**3. Results and discussion**

#### **3.1. Desalination process operating parameters**

The results obtained during the operation of the desalination process are shown in **Table 1**.

The analysis of the RO desalination plant shows that it works as intended, since the concentration of salts in the produced water decreased significantly with respect to the feed water. Observed salt rejection was 92% compared to the salinity level of the brackish well, this through the action of semi-permeable membranes. On the other hand, the temperature of the retentate and permeate flows was always higher than the feed rate, due to the friction that occurs during pumping in RO, as well as the friction within the membrane modules. Care should be taken to ensure that the temperature does not exceed 45°C in the feed water, as this can shorten the working life of the equipment. Operating at high temperatures would increase permeate flow and decrease rejection (increased salt passage) as the diffusivity of both water and salt in the membrane increases with temperature. However, if temperature is increased significantly, changes in the polymer structure of the membrane can also occur,

**Sample pH Temperature (°C) Electrical conductivity (μS/cm) Total dissolved solids (mg/L)**

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/d desalination plant.

Feed 7.68 24.69 6096.00 3901.40 ± 222.55 Permeate 6.16 25.01 446.00 285.00 ± 51.20 Retentate 8.08 25.89 17,496.00 11,197.44 ± 1389.01

The results of physical-chemical analysis of the water in the feed, permeate and retentate, are presented (**Table 3**). These were obtained using standard analytical techniques and a PROVE-

These data are consistent with the data characterized by field parameters for both experimentation years [8, 11]. It can be observed that the presence of sodium in the permeate is 80.06 mg/L, which does not interfere with the adsorption of the nutrients in the irrigation water when adding fertilizers to the crop. However, special care must be taken in the dosage of nutrients by means of fertilizers in the irrigation water, since fertilizers can present high

The reduction of pH in RO permeate water is caused by the removal of carbonates and bicarbonates from the feed. Brackish well water usually contains bicarbonates (calcium, sodium, magnesium) and carbonates (calcium), which raise the pH of the water. Soil measurements of all physical-chemical parameters, SAR and ESP, at the beginning and end of the experiment

Taking chlorine and sodium ions as reference, as they are the major indicators of salts present in a sample, there is an evident increase in salinity (greater than 600 and 610% on average) attributed to brackish water irrigation for sorghum and tomatillo (*Physalis philadelphica*) in the

which could cause irreversible damage to the membrane.

acidity and salinity, which inhibits the adsorption of nutrients.

**3.4. Soil parameters of the agricultural field**

**3.3. Physical-chemical parameters of process water**

300-Merck spectrophotometer.

**Table 2.** Water characterization at the 150 m<sup>3</sup>

are shown in **Figure 3**.

The pumping equipment pressure is within the desired range as it averages 37.33 psi, very close to the acceptable minimum of 30 psi. This indicates that the water level of the well is adequate, as well as the power and flow rate of the pump used to draw fluid from the well. With respect to the multimedia filter, an average pressure drop of 7.33 psi is observed, which is acceptable for operation. This suggests that the multimedia filter is removing 50 μm particles without clogging in its filter media. On the other hand, the cartridge filter had an average pressure drop of 6.33 psi, which suggests that the removal of 5 μm suspended particles is occurring without any problem, and that the membrane system should be operating as intended. The flow rate supplied from the desalination process to irrigation, for both study years was in the range of 1.5–1.7 L/s.

#### **3.2. Process water field parameters**

Measurements at the desalination plant show that when the feed water presents about 3900 mg/L TDS, the permeate and retentate currents have 285 and 11,200 mg/L TDS, respectively. There is an increase in temperature of 0.32 and 1.2°C in the permeate and retentate respectively, considering that the temperature in the feed water is 24.69°C (**Table 2**).


**Table 1.** Operation of the desalination process.


**Table 2.** Water characterization at the 150 m<sup>3</sup> /d desalination plant.

contact angle between water and soil particles, is the main mechanism of water retention in light and middle soils within certain moisture intervals, and in heavy soils. In this context, a matric potential between 30 and 40 kPa indicates that the soil needs irrigation, whereas a

The results obtained during the operation of the desalination process are shown in **Table 1**.

The pumping equipment pressure is within the desired range as it averages 37.33 psi, very close to the acceptable minimum of 30 psi. This indicates that the water level of the well is adequate, as well as the power and flow rate of the pump used to draw fluid from the well. With respect to the multimedia filter, an average pressure drop of 7.33 psi is observed, which is acceptable for operation. This suggests that the multimedia filter is removing 50 μm particles without clogging in its filter media. On the other hand, the cartridge filter had an average pressure drop of 6.33 psi, which suggests that the removal of 5 μm suspended particles is occurring without any problem, and that the membrane system should be operating as intended. The flow rate supplied from the desalination process to irrigation, for both study

Measurements at the desalination plant show that when the feed water presents about 3900 mg/L TDS, the permeate and retentate currents have 285 and 11,200 mg/L TDS, respectively. There is an increase in temperature of 0.32 and 1.2°C in the permeate and retentate

respectively, considering that the temperature in the feed water is 24.69°C (**Table 2**).

**Parameter Units Min Max Sample Mean**

Well discharge pressure psi 30 80 40 36 36 37.33 Multimedia filter inlet pressure psi 30 70 38 33 33 34.66 Multimedia filter outlet pressure psi 20 60 30 26 26 27.33 Multimedia filter pressure drop psi 8 12 8 7 7 7.33 Cartridge filter inlet pressure psi 20 40 33 29 28 30.00 Cartridge filter outlet pressure psi 20 40 32 28 28 29.33 Cartridge filter pressure drop psi 5 10 6 6 7 6.33

**1 2 3**

matric potential between 0 and 10 kPa indicates that the soil is saturated [11].

**3. Results and discussion**

8 Desalination and Water Treatment

years was in the range of 1.5–1.7 L/s.

**3.2. Process water field parameters**

**Table 1.** Operation of the desalination process.

**3.1. Desalination process operating parameters**

The analysis of the RO desalination plant shows that it works as intended, since the concentration of salts in the produced water decreased significantly with respect to the feed water. Observed salt rejection was 92% compared to the salinity level of the brackish well, this through the action of semi-permeable membranes. On the other hand, the temperature of the retentate and permeate flows was always higher than the feed rate, due to the friction that occurs during pumping in RO, as well as the friction within the membrane modules. Care should be taken to ensure that the temperature does not exceed 45°C in the feed water, as this can shorten the working life of the equipment. Operating at high temperatures would increase permeate flow and decrease rejection (increased salt passage) as the diffusivity of both water and salt in the membrane increases with temperature. However, if temperature is increased significantly, changes in the polymer structure of the membrane can also occur, which could cause irreversible damage to the membrane.

#### **3.3. Physical-chemical parameters of process water**

The results of physical-chemical analysis of the water in the feed, permeate and retentate, are presented (**Table 3**). These were obtained using standard analytical techniques and a PROVE-300-Merck spectrophotometer.

These data are consistent with the data characterized by field parameters for both experimentation years [8, 11]. It can be observed that the presence of sodium in the permeate is 80.06 mg/L, which does not interfere with the adsorption of the nutrients in the irrigation water when adding fertilizers to the crop. However, special care must be taken in the dosage of nutrients by means of fertilizers in the irrigation water, since fertilizers can present high acidity and salinity, which inhibits the adsorption of nutrients.

#### **3.4. Soil parameters of the agricultural field**

The reduction of pH in RO permeate water is caused by the removal of carbonates and bicarbonates from the feed. Brackish well water usually contains bicarbonates (calcium, sodium, magnesium) and carbonates (calcium), which raise the pH of the water. Soil measurements of all physical-chemical parameters, SAR and ESP, at the beginning and end of the experiment are shown in **Figure 3**.

Taking chlorine and sodium ions as reference, as they are the major indicators of salts present in a sample, there is an evident increase in salinity (greater than 600 and 610% on average) attributed to brackish water irrigation for sorghum and tomatillo (*Physalis philadelphica*) in the


**Table 3.** Water quality assessment via physical-chemical parameters, in mg/L.

study area. On the other hand, under desalinated irrigation, the concentration of the sodium ion is reduced to 96%, which can be directly attributed to the salt removal by the RO process [11, 12].

Moreover, the SAR and ESP at the beginning and end of the experiment did not show significant changes in the samples irrigated with desalinated water, mainly due to the ease of internal soil drainage [13]. However, brackish irrigation samples show an average increase of 230% in SARs and 610% in ESP.

#### **3.5. Desalinated water production cost**

The economic data of the desalination process are shown in **Table 4**.

The economic evaluation of the process shows that the cost of producing desalinated water is \$0.338 USD/m<sup>3</sup> very similar to that reported by the International Desalination Association [11, 14, 15], which is \$0.368 USD/m<sup>3</sup> , both for brackish water. To determine the viability of this desalination technology applied to agriculture, farmers should look for high-yield crops so that the cost-benefit effect is profitable, such as vegetables (e.g., tomatoes, chiles), and using drip irrigation systems [16].

**Figure 3.** Physical-chemical parameters in the agricultural field soil.

High pressure pumps

Operating personnel Technical assistance

Piping and accessories

**Table 4.** Operating costs.

Antiscalant RO Clean Sulfuric acid

Soldering

Dosage pumps General energy

**Energy cost 0.207**

**Labor costs 0.095**

**Chemical costs 0.0043**

**Maintenance costs 0.031**

**Total 0.338**

**Concept Cost (USD \$/m<sup>3</sup>**

**)**

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#### **3.6. Crop yields**

#### *3.6.1. Sorghum (2014)*

There was a notable difference in the height of the plants, with the part irrigated with desalinated water being 10–15 cm higher on average. In addition, the plants irrigated with brackish water showed what appeared to be burned tips on the leaves of the plants: This is due to the excess of salts that are concentrated in the crop by the effect of brackish water from the well and possibly the addition of fertilizers. Although the latter was not reflected in burnt tips on the leaves of the plants irrigated with desalinated (**Figure 4**).

In all cases, the average height observed for the sorghum irrigated with desalinated water was higher compared to the average height of the crop irrigated with brackish water. This is directly attributed to soil management and the concentration of salts in the water, and therefore in the soil. These results in salt increase coincide with those reported by other authors [17, 18], who state that high salinity directly affects nutrient assimilation and germination in sorghum crops.

Using Desalination to Improve Agricultural Yields: Success Cases in Mexico http://dx.doi.org/10.5772/intechopen.76847 11

**Figure 3.** Physical-chemical parameters in the agricultural field soil.


**Table 4.** Operating costs.

study area. On the other hand, under desalinated irrigation, the concentration of the sodium ion is reduced to 96%, which can be directly attributed to the salt removal by the RO process

**Water type Ca Mg Na K NO3 HCO<sup>3</sup> Cl SO4 TDS** Feed 65.55 146.32 1079.66 72.74 28.76 33.83 1969.45 445.74 3842.05 Permeate 4.86 10.85 80.06 5.39 2.13 2.51 146.04 33.05 284.91 Retentate 190.70 425.90 3143.70 211.70 83.60 98.50 5733.80 1297.60 11,185.90

Moreover, the SAR and ESP at the beginning and end of the experiment did not show significant changes in the samples irrigated with desalinated water, mainly due to the ease of internal soil drainage [13]. However, brackish irrigation samples show an average increase of

The economic evaluation of the process shows that the cost of producing desalinated water

desalination technology applied to agriculture, farmers should look for high-yield crops so that the cost-benefit effect is profitable, such as vegetables (e.g., tomatoes, chiles), and using

There was a notable difference in the height of the plants, with the part irrigated with desalinated water being 10–15 cm higher on average. In addition, the plants irrigated with brackish water showed what appeared to be burned tips on the leaves of the plants: This is due to the excess of salts that are concentrated in the crop by the effect of brackish water from the well and possibly the addition of fertilizers. Although the latter was not reflected in burnt tips on

In all cases, the average height observed for the sorghum irrigated with desalinated water was higher compared to the average height of the crop irrigated with brackish water. This is directly attributed to soil management and the concentration of salts in the water, and therefore in the soil. These results in salt increase coincide with those reported by other authors [17, 18], who state that high salinity directly affects nutrient assimilation and germination in

very similar to that reported by the International Desalination Association

, both for brackish water. To determine the viability of this

[11, 12].

230% in SARs and 610% in ESP.

10 Desalination and Water Treatment

is \$0.338 USD/m<sup>3</sup>

**3.6. Crop yields**

sorghum crops.

*3.6.1. Sorghum (2014)*

**3.5. Desalinated water production cost**

[11, 14, 15], which is \$0.368 USD/m<sup>3</sup>

drip irrigation systems [16].

The economic data of the desalination process are shown in **Table 4**.

**Table 3.** Water quality assessment via physical-chemical parameters, in mg/L.

the leaves of the plants irrigated with desalinated (**Figure 4**).

At the time of harvest, it was verified that parameters such as the height (m), the number of panicles per m2 and weight per panicle (g) were higher in all cases when using water with lower salt concentration. This led to an increase of 1 ton/ha (10.2%) of sorghum for the desalinated irrigation compared to irrigation with brackish water (**Table 5**). ANOVA analyses show a direct relationship in height and number of fruits, with respect to the salinity of water irrigated, with a 95% reliability.

**Parameter Desalinated irrigation Brackish water irrigation α 95%** Height (m) 1.7 1.5 X

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Number of panicles per m<sup>2</sup> 29.0 28.0

Weight per panicle (g) 30.0 29.0

Yield (Ton/ha) 8.8 7.9

**Figure 5.** Dependence of sorghum crop yield with salinity in irrigation water.

**Figure 6.** Dependence of tomatillo crop yield with salinity in irrigation water.

**Table 5.** Behavior of the sorghum crop parameters.

Sorghum harvesting had a single cut, producing 7.9 ton/ha for the area irrigated with brackish water (4000 mg/L TDS), while the area irrigated with desalinated water (200–285 mg/L) yielded 8.8 ton/ha. Yield in tons shows a difference of 10.2%, demonstrating a higher profit margin when using desalinated water (**Figure 5**).

The results in **Figure 5** are similar to those of a previous study [17, 18] where the effect of saltwater irrigation on sorghum cultivation was verified. That study determined a direct relationship between seedling weight, stem diameter, delayed germination effect, and crop yield.

#### *3.6.2. Tomatillo (Physalis philadelphica) (2016)*

A difference in plant height was observed as a result of a lower salt concentration in the irrigation water. The plants irrigated with desalinated water were 5–6 cm smaller on average than those irrigated with brackish water. This decrease in height was due to greater weight and diameter in the products. These results coincide with other investigations that use water with different concentrations of salts to observe significant differences [16].

Some of the parameters found were similar, such as stem diameter, plant height, germination and yield per cut. Nonetheless, there was an improvement when irrigating with lower salinity water [16, 18]. In addition, the tomatillo (*Physalis philadelphica*) crop was harvested in three

**Figure 4.** Behavior of the mean height of the sorghum crop.


**Table 5.** Behavior of the sorghum crop parameters.

At the time of harvest, it was verified that parameters such as the height (m), the number of

lower salt concentration. This led to an increase of 1 ton/ha (10.2%) of sorghum for the desalinated irrigation compared to irrigation with brackish water (**Table 5**). ANOVA analyses show a direct relationship in height and number of fruits, with respect to the salinity of water irri-

Sorghum harvesting had a single cut, producing 7.9 ton/ha for the area irrigated with brackish water (4000 mg/L TDS), while the area irrigated with desalinated water (200–285 mg/L) yielded 8.8 ton/ha. Yield in tons shows a difference of 10.2%, demonstrating a higher profit

The results in **Figure 5** are similar to those of a previous study [17, 18] where the effect of saltwater irrigation on sorghum cultivation was verified. That study determined a direct relationship between seedling weight, stem diameter, delayed germination effect, and crop yield.

A difference in plant height was observed as a result of a lower salt concentration in the irrigation water. The plants irrigated with desalinated water were 5–6 cm smaller on average than those irrigated with brackish water. This decrease in height was due to greater weight and diameter in the products. These results coincide with other investigations that use water with

Some of the parameters found were similar, such as stem diameter, plant height, germination and yield per cut. Nonetheless, there was an improvement when irrigating with lower salinity water [16, 18]. In addition, the tomatillo (*Physalis philadelphica*) crop was harvested in three

different concentrations of salts to observe significant differences [16].

and weight per panicle (g) were higher in all cases when using water with

panicles per m2

12 Desalination and Water Treatment

gated, with a 95% reliability.

margin when using desalinated water (**Figure 5**).

*3.6.2. Tomatillo (Physalis philadelphica) (2016)*

**Figure 4.** Behavior of the mean height of the sorghum crop.

**Figure 5.** Dependence of sorghum crop yield with salinity in irrigation water.

**Figure 6.** Dependence of tomatillo crop yield with salinity in irrigation water.

cuts. The average yield for the area irrigated with brackish water was 30.82 ton/ha, while the section irrigated with desalinated water yielded 35.88 ton/ha (**Figure 6**).

**Author details**

**References**

Germán Eduardo Dévora-Isiordia1

Ma. Araceli Correa-Murrieta1

Cd. Obregón, Sonora, México

ISBN: 978-953-307-311-8

10.1175/JCLI4101.1

2009;**5**(1):31-41

memsci.2012.05.016

10.1016/j.desal.2015.03.001

, María del Rosario Martínez-Macías<sup>1</sup>

, Jesús Álvarez-Sánchez1

1 Departamento de Ciencias del Agua y Medio Ambiente, Instituto Tecnológico de Sonora,

[1] Burn S, Hoang M, Zarzo D, Olewniak F, Elena C, Bolto B, Barron O. Desalination techniques. A review of the opportunities for desalination in agriculture. Desalination. 2015;

[2] Val S. Frenkel. Seawater desalination: Trends and technologies. In: Michael S, editor. Desalination, Trends and Technologies. Croatia: IntechOpen; 2011. DOI: 10.5772/13889,

[3] Hallack-Alegría M, Watkins DJ. Annual and warm season drought intensity–duration–frequency analysis for Sonora, Mexico. Journal of Climate. 2006;**20**:1897-1909. DOI:

[4] Dévora-Isiordia GE, Gonzalez ER, Saldivar CJ. Diseño de procesos de desalinización de aguas subterráneas salobres mediante simulación química de electrodiálisis reversible, con propósitos de consumo humano. Revista Latinoamericana de Recursos Naturales.

[5] Nikolay V. Energy use for membrane seawater desalination current status and trends.

[6] Shaffer DL, Yip NY, Gilron J, Elimelech M. Seawater desalination for agriculture by integrated forward and reverse osmosis: Improved product water quality for potentially less energy. Journal of Membrane Science. 2012;**415-416**:1-8. DOI: 10.1016/j.

[7] Quist-Jensen CA, Macedonio F, Drioli E. Membrane technology for water production in agriculture: Desalination and wastewater reuse. Desalination. 2015;**364**:17-32. DOI:

[8] Dévora-Isiordia GE, Robles A, Fimbres GA, Álvarez J. Comparación de métodos de descarga para vertidos de salmueras, provenientes de una planta desalinizadora en

Desalination. 2017;**431**:2-14. DOI: 10.1016/j.desal.2017.10.033

2 CONACYT-ITSON, Departamento de Ciencias del Agua y Medio Ambiente, Instituto

\*Address all correspondence to: gustavo.fimbres@itson.edu.mx

Tecnológico de Sonora, Cd. Obregón, Sonora, México

**364**:2-16. DOI: 10.1016/j.desal.2015.01.041

,

http://dx.doi.org/10.5772/intechopen.76847

Using Desalination to Improve Agricultural Yields: Success Cases in Mexico

and Gustavo Adolfo Fimbres-Weihs2

\*

15
