The circular economy aims to reduce the volume of waste generated in the world, transforming it into resources. The concept of indicator of circular economy was introduced to evaluate the improvement obtained regarding efficiency in terms of reduction, reuse and recycling of waste generated on the campus of the University of Lome (Togo). These indicators showed that 59.5% of the waste generated on the campus in 2018 could be introduced into the circular economy paradigm through composting, and 27.0% of the energy consumed could be replaced by clean energy obtained from biogas. The entire plastic fraction can be introduced into the circular economy paradigm by reusing plastic bottles and selling the rest in the port of the city. Thus, the income obtained could range from €15.5/day in 2018 to €34.5/day in 2027. Concerning old tires, 1.5% of the rubber needed to pave the entire roadway of the campus could be replaced by the waste generated by the tires currently existing there. Consequently, waste management on the campus could be controlled thanks to these indicators, and this could serve as a model for the rest of the country.

The optimization of water management in industrial processes is paramount in diminishing or mitigating, as far as possible, the negative externalities generated by its current use within the linear economy model. This research presents methods for the optimization of wastewater from paper mills which are associated with the new sustainability and circular economy model. In this way, the concept of circular economy was applied to the wastewater treatment from a paper mill, with the objective of recovering the resources contained in this type of effluent. The wastewater treatment plant is based on a biological reactor of activated sludge, and treats a flow of 4868 m³·day⁻¹. This study proposes the development and evaluation of indicators of circular economy applied to wastewater from a paper mill, as well as the assessment of the removal performance of color, total suspended solids (TSS), biochemical oxygen demand on the fifth day (BOD₅), and chemical oxygen demand (COD), which are higher than 96% in all cases. Per 1 m³ of wastewater from a paper mill, a volume of 0.9 m³ of potentially reusable water and a recovered sludge mass of 0.7 kg are generated; the latter is reused as a mineral filler during the process itself. In light of this, a multivariable statistical analysis was applied to determine the relationship of the operation variables and indicators of circular economy. In this way, wastewater from the paper mill can be regarded as a technological nutrient, which is partially reintroduced into the production process, enabling the recovery of the water and mineral fillers that it contains.

The increasing demands of infrastructures in terms of energy consumption, raw material demand, greenhouse gas emissions, waste management, treatment of components after their lifetime period, and financial costs are nowadays a serious threat for sustainability. Given that the resources are limited, it is difficult to ensure an accurate level of well-being for future generations. For this reason, new perspectives in design, production and consumption are necessary. In this work, the principles of circular economy are applied to concrete branches of engineering. Departing from a design orientated to new uses after life period of infrastructures, a circular economy-aimed engineering makes possible the connection and mutual profit of such different branches like waste management and tunnel lighting. The benefits in environmental and financial terms are a strong argument in favor of a stronger link between engineering and circular economy.

Antecedentes: El sector de la construcción es uno de los sectores económicos en Colombia con mayor crecimiento, generando grandes cantidades de residuos como producto del proceso de construcción, y/o demolición, o en su defecto en la fabricación de los materiales de construcción. Objetivo: facilitar el acceso a información académicocientífica actualizada sobre reciclaje de residuos industriales y su aplicación en la fabricación de materiales de construcción. Así mismo se emplea el término de economía circular, el cual hace referencia a la integración de las actividades de reducción (consumo de energía y residuos), reutilización y recuperación durante la producción, el intercambio y consumo. Conclusión: además de reducir la contaminación generada por los residuos de los sectores productivos, con el aprovechamiento de los subproductos ha sido posible mejorar ciertas propiedades tecnológicas de estos materiales de construcción.Palabras Clave: economía circular, materiales de construcción, nutriente tecnológico, reciclaje, residuos industriales. AbstractBackground: The construction sector is one of the economic sectors with the highest growth in Colombia, generating large amounts of waste as a result of the construction process, and / or demolition, or otherwise in the building material manufacturing. Objective: to facilitate the access to updated academic-scientific information on recycling of industrial waste and its application for the building material manufacturing. Moreover, the concept of circular economy is used, which refers to the integration of the reduction activities (energy consumption and waste),reuse and recycling during the production, exchange and consumption. Conclusion: in addition to the reduction of the pollution generated by waste from the productive sectors, certain technological properties of these building materials have been improved through the use of waste. Keywords: circular economy, building materials, technological nutrient, recycling, industrial waste. Resumo Antecedentes: Na Colômbia, o sector da construção é um dos setores económicos com maior crescimento, gerando grandes quantidades de resíduos como produto do processo de construção, e/ou demolição, ou falha na fabricação dos materiais de construção. Objetivo: facilitar o acesso à informação académico-científica atualizada sobre reciclagem de resíduos industriais e sua aplicação na fabricação de materiais de construção. Da mesma forma, foi empregado o termo de economia circular, o qual faz referência à integração das atividades de redução (consumo de energia e resíduos), reutilização e recuperação durante a produção, a troca e consumo. Conclusão: além de reduzir a contaminação gerada pelos resíduos dos setores produtivos, com o aproveitamento dos subprodutos tem sido possível melhorar certas propriedades tecnológicas destes materiais de construção. Palavras-chave: Economia circular, materiais de construção, nutriente tecnológico, reciclagem, resíduos industriais.