KÆRGÅRD PLANTAGE ISCO LABORATORY TESTS Lars R. Bennedsen, Torben H. Jørgensen, Rambøll Jarl Dall-Jepsen, Lars Nissen, Cowi Neal Durant, Leah MacKinnon, Geosyntec Prasad Kakarla, Isotec Erik G. Søgaard, Aalborg University Joseph Pignatello, Connecticut Agricultural Experiment Station Mette Christophersen, Jørgen Fjeldsø Christensen, Region Syddanmark Preben Bruun, Miljøstyrelsen
KÆRGÅRD PLANTAGE
CONTAMINATION About 286,000 m 3 wastewater legally discharged i 6 waste pits from 1956-1973, including: 40,000 ton inorganic salt 15,000 ton salts of organic acids 1,500 ton sulfonamoides, barbiturates, aniline, pyridine, phenols, benzene, toluene. 340 ton chlorinated solvents Lithium, mercury, cyanide, etc.
CONCEPTUAL MODEL Treatment area
REMEDIATION IN KÆRGÅRD FIRST STAGE Divided into 3 parts: 1. Excavation of highly contaminated soil in pit 1 and 2 (2008-2009) 2. Test, selection, and design of remedation technique for contamination located below the ground water tabel (2009-2011) Chemical - Modified Fentons Reagent (MFR) Chemical - Activeted sodium persulfate (ASP) This presentation Thermal Steam Biological Reductive dechlorination 3. Full scale treatment of contamination in pit 1 and 2
CONTAMINANTS IN PIT 1 AND 2 Pit 1 Pit 2 PCE 10,000 kg 40,000 kg Benzene 65 kg 5 kg Toluene 600 kg 350 kg Mercury 100 kg 100 kg Cyanide 200 kg 100 kg
TYPICAL CONCENTRATIONS - PIT 1 Soil (mg/kg) Water (mg/l) PCE 100-1000 100 Toluene 1-50 0.1-10 Benzene 1 0.1-10 Sulfonamides - 0-100 Barbiturates - 0.2-0.3 Aniline - 0.05-0.1 Cyanide 1-100 - Hg 10-100 - Concentrations vary with depth and geology
TYPICAL CONCENTRATIONS - PIT 1 Treatment area ph 6-8 Conductivity 30-1000 Bicarbonate Oxygen Nitrate Iron Sulfate Methane 75-125 mg/l <1 mg/l <0.5 mg/l 1-20 mg/l 10-1000 mg/l 5-20 mg/l
OBJECTIVES LABORATORY TESTS Evaluate the applicability of MFR and ASP in Kærgård Plantage and ensure an optimal design and treatment strategy for the pilot tets by determining: 1. Buffer capacity 2. Stability of oxidants 3. Best activation technique for persulfate 4. Oxidation effectiveness 5. Mobilization og cyanide and metals 6. Byproductformation 124 batch and column experiments at AAUE
INTRODUCTION Soil samples M105 (sand, gravel) 4-7 (1mg/kg Hg, 7mg/kg CN, Free phase) 8-10 12-14 Mix 4-14 (100-250 mg/kg PCE) Water samples M105 (3-6, 13.5-14.5 m bgs) Oxidant dosages Comparable to the suggested pilot test
CONCEPTUAL MODEL - PIT 1 Pit Test cell
BUFFER CAPACITY
ACTIVATION OF PERSULFATE
STABILITY OF OXIDANT MFR ASP
DEGRADATION
MOBILIZATION - BATCH Very similar mobilization with MFR and ASP No mobilization og Hg to air or water Indications of cyanide mobilization Cr increased from 2-5 to 25-53 µg/l for both MFR and ASP
MOBILIZATION - COLUMN Oxidant injection started Cr increased from <2.5 µg/l to 73 and 119 µg/l for MFR and ASP
BY-PRODUCTS FROM ASP (MFR AVTIVATED)
CONCLUSION MFR ASP (MFR activated) ph 2-4 1-2 Longevity t ½ =60-230 h t ½ =>300 h Longevity (activated) t ½ =7-10 h t ½ =2-3 h PCE and BTEX removal 99-100% 98-100% Secondary COC - effect Good Good Mobilization Some CN, Cr More Cu, As, Pb, Zn Some CN, Cr More Cu, As, Pb, Zn Gas production Gas is created Less gas due to lower H 2 O 2 conc. Decomposition products Decomposes to carbon dioxide and water 1 kg sodium persulfate decomposes to 0.81 kg sulphate and 0.19 kg sodium. Generates acidity.
PILOT TESTS Oxidant dose: MFR (~13 g H 2 O 2 /kg soil) ASP (~15 g Na 2 S 2 O 8 /kg soil +~6 g H 2 O 2 /kg soil) Based on contaminant mass and soil oxidant demand(sod) 3-5 injection events Start up: spring 2010
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