Urban rivers are essential resources for human societies; however, their degradation poses serious public health, economic, and environmental risks. Conventional physical remediation methods can partially mitigate pollution by targeting specific contaminants, but they are often limited in scope, lack long-term sustainability, and fail to restore ecological functions. In contrast, biotechnological approaches integrated with ecological engineering offer sustainable and nature-based solutions for river depollution, conservation, and revitalization. Although these strategies are supported by a solid theoretical framework and successful applications in other aquatic systems, their large-scale implementation in urban rivers has only recently begun to gain momentum. This review critically examines strategies for the revitalization of polluted urban rivers, progressing from conventional remediation techniques to advanced biotechnological interventions. It highlights real-world applications, evaluates their advantages and limitations, and discusses policy frameworks and management strategies required to promote the broader adoption of biotechnological solutions for sustainable urban river restoration. The goal is to demonstrate the transformative potential of integrated biotechnological, eco-engineering, and data-driven approaches—particularly microbial, phytoplankton-based, and biofilm systems—to reduce energy demand and carbon emissions in urban river restoration while highlighting the need for scalable designs, adaptive management, and supportive regulatory frameworks to enable their large-scale implementation.

This systematic review investigates the use of coconut fiber and marble powder as alternative aggregates in geopolymer concretes, focusing on their mechanical performance and durability. Conducted systematically between July and November 2025, this study analyzed 75 records identified across Scopus, Web of Science, SciELO, and Google Scholar, covering publications from 2010 to 2025. Following a rigorous selection process that excluded non-experimental patents and secondary reviews, 55 primary publications (articles, dissertations, and theses) were critically evaluated. Although replacement levels of up to 40% have been reported in the literature, the most consistent evidence supports replacement rates between 15 and 20% for marble powder and up to 8% for coconut fiber. Higher substitution levels may produce satisfactory results under specific experimental conditions, particularly when coupled with alkaline activation (NaOH/Na₂SiO₃); however, these outcomes are not consistently reported across studies. Therefore, caution is recommended when extrapolating higher values. It is concluded that incorporating these industrial and agricultural residues represents a viable and sustainable alternative for the construction industry, provided that their utilization is supported by careful technical optimization.

This systematic review investigated the use of coconut fiber and marble powder as alternative aggregates in geopolymer concretes, focusing on mechanical performance and durability. A total of 75 documents were analyzed. Of the total documents analyzed, 10 patents and 10 systematic review articles were excluded for not meeting the established methodological criteria. The patents were discarded for not presenting experimental data related to the properties of the composites as a substitute for cement. In turn, the review articles were excluded for not providing primary results, which would make consistent comparative analyses unfeasible. 55 publications (including articles, dissertations, and theses) remained at the end. This survey was conducted during the months of July, August, September, October, and November 2025, covering publications between 2010 and 2025, using databases such as Scopus, Web of Science, SciELO, and Google Scholar. The results indicate that substitutions between 30% and 40% promote significant improvements in compressive strength, tensile strength, and chemical durability, especially when combined with alkaline activators such as NaOH and Na₂SiO₃. The presence of CASH gel and siloxane bonds was recurrent in the studies with the best performance. It is concluded that the use of these residues represents a viable and sustainable alternative for the construction industry, with the potential to reduce environmental impacts and promote the circular economy.