1. Chemical Security Program Treatment Technologies for Remediation of Hazardous Waste

2. Treatment Technologies for Remediation of Hazardous Waste

3. Remediation of Hazardous Waste In-situ and Ex-situ Processes
History and Types of Hazardous Waste Sites
Discussion about Past Practices
Remediation Technologies
Containment
Grout curtains, slurry walls, capping
Monitoring
Source Control (Soils, Sediments, Sludges)
Pump and treat, Air/steam stripping, soil vapor extraction
Soil washing, solidification, mobile incineration
Groundwater Treatment
Carbon adsorption, bioremediation

4. The Late 20th Century Became a Time to Focus on Man Made Pollution

5. Surface and Groundwater Contamination Leads to Health Problems, Water Shortage
Mining
Acid mine drainage
Heavy metals – Hg, Cr, Pb
Industrial / Commercial Pollution
Dyes and pigments
Petroleum / gasoline
Agricultural runoff
Pesticides
Nutrients – nitrates, phosphates
Salinization – Sodium, chloride
Sewage
Pathogens - Enteric
Nutrients – Nitrates, phosphates
Contaminated animal feed
Textile Waste
Gasoline
Mining Waste

6. The History of Hazardous Waste Pollution
In 1962, renowned author and naturalist, Rachel Carson, warned growing contamination “great underground seas” (i.e., groundwater) in “Silent Spring.”
Love Canal – New York, USA. Buried barrels of chemicals underneath new housing development (1950s). Became main cause for the Superfund legislation. Removed from Superfund in 2004.
Valley of the Drums – Kentucky, USA, 23 acre site with a large number of leaking drums. Fire at site in Not completely cleaned up until 1990.
Times Beach – Missouri, USA community where contaminated oil was used for dust control from

7. Superfund Sites in the US
Current
Proposed
Complete
Source: Wikipedia Superfund

8. Various Pathways Exist for Contamination From Land Disposal

9. Solid Waste can Directly Impact Human Health
Solvents – Gasoline, diesel, chlorinated
Leachates – Acid waste, heavy metals
Hazardous waste – Metals, paints, solvents, pesticides
Leaking fuel tanks – Gasoline, diesel
Refuse - Decaying animal and plant matter

10. Contaminated Land Disposal is Closely Linked to Water Cycle

11. Drinking Water, Wastewater Contaminants Directly Affect Public Health
Pathogens
Bacteria – Enteric, fecal
Protists – Cysts and spores
Virus - Enteric
Metals
Copper
Lead
Arsenic
Disinfection byproducts
Trihalomethane - CHCl3,,CH2Cl2, CH2ClBr
Haloacetic acid – CH2ClCO2H
Pesticides

12. General Lessons Learned in Remediating Hazardous Waste Sites
The larger the scope of contamination, the more limited the cleanup options.
After the pollutant has dispersed the groundwater may be undrinkable for years
Liability and funding for remediation may be quite expensive

13. More Lessons Learned
Cleanup is much more costly and time consuming than properly managing wastes in the first place.
Treatment and excavation costs
Continuous expense for monitoring
Landfills, lagoons, piles and land spreading will often create large areas of contamination
Chlorinated solvents are often high density and thus will “sink” toward groundwater. (DNAPL)

14. Remediation can Take Various Pathways
Containment:
Seals off all possible exposure pathways between a hazardous waste disposal site and environment.
Slurry Walls
Grout curtains
Drainage systems
Capping
Monitoring

15. Slurry Walls and Grout Curtains are Containment Technologies
Basic Grout Curtain Containment System

16. Containment Remediation- Slurry Wall Emplaces Impermeable Barrier
Dig trench around an area
Backfill trench with an impermeable material (clay) slurry
Cross Section of a Slurry Wall

17. Slurry Walls are Impermeable Barriers Made of Clay Materials
Slurry Walls can be placed in a circular fashion to divert groundwater around contaminant
Plan View Slurry Wall

18. Grout Curtains Injected in the Subsurface Solidification Reduces Permeability
Grouting
Inject liquid, slurry, or emulsion under pressure into the soil
Slury fills pore space
Two types
Particulate – solid + liquid solidifies
Chemical – Liquid +liquid that gels
Grouts are limited when high water table or rapid GW flow

19. Containment Remediation Proceeds in Steps, Combined with Extraction
Downgradient Barrier and Extraction Wells (Top and Side Views)
Upgradient Barrier and Extraction Wells

20. Love Canal Capping Containment and Drain
Love Canal Barrier, Drain and Capping System

21. Groundwater Monitoring is Necessary to Protect Drinking Water
All containment remedies are accompanied by an extensive groundwater monitoring.

22. Different Technologies used for Groundwater Remediation

23. Groundwater Remediation Reduces Spread of Contamination
Principally used to remove or reduce hazardous waste contamination from the groundwater aquifer passing through or near the site.
Pump and Treat (including lowering of GW table)
Steam Stripping
Air Stripping
Carbon Adsorption
Bioremediation

24. Source Control Prevents Continued Release or Spread of Contaminants
Used to remove or reduce hazardous waste contamination from sludges and soils near the site.
Soil Vapor Extraction (SVE)
Air Sparging
Bioremediation (including Bioventing and Bioreactors)
Air Stripping and Steam Stripping
Soil Washing and Soil Flushing
Stabilization/Solidification
Vitrification
Thermal Desorption
Mobile Incineration

25. Pump and Treat
Basic Pump and Treat System (Top and Side Views)

26. Air and Steam Stripping for Source Control
Steam Stripper
Air Stripper
These can be used in conjunction with Soil Vapor Extraction or Groundwater Treatment

27. Air Stripping Process - Water Treatment
Air Stripping System
Packed Tower

28. Steam Stripping Process : Water Treatment
Typical Steam Stripping Flow Diagram

29. Carbon Absorption : Water Treatment and Soil Vapor
Fixed-bed Carbon Adsorption Unit
Carbon Adsorption System

30. Different Technologies used for Soil Remediation

31. Soil Vapor Extraction (SVE)
Volatiles swept from groundwater
Optional air sparge
Volatiles captured or treated at surface

32. Soil Vapor Extraction (SVE)

33. Air Sparging Enhanced SVE
SVE commonly enhanced with air sparging.
Air sparging involves the active pumping of ambient air into the subsurface soil and groundwater to enhance the collection of volatiles through the SVE system.

34. Bioremediation can Occur In-situ or Ex-situ
In-situ typically enhances naturally occurring biological activity
circulating nutrient and oxygen-enriched water-base solution
forced air movement provides oxygen to enhance naturally occurring microbes.
Bioventing has air flow rate lower than Soil Vapor Extraction (SVE)
deliver oxygen
minimizing volatilization.
In-situ biological treatment is effective for non-halogenated volatiles and fuel hydrocarbons.
Technology is less effective for non-biodegradable compounds and for soils with low permeability.

35. Biotreatment of Groundwater (In-situ)
Use natural occurring and/or enhanced organisms
Enhanced biotreatment involves add O2 and nutrients.
Proper mixture of O2, nutrients and bacteria are site-specific and chemical-specific.
Technique limited by pH, temp, toxicity of contaminants, and to aquifers with high permeability.
Advantages:cost, minimal surface facilities minimal public exposure.

36. In-situ Bioremediation

37. Bioremediation for Petroleum Waste (Ex-situ)
Ex Situ bioremediation involves excavating the contaminated soil
Placing it into biotreatment cells
Adding nutrients to enhance biological activity
Periodically turning it over to aerate the water.
The moisture, heat, nutrients, oxygen, and pH are usually controlled in the process.
Separation of decontaminated solids

38. Ex-situ Bioremediation for Petroleum Waste

39. Bioremediation Organisms
A variety of bacteria and yeast have been successfully deployed in-situ and ex-situ biological treatment systems.

40. Soil Washing: Ex-situ Excavation
Wash soil with leaching agent or surfactant
Not effective with clay or high organic content

41. Soil Flushing : In-situ
Apply water solution to enhance contaminant mobility
Generated leachate intercepted
Especially good for halogenated and high permeability soil

42. Solidification – Stabilization (S/S)
Solidification methods physically encapsulate hazardous waste into a solid material matrix of high structural integrity.
Stabilization techniques chemically treat hazardous waste by converting them into a less soluble, mobile or toxic form.
Principally used for metal-bearing wastes.
Limited applicability to organic wastes.
Typically used to concentrate contaminants prior to S/S.
2 Main types of processes: cement and pozzolanic.

43. Cement Stabilization (Ex-situ)
Description
Slurry of wastes and water is mixed with portland cement to form a solid.
Advantages
Low cost
Readily available mixing equipment
Relatively simple process
Suitable for use with metals
Disadvantages
Solids are suspended, not chemically bound
subject to leaching
Doubles waste volume
Requires secondary containment
Incompatible with many wastes
Organics, some sodium salts, silts, clays, and coal or lignite.

44. Pozzolanic Processes (Ex-situ)
Description
Waste is chemically reacted with lime and a fine-grained siliceous material (fly ash, ground blast furnace slag, cement kiln dust) to form a solid.
Advantages
Low costs;
Readily available mixing equipment;
Suitable for power-plant wastes (FGD sludges, etc.) as well as a wide range of industrial wastes, including metals, waste oil, and solvents
Disadvantages
Increases waste volume
May be subject to leaching
Requires secondary containment.

45. Generic Elements Of A Typical Ex-situ S/S Process
Solidification - Stabilization

46. Metals/Cyanide S/S Treatment Train
S/S most commonly used for heavy metals and or cyanides.

47. In-situ Vitrification Process : Specialized S/S
Thermal process converts contaminated soil to chemically inert stable glass/crystalline product.
Electrical current produces heat –melts soil
Molten zone grows destroying/encapsulating hazardous constituents and metals
Hood for volatile emissions

48. Mobile Incineration
Involves a wide variety of units such as small liquid waste incinerators at right.
Multiple trailer rotary kiln for complex sludges and drummed waste, below.
Infrared (electrically heated) “soil roaster” are also used. Infrared is a form of indirect heating using electric current instead of fuel oil to generate heat.

49. Acknowledgement and Background
Richard Fortuna, President, Strategic Environmental Analysis, L.C.
31 years experience evaluating technologies and developing preventive policies for HW management
Developed key provisions of the U.S. statute governing daily waste management; The Resource Conservation and Recovery Act (RCRA)
Participated in enactment of the “Superfund” cleanup law. RCRA is intended to prevent the creation of additional “Superfund” or leaking waste sites
Worked with over 200 companies in evaluating waste treatment technologies and policies
Authored a text on major reforms to RCRA.