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The climate change and increasing anthropogenic pressures are expected to limit the availability of water resources. Hence, active measures must be planned in vulnerable regions to ensure a sustainable water supply and minimize environmental impacts. A pilot test was carried out in the Llobregat River (NE Spain) aiming to provide a useful procedure to cope with severe droughts through indirect water reuse. Reclaimed water was used to restore the minimum flow of the lower Llobregat River, ensuring a suitable water supply downstream for Barcelona. A monitoring was performed to assess chemical and microbiological threats throughout the water treatment train, the river and the final drinking water, including 376 micropollutants and common microbiological indicators. The effects of water disinfection were studied by chlorinating reclaimed water prior to its discharge into the river. Data showed that 10 micropollutants (bromodichloromethane, dibromochloromethane, chloroform, EDDP, diclofenac, iopamidol, ioprimid, lamotrigine, ofloxacin and valsartan) posed a potential risk to aquatic life, whereas one solvent (1,4-dioxane) could affect human health. The chlorination of reclaimed water mitigated the occurrence of pharmaceuticals but, conversely, the concentration of halogenated disinfection by-products increased. From a microbiological perspective, the microbial load decreased along wastewater treatments and, later, along drinking water treatment, ultimately reaching undetectable values in final potable water. Non-chlorinated reclaimed water showed a lower log reduction of E. coli and coliphages than chlorinated water. However, the effect of disinfection vanished once reclaimed water was discharged into the river, as the basal concentration of microorganisms in the Llobregat River was comparable to that of non-chlorinated reclaimed water. Overall, our study indicates that indirect water reuse can be a valid alternative source of drinking water in densely populated areas such as Barcelona (Catalonia - NE Spain). A suitable monitoring procedure is presented to assess the related risks to human health and the aquatic ecosystem., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Most of the Mediterranean rivers are suffering the effects of industrial, urban and mining discharges, as well as a reduction in water quantity and quality. Additionally, due to the Mediterranean climate, the natural water resource availability is periodically lower than the water demand in the area. Operation of drinking water plants in these geographical areas needs advanced process control systems where real-time and in-line water quality monitoring tools are key components. Data sets with parameters generated by monitoring sensors and from laboratory analysis are used to reveal the main factors that characterize water quality. Chemometric tools like Principal Component Analysis (PCA) can be used to explore and analyze correlations among different physicochemical and microbiological parameters with the aim to assess the river water quality at the water intake of drinking water treatment plants (DWTPs). Strong seasonal trends in the organic and inorganic matter contents and unusual events in the raw river water quality at the DWTP water intake are revealed. Organic and inorganic patterns are then associated with climatological, meteorological and industrial pollution circumstances typical for the geographical region under study. In addition, microbiological events can be detected at the water intake of DWTP which may occur simultaneously with increasing water contents of organic matter, especially at the beginning of rainfall episodes. The application of PCA on sensors data in the water intake at DWTPs offers new possibilities for improved quality assurance and control procedures for DWTP management and its strategy., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A simple, selective and sensitive method for the analysis of the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its brominated analogues (BMXs) in chlorine-treated water has been developed. The method is based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS), previous liquid-liquid extraction (LLE) of a smaller sample volume compared to other methods and on-line derivatization with a silylation reactive. GC-QqQ-MS/MS has been raised as an alternative easier to perform than gas chromatography coupled to high resolution mass spectrometry (GC-HRMS) for the analysis of MX and BMXs, and it allows to achieve low LODs (0.3 ng/L for MX and 0.4-0.9 ng/L for BMXs). This technique had not been previously described for the analysis of MX and BMXs. Quality parameters were calculated and real samples related to 3 drinking water treatment plants (DWTPs), tap water and both untreated and chlorinated groundwater were analyzed. Concentrations of 0.3-6.6 ng/L for MX and 1.0-7.3 ng/L for BMXs were detected. Results were discussed according to five of the main factors affecting MX and BMXs formation in chlorine-treated water (organic precursors, influence of bromide ions, evolution of MX and BMXs in the drinking water distribution system, groundwater chlorination and infiltration of water coming from chlorination processes in groundwater)., (Copyright © 2015 Elsevier B.V. All rights reserved.)