Chemical Security Program Treatment Technologies for Remediation of Hazardous Waste

Treatment Technologies for Remediation of Hazardous Waste

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

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

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

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 1966. Not completely cleaned up until 1990. Times Beach – Missouri, USA community where contaminated oil was used for dust control from 1972-1975.

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

Various Pathways Exist for Contamination From Land Disposal

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

Contaminated Land Disposal is Closely Linked to Water Cycle

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

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

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)

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

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

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

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

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

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

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

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

Different Technologies used for Groundwater Remediation

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

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

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

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

Air Stripping Process - Water Treatment Air Stripping System Packed Tower

Steam Stripping Process : Water Treatment Typical Steam Stripping Flow Diagram

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

Different Technologies used for Soil Remediation

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

Soil Vapor Extraction (SVE)

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.

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.

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.

In-situ Bioremediation

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

Ex-situ Bioremediation for Petroleum Waste

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

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

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

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.

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.

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.

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

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

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

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.

Acknowledgement and Background Richard Fortuna, President, Strategic Environmental Analysis, L.C. www.richardfortuna.com SEA.LLC@richardfortuna.com 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.