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In Situ Radio Frequency Heating (ISRFH) at a Former Service Station in Kent.

In Situ Radio Frequency Heating (ISRFH) at a Former Service Station in Kent. Contaminated Land and Brownfield Remediation London 22 September 2009 Giacomo Maini, BSc, PhD Managing Director Ecologia Environmental Solutions Ltd. Ecologia. We are a technical remediation contractor

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In Situ Radio Frequency Heating (ISRFH) at a Former Service Station in Kent.

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  1. In Situ Radio Frequency Heating (ISRFH) at a Former Service Station in Kent. Contaminated Land and Brownfield Remediation London 22 September 2009 Giacomo Maini, BSc, PhD Managing Director Ecologia Environmental Solutions Ltd

  2. Ecologia • We are a technical remediation contractor • We are a UK company • Offices in Kent, Devon, Staffordshire and Bologna • Our workshops are at our headquarters in Kent

  3. RF Technology • Background of the RF technology • Partnership with Hemholtz-Centre for Environmental Research - UFZ in Germany • Trial tests performed at the Kent Science Park (Sittingbourne) on pristine soils • Commercial project in Watford • Trial test at former petrol station in Kent owned by Total UK • CL:AIRE Technology Development Programme (TDP) 28 • Covered by joint (Ecologia-UFZ) European Patent

  4. Principle of the RF Technology

  5. Principle of the RF Technology Electromagnetic field emitted into the soil Polar Molecules excited by the electromagnetic field Heat generated Increase rate of volatilisation Reduction in time required for SVE

  6. Elements of the RF system • RF Generator • Matchbox • Electrodes • Shielding • Sensors • Laser • Overall system Fiber optic Thermo-couple

  7. Health and Safety • No existing standard in UK • Guideline International Committee on No-Ionizing Radiation Protection (ICNIRP) • Maximum level

  8. Manston field trial • Soil – Chalk • Groundwater table – approx. 55 m bgl • Type of Contamination – BTEX and light (<C8) to medium molecular weight (>C12-C16) hydrocarbons • Depth of contamination – In the unsaturated soil mostly between 3 to 10 m bgl.

  9. Manston field trial 3D

  10. The Field Trial Set Up

  11. Contaminant Concentration T=0

  12. Operation Methodology

  13. Monitoring Methodology • Extracted VOC measured on line using a Total Volatile Organic Sensor (TVOC) • TENAX tubes followed by GC-MS at set intervals. • PID • Airflow • Soil and air temperature

  14. TVOC vs. TENAX Conversion factor 1.74

  15. Results – Temperature

  16. Extraction Rates vs. Temperature

  17. Extraction Rates vs. Temperature

  18. Cumulative VOCs Removal vs. Temperature

  19. Cumulative VOCs Removal

  20. Soil Validation – TPH

  21. Observations • Volatile compounds (BTEX and TPH >C8–C10) >90% - 99% reduction). • Lower removal was measured near extraction well SVE 2 suggesting that the remediation process had not been fully completed at the end of the trial. • Higher molecular weight hydrocarbons (TPH fraction >C10-C16) reduced approx 80% on average). Some concentration build up near the SVE wells where soil temperature is likely to be lower. • TPH fractions >C16-C35 lower initial concentration but showed similar behaviour as semi-volatile fractions. • The extent of the reduction observed for the s-VOC (approx 80%) cannot be solely attributed to analytical error. • Biodegradation and in-situ hydrolysis were considered as two potential explanations for such reduction.

  22. Mass Balance

  23. Energy Requirements kWh cost set @ £0.12

  24. Cooling Rate SVE Only °C/Day = 0.374

  25. Energy Input to Remove Same Mass of Contaminant (945 kg)

  26. Observations • ISRFH technology would reduce: • Time required for remediation by 86% (i.e.7 fold 46 days vs. 325 day) • Energy input by 42% when compared to a traditional SVE with no heating.

  27. Estimated costs (based on 480 m3 of soil treated) • ISRFH (10 weeks treatment) – inclusive of CAPEX depreciation, maintenance monitoring, energy - £194/m3 or £96/tonne (Chalk density = 2.022 g/cm3). Note:Energy cost to achieve average 50°C in soil approx 20% of the remediation costs. • Excavation and disposal to landfill as hazardous waste (5 weeks operation) - inclusive of sheetpiling, backfilling and site set up -£398/m3 or £197/tonne

  28. Additional Considerations • ISRFH treatment vs. traditional in-situ technologies– • Speed of the ISRFH technology in removing volatile contaminants • Can SVE alone actually remove the contaminants?

  29. Conclusions ISRFH significantly improves the removal rate of VOCs and s-VOC from the unsaturated Chalk with a marked reduction in treatment times without entailing excessive energy costs

  30. Thank You

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