Seawater desalination represents an alternative solution to face the challenge of water scarcity in Chile. However, the uncertainty toward potential environmental impacts of desalination plants represent a barrier to achieving water sustainability and socioeconomic development in Chile. This study aimed to assess the quality of environmental monitoring plans (EMP) and determine the aspects to be improved within it, in order to enhance the management of desalination plants during the operation phase and guarantee a sustainable development of the activity. The Environmental Impact Assessments (EIAs) and Environmental Impact Studies for seawater desalination projects published in the Environmental Impact Evaluation System (SEIA) in Chile between 1997 and 2018 were reviewed. The results of the brine production from desalination plants showed a significant increase in the last decade (about 1.6 Mm³ per year estimated according to the projects approved or under implementation). The EMPs data show heterogeneity and increasing requirements over time, which can be attributed to the governmental effort to improve environmental protection. Furthermore, a high frequency of irrelevant descriptors was identified in the current EMPs. The study thus recommended standardizing the environmental requirements included in EMPs based on empiric scientific knowledge to enhance the environmental protection programs in Chile.

We studied the relative catch performance of a modified trawl fitted with an extension piece using a 90º turned mesh (T90) in comparison with a standard trawl net used in NW Mediterranean bottom trawl fisheries employing a diamond mesh net. The comparison was made by means of paired experimental hauls using the same fishing vessel with alternate deployments of the standard net (control) and the experimental net. We used the catch comparison approach for three target species of the fishery: European hake, red mullet and striped red mullet. Our results show that the experimental net significantly reduces the catches of small-size hake and red mullet (though there was no discernible difference for striped red mullet), reducing unwanted catches of regulated species under the Landings Obligation. The overall catch rates of hake, pooled over all sizes, also increased by an estimated 50%, while the catch rates of red mullet and striped red mullet were significantly lower. However, considering all commercial species, the experimental net produced losses of commercial catch and income estimated at 17% and 18%, respectively, which may pose a barrier to the adoption of this relatively simple, inexpensive solution.

Seawater desalination is one of the most feasible technologies for producing fresh water to address the water scarcity scenario worldwide. However, environmental concerns about the potential impact of brine discharge on marine ecosystems hinder or delay the development of desalination projects. In addition, scientific knowledge is lacking about the impact of brine discharges on the South America Pacific coast where desalination, is being developed. This paper presents the first monitoring results of brine discharge influence areas from seawater reverse osmosis desalination plants (SWRO) on the South America Pacific coast, using Chile as case study. Our results indicate that the combination of favorable oceanographic conditions and diffusers, results in the rapid dilution of brine discharge on coastal ecosystems; showing a faster dilution than other SWRO plants in other regions, such as Mediterranean or Arabian Gulf, with similar production characteristics. Also, the increase in salinity over the natural salinity in the brine-discharge-affected area was <5 % in a radius of <100 m from the discharge points. Further, according to the published literature and on our monitoring results, we propose a number of considerations (environmental regulation, best scientifically tested measures, environmental requirements) to achieve a long-term sustainable desalination operation.

The expansion of seawater desalination is presented as a new way to supply fresh water for many coastal regions as an effort to counteract the increasing water scarcity. However, brine discharges also pose significant environmental challenges regarding their potential environmental impacts of marine ecosystems. The main objective of this study was to assess the physico-chemical impact of the brine discharges from Seawater Reverse Osmosis (SWRO) desalination plants on South America pacific coastal ecosystems, assessing its potential physical-chemical impact (temperature, salinity, density and dissolved oxygen) on the receiving marine environment, and evaluating the oxidative and osmotic stress responses of the red macroalgae Rhodymenia corallina through diagnostic biomarkers in field-transplantation experiments. Our results showed that the increase over natural salinity in the affected area was less than 3.5 % in a radius of 50 m from the discharge point. Also, we demonstrated that the brine discharges increase the density but not significant affect the temperature and dissolved oxygen of the marine environment. In addition, diagnostic biomarkers showed a negative effect on oxidative, osmotic and antioxidant stress responses in R. corallina after two days of brine exposure, particularly at the nearest brine diffuser transplantation site. However, after five days, antioxidant and osmotic parameters exhibited full recovery, indicating the cessation of the redox imbalance. Based on the results obtained, we demonstrated that the use of appropriate mitigation measures combined with an appropriate oceanographic location of the submarine outfall, would ensure a sustainable desalination operation without generating significant environmental impacts on the coastal ecosystems.