Biochar is a carbonized material obtained from the pyrolysis of biomass produced in a limiting environment of zero or very low oxygen. Its interest lies in its versatility for different applications in the water treatment, soil pollution, mitigation of greenhouse gases, etc. The synergy of this product with other amendments such as compost has been studied for different applications in the soil, including environmental remediation, crop yield, etc. The aim of the research is to identify the relevant aspects in the scientific literature of biochar, compost and soil through a bibliometric analysis for which 753 articles were selected from the Scopus database, having as keywords “biochar”, “compost” and “soil”. This research used R software, specifically the package Bibliometrix, to analyze descriptive analysis, author sources, document metrics, citation, co-citation analysis, co-occurrence network, co-word analysis, and collaboration analysis. Results showed that Zhang Z is the author with the greatest number of documents, and with a higher H index. Science of The Total Environment, Bioresource Technology, and Agronomy are the 3 topmost relevant sources. The keywords according to bond strength and most frequent use were biochar (538 occurrences), composting (349 occurrences), compost (436 occurrences), charcoal (295 occurrences), soil (255 occurrences). China is the country with the most collaboration. It is hoped that the bibliometric review will help to identify current research trends and provide information on the application of biochar and compost in the soil.

This study presents a scientometric analysis of renewable energy applications in low-temperature regions, focusing on green hydrogen production, carbon storage, and emerging trends. Using bibliometric tools such as RStudio and VOSviewer, the research evaluates publication trends from 1988 to 2024, revealing an exponential growth in renewable energy studies post-2021, driven by global policies promoting carbon neutrality. Life cycle assessment (LCA) plays a crucial role in evaluating the environmental impact of energy systems, underscoring the need to integrate renewable sources for emission reduction. Hydrogen production via electrolysis has emerged as a key solution in decarbonizing hard-to-abate sectors, while carbon storage technologies, such as bioenergy with carbon capture and storage (BECCS), are gaining traction. Government policies, including carbon taxes, fossil fuel phase-out strategies, and renewable energy subsidies, significantly shape the energy transition in cold regions by incentivizing low-carbon alternatives. Multi-objective optimization techniques, leveraging artificial intelligence (AI) and machine learning, are expected to enhance decision-making processes, optimizing energy efficiency, reliability, and economic feasibility in renewable energy systems. Future research must address three critical challenges: (1) strengthening policy frameworks and financial incentives for large-scale renewable energy deployment, (2) advancing energy storage, hydrogen production, and hybrid energy systems, and (3) integrating multi-objective optimization approaches to enhance cost-effectiveness and resilience in extreme climates. It is expected that the research will contribute to the field of knowledge regarding renewable energy applications in low-temperature regions.

This research reports a bibliometric analysis using the bibliometrix package with information from the SCOPUS database. A descriptive analysis was performed to provide an overview of the countries, institutions, authors, journals and keywords of 80 manuscripts published between 1997 and 2022 in the field of study of emergy and its application in wastewater treatment. The results showed 2 sources with the highest h and g impact index (Ecological Engineering and Journal of Cleaner Production) with a significant growth since 2009. The most cited keywords were "emergy" and "wastewater", and the countries with the most important scientific networks were China, Japan, Saudi Arabia, USA, Brazil, Colombia and Italy. In addition, it shows that collaborative groups among the authors from China and USA are the ones that consolidate the main research network, as well as the largest scientific production with the most cited articles in the field of study of emergy in wastewater treatment. Therefore, the application of the emergy method in wastewater treatment requires extensive research in different types of treatments. This type of analysis would allow the development of a new approach in the application of wastewater treatment in terms of sustainability and the introduction of Latin American countries in this emerging field.

Los glaciares tropicales son indicadores sensibles del cambio climático. La pérdida del volumen de los glaciares tropicales en la cuenca Parón (Cordillera Blanca, Perú) es una muestra de esto a nivel global y se espera que tales cambios afecten a los servicios ecosistémicos que son únicos e insustituibles. Este estudio estimó el valor económico de los servicios ecosistémicos asociados con el recurso hídrico impactados por el retroceso glaciar en la cuenca de Parón-Parque Nacional Huascarán (Cordillera Blanca, Perú) entre los años 2009 y 2018. La metodología inició cartografiando los glaciares de 2009 a 2018 usando imágenes satelitales de alta resolución tomadas en temporada seca. Luego, se reconstruyeron las superficies 3D de los mismos usando la herramienta GLABTOP permitiendo calcular el volumen. Con los datos obtenidos se calculó el valor del servicio ecosistémico del turismo y recreación, y provisión de flujo hídrico. Los resultados indican que los glaciares de la cuenca Parón se han reducción de ~1.82% del área glaciar y en una tasa de deglaciación máxima de 0.08 (km2/año). Los resultados de la reconstrucción 3D muestran un 1.8% más de espesores entre los 40 y 60 m, con una pérdida de hielo de 1.02 km3, a una tasa máxima de 0.14 km3/año. Los valores monetarios presentes de los servicios de 2009 a 2018 se estimaron en $52 029.34 para el servicio de turismo y recreación y de $3 213 258.21 para el servicio de provisión de flujo hídricos, calculados a 8% de tasa de descuento. Por lo tanto, se recomienda que se debe incrementar la inversión en programas sobre la red hídrica de la cuenca de Parón, como mayores servicios, usos poblacionales o industriales.

The co-treatment of acidic water (AW) and urban wastewater (UWW) is a technique that allows mitigating the negative impact of AW on natural aquatic environments, which represents one of the major environmental problems globally. The aim of this research was to determine the optimal conditions through the response surface methodology (RSM) with a central composite design (CCD) for the co-treatment of AW from the Quiulacocha lagoon in Pasco and UWW from a municipality in Lima, Peru, having as factors the molar ratio of total iron (FeT) and total phosphorus (PT), time (min) and stirring speed (rpm). Data processing was performed using the Design-Expert 11 software, and analysis of variance (ANOVA) with a confidence interval of 95% (α = 0.05) was used. The statistical models obtained showed high determination coefficients (R²), higher than 92% for pH, conductivity and FeT removal. While the removal of COD, PT and obtained a value of R²>0.80, as well as evidenced compliance with the level of significance P value > 0.05. The optimal conditions determined by the statistical model were given at a FeT /PT molar ratio (33:1), a stirring time of 5 min and a speed of 255 rpm. In these conditions, the COD was reduced by 71.78%, FeT by 99.48%, and PT by 84.29% with a residual concentration of 1.3 mg/L; the pH obtained a value of 5.7 and the turbidity 56 NTU. Better efficiency of the co-treatment for the reduction of pollutants in the AW of the Quiulacocha lagoon is evidenced, applying an experimental design to optimize the operating conditions, taking into account that the molar ratio is a significant factor and that optimizing it would allow the co-treatment to be replicated. Co-treatment is a sustainable and promising alternative for the treatment of AW and UWW, since it does not require the use of chemical agents to treat water. However, post-treatments would still be required to comply with certain regulations or to reuse the treated water on a larger scale.

This study optimized a homogeneous photo-Fenton process for the simultaneous degradation of the emerging pesticides atrazine and methomyl in water using Response Surface Methodology (RSM). A synthetic agricultural effluent containing 2.0 mg L⁻¹ of each pesticide (COD = 103.2 mg O₂ L⁻¹; TOC = 26.1 mg C L⁻¹; BOD₅ = 45.8 mg O₂ L⁻¹) was treated in a recirculating UV–H₂O₂/Fe²⁺ reactor. A 2³ factorial design with replication and five central points identified the H₂O₂/Fe²⁺ ratio and irradiation time as the main factors controlling mineralization, achieving up to 88.9% COD removal in the best screening run. Steepest-ascent experiments were then performed to approach the region of maximum response, followed by a rotatable Central Composite Design (20 runs). The resulting quadratic model explained 98.14% of the COD variance (R² = 0.9814; adjusted R² = 0.9646; predicted R² = 0.8591; CV = 0.2736%) and predicted a maximum COD removal of 94.5% at a volumetric flow rate of 0.466 L min⁻¹, a Fenton ratio of 12.713 mg mg⁻¹, and a treatment time of 71.0 min. Experimental validation under these optimized conditions yielded highly reproducible removals of 94.2 ± 0.04% COD and 81% TOC, confirming the predictive capability of the RSM model and demonstrating a high degree of organic mineralization. The response surfaces revealed that increasing the Fenton ratio enhances oxidation up to an optimum, beyond which hydroxyl-radical self-scavenging slightly decreases efficiency. Overall, the integration of multivariable experimental design and RSM provided a robust framework to maximize photo-Fenton performance with moderate reagent consumption and operating time, consolidating this process as a viable alternative for the mitigation of pesticide-laden agricultural wastewaters.