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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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Distribution of water on earth
Distribution of water on earth AND WATER QUALITY STANDARDS

  • Ocean and sea - 97%

  • Snow and ice caps - 2%

  • Rivers,lakes, Ground water - 1%


Universal solvent
UNIVERSAL SOLVENT AND WATER QUALITY STANDARDS

  • QUALITY

  • DEMERIT

  • 45 LAC WELLS

    AND

    50 LAC SEPTIC TANKS ( ?)


Contamination
contamination AND WATER QUALITY STANDARDS

  • Geological

  • Human activities

    . Organic waste

    Industrial waste


Aquifiers
Aquifiers AND WATER QUALITY STANDARDS


Safe drinking water
Safe drinking water AND WATER QUALITY STANDARDS

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 AND WATER QUALITY STANDARDS

  • Physical parameters

  • Chemical

  • Bacteriological


Colour
Colour AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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


Welcome 3762879
pH AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

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 AND WATER QUALITY STANDARDS

  • 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… AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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


Welcome 3762879
IRON AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

Three types of Fluorosis

1. Dental Fluorosis

2. Skeletal Fluorosis

3. Non-skeletal Fluorosis


Arsenic
ARSENIC AND WATER QUALITY STANDARDS

  • 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 AND WATER QUALITY STANDARDS

  • Present as mineral in soil and rocks of earth

  • Human activities

    Battery – Lead & Nickel

    Textile - Copper

    Photography – Silver

    Steel production – Iron


Pesticides
Pesticides AND WATER QUALITY STANDARDS

  • Cancer

  • Birth defects

  • Blood disorder

  • Nervous disorder

  • Genetic damage


Essential bacteriological standards
Essential bacteriological Standards AND WATER QUALITY STANDARDS


Residual chlorine
RESIDUAL CHLORINE AND WATER QUALITY STANDARDS

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 AND WATER QUALITY STANDARDS


Common problems
Common problems AND WATER QUALITY STANDARDS


Welcome 3762879

Measures of Water Quality AND WATER QUALITY STANDARDS

Some of the Most basic and Important Measures

Dissolved Oxygen

Biochemical Oxygen Demand

Solids

Nitrogen

Bacteriological


Welcome 3762879

Dissolved Oxygen (DO) AND WATER QUALITY STANDARDS

Typically Measured by DO probe and Meter

Electrochemical Half Cell Reaction


Welcome 3762879

Biochemical Oxygen Demand (BOD) AND WATER QUALITY STANDARDS

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


Welcome 3762879

BOD Test AND WATER QUALITY STANDARDS

Dark

20oC

Time

Standard – 5 days

Ultimate


Welcome 3762879

BOD = I - F AND WATER QUALITY STANDARDS

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) D D = dilution as a fraction

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

BOD = (8 – 4) 10 = 40 mg/L


Welcome 3762879

For the BOD test to work microorganisms have to be present. AND WATER QUALITY STANDARDS

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 AND WATER QUALITY STANDARDS

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


Welcome 3762879

Thank you AND WATER QUALITY STANDARDS


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