1. Environmental Engineering
Water Pollution

2. Outline Water pollution categories Causes of water pollution
Measurement of water pollution

3. Water pollution categories
Sources of surface water pollution are generally grouped into two categories based on their origin.
Point source pollution
is a single identifiable localized source of air, water, thermal, noise or light pollution.
The sources are called point sources because in mathematical modelling, they can be approximated as a mathematical point to simplify analysis.
Pollution point sources are identical to other physics, engineering, optics and chemistry point sources.

4. Water pollution categories
Non-point source pollution pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often accumulative effect of small amounts of contaminants gathered from a large area. NPS Examples such as: discharges from vehicle emissions, construction site, Urban Runoff, forestry etc.

6. Causes of water pollution
The specific contaminants leading to pollution in water include chemicals, pathogens, and physical or sensory changes such as elevated temperature and discoloration.
Three main sources causing water pollution are:
 Pathogens
- Thermal pollution

7. Causes of water pollution
Pathogens
The most important biological organisms in water are pathogen
These organisms are capable of infecting and transmitting diseases to human
Pathogens are not native to aquatic system and usually require an animal host for growth and reproduction.
Major groups of pathogens of interest in water supply and treatment are bacteria, viruses, protozoa, fungus and algae.

8. Causes of water pollution
Pathogen Indicator
The presence of pathogenic microorganisms is shown by indicator organisms.
Their presence shows that pollution has occurred and suggests the nature, type and level of pollution.
Indicator micro-organisms properties;
Can be used for all type of waters,
Always present when pathogen is absent,
Easily experimented and give reliable results,
Not be a pathogen itself

9. Causes of water pollution
Thermal pollution Thermal pollution is the rise or fall in the temperature of a natural body of water caused by human influence. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers.

10. Causes of water pollution
Thermal pollution can also be caused by the release of very cold water from the base of reservoirs into warmer rivers. Elevated water temperatures decreases oxygen levels (which can kill fish).

11. Water Quality
Water quality is a neutral term that relates to the composition of water as affected by natural processes and human activities.
The quality of water also is related to its specific use, and usually measured in terms of the concentration of its constituents.
Water quality measurements include physical, chemical, and biological parameters.

12. Water Quality Parameters
Physical Parameters
Chemical Parameters

13. Water Quality Physical Parameters
Physical parameters define those characteristics of water that respond to the sense of sight, touch, taste, or smell.
The six most commonly considered physical characteristics are suspended solid, temperature, taste and odour, colour

14. Water Quality Physical Characteristics
a) Suspended solid – measured in mg/L
Sources:
(i) Inorganic compounds such as clay, silt, sand
(ii) Organic compounds such as fine organic matter, human waste
Effect:
(i) Aesthetic (affect turbidity and transparency of water
(ii) Health aspect
(iii) Adsorption point/centre for chemicals and micro-
organisms

15. Water Quality

16. Water Quality
b. Turbidity – measured in NTU/FTU (nephelometric / Formazin turbidity units)
Sources:
(i) Inorganic compounds such as clay, sand
(ii) Organic compounds such as plant fiber, human
waste
Effect:
(i) Aesthetic
(ii) Health aspect
(iii) Adsorption point/centre for chemicals and micro-
organisms

17. Turbidity – measured in NTU/FTU
Water Quality
Turbidity – measured in NTU/FTU

18. Water Quality (i) Inorganic compounds such as minerals, metals,
c. Odour and Taste
Sources:
(i) Inorganic compounds such as minerals, metals,
salts (all of them give taste to water but no odour)
(ii) Organic compounds from petroleum and/or
degradation of organic matters (odour and taste)
Effect:
(i) Aesthetic
(ii) Health problem

19. Water Quality d. Temperature – measured in ˚C or ˚F Sources:
(i) Effect from ambience
(ii) Industrial activities such as cooling system
Effect:
(i) Disturb biological activities such as micro organism
and aquatic life
(ii) Chemical properties such as the degree of gas
solubility, density and viscosity

20. Water Quality Chemical Parameters
The chemical characteristics of water are numerous. 
Every substance that dissolves in water can be called a chemical water quality characteristic. 
Chemical parameters are includes total dissolved solid, alkalinity, hardness, metals, organic compounds, and nutrients.

21. Water Quality Chemical Characteristics a) Total Dissolved Solid (TDS)
Sources:
(i) Inorganic compounds such
minerals, metal and gases
(ii) Organic compounds such as product from
degradation of organic matter or organic gas
Effect:
(i) cause taste, colour and odour problem
(ii) Health aspect
(iii) small amount of TDS – water become corrosive
Note:
Recommended TDS concentration for drinking water supply is 500 mg/L

22. Water Quality b) Alkalinity
Definition: the quantity of ions in water to neutralize acid or measure of water strength to neutralize acid
- Main constituents are bicarbonate (HCO3- ),carbonate (CO32- ) and hydroxide (OH- ) ions.
Sources:
(i) Mineral dissolved in water and air
(ii) Human activities such as fertilizers, detergent, pesticide etc.
Effect:
(i) Non pleasant taste
(ii) Reaction between alkaline constituent and cation (positive ion) produces precipitation in pipe.

23. Water Quality
Fertilizer
Agriculture
pesticide

24. Water Quality c) Hardness
Definition: a measure of “multivalent” cations in water such as Ca2+, Mg2+, Fe2+, Mn3+
Sources:
(i) Natural mineral on earth
Effect:
(i) Excessive soap usage
(ii) Precipitate form on hardware
(iii) Precipitate in pipe – temperature and pH increased
Note:
Recommended Iron concentration in Water Supply is 0.3 mg/L
Desirable concentration of Mn in Drinking water is 0.01 – 0.05 mg/L

25. Effects on water supply
Water Quality
Effects on water supply
Iron deposit on valve pipe

26. Water Quality d) Metals – non toxic and toxic Non Toxic
Dangerous for health if the concentration is high
Example: Ca2+, Mn2+, Fe2+, Zn2+, Al3+, + etc.
Source:
(i) Mineral, readily available from nature
Effect:
(i) Colour, odour, taste and turbidity
(ii) Deteriorate health (at high concentration)

27. Water Quality d) Metals – non toxic and toxic Toxic
Stored up in food chain
Example: Pb2+, Hg2+, Cd2+ etc.
Source:
(i) Human activities such as mining and industries
Effect:
(i) Dangerous diseases such as cancer, abortion and deformation in new born baby
Note:
For Domestic Water Supply Metals level should be:
Pb < mg/L Hg < mg/L Cd < mg/L