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In this study, the main elements that can make up a Natural Treatment System for Wastewater (NTSW), its most important parameters and properties of operation and design, have been analyzed, as well as the environmental problems derived from the generation of large amounts of slurry. The objective of this paper is to propose a methodology to improve the operation of these systems, associated with small and medium-sized livestock farms, in insular and isolated systems such as the Canary Islands. An Integrated and Resilient System (IRS) for monitoring and measuring operational variables quasi-continuous and in situ is proposed. Low-cost technology and open source hardware are employed, as well as application of the IoT (Internet of Things) strategies to share and analyze the information collected in the cloud. In view of the high degree of resilience and the simplicity of this type of technology, as well as its low cost, it is concluded that it is feasible to create a measurement system with these characteristics that can be used for NTSW parameterization, and other purposes. Satisfactory results were obtained for several parameters (ambient temperature, relative humidity, UV radiation, atmospheric pressure). It is presented as a novel proposal based mainly on low-cost technology and free software with which to improve the NTSW operation process. [ABSTRACT FROM AUTHOR]

Food security concerns, climate change impacts, and increased pressure on conventional water resources have encouraged the agricultural use of nonconventional water resources in the last decade. As a result, desalinated seawater (DSW) has already consolidated its position as an alternative source to increase the supply for crop irrigation in Spain and Israel, where farmers' acceptance is progressively on the rise. The first experiences in these regions highlighted that DSW agricultural use involves new agronomic, economic, and environmental challenges which require innovative research approaches and imply novel water management strategies. In this Special Issue, eight high-quality papers which present current research trials and study cases, covering a wide range of topics that are relevant when irrigating with DSW, have been selected. The papers came from the three regions of the world that currently have a massive agricultural DSW supply: Southeastern Spain, Israel, and the Canary Islands. [ABSTRACT FROM AUTHOR]

Water deficit in semi-arid regions limits the future of the livestock sector. Also, its high price represents a percentage of the total cost of forage production. Non-conventional water resources applied by subsurface drip irrigation (SDI), in which the safe use lies in the management and not on the level of water treatment, would enhance the ruminant production sustainability. To obtain the optimal benefit, the transformation of water per kilogram of dry matter produced must have a high grade of effectiveness. Under this premise, a maralfalfa crop (Penissetum sp, hybridum) has been established with an SDI system and reclaimed water. Forage yield is analyzed with respect to a 40% irrigation reduction. This study shows that, with the use of these good irrigation management practices, it is possible to harvest an annual production of 90 to 72 t·ha-1 in the warmer regions of the Canary Islands. This implies water consumption between 13,200 and 8100 m3·ha-1. A water consumption of 21,000 m3·ha-1 per year for the same production, at a ratio of 230 L.t-1, can be estimated for the rest of the Canary Islands coastal regions. The use of the water management described in this paper can be profitable in the Canary Islands for fodder production. [ABSTRACT FROM AUTHOR]

The analysis of energy consumption in reverse osmosis desalination plants is the most important and relevant factor to study, because this parameter indicates the level of efficiency and competitiveness of the plant. The direct consequence of the high specific energy consumption (SEC) of a desalination plant in the production of water is one of the main obstacles to the exponential expansion of this technology worldwide. The methodological procedure used to carry out the work is based on the analysis of energy consumption, maintenance costs, staff, membranes, and reagents of three desalination plants with a production of more than 23,000 m3/day located in the Canary Islands (Spain); all data are obtained from real analyses collected "in situ" from 2015 to 2018. One of the main objectives of the current research on desalination plants is to reduce the SEC of seawater desalination plants (SWRO), incorporating energy recovery systems (ERS) and high efficiency pumps (HEP), and to implement different operational configurations with the aim of minimizing the energy requirements necessary to obtain a good product quality at minimum production cost. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) have been identified as significant point sources of microlitter particles (MPs) released into the environment. Simultaneously, they play a crucial role in effectively removing a substantial amount of MPs originated from domestic and industrial activities. This study evaluates the presence and chemical composition of MPs within the range of 5 mm to 25 µm in effluents from three WWTPs in the Canary Islands, each undergoing distinct treatment processes: pretreatment (PRET), activated sludge (AS), and membrane bioreactor (MBR) over an eight-month period. The concentrations of MPs exhibited substantial variations in the three effluent samples: 7461.50 ± 3843.87 MP/L in PRET, 32.71 ± 19.55 MP/L in AS, and 9.53 ± 5.21 MP/L in MBR. The predominant forms of MPs were fragments (58–66%) and fibers (27–33%), with the most prevalent size class being within the range of 150–25 µm. The mass concentrations of plastics, analyzed through pyrolysis gas chromatography–mass spectrometry (Pyr-GC/MS), were determined as 123.33 µg/L for PRET, 17 µg/L for AS, and 10 µg/L for MBR. This study revealed a diverse polymer profile, with polyvinyl chloride (PVC) and polyolefins (PE and PP) predominantly present. This work enhances our understanding of MP dynamics and provides a valuable reference for future assessments, aiding in the selection of effective removal technologies. [ABSTRACT FROM AUTHOR]

The literature on water use in hotels has identified numerous determinants of water consumption, but a consensus has yet to be reached on the influence of some of these factors. This article aims to enhance the current research framework on water use in the hotel sector by presenting a case study of one hotel in Tenerife, Canary Islands. The conceptual framework of water consumption in hotels is presented based on the previous literature. Starting from that, basic statistical analysis and bivariate correlations were performed on water consumption data from 2007 to 2019 to determine the significant factors affecting both total water consumption and consumption per guest night. Special attention was paid to water usage in gardens and the impact of weather conditions, as there is a lack of research focused on them. Additionally, the water management actions of the hotel were classified according to the business' themes proposed for the Sustainable Development Goals, using an internationally recognized guide, thus addressing one of the gaps identified in the literature. The results generally support previous research findings, but some discrepancies were noted regarding the number of guest nights and the effectiveness of implementing water-saving measures. This raises new questions about the characteristics of various water-saving measures, such as room renovation, and their influence on customer behavior, which may alter the intended impact on water consumption. Therefore, the findings of this study can provide an insight into unclear aspects in this area. They could also benefit hotels in terms of sustainability communication by allowing them to position their actions with an internationally recognized framework. [ABSTRACT FROM AUTHOR]

The most recent years of research have shifted the perception of desalination brine from being waste to a high-value resource, in consonance with a circular economy perspective. The Canary Islands, containing the largest number of desalination plants per square kilometre in the world, are a perfect location to study its characteristics and evaluate its potential. A total of 10 heterogeneous seawater reverse osmosis plants were selected to determine the brine's physicochemical characterisation, comprising 37 parameters, and its correlation to the technical and operational aspects of the desalination plants. The results show a stable narrow range of the percentage of major ions concentration in relation to the total dissolved solids (55% Cl−, 29.5% Na+, 8% SO42−, 4% Mg2+, 1.5% Ca2+, 1.2% K+, 0.5% HCO3−, and 0.2% Br−) irrespective of specific differences between plants. The results obtained in this study are highly beneficial to industrial suppliers and future users of desalination brine valorisation (DBV) technologies, allowing an estimation of the chemical composition of a brine through knowledge only of its conductivity. Such information is crucial before investing in and optimizing DBV technologies. Nonetheless, from an environmental, economic, operational, energy-based, and R&D point of view, several improvements are required to promote their large-scale feasibility and viability. [ABSTRACT FROM AUTHOR]

This manuscript presents the advances of a pilot testing, located in Spain, using ultrafiltration (UF) membranes to supply drinking water. These results could be extended to the islands of the Macaronesia area, for instance, Azores, Madeira, Canaries, and Cape Verde. The UF project targeted by the pilot activity is a refurbishment of an existing installation. The existing installation is located at a higher altitude, thus drinking water could be supplied to most of the island without further pumping, reducing the carbon footprint, ecological footprint, and energy consumption. The raw water is soft surface water (mainly of rainwater origin) coming from a dam. On the islands of Macaronesia, water is a scarce resource in high demand. Therefore, this is a technically and economically viable business opportunity with a promising future for isolated water treatment systems to produce drinking water on islands. The Macaronesia area is formed by volcanic islands with a small surface in the Atlantic Ocean, so usually there is not enough space for conventional technology and only a compact UF can be used. The raw water quality is not satisfactory and the municipality receives many complaints from end users, thus a potable water plant with UF membranes is in high demand to supply drinking water of good quality. Membrane processes can be categorized into various, related methods, three of which include the following: pore size, molecular weight cut-off, and operating pressure. Regarding the obtained results, the UF system successfully produced excellent filtrate quality with turbidity readings on average less than 0.03 NTU; furthermore, membrane instantaneous flux of 90 Lmh at 14 °C is achievable with long-term stability under various feed water conditions, peak operations are available at 105 Lmh without a large impact on the filtration performance of the modules, and CIP is only to be performed if the TMP increase reaches the terminal point. [ABSTRACT FROM AUTHOR]

The uncertainty associated with natural magnitudes and processes is conspicuous in water resources and groundwater evaluation. This uncertainty has an essential component and a part that can be reduced to some extent by increasing knowledge, improving monitoring coverage, continuous elaboration of data and accuracy and addressing the related economic and social aspects involved. Reducing uncertainty has a cost that may not be justified by the improvement that is obtainable, but that has to be known to make the right decisions. With this idea, this paper contributes general comments on the evaluation of groundwater resources in the semiarid Canary Islands and on some of the main sources of uncertainty, but a full treatment is not attempted, nor how to reduce it. Although the point of view is local, these comments may help to address similar situations on other islands where similar problems appear. A consequence of physical and hydrological uncertainty is that different hydrogeological and water resource studies and evaluations may yield different results. Understanding and coarsely evaluating uncertainty helps in reducing administrative instability, poor decisions that may harm groundwater property rights, the rise of complaints and the sub-optimal use of the scarce water resources available in semiarid areas. Transparency and honesty are needed, but especially a clear understanding of what numbers mean and the uncertainty around them, to act soundly and avoid conflicting and damaging rigid attitudes. However, the different situations could condition that what may be good in a place, may not always be the case in other places. [ABSTRACT FROM AUTHOR]

A real-scale application experience Natural Treatment Systems for Wastewater (N T S W) operating in continues with livestock farms for one year. These systems are based on digesters, subsurface vertical flow constructed wetlands (S V F C W) and facultative ponds. Chemical Oxygen Demand removal efficiency (C O D R E) has obtained between 70 and 90%. Likewise, it have been possible to compare the operation of cascade flow digesters (C F D) (<76% C O D R E ) versus complete mixing digesters (CMD) (<50% C O D R E ). Facultative ponds (F P) when combined with (S S F C W) , removed a higher percentage of C O D R E compared with ponds (92%). Correlations of interest have been found between the variables evaluated in each plant. Finally, different elements are alternated in the same system, this system is capable of supporting variations in changes in flow rate and organic load coming from the farm, maintaining an adequate elimination of C O D and other parameters of interest. [ABSTRACT FROM AUTHOR]

This article shows a climate change mitigation strategy by means of membranes replacement and determination methodology of carbon footprint in reverse osmosis (RO) desalination plants, valid for all the islands, and even isolated territories in the continent. This study takes the case of study of Canary Islands, where there are more than 320 desalination plants with different sizes, private, and public. The objective is to propose a new method which integrates this analysis with the replacement of membranes, from 0% to 20% per year in sea water reverse osmosis desalination plants, to reduce the carbon footprint and ecological footprint. If it is considered a replacement of 20% of the elements per year, the carbon footprint could be reduced to between 5% and 6% and even more if it is introduced low energy consumption membranes instead of high rejection elements. The factor mix in Canary Islands, according to the technological structure of the generation park that uses oil products, is around 0.678 kgCO2/kWh, much higher than in the Spanish mainland where it is 0.263 kgCO2/kWh. Therefore, it is estimated in Canary Islands 5,326,963 t CO2/year can be emitted, which represents 2.4 tCO2/person/year, 12 times more the admissible admissions per inhabitant in the Canary Islands, only considering the seawater desalination sector. This document shows the different results of the analysis of energy efficiency and the environmental footprints. This study may serve as a tool for the decision-making processes related to how to improve energy efficiency in desalination plants. [ABSTRACT FROM AUTHOR]

In the Canary Islands, there is a hydrological imbalance between water consumption and renewable water availability. To provide more water resources, reverse osmosis (RO) from seawater is used. As boron (B) contents in irrigation water higher than 0.7 mg/L may be dangerous for sensible plants, B concentration in RO water (ROW) may be one of the key factors of irrigation sustainability. Some orchards have been studied after they have used drip irrigation using different water qualities for 30 years. B in water, soils, and banana leaves was determined to check the sustainability of ROW irrigation. When irrigating with ROW, in which B concentration varies between 1.0 and 1.4 mgB/L, B content in banana soils seems to be stabilized at 5–7 mg/kg, and no toxicity has been observed in banana leaves. The proper water and soil management used by the local farmers probably prevent the accumulation of higher B levels in soils. Considering water consumption of 9000 m3∙ha−1∙year−1, 8−11 kgB∙ha−1∙year−1 is applied to the soil. The banana plant removes approximately 1 kgB∙ha−1∙year−1; therefore, only 10% of the total B added gets exported. This raises the following question: is it better to use membranes that are able to reduce B in ROW, increase the leaching fraction, or blend water? [ABSTRACT FROM AUTHOR]