Alternatives to Incineration Conf Presentation1 li

Alternatives to Incineration for Mixed Low-Level Waste : Alternatives to Incineration for Mixed Low-Level Waste Bill Schwinkendorf Vince Maio 2001 International Incineration Conference May 13, 2001 Philadelphia, PA William E. Schwinkendorf: Vince - I prefer just leaving the title at Alternative Treatment. I know this is picky but “Alternative Incineration Technologies” implies different kinds of incineration and that is not what we are about. I though of the title “Treatment Technologies that are Alternatives to Incineration” but that seems unwieldy. If this bunch doesn’t know that we are discussing alternatives to incineration we are in trouble.


Agenda : Agenda Why Alternatives What are the Alternatives Systems Issues Specific Technologies


Regulatory Drivers Requirements for Incineration or Alternatives : Regulatory Drivers Requirements for Incineration or Alternatives Mixed Waste To destroy certain listed organics for land disposal under RCRA Must achieve DRE’s through incineration or an approved alternative Volume Reduction Transuranic Waste To destroy VOCs or hydrogen generating organics to meet NRC/DOT requirements for shipment to WIPP. WIPP is RCRA, but not TSCA exempt.


Reasons for Alternatives : Reasons for Alternatives Public concern over incinerator emissions. Offgas volume and associated contaminants Particulates and PICs Radionuclides/Plutonium Cost to comply with EPA’s requirements to enhance monitoring and treatment of emissions (MACT Rule). Waste streams not amenable to efficient incineration: High energy transuranics, Mercury compounds, Explosives, and/or Reactives. Documented Cost Inefficient Operations


What are the Alternatives to Incineration? : What are the Alternatives to Incineration? Commercial Treatment Providers On-Site Fixed Treatment Facility Replacement of the Idaho AMWTF Incinerator Small Mobile Systems Pending Thermal Desorption at DOE Ohio Sites


Commercial Treatment Providers : Commercial Treatment Providers Allied Technology Group (ATG): Richland, WA Perma-Fix: Gainsville, FL Diversified Scientific Services, Inc. (DSSI): Kingston, TN Materials and Energy Corporation (M&EC): Oak Ridge, TN Waste Control Specialists (WCS): Andrews, TX (pending) Nuclear Sources and Services, Inc. (NSSI ): Houston, TX Envirocare: Clive, UT (pending) Studsvik: Erwin, TN (Low-Level only) GTS Duratek: Oak Ridge, TN (Low-Level only)


Classes of Alternative Incineration Technologies : Classes of Alternative Incineration Technologies Thermal Plasma DC-Arc Vitrifiers Metal Melters Steam Reformers Molten Salt Supercritical Water Catalytic Thermal Oxidation Microwave Pyrolysis Separation Thermal Desorption Solvent Extraction Soil Washing Chemical Oxidation DETOXSM DCO MEO Acid Digestion Dehalogenation Solvated Electron BCD APEG Biological Stabilization Pending Regulations


Slide8 : Plasma Systems Electric Arc Systems Vitrifiers Steam Reformers Metal Melters Molten Salt Oxidation (MSO) Super Critical Water Oxidation (SCWO) Catalytic Thermal Oxidation Microwave Pyrolysis Thermal Destruction Alternatives


Slide9 : High voltage discharge in a gas flowing in a helical pattern forms a plasma (10,000oC) Discharge generated by water cooled copper electrode/torch (short-life) Electrical energy  plasma  radiation & convection  transfers heat to waste High temperature of the melt (1200oC to 1800oC) produces a stable slag waste form with high waste loading Low oxygen causes pyrolysis of organics producing partially oxidized off-gas products Off-gas volumes are 1/3rd that of incineration, but will require off-gas treatment to meet MACT. Plasma Systems


Slide10 : Very robust (takes all waste forms/media with drums) Minimum pretreatment, mature, sufficient characterization is required for refractory compatibility Deployment Status: Meltran in Korea, PEAT in U. S. for hazardous waste Japanese and Swiss installed centrifugal plasma torch melters (Retech) for LLW applications Manufacturers: Retech, Plasma Energy Applied Technology, Inc. (PEAT), Startech, USPlasma, Meltran, Thermal Conversion Plasma Systems (continued)


Slide11 : Issues Waste composition may affect the melt, waste form characteristics, and refractory life. High temp - vaporize liquids, radionuclides & metals entrained or emitted in off-gas Volatile organics may be carried over for treatment in the offgas system High turbulence and particulate carryover Partitioning and fate of radionuclides Torch life is limited and steam explosions are possible Plasma Systems (continued)


Slide12 : Similar to plasma arc systems (except no torch gas so less particulate carryover) - operates at 1450 - 1800oC High voltage discharge between moveable carbon electrode and the waste melt or between carbon electrodes submerged in the melt Electrodes are consumed but continuously inserted into the reaction chamber - easily replaced and inexpensive Heat transferred via radiation, convection, and Joule heating by the submerged electrodes High temperature produces a stable slag waste form with high waste loading Electric Arc Systems Vincent Maio: Do we want to provide an operating temperature ? William E. Schwinkendorf: Done!


Slide13 : Very robust - solids, debris, soils, sludges Low oxygen causes pyrolysis of organics and only partially oxidized off-gases Offgas is typically around 10% of that of an incinerator but still requires an abatement system Steam may be injected to convert soot to CO and generate a syngas No pre-treatment, but characterization to avoid refractory damage Operating: ATG using IET’s hybrid DC Arc/vitrification unit Manufacturers: Electro-Pyrolysis and Integrated Environmental Technologies (IET) Electric Arc Systems (Continued)


Slide14 : Issues Waste composition may affect the melt, waste form characteristics, and refractory life. High temp - vaporize liquids, radionuclides, & metals Volatile organics may be carried over for treatment in the offgas system Partitioning and fate of radionuclides Electric Arc Systems (continued)


Slide15 : Less off-gas than incineration, but will require APC equipment Waste size reduction and removal from container is required Primarily applicable to stabilization of inorganics Operating Systems: ATG & GTS Duratek Joule heated melters for LLW TVS @ Oak Ridge built by Envitco Vortec’s cyclone melter for soil at Paducah Microwave melter using EET technology at NSSI Vitrifiers


Slide16 : Refractory lined vessel with electrodes submerged in melt (1,000oC) Converts inorganics to glass with frit and flux additives - glass chemistry tailored to waste Organics destroyed by pyrolysis or oxidation in plenum, but generally not suited for significant amounts of organic material Cold cap causes insufficient plenum temperature for complete oxidation Joule Heated Melter


 Joule Melter Issues : Joule Melter Issues Homogeneous feed is optimum - controlled, consistent, well characterized, and finely divided When the waste characteristics change the operation needs to change to prevent refractory corrosion and maintain melt chemistry Foaming, splattering & an insulating layer can be produced by CO3, SO4, NO3, organics Some salts won’t dissolve in the glass (chlorides vaporize, others produce scum causing shorting and corrosion) Some metal oxides (Al2O3) will increase viscosity Refractory life depends on acidity or basicity of the melt Temperature limited to prevent electrode and refractory corrosion Loss of containment experienced due to corrosion and thermal cycling Vincent Maio: Add a nice photo of TVS here? We got plenty. William E. Schwinkendorf: Looks good to me!


Other Melter Types : Other Melter Types Cyclone Melter Waste sized to small particles and mixed with coal and a glass former and injected into top of countercurrent reactor Waste combusted and forms small glass particles that are removed at the bottom Significant offgas and particulate carryover Water cooled, inductive skull melters Small volumes. If there is a problem and a freeze-up the small inner chamber could be removed and discarded as waste. Microwave Melter Microwave heating of particulates to from molten droplets Feed rate must be controlled Molten mass collected in bottom of drum.


Slide19 : Al and Fe have high organic reducing potential. Reducing mode possibly avoids dioxin/furan formation Molten metals destroy organic material by reduction, forms char, H2, and syn gas Radionuclides (U,TRU) and other metals are incorporated as free metals in aluminum ingots Inorganics form a slag with salts, later stabilized. Iron system operates at 1650oC - ATG - treats IX resins only Aluminum system operates at 900oC - Clean Technology International, Corp. - Austin, TX Molten Metal Baths


Slide20 : Aluminum process very robust - treats solids, liquids, debris, soils - liquids injected below melt surface, solids held below the surface to avoid sizing pretreatment Secondary waste: Spent off-gas sorbent, scrubber water, metal ingot, slag/salt layer Systems require waste characterization to avoid damage to refractory liner and to control the slag chemistry. Molten aluminum alloy is highly corrosive and a failed refractory or a leak would dissolve the stainless steel vessel and could be catastrophic Whether or not the system generates metal fumes that may be pyrophoric needs to be determined Molten Metal Baths (continued) Vincent Maio: Can add a photo of the CITC pilot unit here if you want. Like the one in the Jackson Summary Presentation William E. Schwinkendorf: Looks good - need graphics to break up the dry text.


Waste Treated with Molten Aluminum : Waste Treated with Molten Aluminum Samples of non-radioactive wastes have been treated: Circuit boards; small amount of ash residue Lab trash (rags, paper towels, cardboard, latex gloves); no visible treatment residue Absorbed oil; residue was clean “kitty litter” PVC pipe; no visible treatment residue PCB-contaminated soils, initially contained 40,000 ppm PCBs, 10,000 ppm chlorobenzene, 4,000 ppm m-xylene; all non-detect after treatment Medical waste Samples of pyrophoric uranium were treated. Final uranium content of the solidified bath was 5,000 ppm.


Slide22 : Bath of sodium carbonate molten salt at 900oC to 1000oC Waste (mostly liquids & particulates) injected with oxygen through a downcomer Solids must be sized to 1/8 “ to be fed Molten salt provides uniform heating, contact with O2, and residence time w/o excessive emissions Acids, radionuclides, and metals retained in salt residue APC system needs no aqueous scrubbers to remove acid gases, but requires system to treat PICs, remove volatile metals, and salt carry over Molten Salt Oxidation (MSO)


Slide23 : Handles organic solvent, and energetic/propellants/explosives slurried in water Excess ash could lead to bed freeze-up Spent salt with soot, char and radionuclides is a considerable secondary waste problem Salt recovery process has not been fully demonstrated and currently involves significant manual labor. Molten Salt Oxidation (continued)


Slide24 : Developed by LLNL and Rockwell ATG to commercialize LLNL process for mixed waste Molten Salt Oxidation Corporation was spun-off from Ajax Electric RMI AJAX/MSO system at Ashtabula LANL Testing process for Pu-238 recovery Molten Salt Oxidation (continued)


Slide25 : Reaction of organics with steam produces a combustible syngas that is treated and oxidized Two types currently available: Drum or screw feed evaporator: GTS Duratek for LLW Fluidized bed: Studsvik for LLW ion exchange resins and Thermochem for hazardous waste, Studsvik also has a Drum Pyrolysis method Relatively robust: Solids (slurries and particulate), liquids, size reduced combustible debris (< 2 to 3”) Chlorides in waste could be limiting depending on the type of reformer Steam Reformers


Slide26 : Fundamental process is pyrolysis with limited oxidation and reduction Less offgas than incineration and less toxic/hazardous constituents with complete oxidation in thermal oxidizer Thermatrix Unit or Catalytic Oxidizer Low flow rate minimizes particulate carryover Metals and radionuclides retained in 1st stage Residues include char/ash, scrubber wastewater, spent off-gas sorbent, inorganic waste constituents with fluidized bed media type Steam Reformers (continued)


Slide27 : H2O is critical at 374o C and 218 atm At super critical conditions H2O is non polar - organics are highly soluble and inorganics are insoluble. Waste mixed with oxygen or H2O2 and reacted at 400 - 650oC and 25.3 MPA (250 atm) Organic liquids and particulates are rapidly converted to CO2 and H2O Organic solids require considerable volume reduction (< 0.125”), minimal off-gas generated Proprietary method in development for organic debris Super Critical Water Oxidation (SCWO)


Slide28 : Secondary wastes include precipitated metal oxides and salts that require stabilization Problems associated with precipitated salts plugging the reactor, acid corrosion and high pressure pumps General Atomics and Foster Wheeler Development Corporation have commercial systems for DOD wastes Swedish company has rights to SCWO process developed by Eco Waste. Eco Waste built a system for Huntsman Chemical in Texas Sandia CA has development capabilities, INEEL has done considerable testing. Super Critical Water Oxidation (continued)


Catalytic Thermal Oxidation : Catalytic Thermal Oxidation Tritiated liquid waste treatment and 3H recovery Thermal oxidation process operating at 450–750oC, P = ambient, and using Pt-coated alumina pellets as catalysts Waste mixture with O2 and/or H2O is optimized to achieve maximum DRE and minimize soot and PICs High DREs - Typically six 9s for chlorinated and non-chlorinated liquids


Catalytic Thermal Oxidation (continued) : Catalytic Thermal Oxidation (continued) Over 10% hydrochloric acid in the gas phase has a negative effect on the catalyst and resulting DRE. Catalyst will degrade and require regeneration after a period of time System developed by R. W. Johnson Pharmaceutical Research Institute will soon be operational at NSSI to process 40 liters/day of liquid organics. Equivalent system also developed at LBNL Tritium Labeling facility Thermal oxidation followed by water treatment to remove residual ions and organics and electrolysis is used to extract hydrogen. Isotope separation based on gas chromatography can process 8 m3/day of hydrogen to recover tritium.


Microwave Pyrolysis (Reverse Polymerization) : Microwave Pyrolysis (Reverse Polymerization) High-energy microwaves break down organic materials at 150C to 350C at atmospheric pressure and under a nitrogen blanket. Low gas flow minimizes offgas and particulates, and low temperature reduces volatilized metals and radionuclides. Waste is loaded in plastic bags on cardboard carriers - a conveyor belt transports the waste into a stainless steel microwave chamber. Offgases are cooled to condense heavy hydrocarbons, scrubbed to remove acid gases, and passed through a thermal oxidizer to treat non-condensable hydrocarbons.


Microwave Pyrolysis (continued) : Microwave Pyrolysis (continued) The process is being applied to tires and medical waste (cloth, laboratory fluids, solvents, paper, plastics, glass and metals). Capacity for medical waste is 1000 to 1400 pounds in 12 to 16 hours or 3000 tires or 27 tonnes of tires per day Volume reduction is 80% for the medical waste. Carbon residue collects on the stainless steel interior walls of the chamber - may contain radionuclides Developed and commercialized by Environmental Waste International of Canada Many questions regarding this process - reliability, DRE, size reduction, secondary waste.


Slide33 : Use oxidizing agents in bath/batch type systems Organics converted to H2O, CO2 & mineral salts in a corrosive aqueous solution at temperatures an order of magnitude lower than incineration Involves chemical redox: organics-oxidized, agents - reduced Systems equipped with methods to regenerate oxidants Reaction and residence times are slower (hours to days) compared to thermal processes Volatile organics may require treatment in an offgas system Chemical Oxidation Aqueous Based Oxidation Processes


Slide34 : Adequate for most liquids - solid/debris must be considerably size reduced, some solids (plastics) and liquids (PCBs) may be too refractory to be treated (frequent bath change out or long residence time) Low off-gas, considerable secondary waste stabilization Systems are complex, immature, and integrated system development is required Most systems use a highly corrosive medium - prone to leaks and corrosion of components Destruction efficiency depends on the process, organic compound, and residence time. Chemical Oxidation Aqueous Based Oxidation Processes


Slide35 : Alternatives: Acid Digestion (HNO3/H3PO4) Ferric Chloride/HCl Oxidation (DETOXSM) Mediated Electrochemical Oxidation (MEO) Silver ,Cerium, or Cobalt Type Systems Direct Chemical Oxidation (DCO) Chemical Oxidation


Acid Digestion: Nitric/Phosphoric Acid : Acid Digestion: Nitric/Phosphoric Acid Developed by SRS and temporarily marketed by CeraChem Process operates at or below 200oC and at 0–15 psig to treat some liquid and many solid organics Primarily applicable to decontamination of organic solids and inorganics (dissolves Pu) Complete system to extract HCl from the NOx offgas and recover nitric acid has not been demonstrated Process has not been shown to destroy the more resistant organic liquids or solids Vincent Maio: Got a pretty simple photo, do you want it?


Slide37 : Developed by Delphi Research, Inc. with support by LANL. Further testing at IT Corp. with DOE funding to treat PCB wastes. Catalytic aqueous process with FeCl3 and HCl at 100oC to 200oC, and 20 to 200 psig. Applicable to size reduced combustible debris, organic liquids and sludges with destruction efficiencies of 99.999% for nonchlorinated organics to 98.9% for PCBs depending on the compound and residence time Corrosion, materials compatibility and leaks are issues. Complex process has not been fully demonstrated Delphi Detox: FeCl3 in HCl


Mediated Electrochemical Oxidation (MEO) : Mediated Electrochemical Oxidation (MEO) AEA uses Ag(II) and CerOx uses Ce(IV) in nitric acid as oxidizing agents at room temperature & pressure Applied in the UK to treatment of IX resin, dry active waste, PUREX waste, chemical munitions, and recovery of Pu. Studies and development of the Ag(II) process are continuing in the UK, Belgium, France, US and Germany Able to oxidize many different organic materials (solids and liquids) but raises issues of corrosion, materials compatibility and leak tightness. Efficient, full scale recovery of Ag from AgCl or Cl2 from NOx offgas has not been demonstrated Systems are highly complex


Slide39 : (NH4)2S2O8 + {organics)  2NH4HSO4 + (CO2, H2O, inorganic residues) Developed by LLNL, available at Permafix. Future availability through the OR Broad Spectrum contract with M&EC and possibly WCS and ATG Ability to treat PCBs and solid organics is unclear. Hydrolysis pretreatment required to solubilize some organics Oxidant regenerated electrochemically but process has not been demonstrated - sulfate may be a significant secondary waste. Least corrosive of the chemical oxidation processes - operates at 80–180oC and ambient pressure Direct Chemical Oxidation: Peroxydisulfate Vincent Maio: Got a photo, want it? It is like the one in the Jackson Summary? William E. Schwinkendorf: Yes, This plus the photo of the DETOX plant at SRS will give them an idea of scale.


Slide40 : Alternatives: Alkali metal polyethylene glycol (APEG) Base catalyzed decomposition (BCD) Birch process (Commodore Advanced Science) Process Replace halogens (e.g. chloride) in hydrocarbons with hydrogen and other groups to produce a less toxic organic For PCBs, pesticides, herbicides, dioxins, CFCs, and warfare agents Further organic treatment may be required: No off-gas issues unless mercury or tritium are present Dehalogenation


Slide41 : Slow process used at Superfund sites for PCB contaminated soils, but not mixed waste Used by Soil Tech and Gulson Remediation Uses KOH/NaOH, polyethylene glycol and dimethylsulfoxide (DMSO) Add heat to dechlorinate (replace Cl with glycol) and create chloride salts of K and/or Na Secondary waste includes soil with dechlorinated organics and alkaline chloride APEG Process


Slide42 : Slow process used at Superfund sites for PCB contaminated soils, but not mixed waste Developed by EPA’s Risk Reduction Engineering Laboratory (RREL) 2 stages for PCBs and soil Heat with sodium bicarbonate to decompose & volatilize PCBs Collected PCBs, scrubber solution residues from off-gas, react with NaOH to produce aliphatic hydrocarbons and chloride salts with a catalyst BCD Process (Base Catalyzed Decomposition)


Slide43 : Fast process applicable to contaminated solids or liquid chlorinated hydrocarbons Sodium metal dissolved in liquid anhydrous ammonia produces solvated electrons that strip chlorine from hydrocarbons Ammonia is flashed off and recovered Residue includes the original inorganic solid waste, dechlorinated organic material (biphenyl), NaOH and NaCl Demonstrations have been performed for site remediation & Navy Weldon Springs Demonstration Material Pre-Treatment (ppm) Destruction Efficiency (%) Shredded Corn Cobs 1270 99.8 Un-Shredded Corn Cobs 944 97.4 Transformer Capacitor Parts 6 97.8 Solvated Electron Process (Commodore)


Solvated Electron Process Issues : Solvated Electron Process Issues Ammonia contact with chemicals such as mercury, chlorine, iodine, bromine, silver oxide, or hypochlorites can form explosive compounds. There are special hazards with chlorine that result in the formation of chloramine gas. Sodium metal may ignite spontaneously on exposure to air.


Slide45 : Alternatives: Thermal Desorption Directly or indirectly heated rotary kiln Indirectly heated screw auger Paddle dryer Continuous belt conveyor dryer Vacuum dryer Soil Washing Solvent Extraction Organic liquids and acids Supercritical fluids Separation Processes


Slide46 : Drying process heats solid waste to 300 - 1200oF Drives off moisture and organic compounds which are usually condensed or captured in carbon beds for subsequent treatment Most systems use a carrier gas to remove volatile and semi-volatile organics Nitrogen used as sweep gas to avoid explosions Vacuum desorbers can be operated without a carrier gas to desorb volatile and semi-volatile organics and pyrolyze non-volatile organic material Thermal Desorption


Slide47 : Contaminant removal is highly dependent on temperature, vacuum, residence time, matrix, contaminant and moisture content Viscous waste may ball and stick to the heat transfer surfaces preventing complete desorption GTS, DSSI operate LLW facilities Envirocare/WCS may have SepraDyne vacuum desorption through the OR Broad Spectrum Many commercial suppliers: CWM, McLaren Hart, IT Corp. ELI Eco Logic, Sepradyne Thermal Desorption (continued) Vincent Maio: Also got that Sepradyne picture from the Jackson summary presentation


SepraDyne Vacuum Desorber System : SepraDyne Vacuum Desorber System Indirectly heated rotary kiln Operates at 750C and ~0.06 atmospheres in an oxygen free environment with no carrier gas Desorbes volatiles and semi-volatiles. Pyrolyzes non-volatile organics to produce volatile organics Commercial operation to extract mercury from mine waste Demonstrated at Brookhaven on mixed waste (organic debris, animal carcasses, etc.) including destruction of dioxins in incinerator ash. Secondary waste includes solids, char, and condensed liquids


EcoLogic System : EcoLogic System Organics are vaporized in the presence of hydrogen-rich hot recirculation gas. Air ingress could form an explosive hydrogen/air mixture. Evaporation chambers available for bulk solids, watery and oily wastes, and soils and sediments Reduction process > 850oC combines H2 with organics to form lighter hydrocarbons, primarily methane. HCl formed from chlorinated hydrocarbons (PCBs). Reaction is enhanced by water, which acts as a reducing agent and a hydrogen source. Applied to PCBs, electrical equipment, contaminated soils, chemical warfare agents, petrochemical wastes, and certain low-level radioactive wastes


Summary : Summary Various potential alternatives Thermal Chemical Dehalogenation Thermal Desorption Stabilization All alternatives have less offgas than incineration and less potential for hazardous air emissions. Offgas contaminants and toxicology from non-combustion environments is largely unknown Thermal processes are the most robust - but temperature and offgas may hinder implementation.


Summary (continued) : Summary (continued) Chemical systems may be more acceptable to the public but can treat fewer waste types. DC-Arc systems appear to provide capabilities equivalent to incinerators Waste stabilization Refractory life and reliability issues Steam reformers may also provide equivalent DREs but require proof for various waste types (e.g., treatability studies) Several niche technologies for liquids/sludges or waste containing volatile metals or tritium