To be palatable, water must be significantly free from colour, turbidly, taste and Adour and of moderate temperature in summer and winter and well aerated. At least 4 human perceptions respond to these qualities.
IMPURITIES IN WATER
Impurities in water may be organic, inorganic and living organisms. Both organic and inorganic impurities may be in the form of suspended, colloidal, sett liable and dissolved state.
SUSPENDED IMPURITIES includes silt, clay, Algae, Tung, organic and inorganic matters and mineral matters etc…. They neither settle down nor dissolve in water and are microscopic and make water turbid. Bacteria cause diseases while silts, clay, Algae, protozoan?s cause turbidity, odor and colour in water. The concentration of suspended matter in water is measured by turbidity.
Colloids are particles in a finely divided state. They are neither in suspension nor insolvable but in condition midway between the two. These particles are so small that their removal in a sedimentation tank is impossible at reasonable overflow rates and detention time. They are not visible to the naked eye and are electrically charged and repel cash other. The size of these particles is between 1 minor to 1 mille micron. They impart colour to the water.
Their numbers may be very large because water is a very good solvent and can dissolve all the salts to which it comes in contact. Salts of calcium, magnesium when dissolved in water cause taste, hardness, alkalinity, etc….
Particles of silt and clay
I)Carbonates and bicarbonates of calcium and mg.
ii)Sulphates and chortles of ca and mg.
iii)carbonates and bicarbonates of sodium
v)chlorides of Na
vi)Fluorides of Na
Hardness & alkalinity
Hardness and corrosion
Excess over 50mg/lit
Methenoglubanemiao r blue babies. Brackish taste
Excess over 1.5mg/L causes Fluor sis.
Taste colour and hardness
Taste and odour
Dead animals, hairs, insects, etc..
Large Quantities of albuminoidal nitrogen with little quantities of ammonia and chlorides.
Large quantities of Albuminoidal nitrogen
Acidity, taste and colour Contamination
Pathogens, contamination due to sewage. Etc…
May bacterias are found in water most of them are of no sanitary significance. Few in numbers are pathogenic. These include bacteria causing typhoid fever, Para typhoid, Dysentery,
Gastro enteric diseases, etc…
Water bacteria may be classified in 4 ways.
1) According to Oxygen Demand
a. Aerobic bacteria = those which require light and free oxygen for their living and development.
b. Anaerobic bacteria = those which do not require light and free oxygen for their living and development.
c. Facultative bacteria = those which can exist in presence or absence or light and free oxygen. They grow more in absence of oxygen.
2) According to Shape
a. Cocci bacteria = Cells are round or spherical.
b. Bacilli = Cells are rod shaped.
c. Spirilla = Spiral shaped cells.
3) According to their diseases producing characteristics
a. Pathogenic bacteria = those which are harmful to human life. They causes diseases like typhoid, Dysentery, cholera, etc…
b. Non-pathogenic bacteria = those do not cause diseases to human.
4) According to the Temperature Flourish
a. Psycryophilic bacteria = which can persist at low temperature only Range 10 - 200C.
b. Mesophillic = which can thieve within the temperature range of 200C to 400C.
c. Thermophillic = It is most effective in the temperature range of 40-650C.
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