Human activities suppose a risk of generating contamination of the environment: all of these activities imply the modification of the media, including the landscape, and frequently also the quality of soil, water, and atmosphere in the surroundings. When these affections go further than certain thresholds, we have a contaminated site. Besides, the human activities also imply frequently the accumulation of wastes; even in the simplest way of life, inhabiting caves, the enlargement of the cave for new born humans generates the need of excavation to create a void, extracting materials that need to be accumulated more or less near the cave entrance, generating a residual heap. Nowadays, the management of contaminated sites and of wastes, many of them created or accumulated during many decades, or even centuries, represents an important need, since their extension has not stopped growing, in particular, from the development of the “Industrial Age.” However, the task is not easy (nor cheap) to carry out, due to both the diverse nature of the “contaminants” distributed in the environment and to the extension of sites affected by this type of problem. Green chemistry is one of the tools developed to try to get solutions to this type of problems, in many different ways, including the development of chemical process able to mitigate the negative effects that certain contaminants may exert on the soil quality, or in the health of biota affected by such contaminants.