE O(t=0-30) B(t=1) B(t=17) B(t=30) _______________________________________________________________ Benzene 0.33-0.02 <0.01 <0.01 <0.01 Toluene 11.64-0.65 <0.01 <0.01 <0.01 Ethylbenzene 2.98-0.81 <0.01 <0.01 <0.01 Xylenes 17.07-4.98 0.06 <0.01 0.02 MTBE 2.42-1.07 <0.01 <0.01 <0.01 Aliphatics C5-C6 1.30-0.26 <0.01 <0.01 <0.01 C6-C8 6.54-12.41 <0.01 <0.01 <0.01 C8-C10 2.76-9.30 0.23 0.04 0.08 C10-C12 2.39-6.62 0.36 0.07 0.11 C12-C16 367.3-471.5 159.4 556.8 158.0 C16-C21 952.3-749.1 405.4 1367.9 441.7 C21-C35 302.6-205.4 120.6 414.4 138.8 Aromatics EC8-EC10 24.19-19.74 0.40 0.06 0.13 EC10-EC12 3.59-9.93 0.54 0.11 0.16 EC12-EC16 0.6-68.7 17.2 9.3 4.4 EC16-EC21 4.3-139.1 48.9 30.2 10. EC21-EC35 0.2-60.5 22.7 49.1 14.3 TPH 1679.96-1753.22 775.63 2427.87 767.65

K/S Samples Concentrations (mg/kg)

____________________________________________________________________________ SAMPLE O(t=0-30) C(t=1) C(t=17) C(t=30) __________________________________________________________________________ Benzene 0.33-0.02 <0.01 <0.01 <0.01 Toluene 11.64-0.65 <0.01 <0.01 <0.01 Ethylbenzene 2.98-0.81 <0.01 <0.01 <0.01 Xylenes 17.07-4.98 <0.01 <0.01 0.02 MTBE 2.42-1.07 <0.01 <0.01 <0.01 Aliphatics C5-C6 1.30-0.26 <0.01 <0.01 <0.01 C6-C8 6.54-12.41 <0.01 <0.01 <0.01 C8-C10 2.76-9.30 0.06 0.03 0.06 C10-C12 2.39-6.62 0.35 0.06 0.04 C12-C16 367.3-471.5 85.0 359.4 211.7 C16-C21 952.3-749.1 261.3 1039.9 682.8 C21-C35 302.6-205.4 84.1 340.9 201.3 Aromatics EC8-EC10 24.19-19.74 0.08 0.05 0.10 EC10-EC12 3.59-9.93 0.52 0.09 0.06 EC12-EC16 0.6-68.7 8.3 1.9 6.4 EC16-EC21 4.3-139.1 29.9 13.5 16.2 EC21-EC35 0.2-60.5 16.2 8.9 19.7 TPH 1679.96-1753.22 485.88 1764.68 1138.39

K/S Leachates Concentrations (µg/l)

_________________________________________________ COMPOUND O(t=30) B(t=1) B(t=30) Benzene <10 <10 <10 Toluene 39 <10 <10 Ethylbenzene 146 <10 <10 Xylenes 958 <10 <10 MTBE 41 <10 <10 Aliphatics C5-C6 52 <10 <10 C6-C8 849 <10 <10 C8-C10 1394 <10 <10 C10-C12 698 <10 <10 C12-C16 <10 52 <10 C16-C21 <10 31 <10 C21-C35 <10 <10 <10 Aromatics EC8-EC10 3195 <10 <10 EC10-EC12 1048 <10 <10 EC12-EC16 14 74 <10 EC16-EC21 <10 48 <10 EC21-EC35 17 33 22 TPH 7306 238 22

K/S Samples

Results Results

Total Petroleum Hydrocarbons in Leachate after one month from CaO mixing

1 10 100 1000 10000 O (t=30) A (T=30) B (T=30) C (T=30)

All samples 90% sand, 10% kaolinite. O control sample. Samples A, B, C mixed with 5, 10 and 20% CaO respectively

Concentration (ug/l)

Control Treated Samples

Conclusions Conclusions

• Changes in Atterberg Limits followed the same behavior as typically

reported in the literature for uncontaminated kaolinite clays. Therefore, it can be concluded that the large initial concentrations of petroleum hydrocarbon compounds present in sand/kaolinite mixtures did not inhibit the occurrence of reactions responsible for Atterberg Limit changes in the soil samples

• Mixing soils with quicklime resulted in a rapid decrease of concentration
• f petroleum hydrocarbon compounds measured in all samples of

London clay and artificial sand/kaolinite mixtures.

Conclusions Conclusions

• The decreases in BTEX and Light Aromatics and Aliphatics can be

explained as mostly due to volatilisation due to temperature increases.

• The decreases of heavy hydrocarbons is though to be in part due to

encapsulation of the compounds in clay macro-aggregates and fixation

• f the compounds within the matrix of the pozzolanic reaction products

and in part to other unknown degradation processes.

• Quicklime mixing caused a progressive reduction in the hydrocarbon
• leaching. After 30 days from mixing, the leachate concentrations were

near or below analytical method detection limits.

Conclusions Conclusions

• The study has confirmed quicklime mixing as a promising on

site treatment method for high to low plasticity clayey soils, contaminated with petroleum hydrocarbon using various mixing water and quicklime contents.