Micropollutant removal from effluent of conventional wastewater treatment has recently become one of the most discussed topics in the design and operation of wastewater treatment plants (WWTPs). This is due to the need to add a post-treatment step to the conventional processes to comply with stricter quality standards for effluents as outlined in the revised Urban Wastewater Treatment Directive (UWWTD). The adoption of on-site or decentralized greywater (GW) treatment in sustainable buildings using vertical-flow constructed wetlands (VFCWs) is a promising direction. It represents an interesting alternative for the removal of micropollutants at the source of pollution, such as personal care products (PCPs) and some pharmaceuticals which are mainly present in this wastewater fraction. Additionally, the treated greywater could be used in households\' water services which do not require potable water quality, thus saving drinking water. In this context, this work compares the results of micropollutant removal from projects using VFCWs as a polishing step of WWTPs effluent, as a centralized solution, to the results from a decentralized GW treatment. The results show that VFCWs can remove the investigated micropollutants (Diclofenac and DEET) with an efficiency of >90 %, in both centralized and decentralized treatments. The admixture biochar from plant residues and from cellulose-toilet paper proved to be a promising substitute for the mineral zeolite when mixed with sand to remove PCPs from GW and, therefore, a circular economy concept can be applied to this technology.

Three paradigms to deal with urban water issues are compared. The analysis focuses on their definition and objectives, the role of different stakeholders, the issues they deal with, and the possible solutions suggested. The paradigms differ in scope (from the narrow focus of the sponge city paradigm to the broad goals of eco-city paradigm) and in terms of the governance structures used to coordinate different stakeholders. The smart and sponge paradigms mainly use existing government structures. In the eco-cities approach, the citizens want to be involved through newly created governance structures. Smart and eco-city initiatives emphasize the involvement of stakeholders, while in the sponge cities approach, the initiative is often taken by the local government. Finally, in terms of expected solutions, the paradigms want to create eco- or healthy cities or improve water management to create a more healthy urban environment. After identifying the issue, alternative water-related technologies are available, like generating energy from wastewater or separating grey and brown water. Cities require different governance structures, and managing information flows in an integrated way to solve water and other issues. The experience in Europe, China, and India may help other cities choose the right paradigm.

The expanding cannabis production sector faces economic challenges, intensified by freshwater scarcity in the main US production areas. Greenhouse cultivation harnesses sunlight to reduce production costs, yet the impact of greenhouse light levels on crucial production components, such as plant growth, branching, and water use efficiency (WUE), remains poorly understood. This study aimed to assess the effects of combined sunlight and supplemental lighting on the crop\'s main production components and leaf gas exchange of Cannabis sativa \'Suver Haze\' in the vegetative stage. Within a greenhouse, LED lighting provided at intensities of ~150, 300, 500, and 700 µmol m-2 s-1 (18-hour photoperiod), combined with solar radiation, resulted in average daily light integrals of 17.9, 29.8, 39.5, and 51.8 mol m-2 d-1. Increasing light levels linearly increased biomass, leaf area, and the number of branches per plant and square meter, with respective rates of 0.26 g, 32.5 cm2, and 0.41 branches per mole of additional light. As anticipated, crop evapotranspiration increased by 1.8-fold with the increase in light intensity yet crop WUE improved by 1.6-fold when comparing the lowest and highest light treatments. Moreover, water requirements per unit of plant biomass decreased from 0.37 to 0.24 liters per gram when lighting increased from ~18 to 52 mol m-2 d-1, marking a 35% reduction in evapotranspiration. These results were supported by increments in leaf photosynthesis and WUE with light enhancement. Furthermore, our findings indicate that even 52 mol m-2 d-1 of supplemental lighting did not saturate any of the crop responses to light and can be economically viable for cannabis nurseries. In conclusion, light supplementation strongly enhanced photosynthesis and plant growth while increasing WUE. Additionally, a comprehensive discussion highlights the shared physiological mechanisms governing WUE in diverse plant species and their potential for water conservation under enhanced lighting conditions.

The two main things needed to fulfill the world\'s impending need for water in the face of the widespread water crisis are collecting water and recycling. To do this, the present study has placed a greater focus on water management strategies used in a variety of contexts areas. To distribute water effectively, save it, and satisfy water quality requirements for a variety of uses, it is imperative to apply intelligent water management mechanisms while keeping in mind the population density index. The present review unveiled the latest trends in water and wastewater recycling, utilizing several Artificial Intelligence (AI) and machine learning (ML) techniques for distribution, rainfall collection, and control of irrigation models. The data collected for these purposes are unique and comes in different forms. An efficient water management system could be developed with the use of AI, Deep Learning (DL), and the Internet of Things (IoT) structure. This study has investigated several water management methodologies using AI, DL and IoT with case studies and sample statistical assessment, to provide an efficient framework for water management.

Polymer electrolyte fuel cells are an essential technology for future local emission-free mobility. One of the critical challenges for thriving commercialization is water management in the cells. We propose small- and wide-angle X-ray scattering as a suitable diagnostic tool to quantify the liquid saturation in the catalyst layer and determine the hydration of the ion-conducting membrane in real operating conditions. The challenges that may occur in operando data collection are described in detail─separation of the anode and cathode, cell alignment to the beam, X-ray radiation damage, and the possibility of membrane swelling. A synergistic development of experimental setup, data acquisition, and data interpretation circumvents the major challenges and leads to practical and reliable insights.

Water is a defining element for cities and their inhabitants. Throughout urban systems, water is either produced or received, used, and finally disposed of as wastewater. As Latin American urbanization accelerates, problems related to wastewater are increasing due to its inclusion as the main source of river pollution, as well as the high cost of infrastructure development and maintenance. The consequences of wastewater disposal are particularly relevant in areas frequently associated with urban expansion, like peripheries whose growth follows constant transitions between rural, peri-urban, and urban areas. Such consequences are often related to heterogeneity, lack of urban services and sanitation infrastructure, water pollution and health risks, as well as the development of informal compensatory systems. A systematic literature review was conducted to broaden research panorama and identify spatial, temporal, and thematic trends and challenges present in wastewater assessments of Latin American urban peripheries, this using the SALSA (search, appraisal, synthesis, and analysis) protocol in a search through international databases Scopus and Web of Science Scielo, in English, Spanish, French, and Portuguese. In these databases, 228 papers satisfied selection criteria and show a growing trend of publications about urban wastewater since 1988. Most case studies are from Brazil (58 %), Mexico (14 %), and Argentina (9 %). Their main approaches are quantitative research (82 %) in urban contexts (57 %). Most studies were found to be operationalized using environmental geochemistry methodologies, suggesting a dominance of technical, reductionist approaches. Integrated and mixed perspectives including actors and other societal elements are suggested as a central research challenge. Without an integrated view, it will be unfeasible to enhance decision-making processes and governance in the pursuit of sustainable water management.

Anion exchange membrane fuel cells (AEMFCs) have recently attracted significant attention as low-cost alternative fuel cells to traditional proton exchange membrane fuel cells because of the possible use of platinum-group metal-free electrocatalysts. Over the past decade, new materials dedicated to the alkaline medium, such as anion exchange membranes (AEMs) and anion exchange ionomers (AEIs), have been developed and studied in AEMFCs. However, only a few AEMs and AEIs are commercially available, and there are no ready-to-use membrane electrodes assemblies (MEAs) with the desired AEMs and AEIs. Consequently, the need to manufacture in-house CCMs or GDEs becomes a reality that we must face. This work deals with the influence of ionomer content on the prepared MEAs with the commercial anion exchange membrane and ionomer from Aemion™ Ionomr Innovations AF1-HNN8-2 and AP1-ENN8/HNN8 respectively and by varying the support (gas diffusion layer or membrane). The prepared MEAs were characterized morphologically by SEM and profilometry, as well as electrochemically by AEMFC polarization curves and cyclic voltammetry. In addition, an attempt to investigate water management was made with and without a reference electrode in the cell to understand the behavior of water in an operating AEMFC. Our results show that CCM-based MEAs can undergo deformation during the anion conversion step, leading to weakening of the membrane and hence faster degradation in the fuel cell. On the contrary, no deformation was observed for the GDEs during the anionic conversion, although the results are poorer due to (i) poor interface contact between membrane and GDE that depends on ionomer ratio in the ink and (ii) a high overpotential at the anode due to the production of water that cannot be effectively evacuated.

This study employs diverse machine learning models, including classic artificial neural network (ANN), hybrid ANN models, and the imperialist competitive algorithm and emotional artificial neural network (EANN), to predict crucial parameters such as fresh water production and vapor temperatures. Evaluation metrics reveal the integrated ANN-ICA model outperforms the classic ANN, achieving a remarkable 20% reduction in mean squared error (MSE). The emotional artificial neural network (EANN) demonstrates superior accuracy, attaining an impressive 99% coefficient of determination (R2) in predicting freshwater production and vapor temperatures. The comprehensive comparative analysis extends to environmental assessments, displaying the solar desalination system\'s compatibility with renewable energy sources. Results highlight the potential for the proposed system to conserve water resources and reduce environmental impact, with a substantial decrease in total dissolved solids (TDS) from over 6,000 ppm to below 50 ppm. The findings underscore the efficacy of machine learning models in optimizing solar-driven desalination systems, providing valuable insights into their capabilities for addressing water scarcity challenges and contributing to the global shift toward sustainable and environmentally friendly water production methods.

Water recycling and reuse are cornerstones of water management, which can be compromised by the presence of pollutants. Among these, pharmaceuticals can overcome standard water treatments and require sophisticated approaches to remove them. Sorption is an economically viable alternative limited by the need for sorbents with a sorption coefficient (Kd) higher than 500 L/kg. The cross-linking of dextrin (Dx) with divinyl sulfone (DVS) in the presence of 1 mmol or 5 mmol of ibuprofen (IBU) yields the insoluble polymers pDx1 and pDx5 with improved affinity for IBU and high selectivity towards erythromycin (ERY) and ERY Kd higher than 4 × 103 L/kg, when tested against a cocktail of six drugs. Characterization of the polymers shows that both pDx1 and pDx5 have similar properties, fast sorption kinetics, and ERY Kd of 13.3 × 103 for pDx1 and 6.4 × 103 for pDx5, representing 26.6 and 12.0 times the 500 L/kg threshold. The fact that new affinities and improvements in Kd can be achieved by cross-linking Dx in the presence of other molecules that promote pre-organization expands the applications of DVS cross-linked polysaccharides as sustainable, scalable, and environmentally friendly sorbents with a potential application in wastewater treatment plants (WTPs).

When chemical pollutants enter the environment, they can undergo diverse transformation processes, forming a wide range of transformation products (TPs), some of them benign and others more harmful than their precursors. To date, the majority of TPs remain largely unrecognized and unregulated, particularly as TPs are generally not part of routine chemical risk or hazard assessment. Since many TPs formed from oxidative processes are more polar than their precursors, they may be especially relevant in the context of persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances, which are two new hazard classes that have recently been established on a European level. We highlight herein that as a result, TPs deserve more attention in research, chemicals regulation, and chemicals management. This perspective summarizes the main challenges preventing a better integration of TPs in these areas: (1) the lack of reliable high-throughput TP identification methods, (2) uncertainties in TP prediction, (3) inadequately considered TP formation during (advanced) water treatment, and (4) insufficient integration and harmonization of TPs in most regulatory frameworks. A way forward to tackle these challenges and integrate TPs into chemical management is proposed.