1. What is pollution….?
• “Pollution is an undesirable change in the physical,
chemical or biological characteristics of our air, land
and water that may or will harmfully affect human life
or that of desirable species, or industrial processes,
living conditions, and cultural assets; or may or will
waste or deteriorate our raw material resources”
………”Waste management and control”
Committee on Pollution, National
Academy of Sciences, 1966
Increasing population and needs of present
…therefore generation of waste
• Air, Water & Solid
…therefore immediate need for systems approach
to manage the environment
4. Ranking of waste management actions … Waste
6. Types of pollutants
7. • Sources
– Point – single large sources
– Non-point - a diffuse source of pollution that cannot be attributed
to a clearly identifiable, specific physical location or a defined
• general runoff of sediments
• pesticide spraying
• fertilisers from farms an urban areas
8. • Water pollution -:may be defined as the presence
in water of such quantity and of such nature as to
impair the use of water for stated purpose.
Pollution and contamination
• Pollution is the general term which includes
contamination. Contamination makes water total unfit for
the best use e.g. drinking. Colored water, saline water,
smelling water, water containing floating bodies are the e.g
of water pollution. Water containing harmful pathogenic
bacteria is an example of water contamination.
9. • Physical -: color, odor, taste, temperature, turbidity
• Turbidity -: suspended matter such as clay, slit etc.
• It is measure of the extent to which light is either absorbed or scattered by
suspended material in water.
• 5-10 units of turbidity
• Turbidity is measured by turbidimeters
• Jackson turbidimeter 25-100 JTU
• Baylis turbimeter or nephelomter 0-2 ppm
• Dissolved OM from decaying vegetation, colored soil etc.
• Iron oxides cause reddish water and managnese oxides cause brown or
• Colored water not aesthetically acceptable to the public. Highly colored
water is unsuitable for dyeing, papermaking, dairy and food industry.
• Excessive growth of algae
• Permisiible limit is 20 ppm
• Tintometer and color matching
• Taste and odor
• Presence of dissolved gases such as H2S, CH4, CO2, O2; mineral
substances like iron compounds, sulphates, Nacl etc.
• It is measured by threshold odor number represents the dilution ratio at
which the odour is hardly detectable.
• It should be 1 and never exceed 3 for public supplies.
10. • Chemical Characteristics
• Total solids and suspended solids
• TS -: Evaporate the water sample and weigh the dry residue left
• S/S -: Filter the water sample and weigh the residue left on the filter paper.
• Aesthetically displeasing and provides adsorption sites for chemical and
• Total dissolved solids: The material remaining after filtration for the
suspended solids. Evaporate the sample and weigh the remaining residue.
• pH-: log of the reciprocal of hydrogen ions
• Indicator of acidity or alkalinity of water
• pH >7 alkaline caused by bicarbonates of calcium and magnesium
• Alkalinity is defined as the quantity of ions in water that will react to
neutralize hydrogen ions.
• Difficulty in chlorination, sediment deposit
• pH < 7 acidic caused by the presence of mineral acids, free carbon
dioxide, sulphates of iron or aluminium.
11. • Nitrogen -: the presence of nitrogen indicates the presence of
organic matter (OM)
• Free ammonia
• Organic nitrogen
• Free ammonia represents the first stage of decomposition of
OM. The value should not exceed 0.15 mg/L
• Organic nitrogen should not exceed 0.3 mg/L.
• Nitrites indicate partly oxidised OM. It should be nil in
• Nitrates represent fully oxidized OM.
• It is limited to 45 mg/L.
• Above it will cause blue baby disease.
12. • Synthetic Organic Compound
• Non Biodegradable
• Persist for long time
• Pesticides and detergents
• Surface runoff from agriculture lands, waste discharge by
• Biomagnification -: accumulation of pollutant as it go higher
in trophic level
• Fresh water (0.00001 ppm) Plankton (0.05 ppm) fish
( 2 ppm) predatory birds (10 ppm)
13. • Detergents
• basic ingredient is the surfactant (10-30%). It lowers the
surface tension and allows the dirt particles to become
linked to water.
• The remainder is polyphosphate salts and whiteners
• Surfactant concentration as low as 1 ppm cause foaming in
rivers and in sewage treatment plant
• Surfactant used earlier was ABS ( alkyl benzene
sulphonate). Resistant to biodegradation
• LAS (linear alkyl sulphonate) which is biodegradable.
• Detergent builders releases phosphates in water bodies
leading to eutrophic conditions.
14. • Hardness -: It is the characteristics which prevents the
formation of sufficient lather or foam, when such hard water
are mixed with soap.
• Lead to greater soap consumption, scaling of boilers, causing
incrustation of pipes.
• carbonate hardness-: bicarbonates and carbonates of calcium
• Removed by simple boiling and adding lime
• non carbonate hardness-: sulphate, chloride and nitrates of
calcium and magnesium.
• 75 ppm- soft; 200 ppm and above hard
• For domestic supplies 75-115 ppm
15. • Flouride :
• Concentration of approximately 1.0 mg/L helps to provide
dental cavities in children
• But if its concentration exceed 1.5 mg/L leads to
discoloration of teeth. Excessive intake leads to bone
fluorosis and other skeletal abnormalities.
• Source: domestic, industrial or agriculture wastewater
• Iron concentration of 0.3 mg/L and manganese
concentration of 0.05 mg/L can cause color problems.
• Toxic metals : arsenic, cd, chromium, lead
16. • Organics:
• Source : wastewater discharge or agriculture source
• Biodegradable and non biodegradable
• Biodegradable material consists of organics that can be
utilized for food by naturally occuring MO’s
• Oxygen demanding nature of biodegradable organics is of
utmost importance in natural water systems
• The amount of oxygen consumed during microbial
utilization of organics is called Biochemical oxygen
• Nonbiodegradable Organics: phenols, cellulose,
detergents, pesticides etc.
• Chemical oxygen demand: it measures both matter
17. • Biochemical Oxygen Demand or Biological
Oxygen Demand (BOD) is a procedure for
determining how fast biological organisms use up
oxygen in a body of water. It is used in water
quality management and assessment, ecology and
19. • BOD measures the rate of oxygen uptake by micro-
organisms in a sample of water at a temperature of 20°C
and over an elapsed period of five days in the dark.
• To ensure that all other conditions are equal, a very small
amount of micro-organism seed is added to each sample
being tested.. The BOD test is carried out by diluting the
sample with de-ionized water with added nutrients,
saturated with oxygen, inoculating it with a fixed aliquot
of seed, measuring the dissolved oxygen and sealing the
sample (to prevent further oxygen dissolving in). The
sample is kept at 20 °C in the dark to prevent
photosynthesis (and thereby the addition of
20. • oxygen) for five days, and the dissolved oxygen is measured again.
The difference between the final DO and initial DO is the BOD
• The loss of dissolved oxygen in the sample, once corrections have
been made for the degree of dilution, is called the BOD5. For
carbonaceous BOD (cBOD), a nitrification inhibitor is added after the
dilution water has been added to the sample. The inhibitor hinders the
oxidation of nitrogen. This inhibition allows for measurement of
carbonaceous oxygen demand (cBOD).
• BOD can be calculated by:
• Undiluted: Initial DO - Final DO = BOD
• Diluted: ((Initial DO - Final DO) x Dilution Factor
21. • Chloride content-:
• Normally present due to Nacl
• Concentration above 250 mg/L produce a salty taste in drinking water.
• Biological characteristics
• Pathogenic or non pathogenic bacteria
• Non Pathogenic-: these are harmless and
• Under certain conditions beneficial to human beings, animals and crops
• Pathogenic bacteria -: harmful bacteria or organisms which can cause
serious water borne diseases.
• Aerobic bacteria-: those require oxygen for their survival
• Anaerobic bacteria-: those which flourish and thrive in the absence of free
• Facultative bacteria-: those which can survive with or without free
23. Difficulties With Routine Testing
Of Pathogens in Water• present in low numbers
• limited survival time
• numerous pathogens to analyze
• time and cost prohibitive
• need an indicator of potential pathogen contamination of water which is
easy, reliable, inexpensive, quick, etc.
• Requirements of Indicator Organisms
• present when pathogens present in water
• absent in uncontaminated water
• present in higher numbers than pathogens in contaminated water
• better survival in water than pathogens
• easy to analyze
24. • The usual routine test are conducted to detect and count the
presence of coliform which in themselves are harmless
• E coli resides in the intestine of human being. It leaves the
human body along with pathogens through body waste. These
Ecoli live longer in water than the pathogenic bacteria, it is
generally presumed that water will be safe and free from
pathogenic bacteria, if no coliforms are present in it.