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Waste Treatment. 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.

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Waste Treatment

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

Commercial Waste

Industrial Waste


Waste load in HK [1]

  • Waste Classification in HK

    • Municipal solid waste

      • Domestic waste

      • Commercial waste

      • Industrial waste

    • Construction & demolition (C&D) waste

    • Chemical waste

    • Special waste (e.g. clinical waste, radioactive waste)

    • Other solid wastes


Waste load in HK [2]

  • Quantity of waste

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


Waste load in HK [3]

  • Composition of waste

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

  • Composting

  • Recycling of recyclable waste

  • Ocean dumping


  • In Incineratorsof 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 Operationsof 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.


kitchen wastes leaves grass clippings

Air

Some soil

Water

fertilizer

Composting In Garden


What is Recycling ? clippings

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.


Recyclable Waste clippings

  • Metals e.g.Aluminium cans

  • Waste paper like newspaper

  • Plastic and glass bottles


- Paper should be separated from other waste clippings

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 Reduction in the present clippings

  • 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 clippings

  • 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 clippings

  • 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 clippings

  • 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 clippings [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 clippings [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 clippings [3]

  • Three Main Areas of the Plan

    • Prevention of Waste Programme

    • Institutional Programme

    • Waste Bulk Reduction Programme


Waste Management in HK clippings [1]

  • Waste Management Hierarchy

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


Waste Management in HK clippings [2]

  • Facilities of Waste Management

    • Landfills


Waste Management in HK clippings [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 clippings [4]

Refuse Truck Unloading at Tipping Face in Landfill

(Source: EPD website, 2001 http://info.gov.hk/wfbu/whatwehavedone/wms/sland/l_fillop.htm)


Waste Management in HK clippings [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 clippings [6]

Operation of Refuse Transfer Station

(Source: : EPD website,2001 http://info.gov.hk/wfbu/whatwehavedone/wms/rts.htm)


Waste Management in HK clippings [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 clippings

  • 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 clippings [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 clippings [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 clippings [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)


Waste treatment in the U.S. clippings

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 clippings

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 clippings

Incineration

Recycling


System flow diagram of the incinerator clippings

Waste Incinerator and Heat Collection System



Relevant websites clippings

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 clippings

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 clippings


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