WATER SOFTENING PLANT
Hard water is frequently unsuitable for many industrial and domestic purpose. When water is referred to as ‘Hard’ it simply means, that it contains excess of calcium (Ca) and magnesium (Mg) Ions than normal water.
Carbonate hardness is known as temporary hardness and non-carbonate hardness is known as permanent hardness.The degree of hardness of the water increases, when more calcium and magnesium ions are dissolves.These ions have their origins in limestone sediments and also from carbon dioxide which is present in all waters exposed to the atmosphere and especially in ground water.The easiest way to soft the hard water is through Ion exchange process.
HASSLES OF HARDNESS:-
- Hard water reacts adversely with detergents. It means even on your little (baby) ones’ Soft towels turn rough on their soft skin.
- Soaps and shampoos do not lather and leave you feeling unwashed. Your skin gets dry. Hard water makes hair dry and rough leads to hair loss.
- Hard water causes residual deposit and scale builds up. Damaging your appliances such as heaters, washing machines, showers, dishwashers etc. Appliances life comes down by 45%; their maintenance cost goes up by 25%. Causes deterioration and fading of fabrics. Also reduces fabric life by 15%.
- Hard water leaves scales which clog pipes, faucets, valves and fixtures. Hard water reduces the cleaning power of detergents. Soft water reduces detergents requirements by about 70%.
- Makes the food and water taste different. Cooking takes longer than ever before. Cooking gas consumption increases by 30%. Causes scale deposit on utensils.
WATER SOFTENING PROCESS :-
Softening is the ion exchange process, it is done through resin, the most common and probably the easiest method of removing hardness (that is calcium and magnesium)from water and suitable for utility purpose. As the name implies ion exchange is a process which undesirable ions are exchanged for more desirable ions.The softening process consists of passing raw water containing hardness through a bed of cation resin in sodium form.The hardness ions Ca & Mg are taken up by resin and in exchange,the sodium ions are relinquished from the resin.This is called the service cycle, where the hard water is being softened.
CHEMICAL REACTION DURING SOFTENING PROCESS:-
Ca (HCO3)2 + Na2 R = RCa + NaHCO3
CaSO4 + Na2 R = RCa + Na2SO4MgCl2 + Na2
R = RMg + NaCl
Raw water will continue to get softened till the resin gets exhausted. Bringing back the resin to its original form is called regeneration. Softener resin is regenerated by sodium chloride- Nacl (Common salt) solution. The common salt solution is kept in the regeneration tank. During the regeneration process, salt solution is injected by the ejector tube into softener. The Nacl (salt solution) replaces ca, Mg (Hardness)from the resin, the regeneration is done every day or every few days or every week depending upon the usage and design of the water softener plant.
CHEMICAL REACTION DURING REGENERATION PROCESS:
RCa + NaCl = RNa + CaCl2
RMg + NaCl = RNa + MgCl2
- Personal grooming –- Bathing with hard water is unpleasant because when hard water combines with soap it creates a curd that sticks to the body. Soap and shampoo will not lather well, leaving the body feeling sticky and hair feeling unclean, brittle, and difficult to manage. Washing one’s body and hair with soft water is significantly better than with hard water.
- Household cleaning–Hard water creates the same type of soap curd on sinks, faucets, bathtubs and shower stalls, which is extremely difficult to remove. Using soft water can reduce the amount of time spent house cleaning and save you money on the cost of cleaning products.
- Clothing— Washing clothes in hard water makes it difficult to get them clean again because the hardness minerals impede the effectiveness of laundry detergents and whiteners and brighteners. Thus,many people who have hard water have to use more detergent and wash their clothes more frequently,which increases the wear and tear on fabrics.Washing clothes with soft water will significantly increase the life of clothing,bedding and towels, and keep the colours looking brighter and the feeling softer and cleaner.
- Demineralized water— Salt is used to remove all (or at least most) of the minerals in the water through the process of ion exchange.Drinking demineralized water can create a mineral imbalance in the body. Even though we get many essential minerals, such as calcium, magnesium, potassium, from food, the intake does not compensate for the naturally occurring minerals in water.The World Health Organization (WHO) conducted a study revealed health risks associated with drinking demineralized water. See reference below.
- Increased sodium content–-Because salt is added to the water to displace the hard minerals, the sodium of soft water is much higher than normal. In addition, the water that is added is refined salt, not the naturally occurring salt that is found in nature.Obviously, people on a salt-restricted diet due to health concerns should not drink soft water.
- Bad taste–- Depending on the degree of hardness, the taste of softened water becomes unbearable for most people.
- Environmental impact— Many states and counties have banned the use of salt-based water softeners because of the concentrated salt solution that is discharged into the waste water. This water is harmful to the environment and it also reduces the ability to reuse the treated wastewater.
- Effects of sodium:- The CDC recommends limiting daily total sodium intake to 2,300 mg per day though the average American consumes 3,500 mg per day. Because the amount of sodium present in drinking water—even after softening—does not represent a significant percentage of a person’s daily sodium intake, the EPA considers sodium in drinking water to be unlikely to cause adverse health effects.
- For those who are on sodium-restricted diets, the use of a reverse osmosis system for drinking water and cooking water will remove sodium along with any other impurities which may be present. Potassium chloride can also be used as a regenerate instead of sodium chloride, although it is more costly. For people with impaired kidney function, however, elevated potassium levels, or hyperkalaemia, can lead to complications such as cardiac arrhythmia.
- Hard water also conveys some benefits to health by reducing the solubility of potentially toxic metal ions such as leadand copper, which are more soluble in soft water than in hard water.
- Use in irrigation:- Softened water (measured as Residual sodium carbonate index) in which calcium and magnesium have been partly replaced by sodium, is not suitable for irrigation use, as it tends to cause the development of alkali soils Non-chemical devices are often used in of traditional water softening, for this application.