Chemical Oxidation. Jim Harrington, Chief Training and Technical Support Section May 7, 2005

Transcription

1 Chemical Oxidation Jim Harrington, Chief Training and Technical Support Section May 7, 2005

2 1 From ITRC Internet Seminar What s New with In Situ Chemical Oxidation ITRC Technical and Regulatory Guidance: In Situ Chemical Oxidation of Contaminated Soil and Groundwater Second Edition

3 Advantages and Disadvantages of ISCO Advantages Fast treatment (weeks to months) Temporary facilities Treatment to low levels Effective on some hard-to-treat compounds Disadvantages Requires earlier spending commitment Involves handling powerful oxidants, and carries special safety requirements Photo provided by MEC x

4 13 Regulatory Review of ISCO Proposals Remediated to applicable groundwater remediation standard Ensure that the injection Will not cause the plume to migrate Will not create adverse vapor impacts Is of sufficient volume to get the job done, and if not, that additional round(s) of injection will be necessary

5 In Situ Oxidants with More Than Ten Years of History Permanganate Potassium permanganate (KMnO 4 ) Crystalline solid Sodium permanganate (NaMnO 4 ) Ozone O 3 (gas) Concentrated liquid Peroxide (Fenton s Reagent) H 2 O 2 and ferrous iron react to produce radicals More accurately catalyzed peroxide propagation

6 20 Emerging Oxidants Persulfate Sodium persulfate - most commonly used Potassium persulfate - very low solubility Persulfate anions (S 2 O 8 2 ) dissociate in water Oxidative strength greatly increased with addition of heat or a ferrous salt (Iron II) Attributed to production of sulfate free radical (SO 4 ) Other oxidants solid peroxides Magnesium peroxide (MgO 2 ) Calcium peroxide (CaO 2 ) Sodium percarbonate (Na 2 CO 3 3H 2 O 2 )

7 Considerations for ISCO Treatment Peroxide Ozone Permanganate Persulfate adose zone eatment Successful (need adequate soil moisture) otential etrimental effects Gas evolution, heat, By-products, resolubilization of metals Gas evolution, By-products, resolubilization of metals By-products, resolubilization of metals By-products, resolubilization of metals H/alkalinity ersistence xidant demand oil permeability nd heterogeneity Effective over a wide ph range, but carbonate alkalinity must be taken into consideration Easily degraded in contact with soil/groundwater unless inhibitors are used Easily degraded in contact with soil/ groundwater Effective over a wide ph range Effective over a wide ph range, but carbonate alkalinity must be taken into consideration The oxidant is very stable Soil oxidant demand varies with soil type and oxidant and contaminant oxidant demand is based on total mass and mass distribution (sorbed, dissolved and free phase) Low-permeable soils and subsurface heterogeneity offer a challenge for the distribution of injected or extracted fluids

8 23 Practicality of Radical Chemistry Generation of radicals is a function of the following ph Chemistry Concentration Temperature

9 Practicality of Radical Chemistry Important points to consider about radical generation Activation is necessary A range of radicals are generated subsequent to initiation Radicals are aggressive and short lived Competition exists between propagation of radicals and radical termination Oxidant demand is a result of the competition between propagation and termination reactions It is difficult to calculate a stochiometric amount of radicals

10 Peroxide (Fenton s) Chemistry Fenton s Reaction (ph 2.5/3.5; 300 ppm peroxide) H 2 O 2 + Fe 2+ (acid) OH + OH - + Fe 3+ (1) Organic Contaminant Alcohols, Acids, CO 2, H 2 O Chain Initiation Reactions (>1 % peroxide) OH + H 2 O 2 HO 2 + H 2 O (2) H 2 O 2 + Fe 3+ Fe 2+ + HO 2 + H + (3)

11 Ozone Chemistry Chain Initiation Reactions: O 3 + OH O 2 + HO 2. (1) Chain Propagation Reactions: HO 2 O 2 +H + (2) HO 2. + Fe 2+ Fe 3+ + HO 2 (3) O 3 + HO 2 OH + O 2 + O 2 (4)

12 Persulfate Chemistry Chain Initiation Reactions (Me is a metal ion; R is an organic compound): S 2 O SO 4 (1) S 2 O RH SO 4 + R + HSO 4 (2) Catalyzed Persulfate: Me n+ + S 2 O 8 2 SO 4 + Me (n +1)+ + SO 4 2 (3)

13 Catalyzed Peroxide Propagation Chain Propagation Reactions (excess peroxide): HO 2 + Fe 2+ HO 2 + Fe 3+ (4) OH + H 2 O 2 HO 2 + H 2 O (5) HO 2 O 2 + H + (6) OH + R R + OH (7) R + H 2 O 2 ROH + OH (8) Chain Termination Reactions (excess iron): HO 2 + Fe 2+ O 2 + H + + Fe 3+ (9) O 2 + Fe 3+ Fe 2+ + O 2 (10) Fe 3+ +n OH Am. iron oxides (precipitate) (11)

14 Ozone Chemistry Chain Initiation Reactions: O 3 + OH O 2 + HO 2. (1) Chain Propagation Reactions: HO 2 O 2 +H + (2) HO 2. + Fe 2+ Fe 3+ + HO 2 (3) O 3 + HO 2 OH + O 2 + O 2 (4)

15 ph < 3.3 Permanganate Chemistry MnO H + + 5e - Mn H 2 O (1) 3.5 < ph < 12 MnO H 2 O + 3e - MnO 2 (s) + 4OH - (2) ph > 12 MnO 4- + e - MnO 4 2 (3) Under acidic conditions 3MnO 2 + 2MnO H + 5MnO 2 (s) + 2H 2 O (4) MnO 2 (s) + 4H + + 2e - Mn H 2 O (5)

16 Persulfate Chemistry Chain Propagation Reactions: Me (n +1)+ + RH R + Me n+ + H + (4) SO 4 + RH R + HSO 4 (5) SO 4 + H 2 O OH + HSO 4 (6) OH + RH R + H 2 O (7) R + S 2 O H + SO 4 + HSO 4 + R (8) Chain Termination Reactions (excess metal/catalyst): SO 4 + Me n+ Me (n+1)+ + SO 2 4 (9) OH + Me n+ Me (n +1)+ + OH (10) R + Me (n+1)+ Me n+ + R (11) 2R Chain termination (12)

17 USGS Topographic Map e Sit Port Jervis South

18 Oxidant Effectiveness xidant eroxide/fe zone zone/ eroxide ermanganate K/Na) ctivated odium ersulfate Amenable contaminants of concern TCA, PCE, TCE, DCE, VC, BTEX, CB, phenols, 1,4-dioxane, MTBE, tert-butyl alcohol (TBA), high explosives PCE, TCE, DCE, VC, BTEX, CB, DCA, CH 2 Cl 2, PAHs phenols, MTBE, TBA, high explosives TCA, PCE, TCE, DCE, VC, BTEX, CB, phenols, 1,4-dioxane, MTBE, TBA, high explosives PCE, TCE, DCE, VC, TEX, PAHs, phenols, high explosives PCE, TCE, DCE, VC, BTEX, CB, phenols, 1,4-dioxane, MTBE, TBA Reluctant contaminants of concern DCA, CH 2 Cl 2, PAHs, carbon tetrachloride, PCBs DCA, CH 2 Cl 2, PAHs, carbon tetrachloride, PCBs Pesticides PAHs, explosives, pesticides Recalcitrant contaminants of concern CHCl 3, pesticides TCA, carbon tetrachloride, CHCl 3, PCBs, pesticides CHCl 3, pesticides Benzene, TCA, carbon tetrachloride, CHCl 3, PCBs PCBs

19 47 Dosage Considerations Radical Chemistry Peroxide Generally 4% to 20% Options: Low ph / iron addition Neutral ph / chelants / iron < 15% High ph Excess peroxide and iron effects the reaction chemistry negatively Ozone < 10% in oxygen; < 1% in air Persulfate < 10%; buffer acidity with sodium carbonate (Na 2 CO 3 ) Excess catalyst and chelant effects reaction chemistry negatively; very corrosive

20 48 Dosage Considerations Natural Organic Matter (NOM) and Reduced Inorganic Matter (RIM) contribute heavily to the oxidant demand High dose strengths increase bacterial stress Nutrients and electron acceptors/donors important to bacterial recovery if post ISCO remediation desirable Non-Radical Chemistry: Permanganate Dosing: Sodium permanganate: Up to 20% - batch / recirculation Potassium permanganate: Up to 4% - batch / recirculation

21 49 Overview of Cost Considerations Site characterization Design parameter evaluation Application well installation Application of reagents Post treatment monitoring Subsequent polishing treatment if necessary

22 74 Section V: Process Monitoring Oxidant-specific monitoring parameters Injection concentrations Volumes Flow rates Return on investment Injection well Temperature Pressure Important component of the health and safety program

23 75 Oxidant Specific Monitoring Parameters Permanganate Monitor well - color, oxidation / reduction potential (ORP), conductivity, chloride, manganese dioxide Persulfate ph, dissolved oxygen (DO), ORP, conductivity, and/or persulfate in monitor wells Ozone Continuous monitoring of ozone gas, carbon dioxide (CO 2 ), volatile organic compounds (VOCs), and oxygen (O 2 ) Peroxide (Fenton s) Injection well - ph, temperature, pressure Monitor well - ph, temperature, color, ORP, DO, conductivity, and VOCs

24 Application of ISCO Waters Edge Property Port Jervis, New York VCP # V

25 Aerial Photograph Waters Edge Site

26 Waters Edge VCP Manufactured Janitorial Chemicals from 1978 until 1993 Bankruptcy left pails, 200 tanks onsite Lead Based Paint UST Soil Cover TCE, DCE, PCE contamination in GW

27 Waters Edge VCP Chemical Oxidation used to Remediate GW Hydraulic Fracturing Fenton s Reagant

28 Waters Edge VCP Four 2 Injection Points to 5 below GW Hydraulic Fracturing 3 Rounds of injection 2000 gallons acid (75 %) 4600 gallons peroxide ( 35 %) 5800 gallons catalyst solution (3.5 %)

29 Typical Groundwater Injection Point Construction Detail

30 Waters Edge VCP - Results 92 % overall reduction 5000ug/l area gone 500 ug/l area reduced 81% gw standards not achieved

31 Pre-Remediation Total VOC Concentration Isopleth Map October 2001

32 Post-Remediation Total VOC Concentration Isopleth Map March 2002

33 Post-Remediation Total VOC Concentration Isopleth Map July 2002

34 Waters Edge Site Photos Artesian sand flow Senior housing development

35 Waters Edge Site Photos Mixing sand slurry Too much gel in mixture

36 Development Completed

37 Development Completed

38 Development Completed