Chloride reduction is an important process in meeting the water quality requirements for many industries. Too much chloride in the water can be detrimental. Chloride can be abrasive to piping, and chloride’s salts, such as magnesium chloride, can generate hydrochloric acid, which is highly corrosive.

Chloride’s destructive nature is evident in the direct ratio of iron dissolving and corrosion rates to chloride content in water. Chloride is also very soluble in water, and it is one of the major anions found in water. Chloride content can range from 10 to 100 mg/L with seawater having 30,000 mg/L in the form of sodium chloride.

How can we treat water to address the need for chloride reduction? What is the most efficient way to mitigate the effects of chloride?

Chloride Reduction and Reverse Osmosis Water Treatment

There are many techniques for achieving chloride reduction, including electro-dialysis, distillation, and strong base anion exchange. However, the most efficient and reliable process for chloride reduction is reverse osmosis. Reverse osmosis can reject salts and remove up to 90% to 95% of chlorides.

Nonetheless, some companies claim that all you need for chloride reduction is DI (de-ionizing resin), and some people will resort to this method as it is initially cheaper than a reverse osmosis system. This is not the case, because the DI process requires anion resin for chloride reduction. This resin will eventually be exhausted and will need to be "regenerated" or "recharged." Regenerating the resin can become very costly and possibly dangerous, because it requires the use of caustic soda or high pH substance.

Customers who resort to DI for chloride reduction usually must pay for the removal of the resin from the customer’s facility to the vendor’s facility to regenerate it. These customers may even utilize a maintenance program that exchanges resin bottles. If chloride levels are around the 100 PPM/mg/L range, then this process might be cost-effective. But that is often not the case. The yearly cost of regenerating the resin and its maintenance program is often better invested in a reverse osmosis system.

Reverse Osmosis Chloride Reduction Applications

One of the major industries that relies on reverse osmosis chloride reduction is growers. Growers are major agricultural farmers dealing with the cultivation of crops, including, avocados, tomatoes, and cucumbers. Crop production requires a substantial amount of water, and such large volume water usage can be problematic for growers, due to the cost of city water.

In response to water costs, many growers resort to drilling water wells on their properties, but this poses a water quality concern: Well water is very high in TDS (total dissolved solids). Growers report well water TDS ranging from 1000 PPM to 10,000 PPM. This is an unacceptable water quality for plants, because TDS at these levels can stunt growth or actually kill plants.

Reverse osmosis is an ideal method of chloride reduction in well water for two reasons: the effectiveness of reverse osmosis in filtering TDS and the minimal energy consumption required for reverse osmosis.

Due to its efficiency and simple maintenance, growers commonly use reverse osmosis systems to manage their well water quality. Reverse osmosis can reduce well water TDS as low as 10 PPM, which is considered purified water in the state of California.

However, this level of TDS in the water is not necessary and can, in fact, be detrimental to plants. Although chloride reduction is necessary, the process can strip water of pH, which some plants require. How can growers control pH levels?

Due to a blend valve incorporated into the reverse osmosis systems, growers can blend raw water and product water, thereby achieved their desired water quality for crop production. To explain the blending, imagine two tanks of gas, one with the highest grade of octane and the other with the lowest grade, connected to one pump with a valve that controls how much gas flows from each tank.

The same concept can be used in a reverse osmosis system, with two tanks for the different quality waters and a blend valve. In effect, reverse osmosis is the most efficient method for chloride reduction as the maintenance is minimal and allows control over the rate of chloride reduction.


Related Markets and Applications

  • Aquaculture
  • Hydroponics
  • Horticulture
  • Green Houses
  • Viniculture
  • Groundwater Remediation
  • Ground Water
  • Groves and Orchards
© 2014 AXEON Water Technologies. All Rights Reserved.