Water Softener – Water softener Systems


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Water softeners

Nanotech supplies custom designed water softening units to be used for a specific application or integrated into a turnkey Nanotech water treatment system. The units we supply have the following features:

Vessels are constructed from GRP, mild steel or stainless steel. Choice of material is dependant on application and operating features. System control can be manual, time control or volume demand.
Configurations are available in simplex or duplex depending on operating conditions.
An electrolytic self-disinfection unit for softener units is available for critical applications.

To properly design and integrate the water softener into a new or existing application, Nanotech has to understand the existing site conditions. We therefore ask potential customers to complete our water system enquiry form. This information will give us a snapshot of their site conditions and allow us to recommend a system/equipment that will meet all expectations.

What is a water softener?

A water softener reduces the calcium or magnesium ion concentration in hard water. These "hardness ions" cause three major kinds of problems. The metal ions react with soaps and calcium sensitive detergents, hindering their ability to lather properly and forming an unsightly precipitate the familiar scum or "bathtub ring". Presence of "hardness ions" also inhibits the cleaning effect of detergent formulations. More seriously, calcium and magnesium carbonates tend to adhere to the surfaces of pipes and heat exchanger surfaces. The resulting scale build-up can restrict water flow in pipes. In boilers, the deposits act as thermal insulation that impedes the flow of heat into the water. This not only reduces heating efficiency, but allows the metal to overheat which, in a pressurised system, can lead to failure. The presence of ions in an electrolyte can also lead to galvanic corrosion, in which one metal will corrode preferentially when in contact with another type of metal. The use of water softeners can aggravate this and cause sacrificial anodes in hot water heaters to corrode more quickly.

Conventional water-softening devices intended for household use depend on an ion-exchange resin in which "hardness" ions trade places with sodium ions that are electrostatically bound to the anionic functional groups of the polymeric resin. A class of minerals known as zeolites also exhibits ion-exchange properties. These minerals were widely used in earlier water softeners.

What makes water hard and how is hardness measured?

Groundwater dissolves rocks and minerals, releasing calcium and magnesium ions that cause water to be hard. These dissolved ions give hard water its characteristics. Water hardness is ordinarily expressed in grains of hardness per gallon (gpg) of water. Water impurities can also be measured in either parts per million (ppm) or milligrams per litre (mg/l). One gpg is equal to 17 ppm (mg/l). Table 1 shows how hardness is classified.

Table 1. Hardness classification

Concentration of hardness minerals

Level of Hardness

milligrams per liter (mg/l) or parts per million (ppm)

soft

Less than 17

slightly hard

17 to 60

moderately hard

61 to 120

Hard

121 to 180

very hard

more than 180

How it works

The water to be treated passes through a bed of the resin. Negatively-charged resins absorb and bind metal ions, which are always positively charged. The resins initially contain univalent sodium ions, which exchange with divalent calcium and magnesium ions in the water. This exchange eliminates precipitation and soap scum formation.
As the water passes through both kinds of resin, the hardness ions replace the sodium, which is released into the water. For most purposes, the low levels of salt in the treated water are innocuous. However because of the increase in sodium concentration, some people believe water softened in this way is not suitable for regular consumption. However, when measured, there is less sodium in a cup of drinking water than there is in three slices of white bread.

Regeneration

As these resins become converted to their Ca²⁺ form, they gradually lose their effectiveness and must be regenerated. This is achieved by passing a concentrated brine solution through them, causing the processes to be reversed. This is a drawback, however, since most of the salt used for regeneration is flushed out of the system and may be released into the soil or sewer. This can be damaging to the environment, especially in arid regions. For this reason, some jurisdictions prohibit such release and require users to dispose of the spent brine at an approved site or to use a commercial service company.

Most water softener manufacturers provide metered control valves to minimise the frequency of regeneration. On most units, it is also possible to adjust the amount of salt used for each regeneration. Both these steps should be used to minimise the impact of water softeners on the environment.