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Waste (also known as rubbish, trash, refuse, garbage, junk) is unwanted or useless materials. Litter is waste which has been disposed of improperly, In living organisms, waste is the unwanted substances or toxins that are expelled from them. Waste is directly linked to human development, both technologically and socially. The compositions of different wastes have varied over time and location, with industrial development and innovation being directly linked to waste materials. Examples of this include plastics and nuclear technology. Some components of waste have economical value and can be recycled once correctly recovered. Waste is sometimes a subjective concept, because items that some people discard may have value to others. It is widely recognized that waste materials are a valuable resource, whilst there is debate as to how this value is best realized. There are many waste types defined by modern systems of waste management, notably 
A dumpster full of waste awaiting disposal 
Transporting waste in Ouagadougou 
A front-loading garbage truck in North America. Waste management is the collection, transport, processing, recycling or disposal, and monitoring of waste materials. The term usually relates to materials produced by human activity, and is generally undertaken to reduce their effect on health, the environment or aesthetics. Waste management is also carried out to recover resources from it. Waste management can involve solid, liquid, gaseous or radioactive substances, with different methods and fields of expertise for each. Waste management practices differ for developed and developing nations, for urban and rural areas, and for residential and industrial producers. Management for non-hazardous waste residential and institutional waste in metropolitan areas is usually the responsibility of local government authorities, while management for non-hazardous commercial and industrial waste is usually the responsibility of the generator 
Waste management in Kathmandu (Nepal) Disposing of waste in a landfill involves burying the waste, and this remains a common practice in most countries. Landfills were often established in abandoned or unused quarries, mining voids or borrow pits. A properly designed and well-managed landfill can be a hygienic and relatively inexpensive method of disposing of waste materials. Older, poorly designed or poorly managed landfills can create a number of adverse environmental impacts such as wind-blown litter, attraction of vermin, and generation of liquid leachate. Another common byproduct of landfills is gas (mostly composed of methane and carbon dioxide), which is produced as organic waste breaks down anaerobically. This gas can create odour problems, kill surface vegetation, and is a greenhouse gas. 
A landfill compaction vehicle in action. 
Landfill operation in Hawaii. There are a number of concepts about waste management which vary in their usage between countries or regions. Some of the most general, widely used concepts include: 
Diagram of the waste hierarchy.
From Wikipedia, the free encyclopedia : Collection of waste harmless |
