Voltea CapDI Horticulture Case Study







Agriculture is an important market for Mexico, with the industry employing 16% of the national workforce. Unfortunately, it also presents a huge, unsustainable demand on water sources. In Mexico, agriculture is responsible for 77% of the total water withdrawn. [1] 38% of countrywide withdrawl is from groundwater aquifers, many of which are over-exploited and located where annual rainfall is insufficient to replace extraction. [2] Water scarcity is causing increased salinity variability as well as increasing water prices [3] , both of which are unfavorable for crop growers. What’s worse is that for many crops, high salinity in irrigation water can cause significant reductions in yield. [1] Mexico UN – water brief; http://www.unwater.org/fileadmin/user_upload/unwater_new/docs/Publications/MEX_pagebypage.pdf [2] Richard Rhode, Tony Burton, Geo-Mexico excerpt, http://www.mexconnect.com/articles/3576-water-consumption-in-mexico [3] Mexico Water Report; http://www.lgaconsulting.com/water/IE-MexicoWaterReport-2011Winter-WaterReuseInMexico.html


A leading Mexican tomato grower was purchasing tomato seedlings from a third party and growing their own greenhouse crops. They needed an optimal, improved feed water quality to grow their own seedlings, rather than purchasing them locally. Tomato seedlings are known to have high sensitivities to salinity, therefore the grower needed a solution to treat their irrigation water to allow for in-house growing.


Voltea provided an IS-12 CapDI System as it requires minimal pre-treatment and can cope with silica levels up to 150 ppm. Additionally, the fully automated cleaning and remote monitoring capabilities minimize user intervention and maintenance, allowing the customer to focus on their core business. CapDI tunably removed sodium and bicarbonates without having to remove all of the more beneficial minerals in the grower’s irrigation water. By implementing a tunable TDS removal solution, they saved on OpEx by reducing the use of fertilizers and allowing water reuse on-site. This Voltea customer now successfully grows their own seedlings in-house without having to purchase from a third party, thus increasing profitability.


Of high importance to the grower was the ability to target a series of different sodium levels as required by different crops. CapDI’s tunable salt removal capability perfectly achieves this by automatically accounting for any variations in feed water quality and flow rate to give a consistent output quality. Table 1 on the following page shows a series of targeted water conductivities and their corresponding sodium and bicarbonate concentrations.


Voltea’s award-winning tunable desalination technology, CapDI © (Membrane Capacitive Deionization), desalinates brackish water at a lower economic and environmental cost than any other available technology. CapDI is a simple and innovative way to remove dissolved salts from water. Voltea’s CapDI technology is scalable and helps consumers and industry reduce water usage and save money.


Operational Data:

Voltea’s IS-12 CapDI System consistently produced the quality and quantity of water required to meet our customer’s demands. 85% water recovery was maintained by Voltea’s fully automated Cleaning-In-Place (CIP) features that automatically clean if the CapDI System measures a rise in differential pressure. This water was treated to a suitable reuse quality, therefore reducing the overall amount of fresh deep well water consumed. The high water recovery also allows a smaller volume of waste that would require treatment before discharge, resulting in a reduced impact to the aquifer. Voltea’s CapDI System is continuing to help this facility with the production of crops at a reduced environmental impact, which in the long term will assist in greater productivity and reduced operating expense.

Table 1


Feed Water

Sample 1

Sample 2

Sample 3

Unit µS/cm ppm

Target Conductivity pH Chloride (Cl - ) Sulfates (SO 4 2- ) Bicarbonate (HCO 3 - ) Potassium (K + ) Sodium (Na + ) Calcium (Ca 2+ ) Magnesium (Mg 2+ )



400 85 38 32 6.3

800 77 78 6.6 51 12 146

353 211 104 7.2


10 18

ppm ppm ppm ppm ppm ppm ppm

< 8 61

89 37

32 8 72 10 24

21 5 16 72

72 190 124

72 22 64

Silica (SiO 2 )

From the short term testing performance in Table 1, the customer was able to select a long term operational setting with which to operate the CapDI System based on the crop to be irrigated and its sodium requirements.

Table 2

Summary Period Period 1

Period 2

Period 3

Period 4

Target Conductivity (µS/cm) Average Output Conductivity (µS/cm) Average Feed Conductivity (µS/cm) Volume Produced (m 3 )

500 489 1,324 1,173

300 302 1,433

700 670 1,433

700 679 1,380




Table 2 shows actual CapDI System data over a five month period at the customer’s site. The tunability benefit can be observed while the targeted water quality was met as changes in irrigation water use demanded different sodium levels corresponding to the overall water conductivity. The removal of only the excess sodium allows the crops to benefit from the nutrients and salts remaining in the water.

Unlocking the world's water potential

Voltea B.V. European H.Q.

Voltea INC. U.S. Office

Voltea B.V reserves the right to modify the design and specification contained herein without prior notice. Please contact your local Voltea sales representative for the most current information, or visit us at www.voltea.com or info@voltea.com.

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