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Waste treatment techniques are used to change
the physical, chemical or biological character of
the waste, to reduce its volume and/or toxicity
and to make the waste safer for disposal.
How is waste being generated?
Raw Material
Acquisition
Material
Processing
Product
Manufacture
Product Use or
Consumption
Waste
Waste
Waste
Waste
Waste generated in the life cycle of a product
Disposal
Type of waste
Domestic Waste
Construction Waste
Commercial Waste
Industrial Waste
Waste load in HK

[1]
Waste Classification in HK
1. Municipal solid waste
• Domestic waste
• Commercial waste
• Industrial waste
2. Construction & demolition (C&D) waste
3. Chemical waste
4. Special waste (e.g. clinical waste, radioactive
waste)
5. Other solid wastes
Waste load in HK
[2]
• Quantity of waste
10000
8000
6000
4000
2000
Domestic
C&I
C&D
Special
9
199
8
199
7
199
6
199
5
199
4
199
3
199
2
199
1
199
0
199
9
198
8
198
7
198
6
0
198
Quantity of Waste (x 1000 tonnes)
The quantities of major types of solid waste disposed of in Hong Kong (1986-1999)
Waste load in HK
[3]
• Composition of waste
4%
1%
3% 3%
38%
20%
3%
28%
Putrescibles
Paper
Glass
Plastics
Metal
Textiles
Bulky Waste
Major components of domestic waste disposed of in Hong Kong
Wood/rattan
Reasons for waste reduction
• Landfill capacity
• Cost of waste managements
–
–
–
–
–
–
Costs of waste facilities
Costs of landfill restoration
Social costs
Environmental cost
Economic value of the waste itself
Economic development
Treatment of Solid Waste
• Disposing in the landfills
• Burning in the incinerator
• Composting
• Recycling of recyclable waste
•Ocean dumping
In Incinerators
of conventional design, refuse is
burned on moving grates in refractory-lined chambers;
• Combustible gases and the solids they carry are burned
in secondary chambers.
• Combustion is 85 to 90 % complete for the combustible
materials.
• In addition to heat, the products of incineration include
the normal primary products of combustion:
- carbon dioxide and water-as well as oxides of
sulphur and nitrogen and other gaseous pollutants;
- nongaseous products are fly ash and unburned solid
residue.
• Emissions of fly ash and other particles are often
controlled by wet scrubbers, electrostatic precipitators,
and bag filters.
In a Modern Landfill, refuse is spread in thin layers,
each of which is compacted by a bulldozer before the next is
spread.
• When about 3 m of refuse has been laid down, it is covered by
a thin layer of clean earth, which also is compacted.
• Pollution of surface and groundwater is minimized by :
1.Lining and contouring the fill,
2.Compacting and planting the cover,
3.Selecting proper soil,
4.Diverting upland drainage, and
5.Placing wastes in sites not subject to flooding or high
groundwater levels.
• Gases are generated in landfills through anaerobic
decomposition of organic solid waste. If a significant amount of
methane is present, it may be explosive; proper venting(making
holes) eliminates this problem.
Composting Operations
of solid wastes include
preparing refuse and degrading organic matter by
aerobic microorganisms.
• Refuse is presorted, to remove materials that might
have salvage value or cannot be composted,
• Then it is ground up to improve the efficiency of the
decomposition process.
• The refuse is degraded biologically to a humus with a
total nitrogen, phosphorus, and potassium content of
1 to 3 %, depending on the material being composted.
• After about three weeks, the product is ready for
curing, mixing with additives, bagging, and marketing.
Composting In Garden
kitchen wastes
leaves
grass clippings
Air
Some soil
Water
fertilizer
Recycling is the act of recovering a waste material for
reuse and processing into another useful product.
• Recycling include collection, processing, and
procurement or reuse of the recovered materials.
• All three activities must be completed in order to
make recycling programs effective.
• Metals e.g.Aluminium cans
• Waste paper like newspaper
• Plastic and glass bottles
- Paper should be separated from other waste
in homes and offices for recycling.
- Re-usable items get thrown away, such as this
wood used to decorate an office or flat.
- Refrigerators and other appliances contain metals
that could be recycled.
Waste treatment in Hong Kong
• Dispose solid waste in the three landfills in
-West New Territories
-South-East New Territories
-North-East New Territories
• Recycle of plastic, paper, metal and than export
• Burning in the incinerator
• Chemical waste including acids, alkalis, cyanides,
heavy metal solution, solvents and mineral oil are treated
at The Chemical Waste Treatment Centre on Tsing Yi.
Waste Reduction in the present
• Waste separation facilities are now
available in all public housing estates
and many private residential
developments.
• Government has provided land to facilitate the
operation of the waste collection and recycling
industry.
Waste Reduction in the future
• The Waste Reduction Committee was established
earlier this year.
Its target is to double the overall rate of municipal
waste reduction and recycling by 2007.
• As for collecting a waste disposal fee, the
Government will put forward a proposal for a
landfill charging scheme shortly.
From 99 Policy Address
Recycling
In 2000, 8% of recoverable domestic waste
was recycled in Hong Kong.
• The government will seek funding in the
coming year to construct new waste
separation facilities.
• The government will also encourage the
new District Councils to explore ways to
increase the recovery rate of reusable
materials in collaboration with the business
sector and local communities.
Waste to Energy
• The government are restoring old landfill
sites at a cost of $2.3 billion and are seeking to
turn the combustible gases into energy.
• The government will be consulting the
community in the coming year on proposals
for new waste management facilities,
including waste-to-energy incinerators.
Waste Reduction Framework Plan
• Targets
– Diverting 58% of municipal solid waste from landfills by
2007 (compared with 30% in 1997).
• Extending the life span of the existing landfills from 2015 to
2019
– Diverting 84% of Construction and Demolition (C&D)
material from landfills by 2007 (compared with 80% in
1997)
• Extending the life span of the existing landfills by further 6
months
[1]
Waste Reduction Framework Plan
• Scope
– To extend the life-span of the strategic landfills
– To minimize the amount of waste produced that requires
disposal;
– To conserve the earth’s non-renewable resources;
– To increase the waste recycling rate
– To identify the true costs of waste management in order
to maximize efficiency and minimize the cost of
collection, treatment and disposal of wastes;
– To improve the institutional arrangement
[2]
Waste Reduction Framework Plan
• Three Main Areas of the Plan
1.
2.
3.
Prevention of Waste Programme
Institutional Programme
Waste Bulk Reduction Programme
[3]
Waste Management in HK
– Waste Management Hierarchy
(source: EPD website, 2001
http://info.gov.hk/wfbu/what
wewilldo/www02.htm)
[1]
Waste Management in HK
• Facilities of Waste Management
– Landfills
[2]
Waste Management in HK
[3]
• Landfills - filling refuse in constructed areas
Typical Landfill
(Source: EPD website, 2001
http://info.gov.hk/wfbu/whatweha
vedone/wms/sland/l_f_sect.htm)
Waste Management in HK
Refuse Truck Unloading at
Tipping Face in Landfill
(Source: EPD website, 2001
http://info.gov.hk/wfbu/whatwehavedo
ne/wms/sland/l_fillop.htm)
[4]
Waste Management in HK
[5]
– Refuse Transfer Stations - Collect and compact
municipal waste for further transport to landfills
Locations of
Operating RTSs
(source: EPD website, 2001
http://info.gov.hk/wfbu/whatweh
avedone/wms/rts.htm)
Waste Management in HK
[6]
Operation of
Refuse Transfer
Station
(Source: : EPD website,2001
http://info.gov.hk/wfbu/whatw
ehavedone/wms/rts.htm)
Waste Management in HK
[7]
– Chemical Waste Treatment Centre - Centre for
treating chemical wastes
CWTC in Tsing Yi
(Source: EPD website,
20001
http://info.gov.hk/wfbu/what
wehavedone/wms/cwtc.htm)
Discussion
•
•
•
•
•
What wastes are generated from our home
and schools?
What can be recycled? How much? How to?
How to reduce waste in our daily life?
What would it be if all the current landfills
are fully filled?
Is there any effective alternatives for waste
treatment?
Relevant Websites
[1]
• Environmental Protection Department
(http://www.info.gov.hk/epd)
– Waste Facilities Business Unit (WFBU)
(http://www.info.gov.hk/epd/waste)
– Strategic Landfills
(http://info.gov.hk/wfbu/whatwehavedone/wms/
ms01.htm#landfill)
Relevant Websites
[2]
• Waste Reduction Committee (WRC)
(http://www.info.gov.hk/wrc/)
– Waste Reduction Framework Plan (WRFP)
(http://info.gov.hk/wrc/main_framework.htm)
– Directory of Recovery/Recycling Companies in
Hong Kong
(http://info.gov.hk/wrc/collst/000821/engweb4a/s
tart.html)
– Outlets for Used Items
(http://info.gov.hk/wrc/main_useditem.htm)
Relevant Websites
[3]
• Locations of Waste Separation Bins at Public Areas
(http://www.info.gov.hk/fehd/pleasant_environment/c
leansing/collect.htm)
• Environmental Campaign Committee (ECC)
(http://www.ecc.org.hk/)
• Green Power
(http://user.hk.linkage.net/~greenpow/html/new/eindex.html)
Waste treatment in the U.S.
Solid Waste Reduction
• Incineration
can be used to treat and destroy
combustible materials in transuranic,
low-level, and some mixed waste.
• Compaction
is a means of reducing the volume of
noncombustible waste by compressing it
into a smaller, denser waste form.
http://www.em.doe.gov/em30/wasttrea.html
Solidification processes
By a calcining process, liquid waste can be solidified
The New Waste Calcining Facility
converts high-level liquid waste
into calcine.
The granular end product is
transported through pipes to
stainless steel bins.
The bins are encased in
underground vaults.
Waste treatment in the Japan
Incineration
Recycling
Waste Incinerator and Heat Collection System
System flow diagram of the incinerator
A Recycling Plant
Relevant websites
Waste treatment in Japan
http://www.greenpeace.org/
http://www.info.gov.hk/epd/E/ehk99/home/chinese/ccontnt7.htm
Waste reduction campaign
http://www.soc.titech.ac.jp/uem/waste/waste.html
http://www.em.doe.gov/em30/wasttrea.html
Littering problem in Hong Kong
The underlying attitudes that lead to
antisocial behaviour.
Education, and acceptable methods of
modifying antisocial behaviour.
The impact of law enforcement via litter
warder and litter courts.
The school environment as a starting point.
The end