Table 27.—Description of Technologies Currently Used for Recovery of Materials
— . . .
Economics Types of waste streams Separation efficiency Industrial applications Technology/description stage of development
Physical separation:
Gravity settling:
Tanks, ponds provide hold-up
time allowing solids to
settle; grease skimmed to
overflow to another vessel
Filtration:
Collection devices such as
screens, cloth, or other;
liquid passes and solids
are retained on porous
media
Flotation:
Air bubbled through Iiquid to
collect finely divided solids
that rise to the surface
with the bubbles
Flocculation:
Agent added to aggregate
solids together which are
easily settled
Centrifugation:
Spinning of liquids and
centrifugal force causes
separation by different
densities
Component separation
Distillation:
Successfully boiling off of
materials at different
temperatures (based on
different boiling points)
Evaporation:
Solvent recovery by boiling
off the solvent
ion exchange:
Waste stream passed through
resin bed, ionic materials
selectively removed by
resins similar to resin
adsorption. Ionic exchange
materials must be
regenerated
Ultrafiltration:
Separation of molecules by
size using membrane
Reverse osmosis:
Separation of dissolved
materials from liquid
through a membrane
Relatively inexpensive; Slurrries with separate phase
dependent on particle size solids, such as metal
Limited to solids (large
particles) that settle quickly
(less than 2 hours)
industrial wastewater
treatment first step
Commonly used in
wastewater
treatment and settling rate
Labor intensive: relatively
inexpensive; energy
required for pumping
hydroxide
Tannery water
Commonly used Aqueous solutions with finely
divided solids; gelatinous
sludge
Good for relatively large
particles
Commercial
application
Relatively inexpensive Aqueous solutions with finely
divided solids
Good for finely divided solids Refinery (oil/water mixtures);
paper waste; mineral
industry
Aqueous solutions with finely
divided solids
Good for finely divided solids
Fairly high (90°/0)
Refinery; paper waste; mine
industry
Commercial practice Relatively inexpensive
Paints
Practiced commercially for smallscale systems
Competitive with filtration Liquid/liquid or liquid/solid
separation, i.e., oil/water;
resins; pigments from
lacquers
Solvent separations;
chemical and petroleum
industry
Commercial practice Energy intensive Organic Iiquids Very high separations
achievable (99 +
0
/0
concentrations) of several
components
Organic/inorganic aqueous
streams; slurries, sludges,
i.e., caustic soda
Very high separations of
single, evaporated
component achievable
Rinse waters from metalplating waste
Commercial practice in
many industries
Energy intensive
Relatively high costs Fairly high Metal-plating solutions Not common for HW Heavy metals aqueous
solutions; cyanide removed
Metal-coating applications
Not used Industrially
Some commercial
application
Relatively high
Relatively high
Heavy metal aqueous
solutions
Fairly high
Heavy metals; organics,
inorganic aqueous solutions
Good for concentrations
less than 300 ppm
Not common: growing
number of applications
as secondary treatment process such
as metal-plating
pharmaceuticals
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
ตาราง 27. ซึ่งลักษณะของเทคโนโลยีที่ใช้สำหรับการกู้คืนของวัสดุ— . . .ประสิทธิภาพในการแยกขั้นตอนคำอธิบายเทคโนโลยีประยุกต์ใช้ในอุตสาหกรรมพัฒนากระแสข้อมูลเศรษฐศาสตร์ชนิดของขยะแยกทางกายภาพ:แรงโน้มถ่วงในการชำระเงิน:ถัง บ่อให้ขึ้นค้างเวลาให้ของแข็งการชำระ ไขมันเอาไปโอเวอร์โฟลว์ในเรืออื่นเครื่องกรอง:ชุดอุปกรณ์เช่นหน้าจอ ผ้า หรือ อื่น ๆผ่านของเหลวและของแข็งสะสมใน porousสื่อFlotation:เป็นฟองอากาศผ่าน Iiquid ไปเก็บของแข็งประณีตถูกแบ่งขึ้นที่พื้นผิวมีฟองอากาศFlocculation:ตัวแทนเพิ่มรวมของแข็งด้วยกันได้แก่จับคู่ได้ง่ายCentrifugation:ปั่นของของเหลว และทำให้แรงเหวี่ยงแยก โดยแตกต่างกันความหนาแน่นแยกส่วนประกอบการกลั่น:ต้มเสร็จเรียบร้อยออกจากวัสดุที่แตกต่างกัน(ขึ้นอยู่กับอุณหภูมิจุดเดือดที่แตกต่างกัน)ระเหย:กู้คืนเป็นตัวทำละลาย โดยการต้มออกจากตัวทำละลายแลกเปลี่ยนไอออน:ขยะผ่านเตียงยาง วัสดุ ionicเลือกเอาตามคล้ายกับยางเรซิ่นดูดซับ แลกเปลี่ยน Ionicวัสดุต้องสร้างใหม่Ultrafiltration:การรวมหรือแยกโมเลกุลโดยขนาดที่ใช้เมมเบรนสารกรองน้ำ:ส่วนยุบรวมหรือแยกจากของเหลวผ่านเมมเบรนแพง Slurrries ด้วยระยะแยกขึ้นอยู่กับอนุภาคขนาดของแข็ง เช่นโลหะจำกัด(มหาชน)กับของแข็ง (มีขนาดใหญ่อนุภาค) ที่ชำระได้อย่างรวดเร็ว(น้อยกว่า 2 ชั่วโมง)industrial wastewatertreatment first stepCommonly used inwastewatertreatment and settling rateLabor intensive: relativelyinexpensive; energyrequired for pumpinghydroxideTannery waterCommonly used Aqueous solutions with finelydivided solids; gelatinoussludgeGood for relatively largeparticlesCommercialapplicationRelatively inexpensive Aqueous solutions with finelydivided solidsGood for finely divided solids Refinery (oil/water mixtures);paper waste; mineralindustryAqueous solutions with finelydivided solidsGood for finely divided solidsFairly high (90°/0)Refinery; paper waste; mineindustryCommercial practice Relatively inexpensivePaintsPracticed commercially for smallscale systemsCompetitive with filtration Liquid/liquid or liquid/solidseparation, i.e., oil/water;resins; pigments fromlacquersSolvent separations;chemical and petroleumindustryCommercial practice Energy intensive Organic Iiquids Very high separationsachievable (99 +0/0concentrations) of severalcomponentsOrganic/inorganic aqueousstreams; slurries, sludges,i.e., caustic sodaVery high separations ofsingle, evaporatedcomponent achievableRinse waters from metalplating wasteCommercial practice inmany industriesEnergy intensiveRelatively high costs Fairly high Metal-plating solutions Not common for HW Heavy metals aqueoussolutions; cyanide removedMetal-coating applicationsNot used IndustriallySome commercialapplicationRelatively highRelatively highHeavy metal aqueoussolutionsFairly highHeavy metals; organics,inorganic aqueous solutionsGood for concentrationsless than 300 ppmNot common: growingnumber of applicationsas secondary treatment process suchas metal-platingpharmaceuticalsTable 27.—Description of Technologies Currently Used for Recovery of Materials—ContinuedTechnology/description Stage of development Economics Types of waste streams Separation efficiency Industrial applicationsElectrolysis:Separation of positively/ Commercial technology; Dependent on concentrations Heavy metals; ions from Good Metal platingnegatively charged not applied to recoverymaterials by application of of hazardous materialselectric currentCarbon/resin absorption:Dissolved materials Proven for thermal Relatively costly thermalselectively absorbed in regeneration of regeneration; energycarbon or resins. carbon; less practical intensiveaqueous solutions; copperrecoveryOrganics/inorganics fromaqueous solutions with lowconcentrations, i.e., phenolsGood, overall effectiveness Phenolicsdependent onregeneration methodAbsorbents must beregeneratedSolvent extraction:Solvent used to selectivelydissolve solid or extractliquid from wastefor recovery ofadsorbateCommonly used inindustrial processingRelatively high costs forsolventOrganic liquids, phenols, acids Fairly high loss of solvent Recovery of dyesmay contribute tohazardous waste problemChemical transformation:Precipitation:Chemical reaction causesformation of solids whichsettleElectrodialysis:Separation based ondifferential rates ofdiffusion throughmembranes. Electricalcurrent applied toenhance ionic movementChlorinolysis:Pyrolysis in atmosphere ofexcess chlorineReduction:Oxidative state of chemicalchanged through chemicalreactionCommon Relatively high costs Lime slurries Good Metal-plating wastewatertreatmentCommercial technology, not commercial for hazardousmaterial recoveryModerately expensive Separation/concentration ofions from aqueous streams;application to chromiumrecoveryFairly high Separation of acids andmetallic solutionsCommercially used inWest GermanyInsufficient U.S. market forcarbon tetrachlorideChlorocarbon waste Good Carbon tetrachloridemanufacturingGood Chrome-plating solutionsand tanning operationsCommercially appliedto chromium; mayneed additionaltreatmentInexpensive Metals, mercury in dilutestreamsChemical dechlorination:Reagents selectively attackcarbon-chlorine bondsThermal oxidation:Thermal conversion ofcomponentsCommon Moderately expensiveRelatively highPCB-contaminated oilsChlorinated organic liquids;High Transformer oilsExtensively practiced Fairly high Recovery of sulfur, HCIsilveraGood implies 50 to 8O percent efficiency, fairly high implies 80 percent, and very high Implies 90 percentSOURCE: Office of Technology Assessment
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