water supply engineering. ce 704. world university of bangladesh. chapter 7

8/12/2019 water supply engineering. ce 704. world university of bangladesh. chapter 7

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INDEXChapter No: Contents:

01 Introduction

02 Water Requirements

03 Ground Water

04 Surface Water Collection & Transportation

05 Pumps and Pumping Machinery

06 Hydraulics of Flow

07 Water Quality

08 Water Purification

09 Distribution System

10 Industrial Water Supply

11 Planning & Design of Water Purification Plant


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To slake mans thirst and other needs, water must be pure.

But pure water is not be found in nature. There are various

impurities present in natural water. The impurities present in

water are classed into four different groups :

(1) Impurities of Mineral Origin(2) Impurities of Organic origin

(3) Living Impurities and

(4) Radioactive Impurities


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TABLE : IMPURITIES PRESENT IN WATER01 02 03 04

In Suspension :

Silt, Clay and colloids

Decomposable organic

matter in sewage, industrialwastes, plants, leaves and

organic colouring matter

Bacteria, algae,

Protozoa, fungiand other

living

organisms.

Radioactive

substances likeradium,

uranium,

cobalt, etc.In Solution :

Carbonates, bicarbonates, sulphates

and sulphides of potassium, sodium,

calcium, and magnesium, hydroxides

of iron, etc.

Organic matter, organic

acids, etc.

In pseodo solution :

Silica, alumina, iron oxides, etc.

Colloidal decomposable

organic wastes such asanimal secretions, etc.

Dissolved gases :

Oxygen, carbon dioxide, nitrogen,

ammonia, hydrogen, etc.

Methane, hydroxide ,

sulphide, etc.


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TABLE : CLASSIFICATION OF IMPURITIES IN RAW-WATERS ACCORDING TO

BEHAVIOR IN CONVENTIONAL WATER-WORKS TREATMENT PLANTS.Class A

Impurity can not be reliably

removed.

Class B

Impurity can not be reliably

removed to within

acceptable limits.

Class C

Impurity interferes with

treatment processes.

Chloride Phenolic

Fluoride substances,

Sulphate Petroleum,

Nitrate hydrocarbons, Arsenic

Dyestuffs,

Lead Synthetic,

Copper organic,

Zinc wastes,

Barium Radioactive,

Selenium substances,

Chromium synthetic,

Cadmium,

Detergents(?),

Magnesium,

Alkali metals.

Bacteria,

Inorganic suspended matter,

Dissolved natural organic

matter (coloured).

Dissolved natural organic

matter (colourless).

Iron

Manganese

Calcium

Magnesium

Free carbon dioxide

Ammonia

Phosphates

Nutrients

Planktonic

Algae, etc.


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EFFECT OF IMPURITIES :The Table shows the effect of impurities present in water.

Name of the Impurities Effect

Bacteria

Algae, Protozoa, Fungi,

Clay and colloids.

Diseases

Diseases, odour, colour, turbidity

Turbidity

Salts of calcium and magnesium

Carbonates

Bicarbonates

Sulphates

Chlorides

Hardness, alkalinity, taste, corrosiveness, scale formation.

Hardness, alkalinity, taste, corrosiveness, scale formation.

Hardness, taste.

Hardness, corrosiveness, taste.

Salts of sodium

Carbonates

Bicarbonates

Sulphates

fluorides

Chlorides

Alkalinity,

Alkalinity,

Foaming and Scaling

Tooth-decay

Taste

Iron Oxides Taste, red water hardness, corrosiveness

ManganeseVegetable dyes

Black or brown water.Colour, acidity.

Gases

Oxygen

Carbon dioxide

Hydrogen sulphide

Nitrogen

Corrosive to metals

Acidity, Corrosive to metals

Odour, acidity, corrosive to metals

Child-desease, algal growth

Radioactive Impurities. Diseases.


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Bacteria are the basic plant unite

being the simplest form of plant life.

Bacteria are the smallest living

organisms and the most numerous in

compost; they make up 80 to 90% of

the billions of microorganisms

typically found in a gram of compost.

Bacteria are responsible for most of

the decomposition and heat

generation in compost. They are the

most nutritionally diverse group of

compost organisms, using a broad

range of enzymes to chemically break

down a variety of organic materials.


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The rod is the most common bacterial form andcan be observed in three distinct groups :

1. Individual cells

2. Diplo or twin cells and

3. Chains of cells.


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The spheres have the most different groups :

1. Individual

2. Diplo

3. Tetrad

4. Cube

5. Chain

6. Clumps.


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# According to metabolism bacteria are dididedinto two distinct groups :

1. Autotrophic Bacteria

2. Heterotrophic Bacteria.


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Fungi are similar to bacteria. In fact, to be technical, the

bacteria are actually fungi, fission fungi. Fungi include molds

and yeasts, and collectively they are responsible for the

decomposition of many complex plant polymers in soil and

compost. In compost, fungi are important because they

break down tough debris, enabling bacteria to continue the

decomposition process once most of the cellulose has been

exhausted. They spread and grow vigorously by producing

many cells and filaments, and they can attack organic

residues that are too dry, acidic, or low in nitrogen for

bacterial decomposition.

Most fungi are classified as saprophytes because they live ondead or dying material and obtain energy by breaking down

organic matter in dead plants and animals. Fungal species are

numerous during both mesophilic and thermophilic phases of

composting. Most fungi live in the outer layer of compost

when temperatures are high. Compost molds are strict

aerobes that grow both as unseen filaments and as gray or

white fuzzy colonies on the compost surface.
http://compost.css.cornell.edu/gifs/08.gif


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The third group of microscopic

plants are the algae. The algae

differ from the fungi and

bacteria in their ability to carryout photosynthesis. The algae

can utilize the energy in light

and do not have to depend

upon the oxidation of matter tosurvive. In fact the algae evolve

oxygen during their growth in

presence of sunlight.


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The viruses are the smallest plants known at present

time. They are intracellular parasites and are highly

specific in their reactions, some with plants and somewith animals, viruses are present both in air and water,

Both types are pathogenic to man, animals and plants.


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Type of virusesType of Disease

caused

Mode of Transmission

Dermotropic Various pox-like

diseases

Close contact, water, air,

food & milk.

Neurotropic Pollimyelitis Water-borne.

Pneumotropic Influenza, colds Nasal and oral discharges,

water, air, food & milk.

Viscerototropic Cancer Water, Food & milk.

Neoplastic Eye diseases Close-contact, air & water.

Enteric Diarrhoea, nauses,

vamiting, Polio-like

diseases and

infectious hepatitis.

Water, Food & milk.

TABLE : VIRUS-DISEASES


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Protozoa are one-celled

microscopic animals. Theyare found in water droplets

in compost but play a

relatively minor role in

decomposition. Protozoa

obtain their food from

organic matter in the same

way as bacteria do but also

act as secondary consumers

ingesting bacteria and fungi.


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Rotifers are microscopic

multicellular organisms

also found in films of water

in the compost. They feed

on organic matter and also

ingest bacteria and fungi.


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The Table shows the bacteria & viruses

responsible for various types of waterborne diseases.Name of Diseases Organisms Responsible

1.Typhoid Fever

2.Paratyphoid Fever

3.Amoebic Dysentery

4.Bacillary Dysentery

5.Cholera

6.Small-pox &chicken pox

7.Gastroenteristis

8.Poliomyelitis

9.Schistosomiasis

10.Infections Hepatitis

11. Anthrax

12.Tularemia

13.Influenza, Colds

14. Pneumonia

15. Diphtheria16. Cancer

17. Polio-like Diseases

18. Urinary Inflamation

19.Wahooping cough

20.Tuberculosis

21. Leprosy

Bacillus Typhi

Eberthela typhosa } Bacteria

Salmonella Paratyphi (Bacteria)

Endamoeba Hystolytica (Protozoa)

Shigella Dysenterie (Bacteria)

Vibrio Comma (Bactria)

Dermotropic Viruses

Enteric Virous

Neurotropic Viruses

Cercarnie (animal parasites)

Enteric Viruses

Bacillus Anthraacis (Bacteria)

Spirochetes (Bacteria)

Pneumotropic Viruses

Diplo Coccus Pneumonia (Bactera)Corynebacterium Diphtheria (Bactera )

Viscerotropic viruses

Enteric Viruses

Escherichia Coli (Bacteria )

Hemophilus Pertussis (Bacteria)

Mycobacterium Tuberculosis (Bacteria)

Mycobacterium Leprae.


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A variety of Poisons may conceivably

Find their way into public water supplis among them

Toxic substances leached from mineral formation suchas fluorapatitis

Phytotoxins produced by specific algae

Heavy metals dillosved from water work structureprincipally metallic pipes & improperly manufacturedplastic pipes

Poisonous compound contained in industrial &

household westes emptied into water courseRadioactive substance in fallout & from the nuclear

energy industry.


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To be palatable water must be significantly free from

turbidity colour taste & odour of moderatetemperature in summer & winter & well aerated

At least four human perceptions respond to these

qualities:

Scnses of sight (colour & turbidity)

Taste (odour)

Smell (odour) &Touch (temperature)


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The term Turbid is applied to waters containing suspendedmatter that interferes with the passage of light through the

water or in which visual depth is restricted.


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Consumers of public water is rendered more difficult & costlywhen turbidity-free water. Laymen are aware that to

domestic sewage is highly turbid.

Filtration of water is rendered more difficult & costly when

turbidity increases. The use of slow sand filters has become

impractical in most areas because high turbidity shortens filter

runes & increases cleaning cost.


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water supply engineering. ce 704. world university of bangladesh. chapter 7

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