Unit - 2

Quality of Water

2.1 Quality of Water

• The quality of water provided for the drinking purpose, needs to have the minimum Indian standards. The water treatment is a costly business.
• So before the water supply scheme is launched, it is necessary to locate the right sources of water where the quality of the natural water itself is better.
• Better the quality of water at the source level lesser I would be the cost of water treatment. So the water samples must collected and analyzed to know the quality of water available at the source.
• If there are more than one source of water the site where the better quality of water is available must be selected for the water supply scheme.

2.2 Sources of Impurities

There are numerous sorts of impurities in water ingesting structures and reserves.

Biological Impurities in Water:

• Biological impurities in water are due to the presence of residing organisms.
• These consist of algae, protozoa, pathogens, bacteria, viruses, microbes, and parasites along side their cysts (eggs) in infected water.
• The latter are really referred to as germs, microorganisms that could reproduce at alarming rates.
• Contaminated water is likewise one of the principal reasons of gastroenteritis for humans of every age throughout the United States.

Colloidal Impurities in Water:

• Colloidal impurities in water consist of natural waste merchandise and amino acids.
• This trouble takes place because of touch with suspended count number and factors like sand, rocks and natural count number flowing in rivers, streams and lakes that renders water undrinkable or non-pure.
• Sources of chemical impurities in water consist of:

1. Gases which might be picked up from the environment with the aid of using rainwater and torrential downpours
2. Decomposing animals and flowers observed close to streams, rivers and lakes
3. Industrial sewage and wastewater
4. High degrees of calcium, iron, magnesium, sodium, and chlorides in river water
5. Organic compounds stemming from agricultural and home commercial waste. These are referred to as anthropogenic contaminants, that are observed in herbal and ingesting water.
6. Inorganic compounds stemming from scientific wastewater and gadget structures

2.3 Common impurities in water and their effects:

Each impurity incorporates its personal dangers to chemical and organic studies, now no longer to say the negative impact they motive to the pleasant of natural water. Here we speak the eight major varieties of water contaminants, and the way they may be prevented.

1. Microorganisms

• Bacteria, algae and fungi all often intervene with sterile studies applications. Bacteria can adversely impact mobileular and tissue tradition via way of means of competing at enzyme-energetic web sites on substrates.
• If free-floating microorganism shape biofilms on surfaces, they may be extraordinarily hard to do away with. These biofilms can develop for numerous years, spontaneously liberating bursts of microorganism, at the side of their related endotoxins and nucleases.
• These nucleases then wreck down DNA and RNA in samples, an and the endotoxins may have a poor impact at the boom and characteristic of cells.

2. Viruses

• Viruses – known as non-residing nucleic acids – adversely have an effect on tissue and mobileular boom. They’re extraordinarily small, with maximum of them falling among 0.01 – 0.3 microns, and they could live to tell the tale for lengthy intervals of time. Once they’ve been noticed in water, they must be eliminated as quickly as possible.

3. Pyrogens

• For mammalian mobileular cultures, and the education of answers or gadgets a good way to later have touch with people and different mammals, it’s important that the water used is pyrogen-free.
• The maximum substantial aspect of pyrogens – a shape of endotoxin – is lipopolysaccharides (LPS), that's derived from Gram-poor micro organism walls. If LPS receives into the blood or spinal fluid, it is able to be poisonous and motive a fever.

4. Dissolved Inorganic Ions

• Silicates, chlorides, calcium, fluorides, magnesium, phosphates, bicarbonates, sulphates, nitrates and ferrous compounds are all sorts of dissolved inorganic ions.
• The instability in water resulting from those ions will negatively impact chemical and organic reactions. Results encompass the formation of protein-protein and protein-lipid interaction, changing enzymatic activity, and delaying the boom of cells and tissue.

5. Dissolved Organic Compounds

• These are derived from animal and plant decay, further to any human sports that contain the advent of alcohol, protein, pesticides, chloramine, herbicides or detergents into the environment.
• Dissolved natural compounds intervene with excessive overall performance liquid chromatography (HPLC), fueloline chromatography and fluoroscopy.

6. Dissolved Gases

• Water consists of evidently dissolved carbon dioxide, nitrogen and oxygen, however those gases can regulate the pH of lab water, which upsets the ionic balance. Concentrations of oxygen and nitrogen can have an effect on the fee of biochemical reactions; and excessive attention of dissolved gases can motive a bubble formation, which obstructs the glide via chromatography columns and micro-channels.
• Dissolved carbon dioxide increases water acidity, lowering the potential of ion change resins in DI systems.

7. Suspended Particles

• When big suspended debris of clay, sand, silt or plants among 1 – 10µm are located in water, they motive turbidity and settle on the bottom.
• Suspended debris can foul opposite osmosis membranes, filters and chromatography columns, specially if the machine stems from a reservoir or tank in the building.

8. Colloidal Particles

• Colloidal debris are a lot smaller than suspended debris, at simply 0.01 – 1.0µm, and that they don’t settle.
• Colloidal debris often intervene with analytical techniques, and skip ion change resins, which bring about decrease resistivity in DI water.

How to Prevent Contaminants:

• The major manner to save you and do away with contaminants are via water purification systems. Different technology had been created, every specialising withinside the elimination of particular contaminants.
• For example, even as the procedure of distillation won’t do away with ionised gases, inorganic ions or dissolved non-ionised gases, they may filter micro organism and pyrogens.
• Reverse osmosis (RO) is hailed as one of the simplest methods of eliminating contaminants, as this procedure gets rid of as much as 99% of impurities in water. Dissolved organics and ionics, suspended impurities, micro organism and pyrogens are all eliminated from water while RO is used.
• To conclude, contaminants may be very adverse to water. Once located, they must be eliminated as quickly as possible, the usage of the simplest shape of water purification technology.

2.4 Water Analysis- Physical, Chemical and Biological Characteristics

Physical Characteristics:

Following physical parameters are used to calculate the physical quality of water.

1. The Colour
2. Taste and Odour
3. Temperature
4. Turbidity

1. Colour:

• The pure natural water does not have any colour. The presence of any organic and in-organic matter in the water gives the colour like green, blue, black, red etc.
• When the industrial waste gets mixed up with the surface water the colour is added to the natural water.
• It is necessary to investigate the source of this chemical contamination must be indentified to reduce the danger of water pollution.
• The changes in the colour of water can be qualified by making use of the space photometer.
• The unit of measurement of intensity of colour in the water is cobalt-platinum (copt) unit.

2. Taste and Odour:

• In fact the pure water is tasteless and odourless. The organic matter, industrial wastes, gives a different odour and the taste also changes.
• In case of stored water, the odour and tastes are developed. The underground water, mainly.
• The well water gets a typical taste and odour also because it gets some dissolved chemicals when it percolates through the rocks. Such water is also called as hard water.

3. Temperature:

• We generally prefer to consume cool water but if the water is warm the growth of micro-organisms is promoted and the taste, odour and colour also get changed.

4.Turbidity:

• It is the suspended matter like mud, clay, algae and micro-organism that make the water turbid.
• This turbidity can be measured by using turbidity meter and the unit of measurement is Nephelometric Turbidity unit (NTU).
• The unit of measurement is PPM or mg/per litre on silica scale e.g. are mg of colloidal silica suspended in one litre of distilled water, produces one unit of turbidity.

Chemical Characteristics:

Following Chemical parameters are used to calculate the chemical quality of water.

1. Total Dissolved Solids (TDS)
2. PH
3. Hardness

1. Temporary hardness
2. Permanent hardness

1.Total Dissolved Solids (TDS)

• They are composed of inorganic salts, mainly the chlorides, sulphates and bi-carbonates of calcium, magnesium, potassium and sodium.
• The industrial waste makes the addition of these TDS. It also is added in case of underground water which collects those inorganic components in the process of percolation.
• The TDS in the water can be measured by simple evaporation method or by using TDS meter. The unit of measurement of T.D.S. Is mg/l (mg/per litre).

2. PH

• It is the value of hydrogen ion concentration in the water on the base of the pH value, it is called as acidic or alkaline.
• The normal pH value of water is seven, if it is less than seven, the water is called acidic water, if it is more than seven it is called as Alkaline water.
• The pH value is measured by pH meter or by using pH paper, which changes its colour when dipped in the water.
• By using the colour code, the pH value can be measured.

3.Hardness

• The hardness to the water is of two types:

a. Temporary hardness:

• It is caused by soluble bicarbonates which can be removed by boiling the water.

b. Permanent hardness:

• It is caused by sulphate and chlorides of calcium and magnesium. It can be removed by using iron exchange methods.

The following components make the water hard:

• Sodium, Iron and manganese, chlorides, sulphate, Nitrates. The Fluorides in the water is an important parameter of good quality of water.
• If the concentration is less than 1.0 mg/l, it gives rise to dental caries among the children and if it is more than 1.5 mg/1, it may cause dental and skeletal flurosis.
• The fluoride content in the water is measured by spectrophotometer.
• The toxic materials like heavy metals, pesticides, industrial chemicals, can have acute effects as the human being if consumed in large quality or for a long period.

Biological Characteristics:

The presence of micro-organism like bacteria and Virus make the water contaminated. All the micro organism are not harmful to human beings but the micro organism which are pathogenic cause water bome diseases.

Biological Tests:

For the Biological or Bacteriological following tests are observed.

1. Total count of Bacteria
2. Bactria coli (B-coli) Test or E Coli Test

1.Total count of Bacteria:

• In this, the total number of bacteria present in one millilitre of sample water are counted. The sample water is diluted one millilitre water is diluted in 99 ml of sterilized water.
• Then 1 ml diluted water is mixed with 10 ml of agar of gelatine i.e. culture medium. This mixture is then kept in the Incubator at 37°C temperature for 24 hours or may be at 20°C temperature for 48 hours.
• After this required period the sample is taken out from the incubator and then the colonies of bacteria are counted under microscope.
• This product of the number of colonies and the dilution factor will give the total number bacteria/per ml of the undiluted water sample.

2. Bactria coli (B-coli) Test OR E Coli Test

• Two tests are designed for B-coli. The 1st test is known as presumptive test and the 2nd test is known as the confirmative test.
• In case of 1st i.e. the presumptive test, a definite amount of diluted water sample water, is kept, in standard fermentation tubes, which contain, lactose broth, as a culture medium.
• These tubes are kept in the incubator at 37°C temperature for 24 hrs to 48 hrs.
• If, after this period, a gas is produced in these fermentation tubes, it is an indication of presence of B coli and if these is no gas formation it is an indication of no-presence if B-coli in the sample. In the 2nd i.e. the confirmation test some sample from presumptive tube is taken and is placed in another fermentation tube which contains Brilliant green lactose bile, as a culture medium.
• It is also kept in the incubator at 37°C temperature for 48 hrs. If it again produces gas that confirms the presence of B-coli and water is unsafe for consumption purpose.
• Now a days, an another method has been introduced to find out the B-coli. In is known as "Membrane Filter Technique." It is a very simple technique. The sample water is filtered through a sterilized membrane of special design to collect all the bacteria, present in the sample water. The membrane is then put contact of culture medium i.e. M-Endo's medium, in the incubator at 37°C temperature for 24 hrs.
• After the incubation period the membrane is kept under the Microscope to count the colonies of Bacteria. Previously the standard statistical tables were referred to determine the Most Probable Number (MPN) of B coli per 1000 ml, MPN indicates the density of bacteria in the water sample.
• As the new technique 'Membrane filter' has been. Introduced the MPN methods are not used.
• In drinking water at least 5 samples of 100 ml, each should be collected and tested. The number of C-coli colonies per std sample should not be more than 4 per 100 ml of sample water.

Key Takeaways:

Following physical parameters are used to calculate the physical quality of water.

1. The Colour
2. Taste and Odour
3. Temperature
4. Turbidity

2.5 Water Borne Diseases:

Human health gets affected by the consumption of contaminated water, either directly or through food. The water related diseases may be grouped as:

1. Water borne diseases
2. Water based or water induced diseases
3. Water related vector diseases
4. Water diseases

1.Water Borne Diseases:

• These diseases are caused by the consumption of contaminated water having virus or bacteria. The viral diseases are viral hepatitis A, hepatitis E, Poliomyelitis and rotavirus diarrhoea.
• The Bacterial diseases are, Typhoid, and Paratyphoid fever, Bacillary dysentery, E Coli diarrhoea and Cholera etc.
• Excess levels of nitrates cause blood disorders, the pesticides in the drinking water may cause cancer and neurological disorders. It may cause infertility.

2.Water Based or Water Induced Diseases:

• Aquatic organism that live a part of their life cycle in water and the rest as a parasite in human body lead to several diseases e.g. Guinea worm disease is spread through Cyclops.
• The round worm, thread worm, live in the small intestine mainly of children.

3.Water Related Vector Diseases:

• The insects such as mosquitoes that breed in stagnant water, causes Malaria, Filasia, Dengue fever.
• Among these Dengue fever causes very high mortality.

4.Water Scarcity Diseases:

• In the areas having, scarcity of water and lack of sanitation, there is a high incidence of diseases, such as Tuberculosis (T.B.), Leprosy, Tetanus etc.
• They are the results of poor personal and social hygiene, mainly in the rural areas of India. It may cause the diseases like Trachoma, Conjunctivitis and scabies.
• All the above diseases can be put under control if the safe drinking is made available and the level of personal and social hygiene is improved by the government and non-government organizations.

Key Takeaways:

Human health gets affected by the consumption of contaminated water, either directly or through food. The water related diseases may be grouped as:

1. Water borne diseases
2. Water based or water induced diseases
3. Water related vector diseases
4. Water diseases

2.6 Indian and WHO drinking standard:

• The quality of drinking water depends upon various parameters such Physical, Chemical, and as Microbiological.
• The quality of water used for drinking must be followed to achieve good health and to control various water borne or water induced diseases.
• In the third world countries like the Asian and African countries about 90% of the total morbidity cases, in a year, are related to the consumption of water which does not maintain the given standards of drinking water.
• There are various agencies who play an important role in specifying the norms to fix the water quality standards such as-

1. Indian Standards Institution (I.S.I)
2. World Health Organisation (W.H.O)
3. United States Public Health Service (U.S.P.H.S)
4. Indian Council of Medicine Research (I.C.M.R)

• Let us study the norms put forth by I.S.I. (IS.10500) in 2010 for drinking water specifications:

Quality of water as per IS 10500 (2012):

Table: Physical parameters

Key Takeaways:

The quality of drinking water depends upon various parameters such Physical, Chemical, and as Microbiological.

References:

1. G.B Masters, Introduction to Environmental Engineering and Science, Pearson Education,2013
2. M.Chandrasekhar, Environmental science, Hi Tech Publishers,2009
3. Gerard Kiely, Environmental Engineering, McGraw Hill Education Pvt.Ltd, Special Indian Edition, 2007