environmental issues chapter 11 matakuliah: s0782 - teknik lingkungan tahun: 2009
TRANSCRIPT
ENVIRONMENTAL ISSUESCHAPTER 11
Matakuliah : S0782 - Teknik LingkunganTahun : 2009
Bina Nusantara
ENVIRONMENTAL ISSUES
Bina Nusantara
OUTLINE•Problem statement•Global look at the problem•Solid waste problem•Possible solutions to solid waste problem•Green design•A success story
Bina Nusantara
Facts and Myths
• A world without plastics and composites!
• Unfair bad reputation
• Potential to do better
http://www.epa.gov/epaoswer/non-hw/muncpl/facts.htm
Bina Nusantara
Environmental loads by manufacturing sector
Carbon Dioxide and Toxic Materials per Value of Shipments
00.5
11.5
22.5
33.5
44.5
5
Che
mic
als
Pet
role
uman
d C
oal
Pla
stic
s an
dR
ubbe
r
Prim
ary
Met
al
Fab
ricat
edM
etal
Mac
hine
ry
Ele
ctro
nic
Tra
nspo
rtat
ion
Manufacturing industries
Wei
ght/D
olla
rs
CO2 (metric ton/$10,000)
Toxic Mat'ls (lb/$1000)
EPA 2001, DOE 2001
Bina Nusantara
Waste Definitions• WASTE
• WASTE CLASSIFICATION
• SOLID WASTE:
• Metals• Plastics• Paper• Hybrid Materials• ….
Bina Nusantara
What are the choices?
• Recycling (Physical and/or Chemical)
• Waste to Energy Incineration
• Land filling
• Degradation
Bina Nusantara
Recycling Techniques• Primary: Conversion of waste into materials
having similar properties• Secondary: Conversion of waste into materials
having inferior properties• Tertiary: Conversion of waste into chemicals and
fuels• Quaternary: Conversion of waste into energy
Bina Nusantara
Types of Plastic Recycling• Chemical Recycling
– The depolymerization of certain condensation or addition polymers back to monomers
• Mechanical Recycling– The direct recycling and conversion of plastics from
discarded materials into a reusable form
Bina Nusantara
Factors Impeding Reclaiming• Collection
• Heterogeneous in Nature• Different Plastics• Different Brands
• Non-plastic Contaminants• Metals• Pigments and Dyes• Label Materials• Adhesives• Additives• Filler/Reinforcements• …
• Low Economic Value
Bina Nusantara
Chemical Recycling• Chemicals can be used for feedstock use or fuel• Problems with chemical recycling
– Greater accumulation of air and water pollution– Some regenerated monomers are pollutants– By-products can be pollutants– Requires considerable amount of thermal and chemical energy
to break apart and then more to repolymerize
• Currently there are no chemical recycling plants, everything is experimental
Bina Nusantara
Chemical: Tertiary Recycling• Hydrolysis• Alcoholysis• Hydrogentation• Pyrolysis
Bina Nusantara
Chemical: Quaternary
Astrom, Manufacturing of Polymer Composites, Chapman &Hall1997
Bina Nusantara
Mechanical Recycling• Most economical and common type of plastic
recycling in the U.S.• Currently 1,677 companies handle and reclaim
plastics• Steps to mechanical recycling
– Collection– Sorting– Reclamation
Bina Nusantara
Collection• Commingled or sorted collection
• Curbside or drop-off recycling program
• 63% of nation total has access to recycling program
• Currently the amount of some plastics being collected falls short of the capacity of the recycling facilities
Bina Nusantara
Material Recovery Facility• Two functions
– Separating materials – Prepare materials for the market
• Material is tipped on to the receiving floor• Pushed by front end loader on to the feeder conveyor• Elevated to presort station• Overhead magnetic separation stage• Density separator• Manually sorted• Stored in bunkers until bailed
Bina Nusantara
Material Reclaiming Facility• Sorted plastics are converted into pellets or flakes• Shredded• Contaminant removal
– Air classifier– Float/sink tank– Washed– Dried– Granulated– 2nd air classifier
• Made into pellets by extrusion or boxed for market as flakes
Bina Nusantara
Green Thinking• Reduce waste at source• Increase reuse and recycling• Recover energy• Dispose of unavoidable waste safely
Bina Nusantara
Design for Waste Minimization• Use less raw material• Use less virgin material• Design for equal lifetime of components in an
assembly• Design for transportation• Design for damage tolerance and repair• Design for afterlife potential
Bina Nusantara
Design for Recycling• Design for disassembly• Label components• Use few combination of materials• Design the labels appropriately (same material)• Avoid painting and adhesive joining• Minimize number of metal fasteners• Exclude undesirable melt-reactive combinations• Avoid non-Separable Colorants
Bina Nusantara
Story of PET
Bina Nusantara
Why PET Recycling?
• 8 % (volume %) of this solid waste is PET and HDPE• Almost 50% of all plastic bottles are made from PET• PET is convenient to recycle• Cost effective
Collection $.07/lb.Reprocessing $.30/lb.
Total Cost of recycled PET (flake) $.37/lb. (pellet)
$.46/lb.
Cost of virgin PET $.62/lb.
Savings of $.25- $.16/lb.
Bina Nusantara
Recycled PET• May be reused between 25 and 40 times• Intrinsic viscosity decreases by .02-.03 dl/g every time it is
re-extruded• Can be compounded to produce a wider range of
properties, products, and markets• Alloying polycarbonate (PC) with recycled PET can produce
an injection–moldable compound, done by GM for bumpers and body panel material (50-60%PET/ 40-50% PC) and is 25-30% less expensive
Bina Nusantara
Virgin vs. Recycled PET Uses
Virgin PET Uses Recycled PET Uses
Bina Nusantara
Fiber Market
• Used to make fiberfill which is put in pillows, sleeping bags, ski-jackets, insulation, shoulder pads, etc….– An IV of .58-.65dl/g is adequate– Requires a very clean recycled PET, – cannot use the green recycled PET
• Used to make geotextiles – stabilizers in railroad beds and paved roads– can use the green PET because they are usually pigmented with
carbon black • Used as continuous filament or yarn in such things as carpet
face yarns, or woven carpet backing• Used to make insulation that is as energy efficient as
fiberglass insulation material• Replacing wood fiber
– longer life and less maintenance
Bina Nusantara
Strapping Market• PET strapping replaces metal strapping used in
pallet wrapping– made by an extrusion process – requires high IV– Mixed with virgin PET or solid stated to increase IV
Bina Nusantara
Sheeting Market• Used in blister packaging clamshell packages, cups, food
trays, egg cartons, cassette cases, etc…– Needs a high IV
• Making foamed sheets for insulation– uses the green recycled PET with an additive to raise the
normally low melt viscosity– same insulation properties as foamed polystyrene but with
superior cost/performance qualities
Bina Nusantara
Bina Nusantara
Some Hope• Each Problem Has at Least One Solution
• Some Solutions are Demonstrated Commercially
• There is a Price to Pay for the Solution
• There Are Some Success Stories