REMEDIATION AND REUSE OF CONTAMINATED SEDIMENTS: A NEW PHYSICAL-CHEMICAL PROCESS TO THE POINT G. Ferrari, A. Careghini, S. Dastoli, L.Bonomo, L.DePropris, M.Gabellini, S.Saponaro 2nd International Workshop: Mechanism and Modelling of Waste/Cement Interactions Le Croisic, October 12-16, 2008 october 2008
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point VOLUME OF SEDIMENT TO BE DREDGED 13.000.000 m 3 VOLUME OF SEDIMENT TO BE REMEDIATED 6.000.000 m 3
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point Analytical results of most contaminated sediment selected for this work (600.000 m 3 ) ISPRA D. Lgs. Hazardous Concentration Compound intervention 152/06 Substances (mg/kg d.w.) values column B limits Chromium (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 HCB 0,003 0,005 5 1 000 PAH (total) 5 4 100 1 000 PCB (total) 3 0,2 5 50 >C12 petroleum 5 000 - 750 1 000 hydrocarbons PCDD/F 2,8 · 10 –4 0,3 · 10 –4 1 · 10 –4 1 · 10 –2 TBT 0,003 0.07 - 2 500
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point 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. 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
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point MAPEI HPSS SYSTEM High Performance Solidification/Stabilization 2 STEPS 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 aspect Service life Mechanical properties
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process for the purpose LOWER W/C AND HIGHER WATERTIGHTNESS MEANS Lower leaching of Stronger bonds Lower permeability contaminants HIGHER HIGHER HIGHER ENVIRONMENTAL MECHANICAL DURABILITY COMPATIBILITY STRENGTH
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point First step: granulation High shear mixer Rotating plate Formulation: • Augusta harbour sediment (60%, dry basis) W/C = 0.8 • Cement (CEM I, 52.5) (21%) W/C+S = 0.2 • Additives: Mapeplast ECO 1-A e ECO 1-B (2 %) • Water (17%)
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point 40 RETAINED FRACTION (%) TYPICAL PARTICLE SIZE 35 DISTRIBUTION OF GRANULAR 30 MATERIAL FROM STEP 1 25 20 15 10 5 0 <1 1 2 4 5,6 >8 MESH SIZE (mm)
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point First step: granulation INDUSTRIAL PLANT CAPACITY 4m 3 /h
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point MAPEI HPSS SYSTEM High Performance Solidification/Stabilization 2 STEPS Second step : thermal vacuum distillation (TDV) of the granular materials from step 1. It is necessary when soil or sediments contain organic/volatile/semivolatile contaminants. Low temperature distillation (max 250 °C) under high vacuum ( ≤ 20 mm Hg) No degradation of cement matrix No gas emissions because the process is operating in high vacuum conditions No dust problems because the process is operated on the granular materials
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point THERMAL VACUUM DISTILLATION EQUIPEMENTS LAB SCALE (LEFT) – PILOT SCALE (RIGHT)
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point FISRST STEP - CEMENT HYDRATION XRD after 24 hours XRD after 28 days • no negative effect of sediment on set and hydration rate • portlandite consumption • monocarbonate formation
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point FISRST STEP - CEMENT HYDRATION ESEM images after 24 hours of hydration Fine quartz sand mortar Sediment based granular material W/C = 0.8 W/C = 0.8
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point FISRST STEP - CEMENT HYDRATION ESEM images after 7 days of hydration Fine quartz sand mortar Sediment based granular material W/C = 0.8 W/C = 0.8
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point FISRST STEP - CEMENT HYDRATION ESEM images after 28 days of hydration Fine quartz sand mortar Sediment based granular material W/C = 0.8 W/C = 0.8
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD 300 TEMPERATURE (°C) 250 200 150 100 50 0 0 2 4 6 8 10 12 TIME (HOURS) Evaluation of three different conditions development process parameters 1. Temperature = 150 °C and t residence = 16 hours; SELECTED CONDITIONS: 250 °C FOR 4 HOURS 2. Temperature = 200 °C and t residence = 6 hours; 3. Temperature = 250 °C and t residence = 4 hours.
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of morphological analysis 150 °C, 16 250 °C, 4 hours hours
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of chemical analysis (1/3) Mercury C > 12 petroleum hydrocarbons 7000 300 6000 250 5000 200 mg / kg d.w. mg / kg d.w. 4000 150 3000 100 2000 50 1000 0 0 Sediment Step one 150 °C x 200 °C x 250 °C x gravel 1 gravel 2 Sediment Step one 150 °C x 200 °C x 250 °C x gravel 1 gravel 2 16 h 6 h 4 h 16 h 6 h 4 h
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of chemical analysis (2/3) PAHs (total) PCBs (total) 10 6 9 5 8 7 4 mg / kg d.w. mg / kg d.w. 6 5 3 4 2 3 2 1 1 0 0 Sediment Step one 150 °C x 16 h 200 °C x 6 h 250 °C x 4 h Sediment Step one 150 °C x 16 h 200 °C x 6 h 250 °C x 4 h
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of chemical analysis (3/3) PCDD/Fs ( WHO-TE index) 400 350 300 250 ng / kg d.w. 200 150 100 50 0 Sediment Step one 150 °C x 16 h 200 °C x 6 h 250 °C x 4 h
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of leaching test (EN 12457-2) Mercury Lead 60 1.2 50 1 40 0.8 μ g / L μ g / L 30 0.6 0.4 20 0.2 10 0 0 Step one 150 °C x 16 200 °C x 6 h 250 °C x 4 h gravel 1 gravel 2 Step one 150 °C x 16 200 °C x 6 h 250 °C x 4 h gravel 1 gravel 2 h h
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point SECOND STEP: THERMAL VACUUM DISTILLATION TVD Results of leaching test (EN 12457-2) Copper Nickel 250 60 50 200 40 150 μ g/L μ g/L 30 100 20 50 10 0 0 Step 1 150 °C x 16h 200 °C x 6h 250 °C x 4h Step 1 150 °C x 16h 200 °C x 6h 250 °C x 4h Identified problems: • pH value too high (13) – conditioning step in water • Chlorides • Selenium
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point BEFORE VTD AFTER VTD (250 °C FOR 4 HOURS) CONDITIONING STEP IN WATER FOR 7 DAYS AFTER REHYDRATION
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point 40 35 30 25 ACV (%) 20 15 MAPEI HPSS 10 SYSTEM 5 0 EFFUSIVE LIMESTONE MIXED SILTY BLAST FURNACE ROCKS AGGREGATE LIMESTONE SLAG TYPE OF AGGREGATE
Remediation and Reuse of Contaminated Sediment: a new physical-chemical process to the point CONCLUSIONS (1/2) 1. MAPEI HPSS TREATMENT WAS EFFECTIVE IN STABILIZING INORGANIC AND REMOVING VOC AND SVOC WHEN APPLIED TO MARINE SEDIMENT OF THE AUGUSTA HARBOUR (SICILY) 2. 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) 3. THERMAL TREATMENT OF HYDRATED GRANULAR PRODUCTS HAD A POSITIVE EFFECT IN REDUCING THE LEACHING OF COPPER, NICKEL AND COBALT 4. THERMAL TREATMENT OF HYDRATED GRANULAR PRODUCTS DECOMPOSED AFt AND AFm PHASES BUT REHYDRATION IN WATER PROMOTE THEIR REFORMATION
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