Most purification systems work correctly from the point of view of water quality; purification, like any industrial process, must also be carried out efficiently with a minimization of costs. The overall project examined the potential benefits of using a recommended methodology for process evaluation and energy optimization in the aeration stage of activated sludge in the biological reactor at wastewater treatment plants (WWTP), which accounts for more than 44% of total operating costs. This energy control methodology encompasses the process, the installation and the control system. These three phases are examined in separate articles to make it easier to guide the user in the arduous task of optimizing energy efficiency of the WWTP from start to finish. This article focuses on Phase I of the methodology, the stage in charge of selecting the correct variables to control the best process conditions in the activated sludge system of the WWTP. Operating conditions that are a function of the recommended sludge age are influenced by exogenous factors such as temperature. The implementation of a real-time control system of the selected process variables, adapted to the needs, achieves reductions in the overall energy consumption of the installation, in this phase alone, of more than 15%, by reducing the oxygen requirements of the system and the recirculation ratios.

The proposed methodology for optimizing energy efficiency, based on good management of the aeration process through the implementation of an appropriate control strategy, achieved reductions of more than 40% in energy consumption at the San Pedro del Pinatar Wastewater Treatment Plant (WWTP) (Murcia, Spain). Phases I and II of this methodology managed to reduce the oxygen needs of the microorganisms in the biological system, optimize the efficiency of oxygen transfer to the biological reactor and redesign the installation to correct abnormal energy loss situations. In addition, we established the basis for Phase III, which implemented a control strategy to achieve stable values close to the setpoints of the fundamental operating parameters of the aeration process. The control system is based on the measurements recorded by strategically installed sensors and mathematical algorithms based on models, achieving an expert adaptive-predictive system that regulates aeration both in the biological stage by activated sludge and the aeration of the installed ultrafiltration membrane system. The objectives were: (i) to achieve automatic execution of the best management strategy; (ii) to reduce the energy demand; (iii) to improve the operation and stability of the process; (iv) to reduce operating costs; and (v) to contribute to the fulfillment of the sustainable development objectives.

Phase I of the proposed energy optimization methodology showed how the selection of best management criteria for the biological aeration process, and the guarantee of its control at the wastewater treatment plant (WWTP) in San Pedro del Pinatar (Murcia, Spain) produced reductions of around 20% in energy consumption by considerably reducing the oxygen needs of the microorganisms in the biological system. This manuscript focused on phase II of this methodology, which describes the tools that can be used to detect and correct deviations in the optimal operating points of the aeration equipment and the intrinsic deficiencies in the installation, in order to achieve optimization of the oxygen needs by the microorganisms and improve the efficiency of their transfer from the gas phase to the liquid phase. The objectives pursued were: (i) to minimize the need for aeration, (ii) to reduce the pressure losses in the installation, (iii) to optimize the air supply pressures to avoid excessive energy consumption for the same airflow, and (iv) to optimize the control strategy for the actual working conditions. The use of flow modeling and simulation techniques, the measurement and calculation of air transfer efficiency through the use of off-gas hoods, and the redesign of the aeration facility at the San Pedro del Pinatar WWTP were crucial, and allowed for reductions in energy consumption in Phase II of more than 20%.

Considering the important role that wastewater reuse plays in the water cycle and in the current water scenario immersed in a severe drought, the search for technologies that allow obtaining quality water for reuse is increasingly relevant. In this sense, the membrane biological reactor (MBR) is an alternative to traditional activated sludge systems, in which the separation of biomass and treatment water is carried out by membrane filtration instead of decantation. This study made it possible to confirm the presence of emerging pollutants in the wastewater entering the WWTPs under study, to study the behavior and performance of MBR systems with hollow fiber membranes and flat membranes in obtaining reclaimed wastewater for subsequent reuse, and to compare it with the degree of elimination obtained in conventional biological treatment. It has been demonstrated that this technology is almost 100% effective in the elimination of nutrients, organic matter, pathogens, organic micropollutants, metals, etc., and has achieved different percentages of success in eliminating emerging pollutants depending on their nature: 35% in insecticides and herbicides, 45% in anxiolytics, psychiatric drugs, and industrial disinfectants, 75% in antibiotics, and around 100% in analgesics, anti-inflammatory drugs, and hormones. It has also contributed to the establishment of monitoring protocols for emerging pollutants in the WWTPs under study and to the evaluation of their risks, as well as the development and implementation of advanced regeneration systems that are economically favorable for increasing the quality of WWTP effluents for their reuse.

Water is an essential resource whose quality is threatened by emerging pollutants, including microplastics (MP), whose persistence, bioaccumulation capacity and ecotoxic potential pose a growing risk to ecosystems and human health. Wastewater treatment plants (WWTPs) have been identified as one of the main sources of these pollutants, as conventional treatments are insufficient to remove them completely. In response to this problem and with the aim of finding more efficient and sustainable solutions, a study has been carried out at WWTP with a pilot MP capture plant capable of detecting, quantifying and removing these particles from different wastewater sources with high precision and sustainability. This proposal represents a significant advance in the mitigation of invisible pollution, contributing to the protection of the environment and public health, achieving an efficiency of over 80% in the removal of plastic particles. This system not only addresses the challenge of environmental protection but also represents an unavoidable commitment to a healthier, more equitable, and sustainable development model for current and future generations, directly contributing to strategic action to advance the fulfillment of several Sustainable Development Goals (SDGs) promoted by the UN (SDG 3, SDG 6, SDG 12, SDG 14 and SDG 15).

This study analyses the impact of augmented reality (AR) using GeoGebra 3D on teaching volumetric geometry and improving spatial intelligence in secondary school students. Spatial intelligence, fundamental in STEM areas, is developed through the visualisation and manipulation of three-dimensional objects, skills that are not fully developed by traditional teaching methods. A quasi-experimental design was implemented with an experimental group using GeoGebra 3D with AR and a control group using traditional methods. The sample consisted of high school students and included the PSVT:R test to measure spatial ability, academic tests and perceptual questionnaires. The results show a significant improvement in visualisation and spatial rotation skills in the experimental group, as well as an increase in student motivation and interest. AR facilitated interaction and understanding of complex geometric concepts, promoting more active and meaningful learning. In conclusion, the integration of GeoGebra 3D with AR improves spatial intelligence and optimises the teaching process of volumetric geometry, positioning itself as an effective and innovative technological tool in secondary education. Este estudio analiza el impacto de la realidad aumentada (RA) mediante la aplicación GeoGebra 3D en la enseñanza de la geometría volumétrica y en la mejora de la inteligencia espacial en estudiantes de secundaria. La inteligencia espacial, fundamental en áreas STEM, se desarrolla a través de la visualización y manipulación de objetos tridimensionales, habilidades que los métodos tradicionales de enseñanza no logran potenciar completamente. Se implementó un diseño cuasi-experimental con un grupo experimental, que utilizó GeoGebra 3D con RA, y un grupo control, que trabajó con métodos tradicionales. La muestra incluyó estudiantes de secundaria y se aplicaron el test PSVT:R para medir habilidades espaciales, pruebas académicas y cuestionarios de percepción. Los resultados muestran una mejora significativa en las habilidades de visualización y rotación espacial en el grupo experimental, así como un incremento en la motivación y el interés de los estudiantes. La RA facilitó la interacción y comprensión de conceptos geométricos complejos, favoreciendo un aprendizaje más activo y significativo. En conclusión, la integración de GeoGebra 3D con RA mejora la inteligencia espacial y optimiza el proceso de enseñanza de la geometría volumétrica, posicionándose como una herramienta tecnológica eficaz e innovadora en la educación secundaria.