CE/Geol/ChE 174 Hazardous Materials Treatment of Commercial and Industrial Hazardous Wastes Christopher Vais [email protected] 510-610-3396 jennimi/Classes/CHE174

CE/Geol/ChE 174Hazardous Materials

Treatment of Commercial andIndustrial Hazardous Wastes

Christopher [email protected]

510-610-3396http://www.engr.sjsu.edu/~jennimi/Classes/CHE174/

Examples of Industrial Haz. Wastes

• Photo and X-ray processing

– silver rich fixers– developers

• Electroplating– cyanide– acids– solvents and

strippers

• Paint stripping– methylene chloride– solvents– alkali

• Wastewater from pulp and paper mills

– wood pulp• Wastewater from refineries

– sour water– phenols

Most HW Generated is Wastewater

238 million tons of haz waste generated inU.S. annually

– 90% is wastewaterThe hazardous constituents in wastewatermust be either

– treated prior to discharge to a wastewater treatment plant– Collected for disposal at a HW landfill– Collected for treatment off-site

Common Constituents of IndustrialWastewater

1. Suspended solids2. Soluble organics3. Toxic organics4. Heavy metals and cyanide5. Color and turbidity6. Nitrogen and phosphorus7. Refractory substances (resistant to biodegradation)8. Oil and floating material9. Volatile materials

Treatment of Industrial Wastewater:Depends on Final Destination

• Wastewater treatment plant– For additional treatment

• Directly to the environment– Surface water– Groundwater / aquifer recharge– Direct use

Prior to Discharge to a POTW

• Water must meet requirements developed by the local POTW for your industrial facility

– Discharge limits typically listed in a permit– Periodic sampling and analytical requirements

• Typical Limits– Biochemical oxygen demand– Suspended solids– Fats, oils and grease– Heavy metals– Toxic organics

Direct Discharge to Water Body

• Requires a National Pollutant Discharge Elimination System (NPDES) permit

• Effluent must meet strict standards– Specific to discharger (e.g., a north bay refinery)– Specific to the receiving water (e.g., shallow vs. deep areas of SF Bay)

Types of Waste Treatment

• CHEMICAL TREATMENT• PHYSICAL TREATMENT• BIOLOGICAL TREATMENT• THERMAL (INCINERATION)

Deciding Amongst TreatmentTechnologies

• Partitioning between water and air– What factor or coefficient?? ______________• Partitioning between water and organics– What factor or coefficient?? ______________• Biodegradability– What factor or coefficient?? ______________• Moisture content

Parameters for Selected PriorityPollutants

Compound Biodegradationconstant(100 L/mg-hr)

Henry’s LawConstant(1000 atm-m3/mole

Octanol-WaterPartitionCoefficient (Kow)

Acetone 0.02 0.0025 0.57

Benzene 2.9 5.5 140

Chlordane 3 x 10 0.094 3 x 10⁵

Hexachloro-benzene

3 x 10⁻⁴ 0.68 2.6 x 10⁶

Tetrachloroethane 3 x 10⁻⁴ 11 1100

Vinyl Chloride 0.30 11.9 140

Chloroform <010 3.4 91

Chemical Treatments

• Catalysis• Electrolysis• Hydrolysis• Neutralization

• Photolysis• Oxidation / Reduction• Precipitation

Catalysis

Increase of rate and mechanism of a chemical reaction• dechlorination of chlorinated hydrocarbons• complete air oxidation of cyanides

Electrolysis

Oxidation or reduction at an electrode surface immersed in a conductive solution under the influence of an applied potential.

Hydrolysis

• reaction of a salt with water to form an acid and a base

XY + Water ------> HY + XOH• Drawbacks? ____________________

Neutralization

• Adjustment of the pH by addition of either an acid or a base.

• Continuous or batch reactors

Photolysis

• breakdown of chemical bonds under UV or visible light

• Becoming common form of disinfection

Oxidation / Reduction

• Oxidation– Transfer of electrons from the chemical being

oxidized to the oxidizing agent– Common oxidants: ________________________

• Reduction– transfer of electrons from the reducing agent to

the chemical being reduced,

EXAMPLE: reduction of Cr+6 (hexavalent state) to Cr+3 (trivalent state) using sulfur dioxide

Precipitation

• Change in the solubility of compounds by addition of:

1. ________________________2. ________________________3. ________________________4. ________________________

Physical Treatment Processes

• Trying to achieve one or more of the following:

1. _________________________2. _________________________

3. _________________________

Physical Treatment Processes

• Adsorption• Air Stripping• Centrifugation• Distillation• Electrodialysis• Evaporation• Filtration

• Flocculation,• Precipitation, and

Sedimentation• Flotation• Freeze Crystallization• Ion Exchange• Solidification

Adsorption

• Separates organics (and some inorganics) from an aqueous waste stream• attraction and accumulation of the adsorbate (the organic) contained in water or some aqueous phase onto the surface of a rigid, solid phase (the adsorbent) such as activated carbon.

Air Stripping

• Volatile components are transferred from a liquid mixture (water) to a gas (air).

• Driving force:– departure of the vapor-liquid phase

concentrations from equilibrium– mass transfer in the direction of decreasing

concentration.

Centrifugation

• Centrifugal force is used to separate liquid from the solid in an enclosed environs.

• Used to– dewater sludge resulting in a reduction of the sludge volume, reduce slurry

volumes• Results in an increased solids concentration in

the waste streams

Distillation

• Nondestructive liquid phase separation process

• used for organic component recovery• based on differences in _______________

Electrodialysis

• Separates ionic components of a waste• stream• Uses synthetic membranes and an electrical field

– membrane is a semi-permeable one, allowing either anions or cations to pass

through it– electric field causes separation of positive from negative ions

Evaporation

• Concentrates the waste and reduces its volume by heating the mixture in pipes, ponds

• The vapor phase is not collected and/or condensed as in distillation

Filtration

• Liquid passes through a porous media that traps the solids

• Typical media:– _________________– _________________

• Backwash to clean filter

Flocculation, Precipitation, andSedimentation

• Removes suspended solids, colloids• Enhance conditions for floc formation

– Changing solubility of metals– Settling chamber

• Flocculating particles aggregate or coalesce thereby changing the particle size, shape, and even specific gravity

Flotation (Dissolved Air Flotation)

• removes solids suspended in the waste– via agitation– sometimes via chemical addition

• Air bubbles reduce the solid density – Bubbles carry particles to the surface of the

tank.• A froth or foam forms at the top and contains the

solids– removed with a skimmer arm

Freeze Crystallization

• The waste water is cooled to form purified ice crystals

• Remaining liquid will be more concentrated• The process can be repeated on the same waste to further concentrate

Ion Exchange

• A synthetic or natural resin material• Used to removed dissolved solids• Heavy metals and anions attach to the resin• surface, exchanged for other anions that were

previously on the surface• Occurs quickly, unless/until all the exchange sites are filled

– “Breakthrough” – requires ______________

Solidification

• Fixes or encapsulates the wasteo Rendering the HWinto a nonhazardous solid product

Solidifying agents:• Silicates• Cement-based

(Portland is common; results in rock-like solid)

• Lime-based• Thermoplastics• Organic polymers

Types of Waste Treatment

• CHEMICAL TREATMENT• PHYSICAL TREATMENT• BIOLOGICAL TREATMENT• THERMAL (INCINERATION)• ULTIMATE DISPOSAL

– LAND TREATMENT

REFRESHER: Deciding AmongstTreatment Technologies

• Partitioning between water and air– Henry’s Law coefficient

• Partitioning between water and organics– Kow – octanol water coefficient

• Biodegradability– Biodegradation rate constant

• Moisture content

Biological Treatment

• Uses microbes to decompose organic wastes• In addition to biodegradation, sorption and

stripping also occur.

Fate of Hazardous Compounds DuringBiological Treatment

• Biodegradation– Desired outcome

• Volatilization– Environmental impacts? ____________________

• Sorption– Environmental impacts? ____________________

• Pass-Through– Environmental impacts? ____________________

Parameters for Selected PriorityPollutants

Compound Biodegradationconstant(100 L/mg-hr)

Henry’s LawConstant(1000 atm-m3/mole

Octanol-WaterPartitionCoefficient (Kow)

Acetone 0.02 0.0025 0.57

Benzene 2.9 5.5 140

Chlordane 3 x 10 0.094 3 x 10⁵

Hexachloro-benzene

3 x 10⁻⁴ 0.68 2.6 x 10⁶

Tetrachloroethane 3 x 10⁻⁴ 11 1100

Vinyl Chloride 0.30 11.9 140

Chloroform <010 3.4 91

Types of Biological Treatment

• Aerated lagoons• Activated Sludge• Anaerobic Digestion• Composting• Trickling Filters• Waste Stabilization Ponds

Aerated lagoons

• Three types– Well mixed (all

aerobic)– Facultative– Settling lagoons

• 3 to 5 meters deep

• Treatment efficiency– Oxygen availability– Waste biodegradability– Nutrients (N & P)– Detention time

Activated Sludge

• Similar to aerated lagoons• 2-stage process

– Aeration basin– Clarifier

• Some microbes are wasted, others are returned to the system (“activated”)

Anaerobic Digestion

• Uses microbes that do not need oxygen to respire

• Not usually suitable for industrial wastes

Composting

• Land reclamation, landfarming• Biodegradation of organics in the soil• Requires collection of leachate and runoff for groundwater protection• Can aerate by turning the soil

Trickling Filters

• Microbes are supported on a solid media structure (e.g., rock, plastic)

• Wastewater is trickled over the media• There is a biofilm layer

– Aerobic outer layer– Inner layer may be anaerobic– Waste concentration changes within the biofilm

Waste Stabilization Ponds

• Dilute industrial wastes• Shallow basins

– 1 to 2 meters deep• Wind provides limited aeration

– Deep ponds are anaerobic at the bottom• Photosynthetic algae of surface

Prior to Discharge to POTW

Post-Treatment: Equilization prior todischarge to WWTP

1. Prevents shock loading of biological systems by dampening organic fluctuations.

2. Enables better pH control, and can reduce chemical requirements for neutralization.3. Minimizes flow surges to physical/chemical treatment systems.4. Provides continuous feed to biological systems5. Enables controlled discharge to POTWs enabling even distribution of the waste load.6. Prevents high concentrations of toxics from entering the biological treatment plant too rapidly.

Processes at the WWTP

• Primary• Secondary• Tertiary / Advanced

Primary Treatment

• Physical treatment – settling basins– Use gravity to remove suspended solids

• Screens, grinders, grit removal

Secondary Treatment

• Biological Treatment– Aerobic

Aerated lagoonsActivated sludgeTrickling filters

– Anaerobicdigesters

Tertiary/ Advanced Treatment

• Filtration to remove solids• Removal of nitrogen and phosphorus• Disinfection

– Chlorine gas– UV light

Ultimate Disposal Options

• Following treatment, remaining wastes often incinerated or disposed to land

– Waste streams remaining from wastewater treatment at the industrial site

– Solid wastes not discharged to sewer– Solids/sludge from the wastewater

treatment plant

Incineration

• Destruction of wastes– Combustion

• Suitable for:– Gases– Liquids– Slurries– Sludge– Solids– Containerized wastes

Incineration Destroys Structure

• Destroys molecular structure of waste– Not elemental composition

• Molecules with more stable structures and stronger chemical bonds require longer residence times and/or higher temperatures• “Incinerability”

– Based on heat of combustion per unit weight

Incinerator Operating Conditions

• Combustion temperature• Residence time• Degree of mixing• Presence of excess air

Examples of Incinerators

• Liquid injection– Any pumpable waste– Converts liquid waste to gas prior to combustion

• Kilns– Used on solids, liquids, and gases– Many different types (e.g., rotary kilns, cement kilns, lime kilns, aggregate kilns)

• Calcination or sintering– 1800°C and atmospheric pressure.– Destroys organics; reduces the volume of inorganics

Incinerator Performance

• Destruction and Removal Efficiency (DRE)– EPA will determine the DRE required for a waste stream– Example: RCRA requires DRE of 99.99% for all “principal organic hazardous

constituents”(POHCs)Example: Wastes containing dioxins and furans requires 99.9999% DRE

Incineration: Needs Air PollutionControl Equipment (APCE)

• Incomplete combustion – afterburners for exhaust– Combust the exhaust at higher temperature than the combustion of primary waste stream– Example: dioxin and furan creation

More toxic than precursors75 dioxin congeners; 135 furan congeners

• Particulate control– baghouses, water scrubbers

• Control of acid formation– HCl from combustion of chlorinated organics

Land Farming

• Organic wastes only– biodegradation

• Upper layers of soil• Effective, low cost, simple• Can enhance soil

• Degradation factors– Waste Composition– Contact between the waste and the

microbes– Soil Temperature– Soil pH– Oxygen– Inorganic Nutrients-

N & P– Moisture Content

Landfilling

• Area filling– Disposal is above ground

– Advantages: ____________________________• Trenching

– Below-grade– Advantage: ____________________________

• Both produce gases (explosion issue) and leachate (GW and SW contamination issue) that must be monitored and treated

Deep Well Injection

• Transfer of liquid waste deep underground– Far away from freshwater sources

• Criteria for waste waters:– Low Volume, High Concentration Waste– Difficult to treat by other methods– Compatible with material in disposal zone– Biologically Inactive– Non corrosive

• Over 9 billion gallons/year HW injected in the US

Five Well Classes

Regulated by U.S. EPA

• Under the Safe Drinking Water Act• Administered by the Underground Injection Control (UIC) program of EPA

Injection Well Operation Requirements(Class I, II & III)

• Site free of faults & other adverse geologic features• Drill below potential drinking water (any water

in formation must have TDS > 10,000 mg/L)• Double piping: Tubing in Casing

– Multiple containment layers• Test well integrity every 5 years

California Examples of Permitted DeepWell Injection

• Class I– California Specialty Cheeses

– Hilmar Cheese• Class II

– Greka Integrated, Inc.(Fined $$ in Summer 2006 for improper use)

• Class V Experimental– City of Los Angeles

CO2 Sequestration

What about Underground Injection asClimate Change Solution??

Geologic Sequestration of CO2

• Process of separating and capturing carbon dioxide (CO2) from a source, such as a coal fired

electric generating power plant, transporting the CO2, and injecting it through a well into the deep subsurface.• Once underground, it is believed the CO2 will be trapped, or sequestered, for a long period of time.

Geologic Sequestration of CO2

• Earth has widely-distributed geologic formations which have capacity to store injected CO2• Current estimates indicate that the storage capacity is extremely large and widespread.• With proper site selection and management, geologic sequestration could play a major role in reducing CO2 emissions.

Pilot Tests of CO2 Sequestration

• Currently using Class V experimental technology well classification to pilot the technology

• Pilot projects will provide information about how CO2 behaves in the sub-surface and additional technical information on proper well construction and operational procedures.• The results will be used to decide if there is a need to develop new UIC regulations for commercial-scale CO2 injection projects