2.1. ‪This is waste, or maybe not

‪2.2. ‪The difficulty of establishing a classification

The economic development of society is sustained thanks to a series of activities that utilize an important quota of natural resources. ‪The problem is when these resources, which are found in our environment and have been exploited throughout the history of humanity to a greater or lesser extent depending on the technical and technological capabilities, are mostly non-renewable resources. ‪In other words, their generation rates are below the current rates of exploitation. ‪In turn, during both the extraction of these resources, as well as during transportation and processing / utilization, there exists a possibility or the risk of causing environmental impacts of various magnitudes. ‪These impacts affect a territory in that it has a certain capability to accommodate socioeconomic activities (physical sustenance), as well as, an increasingly dense network of transportation infrastructure and communication, not to mention the settlements where we live and also occupy space. ‪For all these reasons, true human development must take into account economic aspects, but also social and environmental ones.

‪Along with the need to use resources properly and occupy and transform the territory in an orderly manner, a third key element is waste, or rather, what to do with waste. ‪One of the main characteristics of the most economically developed societies is the production and consumption of a large number of products to meet their own needs, whether they be basic or not. ‪These products, generated from materials of diverse origins, are largely characterized by having a short life cycle, in other words, when they complete their life cycle they can be regarded as waste. ‪The increase in consumption of materials during the twentieth century and early twenty-first century has been spectacular, especially in the case of construction materials. ‪But to these useable materials, that can potentially become waste, we must add materials generated during the different production processes and are not used, these are called ecological backpacks. ‪This concept was created by Schmitdt-Bleek in 1994 and serves to explain what he called "material intensity per unit of service", namely the amount of material used throughout the product's entire life cycle.

As stated in Gomez (2003), the environmental integration of different human activities and, consequently, the move towards long-awaited sustainable development will become reality when we become aware and act accordingly to the fact that we have a limited amount of natural resources, that each territory has a different ability to accommodate settlements, activities and infrastructure and, finally, that this same territory has limited capacity to assume the increasing amount of waste generated. For this reason and referring to the issue of waste, we must carry out a proper management of generated waste, as well as, implementing policies to reduce the amount produced and selectively collect the vast majority. ‪Otherwise, waste can become an environmental problem of first order.