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WATER CHEMISTRY:


What is Water?
Water is a Universal Solvent. Almost everything dissolves in water to some extent… This is due to the electrically polar nature of the water molecule. Due to the polarity of the water molecule it has a tendency to form hydrogen bonds with other molecules. When a solute is dissolved in a solvent, the attractive forces between the solute and solvent are greater than the attractive intermolecular forces within the pure solute or within the pure solvent. Water would rather bond to Na+ and bond to Cl- rather than keep its water-water hydrogen bond. Na+ would rather bond with water instead of Cl-.The charged ions are attracted to the + or - end of the water molecule, and the water molecules surround the ions and keep them dissolved.The chemical symbol of water molecule is expressed as H2O and consists of 2 Hydrogen atoms and 1 Oxygen atom.

Structure of water:


Water, as discussed above, is a molecular compound containing H2O molecules in which two hydrogen atoms are bound to the oxygen atom forming an angle of 104.5°.The electron arrangement in the water molecule can be represented as follows.
Each pair of dots represents a pair of unshared electrons (i.e., the electrons reside on only the oxygen atom). The O-?H distance (bond length) is 95.7 picometres. Because an oxygen atom has a greater electronegativity than a hydrogen atom, the O?-H bonds in the water molecule are polar, with the oxygen bearing a partial negative charge and the hydrogens having a partial positive charge. In the water molecule, electrons cluster toward the oxygen. This results in the oxygen “end” of the molecule having a negative charge and the hydrogen “end” having a positive charge. The molecule is POLAR.
The positive (+) end of one water molecule feels an electrostatic attraction to the negative (-) end of a second water molecule, and they form a weak hydrogen bond.

HYDROGEN BONDING IN WATER IS WHAT GIVES WATER ITS HIGH HEAT CAPACITY, ITS DENSITY BEHAVIOR, AND DISSOLVING ABILITY.
Water, Water, Every where……… But Not a Drop to Drink?

Life on earth totally depends on water.
Pure Drinking Water is a colorless liquid free from undesirable elements and pathogens that quenches our parched tongues and becomes a necessary part of life as it delivers essential nutrients and minerals needed to stay a healthy life. The immediate effect is to cool you down and re-hydrate your body. It should be alkaline and be antioxidant. The bodies of all living organisms are composed largely of water. About 70 to 90 percent of all organic matter is water.

Water benefits to our human body:

• Supplies nutrients and minerals essential for life
• Balances the acidic state of your body.
• It serves as a lubricant for body joints.
• Forms the base for saliva.
• It forms the fluid that surrounds the body joints.
• It regulates the body temperature, as the cooling and heating is distributed through perspiration. Regulates metabolism.
• It helps to alleviate constipation by moving food through the intestinal track thereby eliminating waste.
• It also plays a vital role in prevention of diseases. Drinking 08 glasses of water daily can decrease the risk of colon cancer by   45%  and bladder cancer by 50%.

What is pH of drinking water?

An acid is a substance that increases the concentration of hydrogen ions (H+) in water. A base is a substance that decreases the concentration of hydrogen ions and increases the concentration of hydroxide ions OH-. The degree of acidity or alkalinity of a solution is measured in terms of a value known as pH (Potential of Hydrogen ion), which is the negative logarithm of the concentration of hydrogen ions: pH = 1/log[H+] = -log[H+]

The pH scale, ranges from 0 on the acidic end to 14 on the alkaline end, as shown in th diagram below. The solution is neutral if its pH is 7. At pH 7, water contains equal concentrations of H+ and OH- ions. Solutions with a pH less than 7 are acidic because they contain a higher concentration of H+ ions. Solutions with a pH higher than 7 are alkaline because they contain a higher concentration of OH- than H+ ions. The pH scale is a log scale and a change of one pH unit means a tenfold change in the concentration of hydrogen ions.

pH of Drinking Water is in the range of 6.5 to 8.5 on pH scale.

Living things are extremely sensitive to pH and function best when solutions are nearly neutral. Most interior living matter has a pH of about 6.8. Blood plasma and other fluids that surround the cells in the body have a pH of 7.2 to 7.3.

Neutral solution [H+] = [OH?] pH = 7
Acidic solution [H+] > [OH?] pH < 7
Basic solution [OH?] > [H+] pH > 7

In 1909, it was S.P. Sorensen who introduced the pH scale to measure the "potential of Hydrogen". pH refers to the concentration of hydrogen ions (H+) on a scale of 1 to 14. On this scale, pH values of less than 7 indicate an acid, while those greater than 7 indicate a base (alkaline substance). Pure water is neither an acid nor a base – it is a neutral with a pH value of.

7. Vinegar has a pH of 3. Rainwater is slightly acidic with a pH of 6.5. Ammonia has a pH of 11 or 12. Most fish tolerate a pH range of between 6 and 8.5. This is shown in the fig -1below.

pH Values Of Different Drinks:


• A popular brand of cola — 2.5.(It takes 32 glasses of a 10.0 pH alkaline water to neutralize one can of cola)
• Diet soft drinks —3.2 pH
• Popular brand beer — 4.7 pH.
• Distilled water —7.0 pH. Filtered tap water — 8.4 pH.
• Fresh vegetable juice (greens) — 8.9 pH.
Pure water does not exist, except in the lab. When water is considered pure, it is made up of two hydrogen atoms and one oxygen atom – H2O. But water mixes with many things – as a raindrop, it mixes with minerals in the soil and carries those minerals with it to the groundwater or as it flows toward a stream or river. When water is full of minerals, it is known as Hard water. When water has a few quantities of Calcium and Magnesium in it, it is generally called Soft water. Distilled water is water that has been softened.

Hard water can cause problems in plumbing because it deposits minerals in the pipes, causing a build up. It is difficult to get a lather when shampooing or if there isn't much sudsing when you are washing dishes by hand. Soft water produces more suds and, therefore, it is better for cleaning. Many people install water softeners in their homes for that reason. Water softeners use salts to remove most of the calcium and magnesium from tap water.

Water reacts with many different substances:

• When some metals (such as sodium) are added to water, the reaction produces hydrogen gas as one of the products;
• When some non-metallic oxides are added to water they form compounds called acids (a major ingredient of acid rain –    carbonic acid – is formed when carbon dioxide reacts with water);
• When a metallic oxide reacts with water, compounds called bases are formed;
• Many compounds, when mixed together in a dry state, do not react. If some water is added to the mixture, a reaction    often begins. Baking powder is a mixture of dry chemicals which releases bubbles of gas only after water is added.

Water is a dynamic and mobile substance which is constantly going through chemical and physical transformations. It has been called "nature's magician", since it can appear in many forms. Water is found naturally in all three states of matter; solid, liquid and gaseous; a rare occurrence among other natural substances. This is explained in fig - 2 above as shown in the water cycle. The water cycle (known scientifically as the hydrologic cycle) refers to the continuous exchange of water within the hydrosphere, between the atmosphere, soil water, surface water, groundwater, and plants.

The water cycle has no starting or ending point. The sun, which drives the water cycle, heats water in the oceans. Some of it evaporates as vapor into the air. Ice and snow can sublimate directly into water vapor. Rising air currents take the vapor up into the atmosphere, along with water from evapotranspiration, which is water transpired from plants and evaporated from the soil. The vapor rises into the air where cooler temperatures cause it to condense into clouds. Air currents move clouds around the globe, cloud particles collide, grow, and fall out of the sky as precipitation. Some precipitation falls as snow and can accumulate as ice caps and glaciers. Most precipitation falls back into the oceans or onto land, where, due to gravity, the precipitation flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with stream flow moving water towards the oceans. Runoff, and ground-water seepage, accumulate and are stored as freshwater in lakes. Water covers 71% of the Earth's surface; the oceans contain 97.2% of the Earth's water; 1.8% is in the form of glaciers; 0.9% is groundwater; 0.02% is fresh water in lakes, inland seas, and rivers; 0.001% is atmospheric water vapor at any given time.

The Antarctic ice sheet, contains 90% of all fresh water on Earth.

WHAT IS IN SEA WATER?

99% of all dissolved ions (nutrients and gases excluded) are:

Ion Symbol Percent of dissolved salt Concentration mg/L (ppm)
chloride
sodium
sulfate
magnesium
calcium
potassium
bicarbonate
Cl-
Na+
SO4-2
Mg+2
Ca+2
K+
HCO3-
55.07 %
30.62 %
7.72 %  
3.68 %
1.17 %
1.10 %
0.40 %
19,350
10,760
2,710
1,290
410
390
140
TOTAL   99.76 % 35,050
Salt in water:

(a) Lowers the freezing point temp (salt melts winter ice)
(b) Raises boiling point temp (cook faster with salty water)
(c) Increases the density of the water

Salinity = (grams of dissolved material)/(kilograms of solution) units: g/kg OR parts per thousand (ppt) or per mil.(They all mean the same thing).

Types of Water: -

1. According to phase

solid - ice o liquid - water
• gaseous - water vapor

2. According to occurrence
• groundwater
• meltwater
• meteoric water
• connate water
• fresh water
• mineral water – contains much minerals
• brackish water
• dead water – strange phenomenon which can occur when a layer of fresh or brackish water rests on top of more dense salt    water, without the two layers mixing. It is dangerous for ship traveling.
• seawater
• brine

3. According to uses
• tap water
• bottled water
• drinking water or potable water – useful for everyday drinking, without fouling, it contains balanced minerals that are not    harmful to  health
• purified water, laboratory-grade, analytical-grade or reagent-grade water – water which has been highly purified for specific    uses in science or engineering.

4. According to other features
• soft water – contains less of calcium and magnesium minerals o hard water – from underground, contains more of calcium and    magnesium minerals
• distilled water, double distilled water, deionized water - contains no minerals
• water of crystallization — water incorporated into crystalline structures
• hydrates— water bound into other chemical substances
• heavy water– made from heavy atoms of hydrogen - deuterium. It is in nature in normal water in very low concentration. It    was used in construction of first nuclear reactors.

5. According to microbiology
• drinking water
• wastewater
• storm water or surface water

6. According to religion
• holy water


The major chemical and physical properties of water are:


• Water is a tasteless, odorless liquid at ambient temperature and pressure. The color of water and ice are, intrinsically, a    very light blue hue, although water appears colorless in small quantities.
• Water is transparent, and thus aquatic plants can live within the water because sunlight can reach them.
• Water is a liquid under standard conditions.
• Since oxygen has a higher electronegativity than hydrogen, water is a polar molecule. The oxygen has a slight negative    charge while the hydrogens have a slight positive charge giving the article a strong effective dipole moment. The    interactions between the different dipoles of each molecule cause a net attraction force associated with water's high    amount of surface tension.
• Another very important force that causes the water molecules to stick to one another is the hydrogen bond.
• The boiling point of water is directly related to the barometric pressure. For example, on the top of Mt. Everest water    boils at    about 68 °C (154 °F), compared to 100 °C (212 °F) at sea level.
• Water sticks to itself. Water has a high surface tension caused by the strong cohesion between water molecules    because it is    polar. The apparent elasticity caused by surface tension drives the capillary waves.
• Water also has high adhesion properties because of its polar nature.
• Capillary action refers to the tendency of water to move up a narrow tube against the force of gravity. This property is    relied    upon by all vascular plants, such as trees.
• Water is a very strong solvent. Substances that will mix well and dissolve in water, e.g. salts, sugars, acids, alkalis, and    some    gases: especially oxygen, carbon dioxide (carbonation), are known as "hydrophilic" (water-loving) substances,    while those    that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances.
• All the major components in cells (proteins, DNA and polysaccharides) are also dissolved in water.
• Pure water has a low electrical conductivity.
• The maximum density of water is at 3.98 °C (39.16 °F)[5]. Water becomes even less dense upon freezing, expanding    9%.    This  causes an unusual phenomenon: ice floats upon water, and so water organisms can live inside a partly    frozen pond    because the  water on the bottom has a temperature of around 4 °C (39 °F).
• Water is miscible with many liquids, for example ethanol, in all proportions, forming a single homogeneous liquid.
• Water forms an azeotrope with many other solvents.
• Water can be split by electrolysis into hydrogen and oxygen.
• Elements which are more electropositive than hydrogen such as lithium, sodium, calcium, potassium and caesium    displace hydrogen from water, forming hydroxides. Being a flammable gas, the hydrogen given off is dangerous and    the reaction of water with the more electropositive of these elements is violently explosive.

Water Specifications:-

S.No. Parameter IS : 10500 Requirement
(Desirable limit)
Undesirable effect outside the desirable limit IS : 10500 Permissible limit in the absence of alternate source
1. pH 6.5 - 8.5 Beyond this range the water will effect the mucous membrane and/or water supply system No relaxation
2. Color (Hazen Units), Maximum 5 Above 5, consumer acceptance decreases 25
3. Odour Unobjectionable -- --
4. Taste Agreeable -- --
5. Turbidity, NTU, Max 5 Above 5, consumer acceptance decreases 10
6. Total hardness as CaCO3, Max 300 ppm Encrustation in water supply structure and adverse effects on domestic use 600 ppm
7. Iron as Fe, Max 0 . 30 ppm Beyond this limit taste/appearance are affected, has adverse effect on domestic uses and water supply structures, and promotes iron bacteria. 1.0 ppm
8. Chlorides as Cl, Max 250 ppm Beyond this limit taste, corrosion and palatability are effected 1000 ppm
9. Total Dissolved solids, Max (TDS) 500 ppm Beyond this palatability decreases and may cause gastro intentional irritation 2000 ppm
10. Calcium as Ca, Max 75 ppm Encrustation in water supply structure and adverse effects on domestic use 200 ppm
11. Magnesium as Mg, Max 30 ppm -- 100 ppm
12. Copper as Cu, Max 0.05 ppm Astringent taste, discoloration and corrosion of pipes, fitting and utensils will be caused beyond this 1.5 ppm
13. Manganese as Mn, Max 0.1 ppm Beyond this limit taste/appearance are affected, has adverse effect on domestic uses and water supply structures 0.3 ppm
14. Sulphate as SO4, Max 200 ppm Beyond this causes gastro intentional irritation when magnesium or sodium are present 400 ppm
15. Nitrates as NO3, Max 45 ppm Beyond this methanemoglobinemia takes place 100 ppm
16. Fluoride, Max 1.0 ppm Fluoride may be kept as low as possible. High fluoride may cause fluorosis 1.5 ppm
17. Mercury as Hg, Max 0.001 ppm Beyond this, the water becomes toxic No ralaxation
18. Arsenic as Se, Max 0.05 ppm Beyond this, the water becomes toxic No relaxation
19. Cyanide as CN, Max 0.05 ppm Beyond this, the water becomes toxic No relaxation
20. Lead as Pb, Max 0.05 ppm Beyond this, the water becomes toxic No relaxation
21. Chromium as Cr6+ , Max 0.05 ppm May be carcinogenic above this limit No relaxation
22. Pesticides, Max Absent Toxic 0.001 ppm
23. Aluminum as Al, Max 0.03 ppm Cumulative effect is reported to cause dementia 0.2 ppm


Water Purification Methods:

Water purification is the process of removing contaminants and other harmful microorganisms from a raw water source. The goal is to produce water for a specific purpose with a treatment profile designed to limit the inclusion of specific materials; most water is purified for human consumption (drinking water). Water purification methods include, but are not limited to: ultraviolet light, filtration, water softening, reverse osmosis, ultrafiltration, deionization and powdered activated carbon treatment.

Water purification may remove: particulate sand; suspended particles of organic material; parasites, Giardia; Cryptosporidium; bacteria; algae; viruses; fungi; minerals such as calcium, silica, and magnesium; and toxic metals like lead, copper, and chromium. Description of Some of the purification methods are as follows --

1. Boiling: Water is heated long enough to inactivate or kill micro-organisms that normally live in water at room temperature. Near sea level, a vigorous rolling boil for at least one minute is sufficient. At high altitudes (greater than two kilometers or 5000 feet) three minutes is recommended.[5] In areas where the water is "hard" (that is, containing significant dissolved calcium salts), boiling decomposes the bicarbonate ions, resulting in partial precipitation as calcium carbonate. This is the "fur" that builds up on kettle elements, etc., in hard water areas. With the exception of calcium, boiling does not remove solutes of higher boiling point than water and in fact increases their concentration TDS (due to some water being lost as vapour). Boiling does not leave a residual disinfectant in the water. Therefore, water that has been boiled and then stored for any length of time may have acquired new pathogen.

2. Granular Activated Carbon filtering: GAC, a form of activated carbon with a high surface area, absorbs many compounds including many toxic compounds. Water passing through activated carbon is commonly used in municipal regions with organic contamination, taste or odors. Many household water filters use activated carbon filters to further purify the water. Household filters for drinking water sometimes contain silver to release silver ions which have an anti-bacterial effect. Activated carbon, prepared by pyrolizing coconut shells, coal or resin beads removes chlorine by a catalytic mechanism and dissolved organics by adsorption and is often found at two locations in a water purification system. The carbon can be used as granules or more conveniently in block form. As thin-film composite reverse osmosis membranes could be damaged by excessive exposure to free chlorine, and, to a lesser degree, fouled by dissolved organics, activated carbon is often placed prior to the RO membrane to remove these contaminants.

Activated carbon is created from a variety of carbon-based materials in a high-temperature process that creates a matrix of millions of microscopic pores and crevices. One pound (0.454 kilograms) of Activated Carbon provides anywhere from 60 to 150 acres of surface area. The pores trap microscopic particles and large organic molecules, while the activated surface areas cling to, or adsorb, small organic molecules.

Activated carbon filters are also often placed in the polishing loop of a water purification system to remove trace amounts of dissolved organics, prior to final ion exchange. Carbon Absorption is a widely used method because of its ability to improve water by removing disagreeable tastes,smell,colour,objectionable chlorine, chemicals & gases and in some cases can be effective against micro-organisms. However, generally it will not affect total dissolved solids, hardness, or heavy metals. Carbon Block Filter Systems have been certified for the removal of lead, asbestos,cysts and coliform. There are two types of carbon filter systems -- GAC (granular activated carbon) and PAC(pressed activated carbon block) each with advantages and disadvantages(can generate carbon fines). These two methods can also work along with a reverse osmosis system.

The ability of an activated carbon filter to remove certain microorganisms and certain organic chemicals, especially pesticides, THMs (the chlorine by-product), trichloroethylene (TCE), depends upon several factors, such as the type of carbon and the amount used, the design of the filter and the rate of water flow, how long the filter has been in use, and the types of impurities the filter has previously removed.

The carbon adsorption process is controlled by the diameter of the pores in the carbon filter and by the diffusion rate of organic molecules through the pores. The rate of adsorption is a function of the molecular weight and the molecular size of the organics. Carbon also protects other purification media in the system that may be sensitive to an oxidant such as chlorine.

3. Distillation: Distillation is the oldest method of water purification. Water is first heated to boiling. The water vapor rises to a condenser where cooling water lowers the temperature so the vapor is condensed, collected and stored. Most contaminants remain behind in the liquid phase vessel. However, sometimes organics such as herbicides and pesticides, with boiling points lower than 100 °C cannot be removed efficiently and can become concentrated in the product water. Another disadvantage is cost. Distillation requires large amounts of energy and water.

Distilled water can also be very acidic, having a low pH, thus should be contained in glass. Distilled water is often called "hungry" water since it lacks oxygen and minerals and has a flat taste, which is why it is mostly used in industrial processes,hospitals,battery's & labs.

4. Microporous Filtration: Microporous filtration membranes provide a physical barrier to the passage of particles and micro-organisms and have absolute ratings down to 0.1 micron or "ultra- micro filters" with a rating of 0.05 micron. Most raw waters contain colloids, which have a slight negative charge (measured by the Zeta potential). Filter performance can be enhanced by using micro filters that incorporate a modified surface, which will attract and retain these naturally occurring colloids, which are generally much smaller than the pore sizes in the membrane. Micro-filters with an absolute pore size of 0.2 micron are widely used in water treatment systems. They trap contaminants, including carbon fines from organic adsorption cartridges, resin particles from ion exchange cartridges and bacteria.

There are three types of Microporous Filtration: Depth, Screen and Surface. Depth filters are matted fibers or materials compressed to form a matrix that retains particles by random adsorption. Screen filters have uniform structures which, like a sieve, retain all particles larger than the precisely controlled pore size on their surface.

Surface filters are made from multiple layers of media. When fluid passes through the filter, particles larger than the spaces within the filter matrix are retained, accumulating primarily on the surface of the filter.

Depth filters are usually used as prefilters because they remove 98% of suspended solids and protect elements downstream from fouling or clogging. Surface filters remove 99.99% of suspended solids and may be used as either prefilters or clarifying filters. Microporous membrane (screen) filters are placed at the last possible point in a system to remove the last remaining traces of resin fragments, carbon fines, colloidal particles and microorganisms.

Disadvantages are basically that it will not remove dissolved inorganics, chemicals, pyrogens or all colloidals. Potentially have high expendable costs and not regenerate able.

5. Ion Exchange: The ion exchange process percolates water through bead-like spherical resin materials (ion-exchange resins). Ions in the water are exchanged for other ions fixed to the beads. The two most common ion-exchange methods are softening and deionization. Softening is used as a pretreatment method to reduce water hardness prior to reverse osmosis (RO) processing. The softeners contain beads that exchange two sodium ions for every calcium or magnesium ion removed from the "softened" water.

Deionization (DI) beads exchange either hydrogen ions for cations or hydroxyl ions for anions. The cation exchange resins, made of styrene and divinylbenzene containing sulfonic acid groups, will exchange a hydrogen ion for any cations they encounter (e.g., Na+, Ca++, Al+++). Similarly, the anion exchange resins, made of styrene and containing quaternary ammonium groups, will exchange a hydroxyl ion for any anions (e.g., Cl-). The hydrogen ion from the cation exchanger unites with the hydroxyl ion of the anion exchanger to form pure water.

These resins are packaged in separate bed exchangers with separate units for the cation and anion exchange beds.
The resin must be "regenerated" once it has exchanged all its hydrogen and/or hydroxyl ions for charged contaminants in the water. This regeneration reverses the purification process, replacing the contaminants bound to the DI resins with hydrogen and hydroxyl ions.

DI systems effectively remove ions, but they do not effectively remove most organics or microorganisms. Microorganisms can attach to the resins, providing a culture media for rapid bacterial growth and subsequent pyrogen generation.
6. Chemical Water Purification: Chemical water purification is concerned with the use of chemicals and methods applied depends on the kind of contamination in the (waste)water. There are two types of chemical treatment: those using iodine and those using chlorine. The effectiveness of all chemical treatment of water is related to the temperature, pH level, and clarity of the water. Cloudy water often requires higher concentrations of chemical to disinfect. Below, many of these chemical purification techniques are summed up.

Chemical addition There are various situations in which chemicals are added, for instance to prevent the formation of certain reaction products.
Chelating agents are often added to water, in order to prevent negative effects of hardness, caused by the deposition of calcium and magnesium.
Oxidizing agents are added to act as a biocide(disinfectants), or to neutralize reducing agents.
Reducing agents are added to neutralize oxidizing agents, such as ozone and chlorine. They also help prevent the degradation of purification membranes.

Iodine Treatment Iodine resin is light sensitive and should always be stored in a dark bottle. It works best if the water is over 68° F (21° C). Iodine has been shown to be more effective than chlorine-based treatments in inactivating Giardia cysts. Some people are allergic to iodine and cannot use it as a form of water purification. Persons with thyroid problems, women over fifty, and pregnant women should consult their physician prior to using iodine for purification. If someone cannot use iodine, use either a chlorine-based product or a non-iodine-based filter.

Emission of iodine from resins is dependent on temperature of water which is being treated for purification. High concentration of iodine in water is poisonous and can burn tissue or eyes. Let the treated water stand for 30 minutes before drinking. Also the water treated with iodine is passed through activated carbon to absorb excess iodine and yellowish colouration which is mainly due to Iodine. In order to destroy Giardia cysts, the drinking water must be at least 68° F (20° C).

Fix the taste by adding vitamin C (about 50 milligrams) to iodized water which will completely eliminate any taste or color of iodine. The vitamin C in drink mixes like Tang™ has the same effect.


Common microorganisms and the filter size needed:
Organism Examples General Size Filter Type Particle Size Rating
Protozoa Giardia,Cryptosporidium 5 microns or larger Water filter 1.0–4.0 microns
Bacteria Cholera, E. coli, Salmonella 0.2–0.5 microns Microfilter 0.2–1.0 microns
Viruses Hepatitis A, rotavirus, Norwalk virus 0.004 microns Water purifier to 0.004
Chlorine Treatment

Chlorine used can be in the form of liquid chlorine or its compounds such as chloramine or chlorine dioxide or bleaching powder. Chlorine is a strong oxidant that rapidly kills many harmful micro-organisms. Because chlorine is a toxic gas, there is a danger of a release associated with its use. Chlorine can react to chloramines and chlorinated hydrocarbons, which are dangerous carcinogens. To prevent this problem chlorine dioxide can be applied. Chlorine dioxide is an effective biocide at concentrations as low as 0.1 ppm and over a wide pH range. ClO2 penetrates the bacteria cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organism. The by-product of this reaction is chlorite. Toxicological studies have shown that the chlorine dioxide disinfection by-product, chlorite, poses no significant adverse risk to human health. Excess chlorine in dissolved state in water can also shift the pH value and makes it acidic.

All forms of chlorine are widely used despite their respective drawbacks. One drawback is that chlorine from any source reacts with natural organic compounds in the water to form potentially harmful chemical by- products trihalomethanes (THMs) and haloacetic acids (HAAs), both of which are carcinogenic in large quantities. The formation of THMs and haloacetic acids may be minimized by effective removal of as many organics from the water as possible prior to chlorine addition. Although chlorine is effective in killing bacteria, it has limited effectiveness against protozoans that form cysts in water (Giardia lamblia and Cryptosporidium, both of which are pathogenic).

Ozone Treatment

Ozone(O3) is a relatively unstable molecule "free radical" of oxygen which readily gives up one atom of oxygen providing a powerful oxidising agent which is toxic to most waterborne organisms. When ozone faces odours, bacteria or viruses, the extra atom of oxygen destroys them completely by oxidation. During this process the extra atom of oxygen is destroyed and there are no odours, bacteria or extra atoms left. It is a very strong, broad spectrum disinfectant that is widely used to inactivate harmful protozoans that form cysts. It also works well against almost all other pathogens. Ozone is made by passing oxygen through ultraviolet light or a "cold" electrical discharge. To use ozone as a disinfectant, it must be created on-site and added to the water by bubble contact.

Some of the advantages of ozone include the production of relatively fewer dangerous by-products (in comparison to chlorination) and the lack of taste and odour produced by ozonation. Although fewer by-products are formed by ozonation, it has been discovered that the use of ozone produces a small amount of the suspected carcinogen bromate, although little bromine should be present in treated water. Another of the main disadvantages of ozone is that it leaves no disinfectant residual in the water. The U.S. Food and Drug Administration has accepted ozone as being safe; and it is applied as an anti-microbiological agent for the treatment, storage, and processing of foods.

7. Ultraviolet (UV) Radiation: Ultraviolet radiation has widely been used as a germicidal treatment for water. Mercury low pressure lamps generating 254 nm UV light are an effective means of sanitizing water. The adsorption of UV light by the DNA and proteins in the microbial cell results in the inactivation of the microorganism.

Recent advances in UV lamp technology have resulted in the production of special lamps which generate both 185 nm and 254 nm UV light. This combination of wavelengths is necessary for the photooxidation of organic compounds. With these special lamps, Total Organic Carbon (TOC) levels in high purity water can be reduced to 5 ppb. Disadvantages are basically it decreases resistivity and will not remove particles, colloids, or ions.

UV is very effective at inactivating cysts, as long as the water has a low level of colour so the UV can pass through without being absorbed. The main disadvantage to the use of UV radiation is that, like ozone treatment, it leaves no residual disinfectant in the water. Because neither ozone nor UV radiation leaves a residual disinfectant in the water, it is sometimes necessary to add a residual disinfectant(chloramines) after they are used. Ultraviolet (UV) is that part of electromagnetic light bounded by the lower wavelength of the visible spectrum and the X-ray radiation band. The spectral range of UV light is ,by definition between 100 and 400 nm (1 nm = 10 - 9m) and is invisible to human eyes. Using the CIE classification, the UV spectrum is subdivided in to three bands :
UVA (long-wave) from 315 to 400 nm.
UVB (medium-wave) from 280 to 315 nm.
UVC (short-wave) from 100 to 280 nm.


A strong germicidal effect is provided by the light in the short-wave UVC band. The most efficient source for generating UVC is the low-pressure mercury discharge lamp, where on average 35% of input watts is converted to UVC watts. The radiation is generated at 254 nm viz. at 85% of the maximum germicidal effect.

The UV light emitted by a source is expressed in watts (W) and the irradiation density is expressed in watts per square meter (W/m2). For germicidal action dose is important. The dose is the irradiation density by the time (t) in seconds and expressed in joules per square meter (j/m2). (I joule is I W.second). UV rays destroys known waterborne viruses, bacteria, parasites and amoeba giving absolutely safe water.
8. Cross flow filtration: Cross flow membrane filtration removes both salts and dissolved organic matter, using a permeable membrane that only permeates the contaminants. The remaining concentrate flows along across the membrane and out of the system and the permeate is removed as it flows along the other side of the membrane.

There are several different membrane filtration techniques, these are: micro filtration, ultra filtration, nano filtration and Reversed Osmosis (RO). Methods used depends upon the kind of compounds that needs to be removed and their particle size. Below, are the techniques of membrane filtration :-

• Microfiltration

Microfiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.1 to 1.5 microns, are separated from a liquid. It is capable of removing suspended solids, bacteria or other impurities. Microfiltration membranes have a nominal pore size of 0.2 microns.

• Ultrafiltration

Ultrafiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.005 to 0.1 microns, are separated from a liquid. It is capable of removing salts, proteins and other impurities within its range. Ultrafiltration membranes have a nominal pore size of 0.0025 to 0.1 microns. The ultrafilter is a tough, thin, selectively permeable membrane that retains most macromolecules above a certain size including colloids, microorganisms and pyrogens. Smaller molecules, such as solvents and ionized contaminants, are allowed to pass into the filtrate. Thus, UF provides a retained fraction (retentate) that is rich in large molecules and a filtrate that contains few, of these molecules. Advantages of ultrafiltration is that it effectively produces highest quality water for least amount of energy disadvantages are, it will not remove dissolved inorganics.
• Nanofiltration

Nanofiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of approximately 0.001 to 0.005 microns, are separated from a liquid. It is capable of removing viruses, pesticides and herbicides.

• Reversed Osmosis (RO)

Reversed Osmosis, or RO, is the finest available membrane separation technique. RO separates very fine particles or other suspended matters, with a particle size up to 0.0001 microns, from a liquid. It is capable of removing metal ions and fully removing aqueous salts.

Reverse osmosis (RO) is a process that overcomes many of the shortcomings of distillation and ion exchange. To explain reverse osmosis let us first look at osmosis.

Osmosis is the diffusion of the solvent through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration. The semipermeable membrane is permeable to the solvent, but not to the solute, resulting in a chemical potential difference across the membrane which drives the diffusion.

The solvent flows from the side of the membrane where the solution is weakest to the side where it is strongest, until the solution on both sides of the membrane is the same strength (that is, until the chemical potential is equal on both sides).

If a pressure greater than the osmotic pressure is applied to the higher concentration side of the membrane, the normal direction of osmotic flow is reversed, pure water passes through the membrane from the concentrated solution and is thus separated from its contaminants. This is the basic principle of reverse osmosis (sometimes call hyper-filtration).
In practice, feedwater is pumped into a pressure vessel containing a spiral or set of hollow fibers of semi-permeable membranes. The purified water passes through the membrane to form the 'permeate'.

The contaminants accumulate in the residual water, called the 'concentrate', which is bled continuously to drain.

The latest generation of polyamide thin film composite reverse osmosis membranes which have replaced early cellulosic membranes, remove 95-98% of inorganic ions, together with virtually all the large non-ionic contaminants and organic molecules with a molecular weight greater than 100. Dissolved gases are not removed.

Due to this exceptional purifying efficiency, reverse osmosis is a very cost-effective technology for water purification system. However, it is limited by the relatively slow rate of production and is, therefore, normally used to fill a reservoir prior to use or further purification. Reverse osmosis tends to protect the system from bacteria and pyrogens. It is often combined with ion exchange to considerably improve product water quality.

The pore structure of RO membranes is much tighter than UF membranes. RO membranes are capable of rejecting practically all particles, bacteria and organics >300 daltons molecular weight (including pyrogens). In fact, reverse osmosis technology is used by most leading water bottling plants.
Because RO membranes are very restrictive, they yield slow flow rates. Storage tanks are required to produce an adequate volume in a reasonable amount of time.

Reverse osmosis is highly effective in removing several impurities from water such as total dissolved solids (TDS), turbidity, asbestos, lead and other toxic heavy metals, radium, and many dissolved organics. The process will also remove chlorinated pesticides and most heavier-weight VOCs. Reverse osmosis and activated carbon filtration are complementary processes. Combining them results in the most effective treatment against the broadest range of water impurities and contaminants.
The basic components are common to all reverse osmosis systems:

1. Cold Water Line Valve: This valve fits onto the cold water supply line and the end attaches to the inlet side of the RO pre filter. This is the filtered water source for the RO system.

2. Pre-Filter(s): Water from the cold water supply line first enters the RO pre filter assembly which removes sand silt, dirt and other sediment. The most commonly used pre-filters are sediment filters. Additionally, carbon filters may be used to remove chlorine, which can have a negative effect on TFC (thin film composite) & TFM (thin film material) membranes. Carbon pre filters are not used if the RO system contains a CTA (cellulose tri-acetate) membrane.

3. Reverse Osmosis Membrane: Reverse Osmosis is a process in which dissolved inorganic solids (salts) are removed from a solution (water). The semi permeable membrane allows only the water to pass through, which is delivered as permeate and the impurities or contaminates are flushed down the drain as retentate.

The TFC RO membrane is the heart of the system. The most commonly used is a spiral wound of which there are two options: the CTA (cellulose tri-acetate), which is chlorine tolerant, and the TFC/TFM (thin film composite/material), which is not chlorine tolerant. These membranes have a porosity of 0.0001 micron and removes pollutants viz. Bacteria, Pyrogens, Viruses, Pesticides, Hydro carbons, Radio active contaminants, Turbidity, Colloidal matter, Chlorine,Detergents, Industrial wastes, Asbestos, Dissolved solids -- Sodium, Calcium, Magnesium, Sulphates, Cadmium.

4. Post filter(s): After the water leaves the RO membrane, the product water goes through the post filter(s) which is generally activated carbon [either in granular(GAC) or carbon block(PAC) form]. Any remaining tastes and odors are removed from the product water by post filtration.
5. Automatic Shut Off Valve (SOV): To conserve water, the RO system has an automatic shutoff valve mechanism which can be of the types viz. Low pressure switch(LPS) or Weight sensor or High pressure switches. When the storage tank is full, this valve stops any further water from entering the membrane, thereby stopping water production. By shutting off the flow this valve also stops water from flowing to the drain. Once water is drawn from the RO drinking water faucet/tank, the pressure /weight in the tank drops and the shut off valves opens, allowing water to flow to the membrane and waste-water (water containing contaminants) to flow down the drain.

6. Check Valve: A check valve is located in the outlet end of the RO membrane housing. The check valve prevents the backward flow or product water from the RO storage tank. A backward flow could rupture the RO membrane.

7. Flow Restrictor: Water flow through the RO membrane is regulated by a flow control also known as reject valve. There are many different styles of flow controls. This device maintains the flow rate required to obtain the highest quality drinking water (based on the gallon capacity GPD of the membrane). It also helps maintain pressure on the inlet side of the membrane. Without the flow control very little drinking water would be produced because all the incoming tap water would take the path of least resistance and simply flow down the drain line. The flow control is located in the RO drain line tubing.

8. Storage Tank: The standard RO storage tank holds up to 2.5 gallons of water. A bladder inside the tank keeps water pressurized in the tank when it is full. The tank can also be a storage type built in or attached to RO system.

9. Faucet: The RO unit uses its own faucet, which is usually installed on the kitchen sink which delivers pure drinking water available to custom.

10. Drain Line: This line runs from the outlet end of the reverse osmosis membrane housing to the drain. This line is used to dispose of the impurities and contaminants found in the incoming water source (tap water). The flow control is also installed in this line.

Why we should drink Alkaline Water ?

When ever our body burns fuel it creates acidic toxins as a by-product and our body becomes acidic which can be due to diet, drinks and stress. These acidic wastes which build up in our body are in the form of cholesterol, allstones, kidney stones, arterial plaque, urates, phosphates and sulphates. These acidic waste products are the direct cause of the following chronic diseases:-

• Cardiovascular damage, including the constriction of blood vessels.
• Weight gain, obesity and diabetes.
• Bladder and kidney conditions, including kidney stones.
• Immune deficiency.
• Premature aging.
• Osteoporosis: weak and brittle bones, hip fractures.
• Joint pain, aching muscles and lactic acid build-up.
• Low energy and chronic fatigue.
• Slow digestion.

When this occurs, our body will restore its optimal pH by depleting certain minerals, such as potassium, calcium and magnesium from organs and bones. Thus our immune system becomes fatigued from dealing with an excess of acid. Our body then stores acidic wastes in muscles rather than releasing the acids into the bloodstream. This can be minimized by neutralizing acid build-up in the blood and maintaining a balanced pH by drinking the right water, exercise and avoiding highly acidic foods & drinks viz. alcoholic, caffeinated and sugar rich beverages because of their poor hydrating qualities.

Ionized Water restores your body's acid and alkaline balance. You'll be drinking a powerful antioxidant.

Waters with pH above 7-- 8.5(USA Standards) and up to 10.8 (BEST O.R.P. -90mV to -250mV) are considered best for drinking and are known by the name as Alkaline Waters. Alkaline water is produced by a small device known by the name as water ionizer which turns ordinary tap water into clean alkaline ionized water. It purifies and enhances domestic water in a two-step process – First, harmful contaminants are filtered out and then electrolysis is used to split the flow into two separate streams: ionized alkaline water for drinking and cooking; and ionized acid water for other household uses.

The alkaline nature of water enables it to neutralize the acids that build up in our bodies due to normal metabolic process and exercise. The electrolytes in alkaline water also act as antioxidants, scavenging for free radicals, if left unchecked.

NOTE On Oxidation Reduction Potential (O.R.P.) --

Virtually all liquids have an Oxidation Reduction Potential (ORP), which is the potential for one liquid substance to reduce the oxidation of another substance, as measured in millivolts (mV). In other words, the more powerful the antioxidant, the lower the ORP level. As things oxidize, the ORP rises. ORP is easily measured with a calibrated meter.

Normal tap water has an ORP of +250 to +400, meaning that its potential for reducing oxidation is nonexistent. Only a negative ORP can reduce or negate oxidation. Alkaline ionized water has an ORP of -200 to -700, depending upon the amount of minerals in the source water and how the ionizer is adjusted. This means it has a very high potential for reducing oxidation. Fresh squeezed orange juice has a -250 ORP, as do most other fresh squeezed juices and vegetables. However, if they have been pasteurized or otherwise processed, the antioxidant properties are diminished or removed.

Tests reveal that bottled mineral waters have an average ORP of approximately +200mV only slightly lower than ordinary tap water.

A simple demonstration of the antioxidant properties of alkaline water-- Steel wool was placed in normal tap water and in alkaline water. The containers were sealed. Steel wool in the tap water was rusted within a few hours; In alkaline water, the steel wool remained unrusted after 4 days. "We are advancing the theory that the most effective and economical source for an antioxidant is ordinary tap water after it is filtered and treated with electrolysis." Hidemitsu Hayashi, M.D. Director, Water Institute, Tokyo Japan.

ALKALINE IONIZED WATER

Lab Analysis of Ionized water from Jupiter water ionizer

The following analyses were performed by certified laboratories on water from a Jupiter Mavello ionizer, a model similar to the new Jupiter Melody.

Oxidation-Reduction Potential and pH:

Ionized Level                      O.R.P.                      pH
Tap Water                           +10mV                        7.0
Level 1 alkaline                    -165mV                       8.7
Level 2 alkaline                    -185mV                       9.7
Level 3 alkaline                    -215mV                       10.3
Level 4 alkaline                    -248mV                       10.8
Purified Water                      -20mV                         7.2
Super Oxide (Acid)               +65mV                        4.5
BEST O.R.P.                        -90mV to -250mV

Summary:

Measurement                     Improvement in ionized water over tap water
pH                                      34% increase
Calcium                              43% increase
Magnesium                          9% increase
Sodium                               20% increase
Potassium                           14% increase
Total alkalinity                     100% increase
Electrical conductivity           24%
ORP                                    100-200% decrease (i.e. more antioxidizing)

Water Glossary:

Anion – A negatively charged ion.

Anion Exchange Resin – An ion exchange material that removes anions from solution by exchanging them with hydroxyl ions.

Bed – Column of carbon, sand or ion exchange resins through which the water passes during treatment.

Biopure Water – Water that is sterile, pyrogen free and has a total solids content of less than 1ppm.

Boiler – The vessel used in distillation systems (or power plants) to convert water into steam.

Buffer – A solution that is capable of opposing small changes in chemical composition; particularly in pH.

Calcium – A metallic element often found in water, usually as dissolved calcium carbonate (CaCO3). Soluble in water, it causes hardness and subsequent scaling.

Carbon – A nonmetallic element that occurs in many inorganic and in all organic compounds. Is capable of chemical self-bonding to form an enormous number of important molecules.

Cation – A positively charged ion.

Cation Exchange Resin – Ion exchange resins capable of removing cations by exchanging them for hydrogen ions.

Chlorine – An element used to kill micro-organisms in water. At room temperature and atmospheric pressure it is a greenish yellow gas.

Condensate – Distillate just after it has been cooled from steam into the liquid state.

Conductivity – The reciprocal of resistivity, it is a measure of the ability to conduct an electric current. Since ionized impurities increase the conductivity of water, it is also an accurate measure of ionic purity. To measure it, current is passed between two electrodes a fixed distance apart. Conductivity is normally expressed as microsiemens/cm, identical to micromhos/cm.

Deionization – Removing dissolved ions from solution by passing it through a bed of ion exchange resins, consisting of polymer beads that exchange hydrogen ions for cations and hydroxyl ions for anions in solution. The ionic impurities remain bound to the resins, and the hydrogen and hyroxyl ions combine with each other to form water.

Demineralization – Sometimes used interchangeably with deionization, it refers to the removal minerals and mineral salts using ion exchange.

Desalination – The removal of dissolved salts from brine to produce potable water.

Dilution – Lowering the concentration of a solution by adding more solvent.

Disinfection – To destroy (but not necessarily all) of the harmful or objectionable microorganisms by means of chemicals, heat, ultraviolet light, etc. Also referred to as sanitization.

Dissolved Solids – Also referred to as Total Dissolved Solids (TDS), it is the amount of nonvolatile matter dissolved in a water sample, and is usually expressed in parts-per-million by weight.

Distillation – The process of separating water from impurities by heating until it changes into vapor and then cooling the vapor to condense it into purified water.

Effluent – The output or discharge from a water treatment process.

Electrolyte – A chemical compound which, when dissolved or ionized in water, allows it to conduct electric current.

Endotoxin – A poisonous substance present in bacteria that is released when the cell disintegrates. In water treatment, it most often refers to pyrogens.

Exhaustion – When absorbents, such as activated carbon or ion exchange resins, have depleted their capacity by using up all active sites. Ion exchange resins may be regenerated to reverse the process.

Feedwater – Water entering a treatment process.

Filtration – Removal of suspended matter by passing it through a porous matrix that prevents particles from getting through, usually by entrapment on or in the filter matrix.

Fouling – When gelatinous coatings, colloidal masses or dense bacterial growth form a compacted crust on membrane or filter surfaces which blocks further flow.

Gel – A continuous mass formed when colloids congeal.

Grains per Gallon – Concentration of dissolved ions in water, generally as calcium carbonate. 7,000 grains is equal to a pound. One grain per gallon is equivalent to 17.1 ppm of Dissolved Solids.

Hardness – Concentration of calcium and magnesium salts in water. Hardness is a term originally referring to the soap-consuming power of water. As such it is sometimes also taken to include iron and manganese. High hardness can cause boiler or pipe scale and failure of reverse osmosis membranes.

Inert – Does not dissolve in water, nor react chemically with other substances.

In-Line – An integral part of the flow path. In a fluid stream, something is said to be in-line if the entire fluid stream flows directly through it.

Inorganic – Commonly referred to as mineral, it includes all matter that is not animal or vegetable. Inorganic substances normally dissociate in water to form ions.

Ion – An atom or group of atoms with an electrical charge that is positive (cation) or negative (anion) as a result of having lost or gained electrons.

Ion Exchange – Also called deionization. A process in which harmless ions attached to the resin beads are exchanged for undesirable ions in solution. Typically, hydrogen ions are exchanged forany cations and hydroxyl ions for any anions. The hydrogen and hydroxyl ions combine to form pure water.

Leach – To dissolve by the action of a moving liquid. For example, high purity water leaches trace impurities from glass vessels.

Megohm-cm
– A measure of ionic purity in water. Resistivity (the reciprocal of conductivity) is a measure of specific resistance to electrical flow. The fewer dissolved ions in water the higher its resistivity. One megohm-cm is equivalent to one million ohms of resistance measured between two electrodes one centimeter apart. The theoretical maximum ionic purity for water is 18.18 megohmcm at 25°C.

Membrane – Filtration membranes are thin polymer films that are permeable to water and other fluids. Microporous membrane filters have measurable pore structures which physically remove particles or microorganisms larger than pore size. Ultrafiltration membranes, (sometimes called molecular sieves), also remove molecules larger than a specified molecular weight. Reverse osmosis membranes are permeable to water molecules, and very little else, rejecting even dissolved ions in water.

Mho – Unit of measurement for conductance; the reciprocal of ohm (resistance). Also see “Megohmcm”.

Micro – Prefix meaning one millionth, as in microgram, micrometer.

Micrometer – One millionth of a meter. Still widely referred to as a micron in the U.S., although micrometer is now the internationally accepted standard.

Micromho – A measure of conductance equal to one millionth of a mho.

Micron – See “Micrometer”.

Milli – Prefix meaning thousandths, as in milliliter, milligram.

Mixed-Bed Ion Exchange – Mixing both anion and cation resins in the same deionizer results in higher efficiency, but lower capacity than separate-bed deionizers.

Nano – A prefix meaning billionths, as in nanogram, nanosecond. One nanogram per liter is equal to one part-per-trillion (ppt is used only in the U.S.)

OHM – The practical unit of electrical resistance in a circuit, where a potential difference of one volt produces a current of one ampere.

Organic – Organic matter is a broad category that includes both natural and man-made molecules containing carbon and hydrogen. All living matter in water is made up of organic molecules. The most common are by-products of vegetative decay, such as tannins, lignins and humic acid.

Osmosis – The diffusion of a solvent through a semipermeable membrane from a less concentrated solution to a more concentrated solution.

Percent Recovery
– In reverse osmosis or ultrafiltration, the ratio of pure water output to feed water input.

Percent Rejection – In reverse osmosis or ultrafiltraion, the ratio of impurities removed to total impurities in the incoming feedwater. For example, RO membranes typically remove (reject) 90% of the dissolved inorganic contaminants in water.

Permeate – In reverse osmosis, the water that diffuses through the membrane, thereby becoming purified water.

pH – The negative log of the hydrogen-ion concentration. A solution with a pH lower than 7 is acidic. If its pH is higher than 7 it is alkaline.

Pico – A prefix meaning one trillionth, as in picogram.

Polished Water – High purity water after it has undergone a second treatment step. Ultrapure water usually undergoes two or more treatment steps; more economical pretreatment processes (e.g., reverse osmosis) are used to remove all but a very small fraction of the impurities, and highly efficient polishing processes (e.g., mixed-bed deionization) are used to remove the impurities that remain.

PPB – Parts per billion, or micrograms per liter. Abbreviated ppb only in the U.S. One part per billion is like seeing a bottle cap on the earth’s equator from an orbiting satellite.

PPM – Parts per million. The most common measure of dissolved ionized impurities in water. The same as milligrams per liter.

Pretreatment – Initial water treatment steps performed prior to final processing to prolong the life of cartridges and filters and to protect downstream elements form premature failure.

Product Water – The purifie