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

Remediation of Soils Contaminated with Remediation of Soils Contaminated with Petroleum Hydrocarbons Petroleum Hydrocarbons Using Quicklime Mixing Using Quicklime Mixing V. Schifano Schifano, C. MacLeod , C. MacLeod V. Arcadis Geraghty Geraghty & Miller International Inc. (UK) & Miller International Inc. (UK) Arcadis A.W.L. Dudeney A.W.L. Dudeney, R. , R. Dudeney Dudeney Imperial College, London (UK) Imperial College, London (UK)

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, O 2 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 on 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 (CO 2 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 0 7.71 LC1A 32 5* 11.37 LC1B 64* 5* 11.51 LC2U 32 0 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 0 6000 P 75 25 29 0 6000 Q 50 50 40 0 6000 R 50 50 60 0 6000 S 50 50 20 0 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 160 140 Temperature (ºC) 120 Beaker w=5%, CaO= 15% 100 Beaker 80 w=10%, CaO 30% 60 Open Tray 40 w=15%, CaO 45% 20 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Time (minutes)

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

Results Results Table 4. Post-Treatment Liquid Limit, w l (%), of 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 Table 4. Pre- and Post-Treatment Plastic Limit, w p (%), 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 0 5 5 W 32 32 64 Concentrations (mg/kg) London Clay Samples Benzene 0.03 <0.01 <0.01 Concentrations (mg/kg) 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

_________________________________________________________________________________ COMPOUND LC2U LC2A LC2B LC2C LC2D CaO 0 5 10 20 5 W 32 32 32 32 64 London Clay Samples _________________________________________________________ Benzene 0.02 <0.01 <0.01 <0.01 <0.01 Concentrations Toluene 0.03 <0.01 <0.01 <0.01 <0.01 Ethylbenzene 0.03 <0.01 <0.01 <0.01 0.03 (mg/kg) 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

Results Results London Clay Samples Concentrations (mg/kg) Hydrocarbon content in London Clay samples LC2U (without quicklime) and LC2B (with 10% quicklime) Concentration (mg/Kg) 100 LC2U 10 LC2B 1 0.1 0.01 E e 6 8 0 2 6 1 5 0 2 6 1 5 e s e s s n B C C 1 1 1 2 3 1 1 2 3 e 1 n c c n C C C C e C i c c c c c e n T i e - - t t E E E E u 5 6 E z e M a a z - - - - - l C C 8 0 2 6 1 n l h m - - - - - n o y 8 0 2 6 1 C 1 1 1 2 e p e T X o 1 1 1 2 C C C C c B i b l r E c c c c A A l y E E E E h t E