Table 27.—Description of Technologies Currently Used for Recovery of Materials—Continued
Technology/description Stage of development Economics Types of waste streams Separation efficiency Industrial applications
Electrolysis:
Separation of positively/ Commercial technology; Dependent on concentrations Heavy metals; ions from Good Metal plating
negatively charged not applied to recovery
materials by application of of hazardous materials
electric current
Carbon/resin absorption:
Dissolved materials Proven for thermal Relatively costly thermal
selectively absorbed in regeneration of regeneration; energy
carbon or resins. carbon; less practical intensive
aqueous solutions; copper
recovery
Organics/inorganics from
aqueous solutions with low
concentrations, i.e., phenols
Good, overall effectiveness Phenolics
dependent on
regeneration method
Absorbents must be
regenerated
Solvent extraction:
Solvent used to selectively
dissolve solid or extract
liquid from waste
for recovery of
adsorbate
Commonly used in
industrial processing
Relatively high costs for
solvent
Organic liquids, phenols, acids Fairly high loss of solvent Recovery of dyes
may contribute to
hazardous waste problem
Chemical transformation:
Precipitation:
Chemical reaction causes
formation of solids which
settle
Electrodialysis:
Separation based on
differential rates of
diffusion through
membranes. Electrical
current applied to
enhance ionic movement
Chlorinolysis:
Pyrolysis in atmosphere of
excess chlorine
Reduction:
Oxidative state of chemical
changed through chemical
reaction
Common Relatively high costs Lime slurries Good Metal-plating wastewater
treatment
Commercial technology, not commercial for hazardous
material recovery
Moderately expensive Separation/concentration of
ions from aqueous streams;
application to chromium
recovery
Fairly high Separation of acids and
metallic solutions
Commercially used in
West Germany
Insufficient U.S. market for
carbon tetrachloride
Chlorocarbon waste Good Carbon tetrachloride
manufacturing
Good Chrome-plating solutions
and tanning operations
Commercially applied
to chromium; may
need additional
treatment
Inexpensive Metals, mercury in dilute
streams
Chemical dechlorination:
Reagents selectively attack
carbon-chlorine bonds
Thermal oxidation:
Thermal conversion of
components
Common Moderately expensive
Relatively high
PCB-contaminated oils
Chlorinated organic liquids;
High Transformer oils
Extensively practiced Fairly high Recovery of sulfur, HCI
silver
a
Good implies 50 to 8O percent efficiency, fairly high implies 80 percent, and very high Implies 90 percent
SOURCE: Office of Technology Assessment.