I. Van Keer, J. Gemoets, K. Touchant, J. Vos & J. Bronders

Transcription

1 16/09/2014 Innovative remediation techniques: THE key to sustainable and green remediation? I. Van Keer, J. Gemoets, K. Touchant, J. Vos & J. Bronders

2 Shrenk et al (2007) Sustainable & Green remediation: IRT = energy resources & waste production 16/09/2014 2

3 Overview number of soil remedation projects in Flanders (period ) Submitted Approved Initiated EEV (declaration; site closure) from Bruneel (2013) 16/09/2014 3

4 PRODEM» PRO motion en 'DEM onstration projects for SME s interested in sustainable and green technologies» Subsidised by the Flemish Government & EFRO» Demonstration & dissemination» Evaluation & selection by VITO & OVAM 16/09/2014 4

5 Selected Projects» In-situ zinc bioprecipitation: from labtest to full scale remediation Antea Group, Santerra en LGEB» Chemical Reduction and Precipitation of Hexavalent Chromium (DivIRed) MAVA & Exobois» Implementation of zerovalent iron for source zone treatment of chlorinated solvents with soilmixing A+E, Smet F&C en Seyntex 16/09/2014 5

6 In-situ zinc bioprecipitation (ISZnBP): from labtest to full scale remediation Case study 1 - Metal processing factory Zinc groundwater pollution» Groundwater concentration [Zn]max = μg/l» Groundwater level: 3 à 4 m-bgl» Subsoil characteristics (2 10 m bgl):» Heterogeneous» Coarse sand & gravel» High permeability aquifer» Hydraulic conductivities: 20 to 100 m/d» Groundwater velocity: 0,2 1 m/d Large groundwater contamination plume 200m x 70m x 7m 16/09/ Ø up to 3 cm

7 ISZnBP: Applicable remediation techniques» Pump & treat?» High sorption coëfficients» Significant mass removal removal huge volumes of groundwater NOT SUITABLE» Chemical enhancements & pump & treat?» solubility» Improve applicability of P&T High energy demands Complicated water treatment system NOT SUITABLE» In-situ immobilization approach» Addition of CaCO 3 or lime» Application of phosphate compounds» Omnipresence of sulfate reducing bacteria BIOPRECIPITATION 16/09/2014 7

8 ISZnBP: principle» Enhanced natural attenuation» Injection of electron donor: Organic Substrate acetate, H 2 (fermentation) sphalerite» Sulfate reduction process SO 4 2- S 2- (sulphate reducing bacteria) Zn precipitation Zn 2+ + S 2- ZnS Laboratory batch tests & long term field pilot test 16/09/2014 8

9 ISZnBP: batchtests» Aquifer samples + groundwater» Incubation time: 3 months» Tested substrates:» Sodium lactate» glycerol» EOS (emulsified sojabean oil)» Abiotic control» Batchtest: sampling 3 months» All substrates were effective 99 % reduction of [Zn] reduction of SO 4 2-» Aerobic & anaerobic leaching tests» stable precipitates with glycerol and EOS» but increase in As & Mn (& Fe) in solution 16/09/2014 9

10 Germany Netherlands INZnBP: Field Pilot test Belgium France Lux EOS M10 M11 M8 M12 M7 302 M9 M6 Glycerol M5 M14 M2 M3 302 M13 M1 M4 M1 P2 Building Dissolved zinc plume Monitoring well Substrate injection well N m 16/09/

11 M9: Outside zone of influence M4: Outside zone of influence 16/09/

12 ISZnBP: conclusion» Bioprecipitation = succesfull» Decrease of Zn concentration with a factor of 100 to 1000» Substrate: both glycerol & EOS are applicable» Long-term monitoring» maintenance injections required» Substrate» Sulfate 16/09/

13 Chemical Reduction and Precipitation of Hexavalent Chromium (DivIRed) Case study 2 - Impregnation of wood near Brussels» Mainly historical contamination» Cr (VI) contamination» soil» Cr(T) max : 800 mg/kg ds» Cr(VI) max : 62 mg/kg ds» Groundwater (4 6 m-bgl)» Cr (T) max : µg/l» Cr (VI) max : µg/l» Contour: 100 m x 35 m x 5,5 m» Low permeable loam» Groundwaterflow» < 1m/y» Direction NW 16/09/

14 DivIRed: Remediation concept Van Herreweghe (Consoil, 2010) dithionite Fe 3+ + dithionite (Na 2 S 2 O 4 ) Fe 2+ (+ Na 2 SO 4 ) 3 Fe 2+ + CrO H Fe 3+ + Cr OH - 16/09/

15 DivIRed: Final concept» top down injection» injection of dithionite without fracturing» 3 injection point» injection depth: 1 6 m-bgl» injection: every 30 cm» expected influence radius ~0,5 m» 600 L (Na 2 S 2 O 4 + FeSO 4 ) per injection per location» Na 2 S 2 O 4 : 2x overdose» FeSO 4 : 3x overdose» Monitoring of EC & concentration data in surrounding wells 1m 16/09/

16 Concentratie SO 2-4, S (SO 2-4 ), EC DivIRed: Concentration data Concentratie Cr(tot), Cr(VI) date Ec (µs/cm) sulphate (mg/l) S (sulphate, mg/l) Cr (total) Cr (VI) 16/09/

17 DivIRed: Conclusions» In-situ chemical reduction of Cr (VI) theoretically proven observed in the field» In wells with seepage (breakthrough) [Cr-VI ] below reference values» Low permeable soil small influence radius» Applied methodology not appropriate with respect to local lithological conditions Estimation full scale remediation cost: ~90 euro / treated m³ 16/09/

18 Implementation of zerovalent iron for source zone treatment with soil mixing (ZVI_SM) Case study 3 - Textile manufacturing site in West Flanders» Historical soil contamination» Chlorinated solvents» Spill TCE >25 years ago» Local discharge point» DNAPL between 7,0 8,0 m-bgl» TCE max concentrations» Soil: mg/kg ds TCE» Groundwater:» 426 mg/l TCE» Small amounts 12DCE & VC» Low permeable sandy clay 4670 mg/kg ds 403 mg/kg ds 16/09/

19 ZVI_SM: Remediation principle» Pump and treat:» » Fluctuation of CAH concentrations» No decreasing trend» Excavation» pollution near building» at great depth» Airsparging/SVEX: risky with pure product layer» In situ chemical reduction» injection of microscale ZVI (zero valent iron) + anaerobic bioremediation» soil mixing 16/09/

20 ZVI_SM: Lab test - results low dose ZVI High dose ZVI TCE degradation > 95 % 16/09/

21 Technical Approach pilot» 14 soil mix piles until 8,4 m bgl» 3000 kg of fine sized micro scale ZVI-H4 (10 piles) and 500 kg ZVI-H20 (2 piles, more reactive)» Guar gum will be biodegraded in time with release of simple sugars that stimulate anaerobic biodegradation.» Stability: gravel piles Challenge keep ZVI in suspension equally distribution of ZVI 16/09/

22 ZVI_SM: Soilmixing field set up 16/09/

23 ZVI_SM: Drilling mud - evolution of CAH with time in lab test» TCE is degraded to cdce, ethene & ethane» After 36 weeks: end-products free of Cl keep on increasing 16/09/

24 ZVI_SM: Soil & groundwater monitoring» Drilling in soil mix column empty liners» Groundwater monitoring 16/09/

25 ZVI_SM: Conclusions» Lab tests have shown that novel microscale ZVI can be effective to remediate chlorinated solvents in source zones» Results of lab monitoring with treated soil samples are promising» Technical Effectiveness of Soil mixing of ZVI + guar gum for distributing µ-zvi within the low permeability soil is indicated efforts to sample the soil mix piles are needed» Groundwater concentrations are still very high. Two more field monitoring campaigns are scheduled 16/09/

26 Innovative remediation techniques: THE key to sustainable and green remediation? Summary case studies» ISZnBP» DiviRed» Labtest:» Labtest» Pilot: coarse sand & gravel» Pilot low permeable loam» Soilmixing» Labtest» Pilot Low permeable sandy clay» Ongoing 16/09/

27 Innovative remediation techniques are PART OF THE key to sustainable and green remediation? Concept IRT Correct conceptual model Sustainable & green remediation Injection methodology Site lithology 16/09/

28 Project partners» ISZnP» Antea» VITO» DivIRed» Mava» VITO» Exobois» ZVI_SM» A+E» Smet F&C» VITO» Seyntex 16/09/