Month: January 2014

Zeolite process for water softening

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What is zeolite
Zeolite is micro-porous mineral which is used as catalyst in many industrial purposes such as water purification and air purification. The zeolites are hydrated aluminosilicates and general composition AlxSiyO2(x+y)  (without water molecules). Zeolites are two types natural and synthetic or artificial. The natural zeolite that is used for water softening is gluconites or greensand. Permutit is the synthetic zeolite that is most used in water softening and its chemical formula is Na2O, Al2O3, nSiO2, xH2O. These are used as ion exchanger and odor removal in water softener. Permutit are more porous, glassy, and have higher softening capacity than greensand.
Zeolites are characteristically soft to moderately hard, light in density, insoluble in water but can act as base exchangers in contact with water containing cations. Hence these can remove Ca2+ and Mg2+ ions from water when hard water is passes through.

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Zeolite process for water softening
Zeolite process for water softening has become a commercial success for the reason that zeolite can be easily regenerated. When Ca2+ and Mg2+ ions containing hard water is passes through a bed of sodium zeolite, the sodium ions are replace by the calcium and magnesium ions.

Na2Ze  + Ca(HCO3)2 → 2NaHCO3 + CaZe
Na2Ze  + Mg(HCO3)2 → 2NaHCO3 + MgZe
Na2Ze  + CaSO4  → Na2SO4 + CaZe
Na2Ze  + MgSO4 → Na2SO4 + MgZe

When all sodium ions are replaced by calcium and magnesium ions, the zeolite becomes inactive. Then the zeolite needs to be regenerated. Brine solutions are passing through the bed of inactivated zeolite. The following reactions are taken place and form Na2Ze.

CaZe + 2NaCl → Na2Ze + CaCl2
MgZe + 2NaCl → Na2Ze + MgCl2

The softening water by this process is used for laundry process and cannot be used for boiler purpose. Because this water softening system contains NaHCO3 in the water; when this water is heated, it produces CO2 which is corrosive for boilerplates.
zeolite water softening process
1 Pound – Clinoptilolite Zeolite Powder

Lime soda process

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Lime soda process is one of the water softener systems. In this system calcium hydroxide and soda ash are used as reagents. By this process soluble magnesium and calcium salts are removed as calcium carbonate and magnesium hydroxide precipitated. After removal of this precipitated, we obtain soft water. Both temporary water hardness and permanent water hardness are removed by this lime softening water softener systems. Before water treatment calculate the amount of temporary and permanent water hardness, and then estimate the amount of lime and soda ash and added control with careful. In case of temporary water hardness the following reactions are take places:

Ca(HCO3)2 + Ca(OH)2 → 2CaCO3 + 2H2O

Mg(HCO3)2 + Ca(OH)2 → 2CaCO3 + MgCO3 + 2H2O

MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3

In case of permanent water hardness the following reactions are take places:

CaSO4 + Na2CO3→ CaCO3 + Na2SO4

MgSO4 + Na2CO3→ MgCO3 + Na2SO4

MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3

There are two type lime-soda process; cold lime soda process and hot lime soda process.

Cold lime soda process
In the cold lime soda process the reactions take place at normal temperature. The raw water is passed into a tank with a static continuous flow, at the same time a calculated amount of chemical mixture of lime and soda ash are also added a static continuous flow and then thoroughly mixed with a stirrer in this mixture tank. Afterward this water is allowed to settle. When the settlement becomes complete the water is passed by continuous up-flow process into another tank which is called filter bed. Then we get soften water.
The cold lime soda process is not suitable for all purposes. It is limited for those purposes where partially softened water needed because this process fails to precipitate completely all the hardness forming salts. The cold lime soda process is used for municipal water and cooling water softener systems. The reason in case of municipal purpose, it is not necessary to remove all water hardness forming ions. Same way cooling water should be free from temporary water hardness. In this process it is possible to remove magnesium water hardness nearly completely but calcium hardness may be remains more than 40ppm.

Hot lime soda process
In the hot lime soda process the reactions take place at higher temperature near about boiling point of water. The chemical mixing process is same as the cold lime soda process, but steam is applied in mixture tank. As a result precipitation becomes almost complete very quickly. This process is more effective than cold lime soda process. The hot lime soda process water softener systems are exclusively used for boiler purpose. In this process it is possible to remove magnesium water hardness completely and calcium hardness may be remains very low. Moreover dissolved corrosive gases also removed by this hot lime soda process.

Hard water vs soft water

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Hard water and soft water are defining depending on water contaminants with some metals ions such as calcium, magnesium. Hard water is not good for all position; same way soft water also not suitable for all applications.

Generally hard water contains greater quantity of calcium and magnesium ions. On the other hand soft water contains little amount or no ions of some metals such as calcium, magnesium. We get soft water naturally such as rain water or conditioning the hard water.

Water for drinking purpose
Hard water is good for health than soft water. In health point of view hard water effects are neutral; some cases are beneficial because it is rich in minerals. Moreover it decreases the solubility of potentially poisonous metal ions as like copper and lead. On the other hand soft water rich in sodium ions, this is not safe to drink. It is health risk such as diabetes or high blood pressure. A study shows that less heart disease in hard water areas than in soft water areas.

Water for domestic cleaning
For domestic cleaning soft water is essential. Hard water is not suitable for this purpose because in hot water heater, steam iron, kettles, coffee makers etc it forms limescale. This water also creates spots on dishes and glassware. Moreover extra soap or detergents are consumed in this case. In addition hard water leaves iron or soap deposits in bathtubs, sinks and basins. On the other hand soft water save soap or detergents and all other hard water effects are not found in case of domestic cleaning.

When people are bathing with soap in hard water, a sticky film formed on the skin. Soil, dirt and bacteria can be trapped in pores beneath the soap scum; this is the possible skin infection.

Water for plumbing system
Domestic or industrial plumbing system is affected by hard water. It buildup limescale in shower head, taps, inner side of pipe, hot water tanks, washing machines, boilers, cooling tower and other industrial equipment. It reduces the life of plumbing system; even clog it. Hence increase plumbing system repairing cost. On the other hand these effects are not found in case of soft water.

Water for industry
In industrial purpose the uses of soft water is significant. Soft water is used for heat transfer, cooling tower, boiler, manufacture of beverages, sugar syrup, gelatin, juice etc in many industries. In contrast hard water is not suitable for industry; it buildup limescale in boiler, cooling tower, hot water tank etc. as a result decrease the life of tank or boiler and need more energy. Water hardness significantly effects on textile dyeing, washing and finishing section.

Soft Water

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What is soft water
Soft water means when the water is free from the ions of chloride, sulfate and bicarbonate of calcium and magnesium salt or presence little amount of these ions; in particular total water hardness less than 150 mg/l calcium carbonate. Also free from some other metals for example iron, zinc, manganese, aluminum, strontium etc. We can also be define soft water depends on foam creation with soap or detergent. Soft water can easily create foam with soap and detergents. The source of soft water mainly rain water; other sources are water that comes from granite or sandstone. Soft water can be classified into two group depends upon total hardness. When total water hardness less than 75 mg/l calcium carbonate; it is called very soft water. If total water hardness is between 75-150 mg/l calcium carbonate; it is called soft water.

Soft water has a tendency to be somewhat acidic. For example:

Water + carbon di-oxide + calcium carbonate = calcium bicarbonate

H2O (l) + CO2 (g) + CaCO3 (s) → Ca(HCO3)2 (aq)

Very Soft water can dissolve metals with which it comes into contact with at static condition or during flow time.  Lead, copper, iron etc are susceptible to attack from this type of water. In this way Lead and copper may lead to poisoning the water, which is at risk for health.  This is one of the main reasons in plumbing installations Lead and copper are no longer used.

soft water

Is soft water safe to drink
There are many reasons soft water is not good for drinking. But conditioning water is good for health. The soft water that contains high sodium ions is not safe to drink. It is health risk such as diabetes or high blood pressure. Sodium should not more than 2300 mg, it is better contains 1500 mg per day. If somebody takes soft water regularly, he/she should be need take vitamin that includes calcium. A study proves that not as much of heart disease in hard water areas than in soft water areas.

Benefits of soft water
Soft water is benefits for washing one’s body and hair because it does not create dryness. Moreover there are no sticky films formed on the skin. People escape from skin disease like Eczema. No limescale can form in kettles, coffee makers, faucets, hot water heaters, steam irons etc in whole household, Increase plumbing system life. It is also reduce cost in laundry purpose.
In industrial purpose the uses of soft water is significant. Soft water is used for heat transfer, cooling tower, boiler, manufacture of beverages, sugar syrup, gelatin, juice etc in many industries.

Coliform Bacteria in water

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What is coliform bacteria
Coliform bacteria are single-celled organisms that are present in the environment such as rivers, lakes and streams and as well as all warm-blooded animals like human. The structure of them is rod-shaped, gram-negative and non-spore forming bacteria. Coliform bacteria can be explained in this way that; it can ferment lactose into acid and gas at 35–37°C. The majority of the coliform bacteria are harmless and certain are harmful. But it is important that it represent the disease-causing organism such as viruses and protozoans might be present in the water. Since both of the organisms come from same sources. Moreover it does not always indicate that pathogenic microorganisms are also present in the water because coliform bacteria can stay alive in tropical condition. However, it indicates that other microorganisms must be checked. The colifoarm bacteria can be classified into three groups or subgroups for example total coliform, fecal coliform and E. coli.

coliform-bacteria

Total coliform Bacteria
The total coliform bacteria are a collection of large number of different types of bacteria in water or soil. Total coliform bacteria are used as the indicator for the source of water so that resolve the problem. If only the total coliform bacteria are present in water and fecal coliform bacteria are absent; it indicates that the source is probably environmental (portable water).

Fecal coliform bacteria
Fecal coliform bacteria are a sub-group of total coliform bacteria that are contamination by warm-blooded animals. If fecal coliform bacteria are present, it indicates that the contamination occur recently. It is larger threatened for human. Moreover it can reduce dissolved oxygen of water which is undesirable for aquatic life. Fecal coliform bacteria test is one of the important water quality tests in many development countries as like USA.

E. coli bacteria
E. coli bacteria are a sub-group of the fecal coliform bacteria that are found in large amount in the intestines of people and warm-blooded animals. Although most of E. coli (Escherichia coli) bacteria are safe but some of them can cause disease; particularly the strain 0157:H7.  If these bacteria are present in water, it indicates recent fecal contamination. It means there is a potential health problem creating pathogens are present. This organism can create some disease for example meningitis, dysentery, typhoid, urinary tract, septicemia, hepatitis and intestinal infections.

How can destroy coliform bacteria
Coliform bacteria are used to study, how the contamination obtained into the water so that eliminate any probable sources. Coliform bacteria can destroy by boiling or treating contamination water including harmful 0157:H7 E. coli bacteria.