M.SC SEM2.ADITI BAJPAI.PAPER3water purification system.Z_22_40.docx.pptx

Lucknow University
Internal Assessment
ISABELLA THOBURN COLLEE
TOPIC- Water purification system
Paper- 3 quantitative biology and bioinstrumentation
Submitted to- department of zoology
Submitted by-
Name- Aditi Bajpai
Class-M.sc semester- 2
Roll No.- z/22/40

1. Introduction
2. Methods of purification
3. Artificial method- on large scale ;on small scale
4. Purification of water on large scale: slow sand filters; rapid sand filters;
desalination;
5. Steps of purification on large scale: storage, filtration, disinfection;
6. Storage: physical changes; chemical; biological changes;
7. Filtration: slow sand filters and rapid sand filters;
8. Slow sand filters;
9. Rapid sand filters(mechanical filters)
10. Chlorination
11. Purification of water on small scale
12. Examination of water
13. WHO criteria for water
contents

 Water purification is the removal of contaminants from raw
water to produce clean water, that is pure enough for human
consumption or for industrial use.
 Many contaminants are removed to improve water’s taste,
smell and appearance.
 Small amounts of disinfectant is left intentionally at the end of
a treatment process to reduce risk of recontamination in the
water.
 It is not possible to tell the purity of water by visual
appearance.
 Most water is purified and disinfected for human
consumption, but water purification may also be carried out
for variety of other purposes, including medical,
pharmacological, chemical and industrial applications.
Introduction

ARTIFICIAL METHODS
A. PURIFICATION OF WATER ON LARGE SCALE
B. PURIFICATION OF WATER ON SMALL SCALE
PUIFICATION OF WATER ON LARGE SCALE
 At large scale, it is done by FILTRATION, which may be-
I. Slow sand filtration
II. Rapid sand filtration
III. Desalination
Methods

 The components of a typical water purification system
comprises one or more of the following measure.
 A typical water supply carries the following steps in
purifying the water
1. Storage or sedimentation
2. Filtration
3. Disinfection or chlorination
Purification of water on large scale

1. Storage
A. PHYSICAL:
 By mere storage the quality of water improves.
 About 90% of the suspended impurities settle down in 24
hours by gravity.
 The water becomes clearer.
 This also improves the turbidity of water.
 This allow penetration of light and reduce the work of
filters.
PURIFICATION ON LARGE SCALE

B. Chemical
 Certain chemical changes also occur during storage.
 The aerobic bacteria oxidize the organic matter present in the
water with the aid of dissolved oxygen.
 As a result the content of free ammonia is reduced and rise in
nitrates occurs.
 c. Biological
 The pathogenic organism die out due to antibiosis and oxidation.
 Stored river water: bacterial count drops by as much as 90%
 One of the greatest benefits of storage
 If the water is stored for long periods there would be development
of plants such as algae which imparts smell to water.
Storage

2. Filtration:
 It is the oldest and universal method of storage.
 Filtration reduces the bacterial content by 90 to 99%, turbidity
by 50PPM to 5PPM and color to colorless.
 There are two types of filters:
a) SLOW SAND FILTERS(BIOLOGICAL FILTER)
b) RAPIDSAND FILTERS(MECHANICA FILTERS)
Purification on large scale

 They are cheap and easy to design and occupy less space.
 First used in 1804 in Scotland and subsequently in London.
 They contain concrete made basin, which contains the
selected graded sand, supported on stones.
Slow sand filtration

TYPES
GRAVITY TYPE
PRESSURE TYPE
STEPS
COAGULATION
RAPID MIXING
FLOCCULATION
SEDIMENTATION
Rapid sand filtration

 In 1885 the first rapid sand filters were installed in the USA.
 Rapid sand filters are of two types:
 A.GRAVITY TYPE( e.g Paterson’s Filter)
 B.PRESSURE TYPE(Candy’s Filter)
 Both types are in use.
 Following steps are involved in the purification of water :
1. Coagulation:
 The raw water is treated with chemical coagulant such as alum.
 The dose of alum varies rom 5-40 mg or more per liter.
2. Rapid mixing:
 The treated water is then subjected to violent agitation in a
“mixing chamber” for few minutes.
 This allows a quick and thorough dissemination of alum.
Rapid sand filtration(Mechanical filters)

3. FLOCCULATION:
 The next phase involves a slow and gentle
stirring of the treated water in a “Flocculation
chamber” for 30 min.
 The mechanical type is most widely used.
 It consists of a no. of paddles which rotates at 2
to 4 rpm with the help of motors.
 It results in the formation of thick, copious,
white flocculent precipitate of aluminum
hydroxide.
 The thicker the precipitate or flock diameter,
the greater the setting velocity.
Rapid sand filters( Mechanical filters)

4.Sedimentation:
 The coagulation water is now led into sedimentation
tanks where it is detained for periods varying from 2-6
hours. When the flocculent precipitate together with
impurities and bacteria settle down in the tank.
 At least 95% of the flocculent precipitate needs to be
removed before the water is admitted into rapid sand
filter.
Rapid sand filters

 Rapid sand filters needs frequent washing daily or weekly.
 Washing is accompanied by reversing the flow of water
through the sand bed which is called back washing.
 It removes impurities and cleans the sand bed.
 The whole process of washing takes about 15 minutes.
 In some rapid sand filters compressed air is used as part of
back washing.
Back washing

3. Chlorination:
 For disinfection on large scale water chlorine is applied either as:
 Chlorine gas
 Chloramines
 Perchloron
 Chlorine gas is the first choice, because it is quick in action, efficient
and easy to apply.
 But chlorine gas is an irritant to eyes and poisonous.
 A special “chlorination equipment” known as Paterson’s chloronome
is required for measuring, regulating and administeration of chlorine
gas to water.
Purification on large scale

 Chlorination is one of the greatest advances in water
purification.
 It is supplement, not a substitute to stand filtration.
 Chlorine kills pathogenic bacteria, but it has no effect
on spores and certain viruses (e.g polio, viral hepatitis).
 It oxidizes iron, manganese and hydrogen sulphide.
 It also helps in destroying some odour producing
constituents, so improves the taste and odor.
 It controls algae and acid coagulation.
Chlorination/disinfection

 At small scale or domestic level, is carried out by:
I. Boiling
II. Chemical disinfection
III. Filtration
IV. Solar radiation
i. BOILING
 To be effective the water must be brought to a “rolling boil”
for 10-20 minutes.
 It kills the bacteria, spores, cysts, ova and yields sterilized
water.
 Boiling also removes temporary hardness by driving off
carbon dioxide and precipitating the carbon dioxide.
Purification of water on small scale

 Bleaching powder:
 Bleaching powder or chlorinated lime is a white amorphous
powder
 When freshly made it contains about 33% of” available
chlorine”.
 Chlorine solution:
 4kg of bleaching powder with 25%chlorine is mixed with 20
liters .of water, it will five a 5% solution of chlorine.
 Chlorine tablet:
 they are good for disinfecting small quantity of water.
 A single tablet of 0.5 g is sufficient to disinfect 20liters of
water.
II. Chemical disinfection

 Water can be purified on small scale filtering though
ceramic filters such as Pastuer chamberland filter.
 Filter candles usually remove bacteria found in
drinking water.
 They should be cleaned by scrubbing with hard brush
under running water.
III. Filtration on domestic level

 This is done by four ways:
1. Physical examination
2. Chemical examination
3. Bacteriological examination
4. Radiological examination
Assurance of water quality

1. No sample should have E.Coli in 100 ml of water
2. Not> 3 coliform should be present in 100 ml of
water.
3. Not> 5% of sample through out year should have
coliform in 100 ml of water.
4. No two consecutive sample should have coliform in
100 ml of water.
WHO criteria for water

 BOOKS:
 Modern trends in biology and economic zoology.
Page no. 16-21, H.C.NIGAM, 2011-12, Vishal publishing
Co.
 Websites:
 https://ihatepsm.com/blog/slow-sand-filter-
biological-filter#google_vignette
 https://www.thewatertreatments.com/wastewater-
sewage-treatment/317/
BIBLIOGRAPHY

M.SC SEM2.ADITI BAJPAI.PAPER3water purification system.Z_22_40.docx.pptx

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