**1. Introduction**

Climate change is already present and will continue to change, affecting societies and the environment [1]. This occurs directly through changes in hydrological systems that are influencing water availability, water quality, and extreme events, and indirectly through changes in water demand, which in turn can have impacts on energy production, social and environmental damages, food security and the economy, among others [2]. On the other hand, communities have increased pressure on water resources, seeking new alternatives to mitigate the lack of this vital element. Among these alternatives is desalination technology, which is a solution to this problem [3], considering that the planet earth is 97.3% saltwater [4] and 2.5% freshwater [5]. However, in spite of being a solution that is becoming more and more common, this technology generates some environmental problems. On the one hand, it generates a product water or desalinated water that can be treated to be suitable for human consumption or irrigation, adding the necessary minerals, and on the other hand, a saline stream called brine that is generally disposed of in the sea, causing serious environmental problems [6]. It is estimated that for every 1 m<sup>3</sup> of desalinated water, between 0.3 and 1 m<sup>3</sup> of brine is generated [7]. Considering that the global product water capacity from seawater desalination plants as of 2020 was 9.72 109 <sup>m</sup><sup>3</sup> /d [4] and according to the above estimate, in the same year, there have been between 2.92 109 and 9.72 <sup>10</sup><sup>9</sup> <sup>m</sup><sup>3</sup> <sup>d</sup><sup>1</sup> of brine. According to Ihsanullah 2021, reusing and recycling brine is presented as a good alternative to minimize the negative impacts it produces, being favorable on a small scale. However, he indicates that more work is needed to assess the feasibility of brine treatment in commercial or larger desalination plants [8].

On the other hand, today's economy is based on a circular model, which assumes that resources are abundant and that one must "take-make-consume-reuse." Therefore, given the large amount of brine produced today, reutilization is a matter of principle that is strongly linked to the circular economy [9]. In that sense, wastewater such as brine is a valuable water, energy, and material resource; therefore, it is essential to manage its use and final disposal, following strategies of reduction, reuse, recycling, recovery, restoration, and regeneration, among others of the circular economy [10]. In addition, it is worth noting that the idea of circular economy through business models that encourage reuse and recycling can be very relevant for arid regions [11], where water is a valuable resource for basic needs such as drinking and sanitation, or for irrigation.

The agricultural sector uses 70% of the world's water and is one of the most important sectors for human beings. According to the WHO, it is estimated that by the year 2050, the demand for food products will be approximately 70% higher than today, as a result of population growth [12]. On the other hand, FAO, in its reports "The State of Food and Agriculture," indicates that 1.2 million people live in agricultural areas with high levels of water stress and 520 millions of them live in rural areas [13]. In addition, special attention is paid to agri-food systems, where foodproducing families engaged in small-scale agriculture are increasingly being put to the test due to the lack of water for irrigation [14]. These potential effects on agriculture are mainly due to climate change, which could lead to regions with increased salinization and desertification in arid areas of South American countries such as Chile and Brazil [15].

The Arica and Parinacota region is located in northern Chile and has arid characteristics. Although this region has available water resources such as the Lluta River or Camarones River, this water is limited and of poor quality due to high concentrations of arsenic, boron, and total dissolved solids (TDSs) [16] that exceed standards such as NCh 409.Of1.2005 for "drinking water" [17] or NCh 1333.Of1978mod1989 "water for irrigation" [18]. This condition limits their use to only a few crops such as corn, tomatoes, alfalfa, among others. Also, the soils of the Lluta Valley and the Camarones Valley, where these rivers are located, are affected by the poor quality of their waters, causing a lack of crop diversification [19]. This condition considerably affects the agricultural and livestock production sector and the local community. One of the most *Use of Saline Waste from a Desalination Plant under the Principles of the Circular… DOI: http://dx.doi.org/10.5772/intechopen.105409*

important crops in this region is alfalfa production, which is the main feed for bovines and goats [16]. On the other hand, there is *Atriplex nummularia*, a halophyte shrub with protein characteristics similar to alfalfa, which could be an alternative for crop diversification [20].

Consequently, to mitigate this lack of water in quantity and quality, research on desalination technologies for water production is being carried out at the Universidad de Tarapacá (Arica and Parinacota region). To this end, a desalination plant has been implemented for the production of drinking water or irrigation. However, one of the problems generated by this type of plant was what to do with the brine produced. Considering this question, this work is expected to evaluate the use of brine for the production of halophytes (*A. nummularia*) considering the principles of circular economy in the region of Arica and Parinacota.
