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

Disposal

Waste Waste Waste Waste

Waste generated in the life cycle of a product

Type of waste

Domestic Waste Construction Waste

Industrial WasteCommercial 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

0

2000

4000

6000

8000

10000

Qua

ntity

of W

aste

(x 1

000

tonn

es)

Domestic C&I C&D Special

The quantities of major types of solid waste disposed of in Hong Kong (1986-1999)

Waste load in HK [3]

• Composition of waste

38%

28%

3%

20%

4%3% 3% 1%

Putrescibles Paper Glass Plastics Metal Textiles Bulky Waste Wood/rattan

Major components of domestic waste disposed of in Hong Kong

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

• Recycling of recyclable waste

• Composting

•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 Composting In Garden

kitchen wastes leaves grass clippings

fertilizer

Air

Water

Some soil

• Recycling include collection, processing, and procurRecycling include collection, processing, and procurement or reuse of the recovered materials. ement or reuse of the recovered materials.

Recycling is the act of recovering a waste material forRecycling is the act of recovering a waste material for

reuse and processing into another useful product.reuse and processing into another useful product.

• All three activities must be completed in order to All three activities must be completed in order to make recycling programs effective.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 [1]

• 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

Waste Reduction Framework Plan [2]

• 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

Waste Reduction Framework Plan [3]

• Three Main Areas of the Plan1. Prevention of Waste Programme

2. Institutional Programme

3. Waste Bulk Reduction Programme

Waste Management in HK [1]

– Waste Management Hierarchy

(source: EPD website, 2001 http://info.gov.hk/wfbu/whatwewilldo/www02.htm)

Waste Management in HK [2]

• Facilities of Waste Management– Landfills

Waste Management in HK [3]

• Landfills - filling refuse in constructed areas

Typical Landfill(Source: EPD website, 2001

http://info.gov.hk/wfbu/whatwehavedone/wms/sland/l_f_sect.htm)

Waste Management in HK [4]

Refuse Truck Unloading at Tipping Face in Landfill

(Source: EPD website, 2001 http://info.gov.hk/wfbu/whatwehavedo

ne/wms/sland/l_fillop.htm)

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/whatwehavedone/wms/rts.htm)

Waste Management in HK [6]

Operation of Refuse Transfer Station(Source: : EPD website,2001 http://info.gov.hk/wfbu/whatwehavedone/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/whatwehavedone/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/start.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/cleansing/collect.htm)

• Environmental Campaign Committee (ECC) (http://www.ecc.org.hk/)

• Green Power (http://user.hk.linkage.net/~greenpow/html/new/e-index.html)

http://www.em.doe.gov/em30/wasttrea.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.

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.

By a calcining process, liquid waste can be solidified

Solidification processes

Waste treatment in the Japan

Incineration Recycling

Waste Incinerator and Heat Collection System

System flow diagram of the incinerator

A Recycling Plant

http://www.em.doe.gov/em30/wasttrea.html

http://www.soc.titech.ac.jp/uem/waste/waste.html

Waste reduction campaign

http://www.info.gov.hk/epd/E/ehk99/home/chinese/ccontnt7.htm

Waste treatment in Japan

http://www.greenpeace.org/

Relevant websites

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