Extending Natural Limits to Address Water Scarcity? The Role of Non-Conventional Water Fluxes in Climate Change Adaptation Capacity: A Review

Photodegradation of Ciprofloxacin and Levofloxacin by Au@ZnONPs-MoS2-rGO Nanocomposites

This study aimed to investigate the photocatalytic performance of diverse zinc oxide catalysts containing gold nanoparticles (AuNPs), molybdenum disulfide (MoS2), and reduced graphene oxide (rGO) toward the degradation of the antibiotics levofloxacin (LFX) and ciprofloxacin (CFX) in aqueous solutions. The obtained results demonstrate that LFX is more resistant to degradation when compared with CFX and that the principal route of degradation under visible light is the formation of hydroxyl radicals. Photoluminescence (PL) measurements were employed to verify the inhibitory effect of electron–hole recombination when AuNPs, MoS2, and rGO are integrated into a semiconductor. The catalyst that achieved the highest percentage of CFX degradation was 1%Au@ZnONPs-3%MoS2-1%rGO, exhibiting a degradation efficiency of 96%, while the catalyst that exhibited the highest percentage of LFX degradation was 5%Au@ZnONPs-3%MoS2-1%rGO, displaying a degradation efficiency of 99.8%. A gas chromatography–mass spectrometry (GC-MS) analysis enabled the identification of reaction intermediates, facilitating the determination of a potential degradation pathway for both antibiotics. Additionally, recyclability assessments showed that the synthesized catalysts maintained stable photocatalytic efficiencies after 15 cycles, indicating that the heterostructures have the potential for further usage and may be tested with other organic contaminants as well.

In Situ Formation of Copper Phosphate on Hydroxyapatite for Wastewater Treatment

Here, we control the surface activity of hydroxyapatite (HAp) in wastewater treatment which undergoes peroxodisulfate (PDS) activation. Loading the catalytically active Cu species on HAp forms a copper phosphate in the outer layer of HAp. This modification turns a low active HAp into a high catalytically active catalyst in the dye degradation process. The optimal operational conditions were established to be [Cu–THAp]₀ = 1 g/L, [RhB]₀ = 20 mg/L, [PDS]₀ = 7.5 mmol/L, and pH = 3. The experiments indicate that the simultaneous presence of Cu-THAp and PDS synergistically affect the degradation process. Additionally, chemical and structural characterizations proved the stability and effectiveness of Cu-THAp. Therefore, this work introduces a simple approach to water purification through green and sustainable HAp-based materials.

Water Resource Management in Hotels Using a Sustainable Balanced Scorecard

It is essential to find a balance between tourism development and sustainable consumption of water resources. To achieve this goal, a Sustainable Balanced Scorecard connected to the Sustainable Development Goals (SDG) is proposed for optimal water resource management in the hotel sector. The Scorecard is based on four perspectives: customer, internal processes, learning and improvement, and financial. The key variables were agreed on with stakeholders in the sector, and the Sustainable Balanced Scorecard was tested empirically on a sample of 70 hotels in island tourism destinations in the Macaronesia region. The results revealed that though more and more hotels have tried to implement strategies to save water, they were still a long way from reaching the international standard of 140 litres per guest night. In addition, there were significant differences concerning water consumption according to hotel category. The Sustainable Balanced Scorecard in this paper adds to the existing works about materiality in sustainability. It can also support business decision making about the SDGs and help potential investors.

Residential Sustainable Water Usage and Water Management: Systematic Review and Future Research

Sustainable water management has vital ramifications for people’s societal, economic and environmental future. To advance research in this domain, this article synthesizes the current state of knowledge regarding water resource management in the residential context. The aim of this paper is to identify research gaps and future research directions for residential water management in order to recommend solutions against water scarcity. To that end, this article applies bibliometric analysis and the Antecedents, Decisions and Outcomes (ADO) framework to the literature on residential sustainable water management. We reviewed the most impactful journals, most frequently cited articles, keyword trends and density-centrality maps. The in-depth analysis on 114 articles underscored three orientations for residential water usage and management: urban, household and consumer. Based on this analysis, we were able to identify the significant topics that structure this research field, as well as research gaps and future directions.

Water Flux Prediction in Direct Contact Membrane Distillation Subject to Inorganic Fouling

Freshwater is a limited resource, which has driven the development of new purification and water-reuse technologies. One promising technology for water treatment is membrane distillation (MD). One of the main problems of MD, and of many desalination technologies, is membrane fouling, which reduces the performance of the membrane. This work presents a mathematical model that aims to predict distillate fluxes in direct-contact MD when fouling occurs as salts are deposited onto the membrane surface, forming an inorganic fouling layer. The mathematical model uses a heat- and mass-transfer formulation for prediction of the distillate flux under steady state conditions, and it is combined with the cake-filtration theory to represent the distillate fluxes after the onset of membrane fouling. Model results agree well with experimental observation of distillate fluxes, both before (~12–14 kg m⁻² h⁻¹) and after the onset of membrane fouling, with root-mean-square errors smaller than 1.4 kg m⁻² h⁻¹ in all the experiments. These results suggest that the cake-filtration theory can be used to represent water flux decline in MD membranes prone to inorganic fouling. From our experiments and from the modelling exercise, we found that the onset of membrane failure was relatively constant; the precipitation reaction constant is conditioned by the physicochemical interaction between the feed solution and the membrane; and the rate of flux decline after membrane fouling depends on flow conditions as well as on the precipitation compound. However, the proposed model has limitations that must be addressed in future investigations to validate it under a wider range of operating conditions, for membranes composed by other materials and with different feed solutions to address organic, biological, and/or colloidal fouling, which typically occur under real conditions.

Constructed Wetlands to Face Water Scarcity and Water Pollution Risks: Learning from Farmers’ Perception in Alicante, Spain

Treated wastewater is constantly produced and relatively unaffected by climatic conditions, while Constructed Wetlands (CWs) are recognized as green technology and a cost-effective alternative to improve treated wastewater quality standards. This paper analyses how farmers consider (1) treated wastewater to face water scarcity risk and (2) CW as mechanisms to face agricultural water pollution in a climate change adaptation context. A survey about climate change perception and adaptation measures was answered by 177 farmers from two irrigation communities near El Hondo coastal wetland and the Santa Pola saltmarshes, both perceived as natural-constructed systems in Alicante, southern Spain. Results highlighted how, even with poor-quality standards, treated wastewater is considered a non-riskier measure and more reliable option when addressing climate change impacts. Overall, physical water harvesting (such as CWs) is the favorite choice when investing in water technologies, being perceived as the best option for users of treated wastewater and those concerned about water quality standards. Consequently, CWs were recognized as mechanisms to increase water supply and reduce water pollution. Policy-makers and water managers can use these learnings from farmers’ experience to identify the main barriers and benefits of using treated wastewater and CWs to address water scarcity and water pollution risks.

Anomaly detection in watershed hydrological behavior due to land use changes in Eskandari Watershed, Iran

In this study, SWAT hydrological model was used to differentiate the effects of drought and changes in land use on hydrological balance of the system in Eskandari Watershed area. To this end, The SWAT model was implemented separately using other user maps to investigate the impact of land use changes on the hydrological cycle of the watershed. Additionally, Van Loon model was used to investigate the effects of drought and water scarcity on discharge. The results showed that the watershed area could meet its environmental needs due to an 11% decrease in rainfall and droughts in 2008 and 2009. Additionally, the average monthly simulated flows were 2.4 m³/s and 2.9 m³/s in the natural and turbulent periods, respectively, indicating a decrease of nearly 18%, which is related to the 11% decrease in rainfall in this Watershed. Furthermore, the average observational flow in the turbulent period was 4 mm, which showed a growth of nearly 13% in comparison to the observational flow in the turbulent period. Decreased rainfall and increased discharge in this period indicated the effect of land use change and human activities on the catchment.

Application of Shrimp Waste for the Synthesis of Polyurethane–Chitosan Materials with Potential Use in Sorption of Oil Micro-Spills in Water Treatment

Shrimp waste is a common waste in seafood processing. It is used as part of the fish meal which is added to feed. Bearing in mind the Green Deal and sustainability development, it was proposed to use northern prawn shells to obtain chitosan (Ch), which could then be used for polyurethane (PUR) modification. In ports, oil micro-spills often flow into the waters of gulfs and, consequently, into the sea. Systematic chemical and petroleum water pollution may pose a threat to flora and fauna. In this study, chitosan, which was obtained from shrimp shells, was used to synthesize polyurethane–chitosan foams (PUR+Ch) with different chitosan concentrations. Selected physico-chemical and sorption properties in relation to oil and water of these materials were determined. It was found that the amount of Ch added to the foam affected its morphology, hardness, density, and thermal and sorption properties. PUR foam with a 1.5% weight of Ch was characterized as having the highest water and oil sorption. The advantages of the tested material as an innovative product with potentially significant proecological values were estimated using strengths–weaknesses–opportunities–threats (SWOT) analysis. The conducted preliminary research made it possible to demonstrate the use of these materials in the processes of water treatment with the mentioned micropollutants.