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Water softening system consists of specialized equipment, installed according to standard procedures, to ensure the removal of hard water elements, especially Calcium and Magnesium.

In the content of the article below, we only refer to the hardness due to Calcium and Magnesium, while other concepts such as temporary and permanent hardness … are only theoretical in school knowledge, difficult to use for the calculation and designing water softening systems.

Softener to remove hardness

Warer softener to remove hardness

1. Reasons to use water softener

1- Water softener is to remove Calcium (Ca) and Magnesium (Mg) from water to limit and avoid problems such as:

  • Causing scale and deposits – reducing operational efficiency in industrial systems such as boilers, cold-hot cooling towers, RO membranes.
  • Deposit, blockage and dirty to domestic water supply system, building, swimming pool, and sauna.
  • Evaporation with steam from boiler then causes steam blockage, dirty to production and condensate line, also bad effect to product
  • Harmful to health from dirty domestic water, drinking water, food production.
  • Deviation of results or finished products for cosmetic, chemical, textile dyeing, printing, fabric washing, etc., which affects spices, odor and color products.

Both regenerate on setted up volume to optimize operating costs

1: Water Softener for rubber factory

2: Water Softener for boiler

Both regenerate on setted up volume to optimize operating costs

2- How much softening or reducing hardness is satisfactory?

Depending on the technical requirements of each system or product, the hardness will be different. For example, the higher pressure boiler the lower the hardness requirement; the cooling tower water according to LEED, Green Mark standards, then make up water hardness will be different, etc. Just contact us to design a water softener system to suit your specific requirements.

2. Water softener combined with other treatment

The frequently asked question is “The hardness after water softener has been passed – good, why is the problem of scale or others still happening?”

The water softener only removes (reduces) Ca, Mg from the water, but there are still many other harmful components in the water, such as:

  • Iron, silica, suspended matter, etc. cause deposits and dirt.
  • Sulphate, Chloride, Carbonate, low pH, Dissolved Oxygen, etc. cause corrosion.
  • Organic compounds, Phosphate, Nitrite,… promote microbial growth.

Therefore, beside hardness, need to check the water source according to many criteria to thoroughly treat it synchronously to ensure stable and long-term quality for the system and production.

3. Working principle of ion exchange resin, design – installation of water softener system

Working principle of ion exchange resin of water softener

In clean water treatment, common ion exchange resins are divided into 4 groups:

  1. Resin for water softener: Ion exchange with Ca, Mg
  2. Cation exchange resin: Ion exchange with all cationic ions (Na, K, Fe…) includes Ca, Mg.
  3. Anionic exchange resin: Ion exchange with all anionic ions (Cl, SO4, NO3…).
  4. Mixed resin (Mixed resin) consists of cationic resin and anionic resin that mixed in a calculated ratio to reach the purified to ultra purified water or always maintain a stable level of ultra-purified water.

In this section, the water softener resin is only mentioned to discuss

Components of a water softener system

Components of a water softener system

Water Softening process: Ca, Mg present in water will be exchanged and retained on the surface of resin, at the same time, Na from resin will be released, entering soft water line to product water

2 RESIN-Na + Ca + Mg of hard water => RESIN-Ca; RESIN-Mg + 2 Na + Soft water

Resin will gradually lose the ability to exchange Ca and Mg, so it must be renewed, called the regeneration..

Regeneration process:  Ca, Mg that connected with resin earlier will be replaced by Na from salt (NaCl) then out of resin – to waste water line.

RESIN-Ca; RESIN-Mg + 2 Na of salt = > 2 RESIN-Na + Ca + Mg + Waste water

Saturated resin was renewed as original for the next Ca and Mg exchange cycle.

Note to the hardness after regeneration: The final step of regeneration, soft water should be used to wash the resin. In the case of using unsoft water to wash then need about 15 minutes after next ion exchange cycle, the soft desired hardness will be just achieved

Steps of design and installation for water softening system

  • Determine the quality of hardness after softening and other indicators to be achieved. Check the water source for hardness and other indicators such as pH, Fe, Mg, TDS, suspended solid, chlorine… to see if need pretreatment to softener or not, such as sedimentation, multi-sand filtration, active carbon filtration … or post-softening treatment such as sterilization by UV, Ozone…
  • Calculation of operating capacity, total amount of soft water used in 1 day to install 1 or more towers.
  • Choose the manual or automatic operation / regeneration (automatic universal valve, electric or pneumatic valve).
  • Regeneration by time setting or by cumulative volume

Steps of design and installation for water softening system

1: Manually operated valve according to scheduled steps

2: Autovalve: Built-in steps and timings in the controller, including the option  regeneration with time or volume

3: Valves automatically controlled by electricity, compressured air   by time or PLC programming

  • Consider if need to monitor and controlling quality such as hardness, flow meter and totalizer devices as well as signal transmission.
  • There is a filter before softener to prevent suspended solid and nozzle after softener to check and avoid resin leakage
  • Discharge ensures environmental standards.

4. Operation, regeneration and maintenance of water softening systems

4.1. Remark before operating and maintaining

If the input water source has stable hardness, system was well equiped enough monitoring and controlling  devices then the operation will be simple, otherwise it will take time to monitor or can not guarantee the stable quality after softening

Beside of checking the water softener system immediately if trouble, during stable operation checklist should be well done daily and monthly.

Daily check list:

  • Salt and problems related to salt
  • Quick test of hardness by EBT, pH and TDS before, after softening.
  • Record, compare the amount of filtered water on the meters.
  • Check the supply pump if any abnormality is found.

Monthly check list

  • Cleaning salt suction line, salt tank.
  • Leaks at valves, joints with rubber rings inside, check all if cracked, leaking, pipeline deformed due to sudden pressure change.
  • Compare operating cycles with Autovalve’s initial setting.
  • Check the input/output pressure to see if there is an internal blockage.
  • Check the supply pump for electrical problems and corrosion.
  • Determine the ability to resin by recounting the hardness test results and the amount of salt used daily compared to the amount of filtered soft water in the past 1 month. If regeneration timer over times but is still not passed, then need to check the quantity and quality of resin and then added if neccessary. In case dirty found, resin can be cleaned with RE-Cleaner or replaced if necessary.

4.2. When to regenerate and how many salt for each regeneration?

The ion exchange capacity of the resin with hardness will decrease over time towards the end of the cycle. Therefore, it is necessary to rely on the operating cycle or the soft water volume to check the hardness.

How to quickly check the hardness of the softening tower at: https://uce.com.vn/calculating-and-optimize-resin-regenerate-for-softener.

Quick test of water hardness

Quick test of water hardness

The amount of salt and volume of water for 1 time of regeneration can be determined at: https://uce.com.vn/calculating-and-optimize-resin-regenerate-for-softener.

For example, the amount of salt and the volume of water for 2 cases: According to the capacity of the softening tower 20m3/h and the volume of resin 500 Liters.

Dry salt quantity for one time regeneration

Dry salt quantity for one time regeneration

To determine softener operated optimizely or not, please refer to section II at: https://uce.com.vn/calculating-and-optimize-resin-regenerate-for-softener.

However, this is much more complicated, it is best to contact us for quick results.

5. UCE Co., Ltd  have helped customers increase the efficiency of the water softener

The most commonly concerned issue is why is the resin efficiency reduced and how can the resin life be increased?

The main reasons causing effecting of resin reduced are:

1- Incorrect design and operation.

2- Resin degraded by nature.

3- The impact of external factors such as dirt suspended solid, Fe,  pH > 7.5 with high hardness, high TDS, microorganisms harmful to the surface, Chlorine, high heat,….

The third above cause will be the main factor. Therefore, it is advisable to pay more attention to the water characteristic with the electromechanical ( M&E) check and maintenance of the water softener system so that the resin work well at the highest level of life – which means the most savings.

We have a laboratory specialized in water, water technology engineers, electrical and mechanical maintenance will support and ensure your water softening system achieves the desired results.