HAZARDOUS WASTE
TREATMENT
HAZARDOUS WASTE MANAGEMENT
1.
Reduce the amount of hazardous wastes
generated
2.
Stimulate “waste exchange”
3.
Recycle metals, the energy content and other
useful resources contained in hazardous wastes
4.
Detoxify and neutralize liquid hazardous waste
streams by chemical and biological treatment.
5.
Reduce the volume of waste sludges generated
in item no. 4 by dewatering
HAZARDOUS WASTE MANAGEMENT
6. Destroy combustible hazardous wastes
in special high temperature
incinerators equipped with proper
pollution control and monitoring
systems.
7. Stabilize or solidify sludges and ash
from items 5 and 6 to reduce
leachability of metals
8. Dispose of monitoring treated residues
in specially designed landfills.
WASTE MINIMIZATION
The key elements necessary for
the success of a waste
minimization program include
•
•
•
•
Top level organizational
commitment
Financial assistance
Technical resources
Appropriate organization, goals
and strategy
WASTE AUDIT
The audit should proceed stepwise:
1. Identify waste stream
2. identify sources
3. establish priority of waste streams for waste
minimization activity
4. screen alternatives
5. Implement
6. Track
7. evaluate progress
HAZARDOUS WASTE
TREATMENT
• Physical Treatment
• Chemical Treatment
• Biological Treatment
Carbon Adsorption
• A surface phenomenon
• Mass transfer process – gas vapors or chemicals in
solution are held to a solid by intermolecular forces
• Activated carbon, molecular sieves, silica gel, and
activated alumina
• Organic material has commercial value – bed is then
regenerated by passing through steam
• Organic material has no commercial value – carbon
may be incinerated or shipped for regeneration.
Activated Carbon
Activated carbon
– also called
activated charcoal
or activated coal
- a form of carbon
that has been
processed to make it
extremely porous.
Solidification
- accomplished by encapsulating the waste in
concrete, asphalt or plastic.
- produces a solid mass of material that is resistant
to leaching.
- another way of solidification - lime , fly ash and
water (cementlike product)
- involves the melting and fusion of materials at high
temperature (about 1600oC or 2900oF), thereby
reducing the potential for leaching of contaminants
Distillation
• The separation of more
volatile materials from
less volatile ones by
means of vaporization
and condensation
• The degree of separation
depends on the relative
differences in the vapor
pressure.
Distillation
• Batch distillation, fractionation, steam
stripping and thin film evaporation
• Batch distillation – applicable for wastes
with high solids concentration
• Fractionation – applicable when multiple
constituents must be separated and when
the waste contains minimal suspended
solids
Fractional
Distillation
(crude oil)
can also be used in
solvent recovery of
hazardous waste
Air Stripping
• Applicable when the
volatility of organic
compound is relatively high
and concentration very low
• Air and contaminated water
are passed counter currently
through a packed tower
• Frequently, this is
accomplished by passing
the air through an activated
carbon column
Steam Stripping
• The physical arrangement of the process is much like
that of an air stripper, except that steam is introduced
instead of air
• For gases of lower volatility or higher concentration
(> 100 ppm)
• Addition of steam enhances the stripping process by
decreasing the solubility of the organic in the aqueous
phase and by increasing the vapor pressure
Ion Exchange
• can remove metals and
ionized organic
chemicals
• The waste stream
containing the ion to be
removed is passed
through a bed of resins
• In the exchange process,
ions of like charge are
removed from the resin
surface in exchange for
ions in solution
• Air Stripping has been used to remove
tetrachloroethylene, trichloethylene, and toluene
from water
• Steam Stripping has been used to treat
aqueous waste contaminated with chlorinated
hydrocarbon, MEK, methanol and
pentachlorophenol
• Ion exchange has been demonstrated
commercially for recovery of plating chemicals
from acid-copper, acid-zinc, nickel,tin cobalt and
chromium plating baths
Reverse Osmosis
OSMOSIS
Fresh
Water
OSMOTIC
EQUILIBRIUM
Salt
Water
REVERSE
OSMOSIS
SEMIPERMEABLE
MEMBRANE
Reverse Osmosis
• Osmosis is the spontaneous transport of a
solvent from a dilute solution to a concentrated
solution across an ideal semipermeable
membrane that impedes passage of the solute
but allows the solvent to flow
• Reverse Osmosis the pressure is increased
above the osmotic pressure on the solution
slide, flow reverse
Incineration
• Incineration is a thermal
–chemical process that
not only can detoxify
certain organic wastes ,
but can essentially
destroy it.
• Combustion detoxifies
hazardous waste
material by altering its
molecular structure and
breaking it down into
simpler chemical
substances
AIR
POLLUTION
CONTAMINATED
ASH
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