Tools and Methods to Reduce Uncertainties Associated with the Use of In Situ Remediation Techniques for Organic Contaminants in Soil and Groundwater

Transcription

1 Tools and Methods to Reduce Uncertainties Associated with the Use of In Situ Remediation Techniques for Organic Contaminants in Soil and Groundwater by Jean Paré, P. Eng. Toronto, ON July 15 th, 2017

2 The Chemistry works but the geology screws it up by Jean Paré, P. Eng. Toronto, ON July 15 th, 2017

3 Presentation Agenda In Situ Technology Review and Limitations Field application challenges and contact issue Tools, testing and tricks Before you get to the field When you re in the field Follow up After injection events Case Study Presentation Chemco-inc.com

4 In Situ Technology Key Drivers Time versus Money Contaminant Accessibility (infrastructures, utilities) Sustainability Contribution (remote disposal site, landfilling without treatment, Energy Output) Polishing steps to achieve Risk Based Criteria Improvement of contaminant removal rate versus natural attenuation Chemco-inc.com

5 Chemical Oxidation Technology Review Oxidants are introduced or mixed into the soil and groundwater to attack the organic contaminants Chemical oxidation treatments are commonly used in potable and wastewater applications Oxidants are non-specific and will react with the targeted contaminants AND with the soil organic content a value called Soil Oxidant Demand - SOD. Chemical oxidation reactions involve the transfer of electrons and the breaking of chemical bonds Water is the carrier for the oxidants used in chemical oxidation (except for ozone) If you have enough oxidant present and sufficient time you will push reaction to FULL mineralization (CO2, H2O, Cl-) of the contaminant of concern Chemical oxidation can slow down the biological activity but will NOT sterilize the soil completely (potential benefit because of lower toxicity after the Chemical Oxidation is completed)

6 Chemical Oxidation Technology Review Common Chemical Oxidants Potassium or sodium permanganate Hydrogen Peroxide alone Catalyzed Hydrogen Peroxide Hydrogen Peroxide with iron (regular Fenton reagent reaction) Need to establish acidic conditions (ideal ph between 4 and 6) Modified Fenton Reagent with chelated metals (neutral ph) Ozone Ozone is a gas and must be produced on site The gas must be injected into the soil Persulfate Requires activation to generate free sulphate radicals. Heat, chelated metal, high ph, surface, organic or hydrogen peroxide can be used to activate the persulphate. Activation method can be adapted to site conditions. Percarbonate Requires activation to generate free radicals SAFETY NOTE: ALL THESE PRODUCTS REQUIRE ADEQUATE HANDLING PRATICES AND SAFETY EQUIPMENT.

7 Chemical Oxidation Limitations (1) All chemical oxidation reactions occur in the WATER or moisture phase (except for ozone) Kinetics of the chemical oxidation reaction is thus influence by the contaminant of concern solubility and availability in the groundwater or moisture phase Sorbed phase contamination might be challenging to remediate (less available) In NAPL containing sites, contamination can persist because of the highly hydrophobic properties of the chemicals that make up the NAPLs Injection technique must induce proper contact between the contaminant and the oxidant for a proper duration for the required reaction to occurs (kinetics)

8 Chemical Oxidation Limitations (2) All oxidants can change the oxidation state of metals and thus increase their solubility and mobility Metals of particular concern are: chrome, lead, uranium, selenium, vanadium In most of these cases, the metals will come back in their reduced state once all of the oxidant has been consumed by the environment Impurities contained in the oxidant must be evaluated In the case of arsenic, oxidation will help immobilizing the metal by reducing its solubility

9 Conditions for Selecting Chemical Oxidation Chemical Oxidation Applicability Limitation / Disadvantage s Possible Alternative Options Mobile NAPL Probably not the best choice High oxidant requirement ($) Liquid Extraction Thermal degradation Residual NAPL (10,000 s mg/kg) Yes, but difficult High oxidant requirement ($) Extraction with air/steam injection Thermal degradation High conc. in soil/groundwater (10 s s mg/kg) Yes, good conditions Normal considerations Extraction with air/steam injection Bioremediation Dissolved plume (< 1 mg/kg) Yes, but could be costly Higher cost due to SOD Bioremediation, Reactive barriers Source : ITRC 2004 NAPL: Non-Aqueous Phase Liquid

10 Compatibility oxidant/contaminant Contaminant/Oxydant MnO4 S2O8 SO4 * Fenton s Ozone Petroleum Hydrocarbon L G/E E E E BTEX L G G/E E E Phenols G L/G G/E E E 1 Polycyclic Aromatic L G E E E Hydrocarbon (PAH) MTBE L L/G E G G Chlorinated Ethenes E G E E E (PCE, TCE, DCE, VC) Carbon Tetrachloride L G L/G L/G L/G Chlorinated Ethanes L G G/E G/E G (TCA, DCA) Polychlorinated L L L G/E G 1 Biphenyls (PCB) Energetics (RDX, HMX) E G E E E L=Low G=Good E=Excellent 1=Perozone Source: Carus Chemical Company

11 Enhanced Bioremediation Advantages Enhances natural in-situ processes already at play (typically uses natural groundwater gradient, naturally occurring biodegradation. Low energy and cost effective Relatively easy to manage and handle. Can be used in tandem with other remedial technologies that address small amounts of residual soil and groundwater contamination

12 Parameters to consider for a successful enhanced bioremediation Temperature, ph Nutrients Balance (C:N:P ratio) Site geology and hydrogeology consideration Proper micro-organisms presence Aerobic or anaerobic conditions to support bioremediation in soil and groundwater.

13 Chemical Reduction Principles In situ // Ex situ In Situ Chemical Reduction (ISCR) is defined as a process that combines biotic and abiotic reactions to treat contaminants by creating reducing conditions ISCR can be enhanced by anaerobic bioremediation ISCR also provides abiotic/chemical degradation component if a metal (zero valent iron or other) is present

14 Chemical Reduction Compatibility reductant/contaminant Chlorinated Compounds PCE, TCE, cdce, 11DCE, VC 1122TeCA, 111TCA, 12DCA CT, CF, DCM, CM Herbicides, Pesticides Toxaphene, Chlordane, Dieldrin, Pentachlorophenol Energetics TNT, DNT, RDX, HMX, Perchlorate Metals and metalloids As, Cr, Pb, Zn, Cd, Hg, Cu, Cr, Ni, Sb, Co Under aerobic conditions you can target HAP, phtalates, perchlorate, petroleum hydrocarbon In Red: need to have an organic substrate and/or a ZVI/carbon combination

15 Common Chemical Reducing Agents Sugars Molasses high fructose corn syrup whey Fatty acids Lactate Butyrate propionate Emulsified Vegetable Oils Soybean Oil Complex Fermentable Carbon complex lecithine polylactate Zero Valent Iron (ZVI) Soluble Iron Compounds

16 Selection Factors Chemical Reductant ORP of the aquifer Hydrogen vs. Acidity produced Biodegradation rate / longevity Ease of injection and distribution

17 Soil Washing Technology Review Organic Contaminants (Petroleum hydrocarbon, PCB, Dioxin, Furans, etc.) are entrapped as pure product (free phase) or at high concentration in various soil matrix. Highly contaminated soils are bringing challenges for an effective low cost remediation. Soil Washing using co-solvent and/or surfactant offers the benefit to treat effectively and economically these high contaminant concentration that allow for soil to be re-used or dispose at a lower cost.

18 Activated Carbon Technology Review Contaminants sorb to activated carbon Decreases groundwater mass immediately Disrupts groundwater/soil mass equilibrium to help drive desorption Concentrated mass accelerates degradation rates Various degradation mechanisms are used to treat Bioremediation (aerobic/anaerobic) Chemical reduction/oxidation Source: AST

19 Field application challenges and contact issue Good treatment require good contact Application challenges Geology (Silts and Clays, Sands, gravel and other) Heterogeneity Low GW Velocity < Fracture Pressures High Volumes to inject Reagent Kinetics Depth - Shallow environment - Deep environment

20 Tools, testing and tricks Before you get to the field Validating the qualification and quantification of the selected amendment with bench scale lab study Soil and Groundwater amendment validation and treatability study are ALWAYS recommended (If it doesn't work in the lab in ideal contact conditions it WON T work in the field) Make sure you have all the necessary data and your injection plan is set properly Chemco-inc.com

21 Tools, testing and tricks Before you get to the field

22 Tools, testing and tricks When you re in the field Making sure you are injecting in the adequate zone SITE CHARACTERIZATION IS KEY Validating the distribution and dilution of the amendment in the subsurface aquifer through the use of an INERT tracer PRIOR to moving in with your expensive oxidant or amendment. Evaluate the pro and cons of the various equipment and techniques to induce proper contact Confirm Injection Pressure and Flow Assumptions Confirm Formation Acceptance of Design Volume Confirm Vertical and Horizontal Distribution of Reagents Over Time

23 Tools, testing and tricks Search and Destroy Methodology Targeted Distribution Data Gap Analysis High Resolution Characterizatio n 3D Graphing & Conceptual Model Technology Selection High Resolution Remediation Design Distribution Testing Optimized Full Scale Application Troubleshooting Source Cascade Drilling 23

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25 Search - Why MIP/HPT or LIF before injecting? Locate contaminant mass through high vertical resolution Define injection flows and pressures Don t get fooled by tight sands or clays with low conductivity

26 MIP 3D Imaging Injection Locations

27 Radius of Influence (ROI) Pore Volume ROI ROI Reagent Per Location 500 gals Injection Volume as a % of Effective Pore Volume 100% Pore Volume ROI 2 feet Advection / Dispersion ROI + = Additional ROI from Advection / Dispersion (Feet) Time Frame To Achieve Advection / Dispersion ROI (Days) 60 days 9 feet 7 feet 60 Days 4 10 ROI = P ROI + A/D ROI ROI = pore volume ROI (ft) + advection/dispersion ROI (ft) 9 feet = 2 feet days Kinetics > ROI T

28 ROI Realities Pore Volume ROI ROI Reagent Per Location 500 gals Injection Volume as a % of Effective Pore Volume 50% Pore Volume ROI 2 feet Advection / Dispersion ROI Additional ROI from Advection / Dispersion (Feet) Time Frame To Achieve Advection / Dispersion ROI (Days) 60 days 9 feet 7 feet 60 Days Tight Soils Low Injection Pore Volumes Tighter Spacing Higher Reagent Concentrations Permeable Soils / Flat Gradient Reagent Persistence Requires High Injection Pore Volume Exceed Fracture Pressure Stay Below Fracture Pressure Permeable Soils / Steep Gradient Lower Residence Time

29 Tools, testing and tricks Search and Destroy Methodology Targeted Distribution Data Gap Analysis High Resolution Characterizatio n 3D Graphing & Conceptual Model Technology Selection High Resolution Remediation Design Distribution Testing Optimized Full Scale Application Troubleshooting ROI Injection Volumes Pressure Delivery Tooling Source Cascade Drilling

30 Tools, testing and tricks Follow up After injection events Validate oxidant/amendment distribution (may integrate inert tracer to evaluate dilution factor) with : Core samples Hydro punch sampling Electrical Conductivity Groundwater sampling through monitoring wells

31 Case Study 1 - Outputs Visual Data Dry Cleaner Case Study Injection Strategic Injection Strategy Source: Cascade Drilling

32 Case Study 1 - Outputs Visual Data MIP Post Injection Injection Pre-Injection MIP Strategic Injection Strategy Post-Injection MIP Source: Cascade Drilling

33 About our Expertise, Products and Services Training and Education: technical transfer session, health and safety training; Technology Site Assessment: technology support and selection (chemical oxidation, co solvent-surfactant soil washing and enhanced bioremediation); Products supply, logistic and storage: nutrients, bacterial preparations strains, oxidants, catalysts, oxygen and hydrogen release compounds, co solvent-surfactant blends Laboratory Services and Analysis: Groundwater Parameter Analysis, Tracer Study, Soil and Groundwater Oxidant Demand Evaluation (SOD), Bench Scale Treatability testing.

34 Acknowledgements Carus Chemical AST EOS Peroxychem Progressive Engineering & Construction Vertex Environmental Inc. Cascade Drilling Thank you for your attention! Have a good day!!! jean.pare@chemco-inc.com Tel: // Chemco-inc.com