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Different waste classification, definition and how to process them properly

Author:Zhongan-ECO Comefrom: Date:2021/9/28 15:40:32


Definition and classification of waste

Waste is a product or substance which is no longer suited for its intended use. Whereas in natural ecosystems waste (i.e. oxygen, carbon dioxide and dead organic matter) is used as food or a reactant, waste materials resulting from human activities are often highly resilient and take a long time to decompose.

For legislators and governments, defining and classifying waste based on risks related to the environment and human health are therefore important in order to provide appropriate and effective waste management. For the producer or holder, assessing whether a material is waste or not is important in identifying whether waste rules should be followed. Definitions are also relevant in the collection and analysis of waste data as well as in domestic and international reporting obligations.

Waste has been defined in most countries and is generally tied to the concept of disposal. 

On the more detailed level, a notable variety of definitions and classification approaches are used globally. Materials and substances that are directed for recycling or re-use are often (but not always) regarded as waste since the producer or holder discards them and they will only cease to be waste if certain procedures are completed and documented. Defining waste can at times also be a case-by-case decision. For example, industrial by-products can on certain conditions be regarded as non-waste. The national waste regulation is the main reference point in this regard.

Waste can be classified based on source (who/what generated the waste? See below Figure 1), substance (what is it made of?), hazard properties (how dangerous is it?), management (who handles it?) or a mix of these concepts.

Figure 1. Waste classification by origin. Different activities generate different types of waste.

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How to process or disposal the waste?

Waste disposal, the collection, processing, and recycling or deposition of the waste materials of human society. 

In industrialized countries, municipal liquid waste is funneled through sewage systems, where it undergoes wastewater treatment, or sewage treatment. This process removes most or all of the impurities from wastewater, or sewage, before they can reach groundwater aquifers or surface waters such as rivers, lakes, estuaries, and oceans.

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Refuse, or municipal solid waste (MSW), is nonhazardous solid waste from a community that requires collection and transport to a processing or disposal site. Refuse includes garbage and rubbish. Garbage is mostly decomposable food waste, and rubbish is mostly dry material such as glass, paper, cloth, or wood. Garbage is highly putrescible or decomposable, whereas rubbish is not. Trash is rubbish that includes bulky items such as old refrigerators, couches, large tree stumps, or construction and demolition waste (e.g., wood, drywall, bricks, concrete, and rebar [a steel rod with ridges for use in reinforced concrete]), all of which often require special collection and handling. Refuse is often deposited in sanitary landfills-that is, pits or other sites sealed with impermeable synthetic bottom liners where waste is isolated from the rest of the environment. 

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Some forms of solid and liquid waste are classified as hazardous because they are harmful to human health and the environment. Hazardous wastes include materials that are toxic, reactive, ignitable, corrosive, infectious, or radioactive. Toxic waste is essentially chemical waste from industrial, chemical, or biological processes that can cause injury or death when it is either ingested or absorbed by the skin. Reactive wastes are chemically unstable and react violently or explosively with air or water. Infectious wastes (such as used bandages, hypodermic needles, and other materials from medical and research facilities) are materials that may contain pathogens. Radioactive wastes (such as spent fuel rods containing fissionable materials used in nuclear power generation and isotopes of cobalt and iodine used in cancer treatment and other medical applications) emit ionizing energy that can harm living organisms. Hazardous wastes pose special handling, storage, and disposal challenges that vary according the nature of the material.

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Electronic waste, or e-waste, is electronic equipment that has ceased to be of value to users or that no longer satisfies its original purpose as a result of either redundancy, replacement, or breakage. Electronic waste includes both “white goods” such as refrigerators, washing machines, and microwave ovens and “brown goods” such as televisions, radios, computers, and cellular telephones. E-waste differs from traditional municipal waste. Although e-waste contains complex combinations of highly toxic substances (such as lead and cadmium in computers and cellular telephones) that pose a danger to health and the environment, which should be treated as hazardous materials with respect to their disposal, it also contains nonrecyclable parts that enter the municipal solid waste stream. Electronic devices also contain recoverable parts made of gold, silver, platinum, and other valuable materials, as well as recyclable materials (such as plastics and copper), that can be used to make new electronic items.