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The evaluation of processes that protect the environment alongside resource and energy consumption to most favourable to least favourable actions.  The hierarchy establishes preferred program priorities based on sustainability. To be sustainable, waste management cannot be solved only with technical end-of-pipe solutions and an integrated approach is necessary.
The waste management hierarchy indicates an order of preference for action to reduce and manage waste, and is usually presented diagrammatically in the form of a pyramid. The hierarchy captures the progression of a material or product through successive stages of waste management, and represents the latter part of the life-cycle for each product.
The aim of the waste hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste. The proper application of the waste hierarchy can have several benefits. It can help prevent emissions of greenhouse gases, reduces pollutants, save energy, conserves resources, create jobs and stimulate the development of green technologies.
The waste hierarchy ranks waste management options according to what is best for the environment. It gives top priority to preventing waste in the first place. If waste is not produced then it has not to be disposed of. When waste is produced, it gives precedence to preparing it for reuse, then recycling, then recovery, and last of all disposal.
Prevention: The prevention of waste is the most vital point in the waste hierarchy. Prevention or reduction minimizes the generation of waste products in the first place. Prevention usually results in the least environmental and economic life cycle costs because it requires no collecting or processing of materials. Prevention also typically produces significant benefits in terms of production efficiencies and the use of resources. It involves using less material in design and manufacture, trying to keep products for longer, and using less hazardous materials.
Reuse: The reuse of waste is the next most desirable option. It is any operation where products or materials that are not waste are used again for the same purpose for which they were intended. Reusing waste often requires collection but relatively little or no processing. It involves checking, cleaning, repairing, and/or refurbishing, entire items or spare parts.
Recycle: Recycling of waste is the next step in priority. It is any activity that includes the collection of used, reused, or unused items that would otherwise be considered waste. Recycling involves sorting and processing the recyclable products into raw material and then remanufacturing the recycled raw materials into new products.
Recovery: The recovery of waste is further separated into categories: the recovery of materials and the recovery of energy. Whichever of these two choices is better for the environment and human health is the preferred option. The recovery of materials is most often preferred and includes activities such as recycling and composting. These management activities generally require a collection system and a method of material processing and conversion into a new product. Recovery of energy, such as incineration, is usually the less preferred option. The conversion of non-recyclable waste materials into usable heat, electricity, or fuel is done through a variety of processes, including anaerobic digestion, gasification, and pyrolysis.
Disposal: The last resort is disposal and is only considered once all other possibilities have been explored. Disposal is any operation that involves the dumping and incineration of waste without energy recovery. Before final disposal, a considerable amount of pre-treatment may be necessary to change the characteristics of the waste in order to reduce the quantity or harmfulness of the waste and that may include physical, thermal, chemical, or biological processes. Landfills are the most common form of waste disposal and the final disposal option.
All products and services have environmental impacts, from the extraction of raw materials for production to manufacture, distribution, use and disposal. Following the waste hierarchy will generally lead to the most resource-efficient and environmentally sound choice but in some cases refining decisions within the hierarchy or departing from it can lead to better environmental outcomes.
Life cycle thinking and assessment can be used to support decision-making in the area of waste management and to identify the best environmental options. It can help policy makers understand the benefits and trade-offs they have to face when making decisions on waste management strategies. Life-cycle assessment provides a scientifically sound approach to ensure that the best outcome for the environment can be identified and put in place. It involves looking at all stages of a product’s life to ﬁnd where improvements can be made to reduce environmental impacts and improve the use or reuse of resources. A key goal is to avoid actions that shift negative impacts from one stage to another. Life cycle thinking can be applied to the five stages of the waste management hierarchy.
For example, life-cycle analysis has shown, that it is often better for the environment to replace an old washing machine, despite the waste generated, than to continue to use an older machine which is less energy efﬁcient. This is because a washing machine’s greatest environmental impact is during its use phase. Buying an energy-efﬁcient machine and using low- temperature detergent reduce environmental impacts.
The European Union Waste Framework Directive has introduced the concept of life-cycle thinking into waste policies. This duality approach gives a broader view of all environmental aspects and ensures any action has an overall beneﬁt compared to other options. The actions to deal with waste along the hierarchy should be compatible with other environmental initiatives.
European Union waste framework directive
In 1975, The European Union’s Waste Framework Directive (1975/442/EEC) introduced for the first time the waste hierarchy concept into European waste policy. It emphasized the importance of waste minimization, and the protection of the environment and human health, as a priority. Following the 1975 Directive, European Union policy and legislation adapted to the principles of the waste hierarchy.
In 1989, it was formalized into a hierarchy of management options in the European Commission's Community Strategy for Waste Management and this waste strategy was further endorsed in the Commission's review in 1996.
In 2008, the European Union parliament introduced a new five-step waste hierarchy to its waste legislation, Directive 2008/98/EC, which member states must introduce into national waste management laws. Article 4 of the directive lays down a five-step hierarchy of waste management options which must be applied by Member States in this priority order.
Waste prevention, as the preferred option, is followed by reuse, recycling, recovery including energy recovery and as a last option, safe disposal.
The task of implementing the waste hierarchy in waste management practices within a country must be clearly delegated to the different levels of government (national, regional, local) and to other possible actors including industry, private companies and households. Local and regional authorities can be particularly challenged by issues when applying the waste hierarchy approach.
Some of those issues or concerns may involve:
- A coherent waste management strategy that must be set up and implemented. It would involve including management plans at all different management levels.
- Separate collection and sorting systems for many different waste streams would have to be established
- New or adequate treatment and disposal facilities being established.
- An effective horizontal co-operation between local authorities and municipalities and a vertical co-operation between the different levels of government, local to regional and when beneficial, also at the national level being established;
- Finding financing for the establishing or upgrading of expensive sustainable waste management infrastructure to address the needs of managing waste.
- A lack of data available on waste management strategies must be overcome and extensive monitoring requirements must be met to successfully implement the waste programs.
- The effective enforcement and control of sound business plans and practices be established and applied to maximize benefits to the environment and human health.
- A lack of administrative capacity at the regional and local level. The lack of finances, information, and technical expertise must be overcome for effective implementation and success of the waste management policies.
Source reduction involves efforts to reduce hazardous waste and other materials by modifying industrial production. Source reduction methods involve changes in manufacturing technology, raw material inputs, and product formulation. At times, the term "pollution prevention" may refer to source reduction.
Another method of source reduction is to increase incentives for recycling. Many communities in the United States are implementing variable-rate pricing for waste disposal (also known as Pay As You Throw - PAYT) which has been effective in reducing the size of the municipal waste stream.
Source reduction is typically measured by efficiencies and cutbacks in waste. Toxics use reduction is a more controversial approach to source reduction that targets and measures reductions in the upstream use of toxic materials. Toxics use reduction emphasizes the more preventive aspects of source reduction but, due to its emphasis on toxic chemical inputs, has been opposed more vigorously by chemical manufacturers. Toxics use reduction programs have been set up by legislation in some states, e.g., Massachusetts, New Jersey, and Oregon.The 3 R 's represent the ' Waste Hierarchy ' which lists the best ways of managing waste from the most to the least desirable. Many of the things we currently throw away could be reused again with just a little thought and imagination.
- Hansen, W., Christopher, M., and Verbuecheln, M. (2002). "EU Waste Policies and Challenges for Local and Regional AUthorities".
- USEPA (2013). "Non-Hazardous Waste Management Hierarchy".
- United Nations Environmental Program (2013). "Guidelines for National Waste Management Strategies Moving from Challenges to Opportunities". ISBN 978-92-807-3333-4.
- Waste-to-Energy Research and Technology Council (2009). "Waste Hierarchy".
- European Commission (n.d.). "Life Cycle Thinking and Assessment for Waste Management".
- European Commission (2014). "EU Waste Legislation".[dead link]
- GOV.UK. "Guidance on Applying the Waste Hierarchy".
- Mark Ruzzin. "Pay-As-You-Throw - Let's Start". Retrieved 2006-11-26.
- Letsrecycle, Letsrecycle.com article on European Debate on Waste Hierarchy
- Getting to Zero Waste
- Recovered Resource Blog
- Action RE-buts in Québec