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Treatment Technologies for Newly Generated Hazardous Waste

Treatment Technologies for Newly Generated Hazardous Waste. Treatment Technologies for Newly Generated Hazardous Waste. 2. Transitioning From Land Disposal to Treatment – The Law Philosophy and Management of Waste Disposal Thermal and Recycling Technologies – Petroleum Wastes

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Treatment Technologies for Newly Generated Hazardous Waste

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  1. Treatment Technologies for Newly Generated Hazardous Waste

  2. Treatment Technologies for Newly Generated Hazardous Waste 2 2 • Transitioning From Land Disposal to Treatment – The Law • Philosophy and Management of Waste Disposal • Thermal and Recycling Technologies – Petroleum Wastes • Pretreatment- Extraction- Separation • Thermal Desorption • Pyrolysis - Coking - Gasification • Oil Recovery/ Spent Catalyst Recovery • Wastewater Treatment • Thermal and Stabilization Technologies – All Wastes • Incineration-Fluidized Bed Combustion • Incineration-Industrial Furnaces (with and without energy recovery) • Plasma Arc • Molten Glass • Solidification and Stabilization • Land Filling • Deep Well Injection

  3. Transitioning from Land Disposal To Treatment • Government policy is essential for managing hazardous waste (HW) • Alone HW will be handled in cheapest way • No natural market forces for HW • Government provides incentive for management • Without regulation dumping will prevail • Even the best designed landfills leak • Cleanup is always more costly than proper management 3 3

  4. Many Lessons have been Learned (US, EU and Canada) • Cost is king – lowest cost is always uncontrolled land or sea disposal • Short term factors provide dominant role – lower costs • Government regulation can provide long term view • When Government specifies a goal • Company will choose the lowest cost treatment technology (among alternatives). • Superior technology that exceeds prescribed performance will be chosen only if cost is acceptable 4 4

  5. Management –Legal Approaches 5 5 U.S. – Canada: Performance Standards – Best Demonstrated Available Technology (BDAT). Before Land Disposal All Wastes Must Be Reduced in Toxicity to the Greatest Extent Possible as Determined by the Performance of the Best Technology(s) Available. Europe: Public Utility Model – Some European Countries Have State Owned and Operated Facilities Accompanied by Mandates on Generators To Use The Facility at Established Rates. Others: Technology-Specific Standards – Other Countries Mandate the Use of Specific Technologies Prior to Land Disposal, Facilities Privately Operated.

  6. Management –Enforcement Issues 6 6 • Proper and strict enforcement is the cornerstone of any successful system. • Restrictions on export to Countries Without Comparable Controls Must Be Imposed. • When done properly “recycling” is the best of all methods: recovery of a resource and treatment of the toxic constituents:

  7. 7 Hazardous Waste Treatment and Disposal is Multifaceted Recycling Incinerators Land Fill Haz Waste Boilers Furnaces Water Treatment Underground Injection

  8. Pollution from Petroleum Refineries can Take Many Forms Air emissions VOCs (volatile organic compounds) Carbon Monoxide (CO), Sulfur Oxides (SOx), Nitrogen Oxides (NOx), Particulates, Ammonia (NH3), Hydrogen sulfide (H2S), Waste water Benzene, phenols, amines, sulphides, caustic, cooling water blowdown, brines Solid waste Metals (spent catalysts), spent acids, water treatment sludge, used equipment, organic residuals. 8 8

  9. Recycling and Waste Minimization in Petroleum Industry • Waste Minimization and Product Recovery • Distillation • Solvent Extraction • Water Treatment • Catalyst Recovery • Energy Recovery • Ash Utilization Quote: “In my country we use all parts of the chicken” Recycling reduces waste transportation ,storage and treatment costs, while improving product recovery. 9 9

  10. Recycling and Thermal Technologies to Treat Refinery Waste 10 10 • Refinery Waste Pretreatment • Extraction and Separation (oil recovery /recycle) • Distillation • Solvent Extraction • Centrifugation - Hydrocyclones • Water Treatment • Wet Air Oxidation • Air and Steam Stripping • Wastewater Processes – DAF, coagulation, filtration, GAC • Thermal Desorption • Pyrolysis-Coker-Gasifier • Fluidized Bed Combustion

  11. Pretreatment of Petroleum Refinery Waste (Slops) • Heating and decantation with gravity separation • De-emulsifying • Electrostatic coalescers • Oil in water • Water in oil • Separation – Centrifugation- Filtration • Solvent extraction • Thermal distillation – Product recovery API Gravity Separator Source: Milton Beychock Wikipedia 11 11

  12. Distillation: Continuous and Batch Source :H. Padleckas-Wikipedia 12 12

  13. Distillation Pros and Cons • Advantages • Recovers useable organic solvents from wastes. • Product purity of a range of levels can be designed into the distillation process, limited mainly by economic considerations. • Disadvantages • Costs of recovery often exceed cost of thermal destruction. • Complex operation high capital cost, high energy costs. • Columns can be large if a high degree of purity is required (200 feet). • Feed must be a free flowing fluid with low solids content. • Must be custom designed for a given waste stream not for variable feed. 13 13

  14. Solvent Extraction and Other Separation Processes 14 14

  15. Petroleum Wastewater Extraction, Separation and Treatment Processes • Solvent Extraction • • Preparation (sorting the contaminated material) • • Extraction • • Separation of concentrated contaminants from solvent • • Removal of residual solvent • • Contaminant recovery, recycling, or further treatment. • Air or Steam Stripping • Similar to distillation – recovery and recycle of organics • Steam stripping can recover low VP and soluble compounds • Centrifugation • Hydrocyclone: oil water separator • Decanter: slop oil, 3 component sludge • Wet Air Oxidation • Organic waste oxidation in water • 150°C-325°C, 300psi-3000 psi 15 15

  16. Coagulation / Flocculation – removes suspended solids whenever natural subsidence rates are too slow to provide effective clarification Water clarification Lime softening Sludge thickening Dewatering Solids / Liquid Separation – gravitational settling Sedimentation Air/Gas Flotation Filtration Centrifugation Wastewater Treatment- Petroleum Generic 16 16

  17. Precipitation (Softening) – removes hardness by chemical reaction and settling Lime softening Silica removal Heavy metals removal Ion Exchange – removes unwanted ions by transferring them to solid material Anion exchange (weak base, strong base) Cation exchange (weak acid, strong acid) Regeneration with neutralization Ion specific resins (boron removal) Wastewater Treatment- Petroleum Generic (continued) 17 17

  18. Neutralization – acid / base addition to adjust pH Neutral pH = 7 Neutral pH range = 6 - 9 Membrane Separation – use membranes to remove suspended and dissolved solids Microfiltration (MF) = removes suspended solids Ultrafiltration (UF) = removes suspended solids Reverse Osmosis (RO) = uses pressure to remove dissolved solids Electrodialysis (ED) = uses electricity to remove dissolved solids Wastewater Treatment- Petroleum Generic (continued) 18 18

  19. Adsorption – uses physical adhesion unto porous media to remove unwanted molecules Activated carbon adsorption Resin columns Fluoride removal with alumina Evaporation – water vaporization / condensation Flow configurations (rising film, falling film, forced circulation) Energy configurations (multiple effect, vapor recompression) Oxidation / Reduction – uses oxidation / reducing agents to remove unwanted constituents Iron & manganese removal Cyanide removal Sulfide removal Wastewater Treatment- Petroleum Generic (continued) 19 19

  20. Thermal Desorption Very Flexible for Petroleum Waste Solids • Typical desorption temperatures are 150°C - 650°C • Desorbed vapor • Trapped onto activated carbon • Condensed • Burned in afterburner or oxidizer • Remaining solids cleaned 20 20

  21. Thermal Desorption can be used for Petroleum Waste or Soils • Rotary kiln or dryers • Mobile or stationary • Co-current or countercurrent • Feed and product handling equipment 21 21

  22. Unit Operations for Product Recovery -Refinery Waste (Thermal Desorb) 22 22

  23. Advantages Low capital operating cost compared to other thermal technologies. Low regulatory hurdles for permitting. Can be applied in the field. Allows for both destruction and recovery of organic contaminants. Disadvantages Material larger than 2 inches needs to be crushed or removed. Plastic soils tend to stick to equipment and agglomerate. Pretreatment- shredding- blending with friable soils/ gypsum. Highly contaminated soils will require multiple cycles. Not amenable to semi-volatile or non-volatile, chlorinated hazardous constituents. (Example: PCBs, pesticides) Fugitive emissions may present exposure risk to workers and environment. Thermal Desorption Pros and Cons 23 23

  24. Pyrolysis Processes: Pyrolysis, Coking and Gasification Pyrolysis: Thermal decomposition by heating in the absence of oxygen. Coking is a specialized form of pyrolysis. Gasification is thermal decomposition (partial combustion). Two Steps: Wastes are heated in oxygen-starved condition to separate the volatile components from non-volatile char and ash (430°C-760°C). Volatile components are combusted in oxygen-rich condition to provide destruction of hazardous constituents. 24 24

  25. Pyrolysis used for Solids, Liquids and Sludges • Indirect Heating : flame does not touch waste • Direct Heating : flame contacts waste in air starved conditions • Wastes (salts and metals) that melt are retained in char (simplifying air pollution control) Rotary Hearth Rotary Kiln Fixed Hearth 25 25

  26. Advantages Lower temperature process compared to incineration, increasing refractory life and reducing costs. High feed rates, up to 5 tons/hour. Downstream APC equipment needs reduced since metals and PM tend to be retained in char. Degree of pyrolytic reaction can be controlled to yield synfuel or products for recovery. Condensable vapors with economic value can be recovered. Non-condensable vapors can be used for energy. Disadvantages High capital cost. Char still retains hazardous constituents and metals, requiring subsequent treatment and controlled disposal. Fume incineration needed to destroy Products of Incomplete Combustion (PICs), and other hazardous organic constituents. Pyrolysis Pros and Cons 26 26

  27. Coking is a Pyrolysis Process :Waste Minimization and Product Formation • Oily Waste • API Separator Sludge • Dissolved Air Flotation Resid • Slop Oil Emulsions • Waste is co fed with Petroleum Bottoms to the Furnace and then Coke Drums 27 27

  28. Coking is a Batch Process– De-coking is Performed using Drill Rig Coker fires can occur if the molten coke contacts air during de-coking operations On oil drum - high temperature pyrolysis Off oil drum - emptied during decoking 28 28

  29. Advantages Allows on-site recovery and reuse of petroleum refining waste, increasing yields of products. Disadvantages Only amenable to petroleum refining waste and certain oily wastes. Significant Safety Hazards and fugitive emissions require extensive vigilance and controls (See EPA/OSHA Joint Report – “Hazards of Delayed Coker Unit Operations” – EPA 550-F-03-001, August 2003) High capital cost makes it practical only in a refinery setting. Petroleum Coke is a very low grade, dirty fuel which concentrates heavy metals. Coking Pros and Cons 29 29

  30. Gasification : Thermal Process Subsequent to Pyrolysis Liquid Synthesis Burn for Power Feeds can be waste solids or liquids. Biofuels, coal and residuum are used as well. Fuel Chemicals 30 30

  31. H - C + O2 CO2 Combustion + C + CO2 Boudouard 2 CO + C + H2O CO + H2 Carbon-steam - CO2 + H2 Water-gas Shift CO + H2O - Hydrogenation C + 2H2 CH4 Reactions Occurring in the Gasifier Composition of gasifier gas depends on the balance of these five reactions and whether air or oxygen is used in the gasifier. • Moving bed • Entrained flow • Fluidized bed

  32. Advantages Beneficial use of waste to produce syngas, energy or useable products. High temperature process provides for destruction of hazardous constituents. Disadvantages Extremely high capital cost $30 – 50M. Large scale operation required to make economics work. Must be integrated into a chemical or petroleum refining plant. Not a free-standing technology like incineration. Off-gas treatment still required, including downstream fume incineration. Residues are generated which, like pyrolysis, may contain hazardous metals that require subsequent managed treatment and disposal. Gasification Pros and Cons 32 32

  33. 33 Spent Catalyst Recovery and Disposal for Petroleum Refineries • Catalytic cracking- Zeolites regenerated in process • Hydrotreating – Ni, Mo, W, Co recovery • Acid and caustic metals separation and precipitation. (Hydrometallurgical) • High temperature fusion (Pyrometallurgical) • Naptha reforming - Pt or Re on silica or silica alumina support (Recycled for precious metal-chlorinated precipitate) • Steam reforming - Ni oxide catalyst on alumina support (Nickel recovery Alumina + NaOH) Source: www.matrostech.com

  34. Generic Hazardous Waste Thermal Treatment Technologies • Incineration • Dedicated (no power or product) • High temperature oxidation • Rotary Kiln • Fixed Grate • Fluidized Bed • Air pollution control (APC) • Industrial Furnaces • Boilers – produces steam for power • Kilns – produces product and reduces fuel • Furnace – provides process heat • APC part of industrial process • Specialized Methods • Molten glass • Plasma arc 34 34

  35. Fluidized Bed Thermal Oxidation • Fluidized sand recirculated • 1,000 units operated world wide • Up to 140 million Btu/hr (2460 MJ/min) • Transportable fluidized bed systems • Halogenated waste (> 99.99% DRE at 1300 F) • Lower capital and operating than rotary kiln • Refractory life longer than rotary kiln 35 35

  36. Advantages Well suited to refinery waste, pumpable sludges and halogenated waste. Excellent contact between gas and solid high DRE. Stable control temperature, residence time vary air velocity at the bottom of bed. Better than other thermal methods for heat recovery. Disadvantages Cannot feed containerized waste directly or non-pumpable solids. Pre-processing (homogenization) of waste is required so that all solids are less than ½ inch. Waste must have heat content > 3500 BTU/lb. Bed agglomeration and failure of the fluidized system can occur in the presence of > 2% sodium or other alkali salts. Fluidized Bed Combustion Pros and Cons 36 36

  37. Incineration is the Controlled Combustion of Waste • Requires 3 “T’s”: • Time: 2 seconds minimum • Temperatures: 1000°C-1200°C • Turbulence: Mixing during burn • Rotary Kiln or Fixed Grate • Secondary Combustion Chamber (afterburner) • Rapid cooling of ash to prevent PCDD and PCDF Source :http://www.pollutionissues.com/ 37 37

  38. 38 Incineration is not the Same as Open Burning Source: EPA/600/SR-97/134 March 1998 Waste to Energy =WTE

  39. Incineration: Rotary Kiln Specifically for Waste Disposal 39 39

  40. Incineration: Feed Systems 40 40

  41. Particulate Matter < 34 mg/dscm Dioxin < 0.2 ng TEQ/dscm Pb&Cd < 240 ug/dscm As, Be & Cr < 87 ug/dscm HCl < 77 ppm Hydrocarbons < 10 ppm CO < 100 ppm DRE > 99.99% PCB and Dioxin waste incinerators must demonstrate a minimum of 99.9999% Destruction Removal Efficiency (DRE) Products of Incomplete Combustion (PICs) must be evaluated in a Human Health and Ecological Risk Assessment. Incineration : Air Emission Standards 41 41

  42. 42 Comparison of 95 U.S. WTE plants with EPA Standard - (2001Success story!) TEQ: Toxic Equivalents are used to report the toxicity-weighted masses of mixtures of dioxins (ng/dscm or mg/dscm): nanograms or milligrams per dry standard cubic meter (ppmv): parts per million by volume Source: http://www.energyanswers.com/pdf/awma_final.pdf

  43. Incineration: Ash Treatment Standards (US EPA regulates 200 constituents) * Toxic Characteristic Leaching Procedure (TCLP) 43 43

  44. Emission standards are tied to continuous feed limits for metals, chlorine and organic hazardous constituents. Laboratory facilities must be in place to test waste feed on an ongoing basis. ICP for metals, GC/MS for Organics, Ion Chromatography for halogens. Incineration: Emissions Monitoring 44 44

  45. Advantages: Can be applied to a wide variety of hazardous wastes. Provides destruction and volume reduction of the waste. Disadvantages Not amenable to waste containing high concentration of heavy metals (> 1%). Waste feed mechanisms often complex High capital cost due to extensive Air Pollution Control (APC) system and sophisticated controls required to meet emission standards. Ash must be treated for leachable metals prior to land disposal. Incineration Pros and Cons 45 45

  46. Kilns Cement Lightweight Aggregate Lime Furnaces Halogen Acid Sulfuric Acid Industrial boilers. Waste types and amount limited Protect product and process quality Cement and lightweight aggregate kilns only liquid waste Minimum heat content > 5000 BTU/lb Thermal substitution rate is limited to 50%. Industrial Furnaces: Kilns and Boilers (APC part of industrial process) 46 46

  47. Alternative Fuels and Raw Materials Kiln Feed Typical Dry Process Cement Kiln Kiln Gases 2000 °C Material 1450°C > 15 min. Retention time > 10 s Clinker Immobilization of metals Precalciner Gases: > 900 °C, Materials 700 °C Retention time > 3 s 47 47

  48. In the U.S., most boilers lack an APC system and therefore are extremely limited in the types of waste that can be burned (liquids, zero halogens and metals) Boilers can have Two Combustion Zones and Air Pollution Control 48 48

  49. Boilers can have Two Combustion Zones and Air Pollution Control APC systems Bag house filtration Electrostatic precipitators 49 49

  50. Advantages: Displace other fuels improve economics Waste producers may pay for service Can be applied to a waster oils and other solid waste (tires). APC equipment in place Residence times in kilns are high Disadvantages Industrial process and products may not permit Waste feed mechanisms add complexity Admixture rate may be low Waste destruction may upset industrial process Boiler and Furnace Pros and Cons 50 50

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