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Wastes can be considered, as those materials no longer required by an individual or industry. Growth of the world's population, increasing urbanization, rising standards of living and rapid development in technology have all contributed in an increase in both the amount and variety of wastes generated by all the activities within a society. Thus, in order to develop frame works within which effective waste management strategies can be planned, it is essential to know the amount of waste generated, their sources, the materials in which waste streams, their properties, potential toxicity and hazards to human health and the environment.
Wastes are produced by all the activities within a society and include the following:
- Municipal waste and Consumer waste: Generated by households and wastes of similar character from shops, markets and offices. A mixture of organic materials, paper, plastics, textiles, glass, metals, ash and grit. With the rapid change in technology and production of new models, the number of bulky or consumer wastes discharged increases e.g. cars, refrigerators, washing machines.
- Litter: Packaging materials (glass and plastic bottles, cans, paper cups, paper and plastic wrappings) are the main constituents of litter. The increase in the volume of litter is attributed in part to changes in pattern consumption, increased used of packaging with a high proportion of non-biodegradable plastics and the increase in the number of non-returnable beverage containers.
- Sewage sludge: It's a residue from the treatment of domestic and industrial waste water at plants designed to minimize the pollution of rivers and oceans by effluents. Sewage sludge is a slurry of fine organic-rich particles with a highly variable chemical composition which will depend on the source of the effluent and the type and efficiency of the treatment process. Heavy metals, water-soluble synthetic organic compounds, greases, oils and bacteria are also present.
- Dredged spoils: It is produced from excavated river estuaries, harbours and other water wastes to aid navigation. It is estimated that 10% of dredged materials are contaminated by oil, heavy metals, nutrients and organochlorine compounds from shipping, industrial and municipal discharges, urban and agricultural run-off.
- Demolition and Construction wastes: The type of wastes produced will depend on the age and type of the structure involved but is usually inert. The main exception is asbestos where special disposal is required.
- Mining and quarrying wastes: Mine tailings and spoils is the waste material that is extracted in the process of mining minerals of economic value. The waste materials may include top-soil, rock and dirt which may be inert. Contamination of mine tailings from ore extractions is due to the use of metals or chemicals in its separation. Mechanization of deep mining process has increased the amount of spoil that reaches the surface and which needs disposal.
- Industrial wastes: Industrial process wastes include a very wide range of materials depending on the nature of the industrial waste. They may occur as relatively pure substances or as complex mixtures of varying compositions and physical status with a significant proportion being hazardous or potentially toxic. Examples are liquid wastes, solid wastes, general factory rubbish, packaging materials, organic wastes from food processing, acids, alkalis, metaliferous sludges and tarry residues.
- Hazardous wastes: There is no agreed definition of the term "hazardous waste". Some countries define it only in terms of the danger to human health while others include damage to the environment. It may also be defined in terms of its physical or chemical characteristics. e.g. flammability or toxicity, or in terms of concentrations of specific substances that they contain. The bulk of hazardous wastes are generated by process industries, the main source being the chemical sector, the mineral and metal processing industries and the engineering industry. Other industrial sectors, hospitals and laboratories may also produce significant amounts. The definition of hazardous wastes excludes domestic wastes although it contains small quantities of hazardous wastes e.g. batteries. Occasionally large quantities of hazardous wastes arise from the clean up of chemical and oil spills.
Mismanagement of wastes may lead to effects on the whole ecosystem and ultimately on human health.
- Liquid wastes disposed on land or solid wastes dumped on the surface or in unsatisfactory landfills are prone to weathering process and leaching by rain. Some of the toxic compounds in these wastes find their way to ground water, aquifers or to nearby surface waters contaminating both the water and the aquatic biota through contaminating their tissues, thus causing health hazards to nearby inhabitants.
- Atmospheric pollution due to the decomposition of solid wastes in landfills result in the production of carbon dioxide and methane gas which are important greenhouse gases. Incineration produces emissions of particulate, unburned waste material and trace quantities of organic compounds and through bio-accumulation may be transferred to people.
- Marine pollution due to the release of pathogens from sewage sludge and the release of toxic substances from industrial waste materials has adverse effects on marine life. Bio-accumulation of these substances in the fatty tissues of marine organisms is transferred to people through the food chain.
Where treatment, incineration and landfills are used judiciously and plant design and management is of high standards. These methods of waste disposal can be effective in safeguarding people and the environment. Thus to ensure proper control of waste disposal practices, countries need national strategies which provide legislative and regulatory frameworks within which enforcement procedures can be implemented. Sound management strategies should be beyond safe storage and disposal practices and considers comprehensively all the alternatives available.
- Policies and Control Strategies on Waste management
- National, regional policies and initiatives
- Control strategies through systems of licensing of operators and/or treatment, storage and disposal facilities.
- Environmental Legislation
- National Legislations and Regulations
International Conventions and Programmes related to waste management such as:
The Basel Convention on the control of transboundary movement of hazardous wastes and their disposal, the Oslo Convention and the London Dumping Convention.
- Institutional Arrangements
- Governmental and Non-Governmental Bodies at a National level dealing with the Environmental Issues
- Overall coordination between the bodies at a national, regional and international level.
- Adopt the Three R Strategy - Reduce, Reuse and Recycle
- Educational Programmes and Public Awareness
Waste Management in the Arab World
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ROPME/GC-9/002, 1999. Regional Report of the State of the Marine Environment
UNEP 1992. Chemical Pollution: A Global Overview