## 3 Results and Discussion
### ASE&C Technology Coupled with RO
Some elements, although low in concentration, play an important role in the world market due to their technological applications; among them are Li, Rb and Sr, as well as trace elements such as rare earth elements. Ref. [21] analyzed the economic potential of brine mining from desalination rejects containing B, Ca, Sr, Mg, Na, Li, Rb and Ga; they concluded that the economic value might range from EUR 13 billion to 29 billion annually. However, annual estimations (gross profit) for the complete recovery of elements with the studied brines (Table 3), applying the same prices to a production capacity of 1000 m\({}^{3}\)/day, ranged from EUR 1 to 11 million for Brine A and Brine B, and from EUR 10 to 21 thousand for Brine C (Table 4). More than 96% of the revenues of Brine A and B come from gallium, due to its elevated market price. Gallium also has specialized uses in small quantities, e.g., optoelectronic devices, with economically viable recovery from seawater and other highly concentrated sources [26]. There would also be an important recovery of rubidium from Brine B. This rare alkali metal has high economic value for its emerging industrial applications (biomedicine, solar cells, electronics, etc. ); it is extracted from land-based mineral ore sources (as a fraction of ores) [27]. However, [27] other alternative sustainable sources such as seawater brine or salt \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Brine A**} & \multicolumn{2}{c}{**Brine B**} & \multicolumn{2}{c}{**Brine C**} \\ \cline{2-7}  & **I** & **O** & **I** & **O** & **I** & **O** \\ \hline EC (mS/cm) & 122,000 & 89 & 70,000 & 91 & 28,000 & 52 \\ Eh (mV) & 296 & 653 & 301 & 660 & 298 & 651 \\ TDS (mg/L) & 78,080 & 56 & 44,830 & 57 & 17,930 & 32 \\ Sulfates (mg/L) & 76,670 & \textless{}5 & 4860 & \textless{}5 & 3870 & \textless{}5 \\ Chlorides (mg/L) & 67,060 & \textless{}10 & 38,550 & \textless{}10 & 14,569 & \textless{}10 \\ Na (mg/L) & 35,990 & \textless{}10 & 20,650 & \textless{}10 & 6458 & \textless{}10 \\ Ca (mg/L) & 1830 & \textless{}10 & 1050 & \textless{}10 & 986 & \textless{}10 \\ Mg (mg/L) & 4880 & \textless{}10 & 2810 & \textless{}10 & 1860 & \textless{}10 \\ K (mg/L) & 1463 & \textless{}5 & 843 & \textless{}5 & 453 & \textless{}5 \\ Bicarbonates (mg/L) & 611 & \textless{}5 & 351 & \textless{}5 & 654 & \textless{}5 \\ Br (mg/L) & 416 & \textless{}0.1 & 240 & \textless{}0.1 & 44.8 & \textless{}0.1 \\ Ga (mg/L) & 650 & \textless{}0.01 & 589 & \textless{}0.01 & & \textless{}0.01 \\ Sr (mg/L) & 52 & \textless{}0.01 & 29 & \textless{}0.01 & 14.4 & \textless{}0.01 \\ Li (mg/L) & 2.7 & \textless{}0.01 & 1.6 & \textless{}0.01 & & \textless{}0.01 \\ B (mg/L) & 17 & \textless{}0.05 & 9.8 & \textless{}0.05 & & \textless{}0.05 \\ Rb (mg/L) & 0.52 & \textless{}0.01 & 0.28 & \textless{}0.01 & & \textless{}0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Physicochemical characteristics of different brines (Brine A: hypersaline; Brine B: desalination brine; Brine C: groundwater brine) before (I) and after (O) treatment with ASE&C technology. lake branes, with less energy extraction consumption and greater concentration than land ones, have been suggested. Some hydrometallurgical techniques can effectively separate Rb as rubidium carbonate (98%) from brines [28] and other minerals and brines [29]. Almost all the revenue from Brine C comes from a combination of Na and Ca due to their high concentrations (there are missing data for the other elements). Calcium removal from seawater/brine has dual benefits: it improves the RO (secondary scaling) [25] and market potential (0.43-1.89 EUR/kg, [21]), thereby minimizing desalination costs. Calcium is sold as calcium carbonate pellets when produced from brackish water, and calcium sulfate when produced from seawater [25]. Sodium, as different sodium compounds (sodium chloride, sodium sulfate), is sold for many purposes (the food industry, cosmetics, and ice-melters, among others).