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WELCOME. PHYSICAL, CHEMICAL & BACTERIOLOGICAL CONTAMINATION OF WATER AND WATER QUALITY STANDARDS. Distribution of water on earth. Ocean and sea - 97% Snow and ice caps - 2% Rivers,lakes, Ground water - 1%. UNIVERSAL SOLVENT. QUALITY DEMERIT

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Welcome 3762879

WELCOME


Physical chemical bacteriological contamination of water and water quality standards

PHYSICAL, CHEMICAL & BACTERIOLOGICAL CONTAMINATION OF WATER AND WATER QUALITY STANDARDS


Distribution of water on earth

Distribution of water on earth

  • Ocean and sea - 97%

  • Snow and ice caps - 2%

  • Rivers,lakes, Ground water - 1%


Universal solvent

UNIVERSAL SOLVENT

  • QUALITY

  • DEMERIT

  • 45 LAC WELLS

    AND

    50 LAC SEPTIC TANKS ( ?)


Contamination

contamination

  • Geological

  • Human activities

    . Organic waste

    Industrial waste


Aquifiers

Aquifiers


Safe drinking water

Safe drinking water

Free from pathogenic organisms

Clear

Not saline

Free from offensive taste or smell

Free from compounds that may have adverse effect on human health

Free from chemicals that cause corrosion of water supply systems


Water quality parameters

WATER QUALITY PARAMETERS

  • Physical parameters

  • Chemical

  • Bacteriological


Colour

Colour

  • May be due to the Presence of organic matter,metals(iron, manganese) or highly coloured industrial waste

  • Aesthetically displeasing

  • Disirable that drinking water be colourless

  • Disirable limit, 5 Hazen unit

  • Permissible limit 25 Hazen Unit


Taste and odour

Taste and Odour

  • Mainly due to organic substances, ,Biological activity, industrial pollution

  • Taste buds in the oral cavity specially detect inorganic compounds of metals like magnesium, calcium, sodium, copper, iron and zinc

  • Water should be free from objectionable taste and odour.


Turbidity

Turbidity

  • Caused by suspended matter

  • High level turbidity shield and protect bacteria from the action of disinfecting agents

  • Disirable limit-5NTU

    should be below 1 NTU when disinfection is practiced

    Permissible limit-10NTU


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pH

  • It is the measure of hydrogen ion concentration

  • Neutral water pH-7

  • Acidic water has pH below 7

  • Basic water has pH above 7

  • Disirable limit 6.5-8.5 Beyond this limit the water will affect the mucous membrane and water supply system


Substances that change ph of water

Acidic

Industries

Sugar - 5 – 6

Distillery 3 - 4

Electro-

Plating unit 2.5-4

Pickle 2 - 3

Basic

Paper 8 – 10

Textile 8.5-11

Fertiliser 6.5- 9

Oil Refine-

ries 6.5-9.5

Substances that change pH of water


Hardness

HARDNESS

  • Capacity of water for reducing and destroying the lather of soap

  • It is total concentration of calcium and magnesium ions

  • Temporary hardness – Bicarbonates of Calcium and Magnesium

  • Permanent hardness – Sulphates, chlorides and nitrates of calcium and magnesium


Hardness contd

Hardness – contd…

  • 0 – 50 mg/l - soft

  • 50 – 150 mg/l - moderately hard

  • 150 – 300 mg/l - hard

  • 300 above - very hard

  • Surface water is softer than ground water

  • Causes encrustations in water supply structures


Alkalinity

ALKALINITY

  • Capacity to nutralise acid

  • Presence of carbonates, bi-carbonates and hydroxide compounds of Ca, Mg, Na and K

  • Alkalinity = hardness, Ca and Mg salts

  • Alkalinity > hardness - presence of basic salts, Na, K along with Ca and Mg

  • Alkalinity < hardness – neutral salts of Ca & Mg present


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IRON

  • One of the earth’s most plentiful resource

  • High iron causes brown or yellow staining of laundry, household fixtures

  • Metalic taste, offensive odour, poor tasting coffee

  • Cause iron bacteria

  • Acceptable limit – 0.3 mg / l


Chloride

CHLORIDE

  • Causes

  • Dissolution of salt deposit

  • Discharge of effluents

  • Intrusion of sea water

  • Not harmful to human beings

  • Regarding irrigation – most troublesome anion

  • Acceptable limit - 250 mg/l


Nitrate

NITRATE

  • Increasing level of nitrate is due to

  • Agricultural fertilizers, manure,animal dung, nitrogenous material ,sewage pollution

  • (blue baby diseases to infants)

  • Maximum permissible limit 45 mg / l


Flouride

FLOURIDE

  • Occurs naturally

  • Long term consumption above permissible level can cause –

  • dental flurosis (molting of teeth)

  • Skeletal flurosis

  • Acceptable limit – 1 mg / l

  • Maximum permissible limit – 1.5 mg / l

  • Remedy – 1) Deflouridation

    2) Mixing Fluride free water

    3) Intake of vitamin C,D, calcium,antioxidants


Flouride causes

FLOURIDE CAUSES

Three types of Fluorosis

1. Dental Fluorosis

2. Skeletal Fluorosis

3. Non-skeletal Fluorosis


Arsenic

ARSENIC

  • Occur in ground water from arseniferous belt

  • Industrial waste, agricultural insecticide

  • High arsenic causes 1) various type of dermatological lesions, muscular weakness, paralysis of lower limbs, can also cause skin and lung cancer

  • Acceptable limit – 0.05 mg / l


Heavy metals

Heavy Metals

  • Present as mineral in soil and rocks of earth

  • Human activities

    Battery – Lead & Nickel

    Textile - Copper

    Photography – Silver

    Steel production – Iron


Pesticides

Pesticides

  • Cancer

  • Birth defects

  • Blood disorder

  • Nervous disorder

  • Genetic damage


Essential bacteriological standards

Essential bacteriological Standards


Residual chlorine

RESIDUAL CHLORINE

Chlorine added to water forms hypochlorite ions and hypochlorite acids

Chlorine demand – Quantity required for killing micro organisms and reacting with ammonia, organic compounds etc.

Free residual chlorine – To take care of post contamination

Desirable – 0.2 mg / liter


Common problems contd

Common problems contd


Common problems

Common problems


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Measures of Water Quality

Some of the Most basic and Important Measures

Dissolved Oxygen

Biochemical Oxygen Demand

Solids

Nitrogen

Bacteriological


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Dissolved Oxygen (DO)

Typically Measured by DO probe and Meter

Electrochemical Half Cell Reaction


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Biochemical Oxygen Demand (BOD)

Amount of oxygen used by microorganisms to decompose

organic matter in a water

Theoretical BOD can be determined by balancing a

chemical equation in which all organic matter is

converted to CO2

Calculate the theoretical oxygen demand of 1.67 x 10-3 moles of

glucose (C6H12O6):

C6H12O6 + O2 CO2 + H2O general, unbalanced eqn

C6H12O6 + 6 O2 6 CO2 + 6 H2O

1.67x 10-3moles glucose/L x 6 moles O2/ mole glucose x 32 g O2/mole O2

= 0.321 g O2/L = 321 mg O2/L


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BOD Test

Dark

20oC

Time

Standard – 5 days

Ultimate


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BOD = I - F

I = Initial DO

F = Final DO

If all the DO is used up the test is invalid, as in B above

To get a valid test dilute the sample, as in C above. In this

case the sample was diluted by 1:10. The BOD can then be

calculated by:

BOD = (I – F) DD = dilution as a fraction

D = volume of bottle/(volume of bottle – volume of dilution water)

BOD = (8 – 4) 10 = 40 mg/L


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For the BOD test to work microorganisms have to be present.

Sometimes they are not naturally present in a sample so we have

to add them. This is called “seeding” a sample

If seed is added you may also be adding some BOD. We have to

account for this in the BOD calculation:

BOD = [(I – F) – (I’ – F’)(X/Y)]D

Where:I’ = initial DO a bottle with only dilution water and seed

F’ = final DO of bottle with only dilution water and seed

X = amount of seeded dilution water in sample bottle, ml

Y = amount of seeded dilution water in bottle with only

seeded dilution water


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Example

Calculate the BOD5 of a sample under the following conditions.

Seeded dilution water at 20oC was saturated with DO initially.

After 5 days a BOD bottle with only seeded dilution water had a

DO of 8 mg/L. The sample was diluted 1:30 with seeded dilution

water. The sample was saturated with DO at 20oC initially.

After five days the DO of the sample was 2 mg/L.

Since a BOD bottle is 300 ml a 1:30 dilution would have 10 ml

sample and 290 ml seeded dilution water.

From the table, at 20oC, DOsat = 9.07 mg/L

BOD5 = [(9.07 – 2) – (9.07 – 8)(290/300)] 30 = 174 mg/L


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Thank you


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