1. Water Pollution and Treatment
Chapter outlines: Water Quality, Water Pollution, BOD, Waterborne Diseases, Nutrients, Sediments,　Eutrophication, Oil Spills,　Groundwater pollution, Wastewater Treatment and Reuse.
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2. Global Water Supplies
Globally, more than 99%of the Planetary Water Supply is unusable.
–97% Saline; 2% Frozen
–of the 1% remaining, extremely uneven distribution.
–Thus, (fresh) Water Conservation is the major issue.
•80% of the water we use is surface, not underground
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3. Water Quality
The term water quality is used to describe the condition of the water, including its
- chemical, physical and biological characteristics
Chemical- DO, BOD
Physical - Turbidity, cloudiness or haziness
Biological- levels of coliform bacteria
- for a particular purpose (i.e., drinking, swimming or fishing) the desirable quality will be different.
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4. Water Pollution Definition –degradation of water quality
Considered polluted if it becomes unsuitable for a specific purpose
Quality depends on potential use ( drinking water or irrigation water has different quality)
EPA ( Environmental Protection Agency in USA) sets limits form concentrations of pollutants in water
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5. Biochemical Oxygen Demand (BOD)
Amount of O2 needed for bacteria to decompose organic matter in water
Natural sources, i.e., runoff, human sewage contribute to increases BOD
Increased BOD = decreased dissolved O2
SAFE OXYGEN LIMIT = 5 ppm in water
< 5 ppm O2 Many aquatic organisms may die
Sudden discharges of organic matter –e.g., raw sewage
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6. BOD
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7. Waterborne Disease
Serious human disease & epidemics result from waterborne pathogens
Modern water treatment facilities can’t always guarantee pathogen-free water supplies
Fecal coliform bacteria
Continual testing is necessary to protect public health
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8. Nutrients Excesses, especially N & P, can lead to serious problems
Eutrophication
Excessive nutrients stimulate growth of aquatic plants, increased decomposition, increased BOD, death of aquatic organisms
Natural or cultural ( Agricultural fertilizers of N, P)
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9. Sediment By volume, most significant water pollutant
–Reduces water quality
–Represents losses of soil (erosion) at point of origin
–Forest land << agricultural lands
– Sediments increase turbidity or haziness
turbidity increases by suspended sediments, algae in water reduces light penetration for
aquatic photosynthesis
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10. Eutrophication or Dying Lake Ecosystem
1. Nutrient addition to lake by runoff of fertilizers, sediments
2. Stimulated growth of aquatic
Plants; i.e, algae (green)　
3. High turbidity,
Less light penetration for photosynthesis, less oxygen　
4. Death of Fish
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11. Died fish in Gulshan lake
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12. Oil Spills Add nutrients to water
Tanker, offshore drilling accidents, shipping activities
In 2010 March, BP= British Petroleum’s Oil rig spill
over 205 million gallons of oil were released into the Gulf of Mexico
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13. Groundwater pollution:
Diagram illustrating leak from a Underground gasoline tank
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14. Pesticides and Water pollution
Pesticide: chemical substance that kills pests, harmful insects, fungi, weeds, rodents, etc
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15. Chemical Pesticides: DDT
Dichlorodiphenyltrichloroethane (DDT)
Persist in the environment for many yrs
• banned in 1972, still persists
Bioaccumulates: concentrates in body tissues (fat)-may remain there for decades
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16. Honeybees Honeybees help flowering process of plant.
Honeybees dramatically improve crop yields by increasing the rate of pollenization.
Honeybees are threatened by disease and pesticide use.
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17. Biomagnifications occurs within a trophic levels, and is the increase in concentration of a substance in certain tissues of organisms' bodies due to absorption from food and the environment.
For example, herring contains mercury at approximately 0.01 ppm and shark contains
mercury at greater than 1 ppm (EPA 1997).
DDT, PCBs, and the organic
forms of Mercury and Arsenic
do biomagnify in nature.
Suedel et al. (1994)
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18. Biomagnifications: Environmental Step in USA
In the United States, the government has an action level for methyl mercury in commercial marine and freshwater fish that is 1.0 parts per million (ppm).
It means, 1 microgram in 1 gram
we know 1 gram = microgram
or, 1 million microgram
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19. Have you ever thought of eating fish of Buriganga river and its biomagnifications in food chain?
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