Abstract The lack of rainfall in the Canary Islands′ Archipelago is leading to the depletion of the existing aquifers throughout the islands, above all in the easternmost isles (Gran Canaria, Lanzarote and Fuerteventura). Due to the increasing water demand in the southern area of the Island of Gran Canaria, appropriate planning has become necessary in order to avoid the depletion of the phreatic water resources that can be found there. One of the most affected areas is the Amurga Mountain Range, where the existing aquifers are depleted, as shown in the Hydrological Plan of Gran Canaria. The aim of this study was to characterize the hydrochemistry of the above-mentioned groundwater bodies. Water quality monitoring was carried out over a period of five years, involving the survey of a total of 288 samples (over 4300 tests). The water from those aquifers has the characteristic of being fairly mineralized, with a prevalence of Cl−, Ca2+ and Na+ ions, salinity levels reaching 8646 mg/L, and chloride levels up to 4200 mg/L. The waters of these aquifers can be divided into two basic types, i.e., those containing high levels of sodium chloride, which can be found around the Tirajana Gorge; and the waters rich in magnesium chloride and sodium sulfate in the Arguineguín Gorge, as well as in the Amurga Massif itself. https://www.mdpi.com/2073-4441/11/4/754#

Abstract Today, one of the main targets of seawater reverse osmosis (SWRO) membrane manufacturers is to increase boron rejection. For drinking water, the regulations in Spain are quite strict in terms of maximum boron content. The aim of this work is to propose a prediction model for average boron permeability coefficient as boric acid by evaluating the fluctuations of boron permeate concentration due to the different operating conditions of the plant under study. The SWRO desalination plant used for this study is located in Spain and has 9 trains with a production capacity of around 7200 m3 d−1 per train. Data from about 1500 operating days were considered. Operating data including pressure, conductivity, flow, temperature, pH and boron permeate concentration were collected during the study period. All racks did not have the same number of pressure vessels or operating conditions. Boron permeate concentration was between 0.5 and 2 mg L−1 for the membrane element TM820S-400 and between 0.25 and 0.75 mg L−1 for the membrane element TM820L-440. The model is based on the superposition of three exponential functions considering the influence of feed pressure, feed-brine temperature and operating time. The obtained results with the proposed model showed more adaptable to the experimental data than previous model.

Abstract Reverse osmosis efficiency depends on the precise prediction, among other factors, of membrane fouling. Although extensive research has been devoted to single foulants, rather less attention has been paid to simultaneous foulants which are more representative of real feed solutions. The main purpose of this research was therefore to characterize and quantify the fouling potential that results from the coexistence of simultaneous foulants. Silica and sodium alginate were used as respective models of inorganic and organic colloidal foulants. In order to understand the possible interactions, membrane fouling was first forced with a single foulant and the results compared to combined fouling. The experiments were carried out under constant pressure and employed synthetic seawater with 32 g/L of NaCl in a pilot-scale reverse osmosis unit. A standard commercial spiral-wound thin-film composite membrane was used. The results showed a more aggravated permeate flux decline in the combined fouling experiments. An exacerbated synergistic effect on membrane fouling was observed when the concentration of sodium alginate was equal to or higher than the concentration of silica. In these cases, the permeate flux decline of combined fouling was more severe than the sum of flux decline of individual foulants. https://doi.org/10.1016/j.desal.2018.03.032