Treatment Technologies

1. Treatment Technologies ENVM 649: Principles of Waste Management and Pollution Control Dr. Robert Beauchamp

2. GENERAL CATEGORIES • THERMAL TREATMENT • PHYSICAL/CHEMICAL TREATMENT • BIOLOGICAL TREATMENT • CONTAINMENT & DISPOSAL

3. THERMAL TREATMENT • INCINERATION • DESTROYS ORGANIC COMPOUNDS, REDUCES VOLUME.CONVERTS LIQUID WASTE TO SOLIDS.HIGH REMOVAL EFFICIENCIES. 900-1500 DEG. C • (ROTARY KILN, LIQUID INJECTION). MOBILE OR FIXED. • THERMAL ADSORPTION • THERMAL DESORPTION: VOLATIZES VOC's. 300-600 DEG. C. • PYROLYSIS, & VITRIFICATION PYROLYSIS: CONVERTS VOC's TO COMBUSTIBLE, GAS, CHARCOAL, LIQUIDS AND ASH. 500-800 DEG. C. VITRIFICATION: • HIGH TEMPERATURE ELECTRODES MELT THE WASTE. • IN-SITU OR EX-SITU. • GASES ARE COLLECTED BY A HOOD FOR TREATMENT. • 4,000 VOLTS REQUIRED - 3,600 DEG. C. • NEED SUFFICIENT GLASS FORMINGMATERIAL. • DEEP WATER TABLE.

4. IN SITU TREATMENT (SOILS) • SOIL FLUSHING • BIOREMEDIATION • VAPOR EXTRACTION • SOLIDIFICATION

5. PHYSICAL TREATMENTS (IN-SITU) • SOIL FLUSHING: • REMOVING SOIL CONTAMINANTS (ORGANIC/INORGANIC) FOR TREATMENT • SOIL WASHING: • SIMILAR TREATMENTUSING: WATER, ACIDIC SOLUTIONS, & SURFACTANTS

6. SOLIDIFICATION/STABILIZATION • POZZOLAN - PORTLAND SYSTEMS (PHYSICAL ENTRAPMENT) • CONTAMINANTS: • METALS, PCB’S, OIL SLUDGES, WASTES (VINYL CHLORIDE, RESINS, ASBESTOS, SULFIDES, ETC.) • POZZOLANS INCLUDE: FLY ASH, PUMICE, LIME KILN DUST. • THERMOPLASTIC TREATMENT: • ASPHALT OR POLYETHYLENE - BIND THE WASTE (I.E., SLUDGES, PAINT, RADIOACTIVE MATERIALS, METALS, ORGANICS)

7. BIOLOGICAL PROCESSES • AEROBIC: • MICROORGANISMS NEED A CARBON & ENERGY SOURCE. • TEMPERATURE AND PH MUST BE CONTROLLED. • NUTRIENTS-NITROGEN, PHOSPHOROUS. • PH 6 - 8 IS BEST. • NEED O2 AERATION IS REQUIRED. • TEMPERATURE > 15 DEGREES C IS BEST. AEROBIC AND ANAEROBIC

8. BIOLOGICAL PROCESSES (cont) • ANAEROBIC DIGESTION: • ABSENCE OF FREE O2 • CONVERTS HYDROCARBONS FROM COMPLEX TO SIMPLER MOLECULES & TO CO2 & METHANE. • REQUIRES NO POWER. • VERY HIGH ORGANIC DESTRUCTION RATES. • METHANE CAN BE OF COMMERCIAL VALUE. • LESS LAND REQUIRED. • DISADVANTAGES: • MAY TAKE A LONG TIME • EXPERIENCE LACKING • DESIGN CAN BE DIFFICULT • A PH = 6 - 8 IS BEST.

9. VAPOR EXTRACTION/AIR SPARGING • IN-SITU AIR STRIPPING PROCESS • AIR STRIPPING: • REMOVES VOC'S - LIMITED TO 100MG/L VOC'S. • HENRY'S LAW GOVERNS EQUILIBRIUM RELATIONSHIP & HELPS DESIGN THE AIR STRIPPER. • STEAM STRIPPING: • TREATS MORE SOLUBLE, LESS VOLATILE VOC'S, AND HIGHER CONCENTRATIONS OF VOC’S. • AIR SPARGING: • REMOVES HIGHEST MOLECULE WEIGHT PETROLEUMCOMPOUNDS AND CHLORINATED SOLVENTS. • AIR IS FORCED BELOW THE H2O TABLE. • VAPOR EXTRACTION SYSTEMS COLLECT CONTAMINANT IN THE AIR AFTER BEING BROUGHT TO THE SURFACE.

10. CHEMICAL PRECIPITATION • A SOLUBLE SUBSTANCE IS CONVERTED TO A INSOLUBLE SUBSTANCE. • CAN BE REMOVED BY SETTLING OR BY FILTERING. • METALS OF CONCERN - ARSENIC, BARIUM, CADMIUM, CHROMIUM, COPPER, LEAD, MERCURY, SILVER, ZINC. • SOURCES OF METALS - METAL PLATING AND POLISHING,THE STEEL AND ELECTRONICS INDUSTRY.

11. CHEMICAL PRECIPITATION PROCESS • A PRECIPITANT IS ADDED - HYDROXIDE (LIME) I.E.CALCIUM HYDROXIDE). • REMOVES METALS AS METAL HYDROXIDE. • METALS PRECIPITATED AS SULFIDES & CARBONATES. • DEPENDS ON: • CONCENTRATION,PH, PRESENCE OF OTHER MATERIALS. • PH OF 9 - 11 IS OPTIMAL • CAN REDUCE TO = OR < 1.0 MG/L • NOTE: METAL HYDROXIDES ARE AMPHOTERIC (SOLUABLE @ HIGH AND LOW PH).

12. SULFIDE PRECIPITATION • SULFIDES ARE NOT AMPHOTERIC • HAVE VERY LOW SOLUBILITIES • SOURCES OF SULFIDE INCLUDE IRON SULFIDE & SODIUM SULFIDE. • PROBLEM - PH NEEDS TO BE > 8 TO PREVENT FORMATION OF HYDROGEN SULFIDE (TOXIC GAS)

13. CARBONATE PRECIPITATION • NEED A LOWER PH - 7.5 - 8.5 (LOWER THAN THE HYDROXIDE METHOD)

14. SODIUM BOROHYDRIDE PRECIPITATION •  A REDUCING AGENT • PH 8-11. GOOD FOR LEAD, MERCURY, NICKEL, COPPER, GOLD.

15. ELECTROLYTIC RECOVERY • WORKS BEST FOR PROCESS STREAMS WITH HIGH CONC. OF METALS. • USES ANODE AND CATHODE ELECTRODES. • CATHODES ARE IMMERSED IN A CHEMICAL MEDIUM UNDER AN APPLIED POTENTIAL. METAL IONS ARE REDUCED TO ELEMENTAL FORM AT THE CATHODE. • ADVANTAGES: • METALS RECOVERED FOR REUSE. • TOXIC DISCHARGE REDUCED. • LOW INITIAL INVESTMENT. • LOW OPERATION EXPENSES. • MINIMAL MAINTENANCE. • DISADVANTAGES: • ONLY GOOD FOR STREAMS WITH HIGH CONCENTRATIONS. • DEPLETION OF METALS IN STREAMS OFFER RESISTANCE TO CONTINUOUS METAL MIGRATION TO THE CATHODE. • GAS FORMATION @ CATHODES (H & CL).

16. ACTIVATED CARBON ADSORPTION • FOR LIQUIDS AND GASEOUS STREAMS • USED WHEN WASTE STREAM IS NOT FULLY UNDERSTOOD. • USED IN TREATMENT TRAIN. • CARBON CAN BE REUSED • GRANULATED CARBON USED IN FLOW THROUGH COLUMNS, AND POWDERED AC IS USED FOR SLURRY REACTIONS.

17. ACTIVATED CARBON ADSORPTION (cont) • 3 PROCESSES: • PHYSICAL ADSORPTION-WEAK • CHEMICAL ADSORPTIONCHEMICAL BONDING • ELECTROSTATIC ADSORPTION - ATTRACTIVE FORCES • ADSORPTION INCREASES AS SOLUBILITY DECREASES ASMOLECULAR WEIGHT OF THE CONNTAMINANT DECREASES. • MICROBIAL ACTIVITY INCREASE DUE TO OXYGEN, NUTRIENTS, & SUBSTRATE MATERIAL. • MICROBES MAY HINDER OR ENHANCE ADSORPTION.

18. ACTIVATED CARBON ADSORPTION (cont) • COSTS: • CAPITAL COSTS ARE HIGH (INCL. EQUIPMEN COMPRESSORS, CONTROLS, ETC.) • OPERATING COSTS ARE LOW. • PROBLEM: • SOLID ACCUMULATION AND FOULING EXHAUSTS THE CARBON. • SOLUTION: • REVERSE THE FLOW AND BACKWASH THE CARBON.