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Social and spatial segregation structures in Latin America are perceived as processes for the selective concentration of social or demographic groups in geographic sectors of the city. This voluntary or forced segregation creates poor, wealthy, and marginal areas, leading to the territory’s marginalization and fragmentation, destroying the symbolic and territorial urban continuity. To understand the behavior of waste pickers in a Mexican city, we sought to know the conditions of the informal collection activity in eight Latin American countries with similar conditions. Therefore, the goal was to carry out a bibliographic evaluation that included the environmental contribution of waste pickers, their organizations, and their link with urban metabolism. The tasks performed by informal waste pickers in the cities of the eight selected Latin American countries, their organizations, and their way of working were studied. Their role in reducing environmental impact and improving the quality of life of city dwellers was evaluated. Web sites, web searches, and face-to-face meetings created electronic communication channels with this community were analyzed. In some cases, they are well organized and become microentrepreneurs with salary, social security, and economical insurance by starting an ecological business. In contrast, marginal groups seeking economic support collect, separate, sort, and group recoverable waste daily and sell it at waste distribution points. This link in the urban metabolism reintroduces valuable solid waste into the production chain. In addition, materials with commercial value, such as metals, plastics, paper, cardboard, and wood, can re-enter the production chain as secondary materials for industry. Thus, a collective of well-organized waste pickers contributes to the city’s sustainability and provides better living conditions for the waste pickers. In Mexico, there is a lack of official information regarding the number of waste pickers, organizations, activities, and their environmental contribution. Therefore, a directory with that information is highly relevant to designing public policies to recognize the essential contributions of this sector.

The burning of fossil fuels is an unsustainable activity, which is leading to an increase in greenhouse gases (GHGs) emissions and related global warming. Among sustainable energy sources, microalgae represent a promising alternative to fossil fuel and contribute to the achievement of important Sustainable Development Goals (SDGs). In particular, the potential contribution of marine microalgae to sustainable development is large as, among other benefits, they represent a carbon negative energy source and may be applied in many coastal areas around the world. Despite this, significant economic and technological improvements are needed in order to make microalgae biofuels viable on a large scale. This review aims to explore how and to what extent third-generation biofuels (marine microalgae, but also the latest advances in freshwater microalgae) can benefit the realization of these SDGs. From this study we concluded that the production of large-scale marine microalgae biofuels is not yet feasible from the economic perspective at a large scale. However, the cultivation of microalgae in seawater holds great potential for increasing the small to medium viability of this biofuel source. The possibilities for improvement along with the contributions to sustainable development lay the groundwork for continuing to study and apply the potential of sustainable production of microalgae bioenergy.