**5.4 Use of brine in halophyte cultivation**

The present proposal considers the use of brine obtained from the RO plant, from which 360 L h<sup>1</sup> are generated (**Figure 4**). If we consider that the plant will operate 12 hours a day for 20 days a month, we obtain 86,400 L h<sup>1</sup> of this saline liquid waste, which can be stored in a pond to be used for irrigation.

### **Figure 4.**

*Diagram of reverse osmosis plant and the use of brine in the cultivation of forage plants (proper elaboration).*

*Use of Saline Waste from a Desalination Plant under the Principles of the Circular… DOI: http://dx.doi.org/10.5772/intechopen.105409*

The soil conditions for the cultivation of the fodder plant should be a fallowed, tracked, and leveled soil, where a drip irrigation system is established, whose Polyvinyl chlorid, PVC, lines could be at a depth of 40 cm. The plants can be produced in a nursery until they reach a size of 20 cm and then transplanted in furrows 1.5 m apart, conditions established for a cultivable land of 1000 m2 [53]. In addition, the distance between plants should be 2.5 to 3 m because these forages generate a high volume of biomass [54]. It is proposed to cultivate 400 halophyte plants in a 1500 m2 plot, considering an irrigation of 6 hours per week and a volume of 75 L plant�<sup>1</sup> week�<sup>1</sup> [19].

The production obtained from *A. nummularia* is 825 kg year�<sup>1</sup> , according to information published by Sánchez et al., 2015 [20]. This fodder plant will be used to feed bovines or goats.

On the other hand, according to the comparison of the chemical analysis between alfalfa and *A. nummularia*, it can be observed that the latter has 4% more crude protein than alfalfa. Likewise, the dry matter and metabolizable energy of *Atriplex nummuralia* meet the optimal nutritional value for a dairy cow (**Table 5**).

It should be noted that the proposed system for the production of halophytes from brine will use 31.319 kWh day�<sup>1</sup> (11,431.435 kWh year�<sup>1</sup> ) of electrical energy obtained from the photovoltaic system.

### *5.4.1 Effect of brines on soil physicochemical properties*

Considering the chemical properties of the soil, the components detailed in **Table 3**, the Lluta Valley soil corresponds to the United States Department of Agriculture (USDA) textural triangle, being classified as a sandy loam soil [56].

In addition, it is worth mentioning that this type of soil has an apparent density of 1.50 g cm�<sup>3</sup> , which indicates the space occupied by the pores in the soil in relation to the volume of water. In addition, these soils have a real density of 2.6 g cm�<sup>3</sup> .

For the determination of the total porosity of the soil (ξ), it is calculated according to the following equation (Ec. (6)) [57]:

$$
\xi = \left(1 - \frac{ad}{rd}\right) \ge 100 \tag{1}
$$

Considering the equation x, we obtain a ξ =43% of total porosity.

This result indicates that they present spaces between the particles of 0.05–2 mm, increasing the size of the pore spaces between the particles and facilitating the drainage and aeration of the soil. This percentage also shows an adequate porosity for the development of halophyte plants. It is worth mentioning that halophyte plants are able to accumulate high concentrations of NaCl in their tissues, and there is


**Table 5.**

*Chemical analysis of* Atriplex nummularia *and alfalfa compared with optimal nutritional value for a bovine [20, 55].*

information of 39% in a shrub [58]. In addition, the use of halophytes plants for phytoremediation appears as a cost-effective, noninvasive alternative to other methods used for contaminated soils [34].
