As part of our information campaign, we often use terms related to ecology, waste and recycling that may give rise to doubts.


In order to clarify them, we have compiled in this glossary those concepts that we believe are interesting to spread:



Waste or residue disposed of after being used/obtained as a resource.



Material that decomposes easily when exposed to external elements. May contain synthetic substances. Although used synonymously, it is not the same as a compostable material.



Biomethanisation is a biological process of anaerobic digestion (without oxygen) aimed at transforming the selected organic fraction in waste treatment plants into two products: biogas and digestate.

The biogas is used as an energy source and the digestate is an excellent raw material for composting.



Climate change is the variation in the planet’s climate, which can be due to both natural causes – a decrease in the earth’s rotational speed, its course of translation, etc. – and human activity – the emission of greenhouse gases, water shortages, etc. -.

Experts indicate that climate change will lead to higher temperatures, lack of clean water, changes in food production conditions and increased mortality rates due to floods, storms, droughts and heat waves.



Material made from substances of natural (organic) origin that through decomposition are converted into compost. For example, if a product is labelled “100% compostable”, its remains can be placed in the brown bin.



Organic material obtained through the composting process, which has a lumpy, dark-coloured, forest-earth odour and has soil-fertilising properties.

Compost is a natural fertiliser obtained from the natural decomposition of organic waste.



It is the process of organic waste degradation carried out under controlled conditions of oxygen and temperature, in which a great variety of microorganisms intervene. Composting is based on the action of these microorganisms, which act on the organic waste depending on different factors – amount of oxygen, temperature, nature of the waste, humidity, etc. – producing high temperatures, reducing the volume and weight of the organic matter and causing its humification and darkening.

The result obtained is compost or natural fertiliser.



The practice of consumption based on the rational use of natural resources (finite) and the use of products that meet certain social, ethical and/or environmental criteria.

Responsible consumption encompasses aspects such as ethical consumption, ecological consumption and solidarity consumption.



A model of economic management that promotes development that can be maintained in the long term without depleting existing resources or causing damage to the environment. The aim is to meet the needs of present generations without compromising the resources of future generations.



A circular economy is one in which available resources, both material and energy, are maximised so that they remain in the production cycle for as long as possible. The circular economy aims to reduce the generation of waste as much as possible and to make the best possible use of waste that cannot be avoided. Thus, raw materials are extracted, products are manufactured and materials and substances are recovered from the waste generated, which are then reintroduced into the production process.



A rise in temperature due to the presence of pollutant gases such as carbon dioxide or methane. These gases retain in the atmosphere near the earth’s crust the energy emitted by the soil when it is heated by solar radiation and cause a warming effect similar to that which occurs in a greenhouse.



It is the matter formed by organic compounds that come from the decomposition of living beings. The organic matter present in the soil is the result of the various life cycles of living beings, whose decomposing bodies create a nutrient-rich and highly usable material.



This is the tool created by the European Commission that will serve as a road map in the countries’ fight against climate change and its effects. The aim is to make Europe the first “climate-neutral” continent by 2050, i.e. with zero greenhouse gas emissions.



This is the process by which a product/waste is incorporated into a new production or consumption cycle, as if it were a new resource.



Municipal waste collection systems may provide for separate collection of waste according to its materials or origin. For example, the city of Madrid has a selective collection system based on the separation of waste into 5 categories: paper and cardboard, packaging, organic, glass and other waste.

Waste not included in the above fractions or that may be considered special – for example, batteries, used oil, paints, printer toner, etc. – must be deposited at the recycling points.



It is the material that we throw away because we have already used it but that can still be recycled or reused as a resource. For example, a paper napkin stained with food waste is waste that, if left in the organic bin, will become a resource in the form of biogas or fertiliser.



This encompasses the practices or processes by which waste generated in cities is produced by-products, reused or disposed of.



Madrid City Council, Ministerio para la Transición Ecológica y el Reto Demográfico, Pequeño diccionario de la ecología (Oniro, 2009), own sources.