Water Pollution, Impurities in Water & Problems - Lecture No-5 include 6.- Chemistry

Topics: Thermodynamics
Subject: ChemistryTopics: Water Pollution, Impurities in Water &  Problems
Subject Code: CHM 4201
Lecture No-5 include 6.- Chemistry

Lecturer: Mr. Jahedul Islam  

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Water Pollution, Impurities in Water & Problems

WATER POLLUTION

•Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, groundwater).

•Water pollution affects plants and organisms living in these bodies of water; and, in almost all cases the effect is damaging either to individual species and populations, but also to the natural biological communities.

•Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds.

SOURCES OF WATER POLLUTION.

•1) INDUSTRY

•Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.

•Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans.

•Pollutants from industrial sources include:

•Asbestos – This pollutant is a serious health hazard . Asbestos fibres can be inhaled and cause illnesses such as asbestosis, lung cancer, intestinal cancer and liver cancer.

•Lead – This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the environment is contaminated.

•Heavy Metals –

•Different colors –

•Toxic chemicals -

2) OIL POLLUTION IN WATER

•Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping.

•Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping.

•An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being split into one place.

•Oil spills cause a very localized problem to local marine wildlife such as fish, birds and sea otters.

•Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish,  gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.

3) RADIO ACTIVE WASTE

•Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats. Nuclear waste comes from a number of sources:

•Operations conducted by nuclear power stations produce radioactive waste. Nuclear-fuel reprocessing plants in northern Europe are the biggest sources of man-made nuclear waste in the surrounding ocean. Radioactive traces from these plants have been found as far away as Greenland.

•Mining and refining of uranium and thorium are also causes of marine nuclear waste.

 IMPURITIES IN WATER

Impurities in water are classified into three heads:

ØSuspended impurities.

ØDissolved impurities.

ØColloidal impurities

SUSPENDED IMPURITIES.

•This impurities are dispersion of solid particles that are large enough to be removed by filtration on surface and heavier one settles down. The suspended particles which have the same specific gravity as hat of water, are mixed in the water.

•Suspended impurities include,

üClay, silts

üAlgae, fungi

üOrganic and inorganic matters

üMineral matters etc.

•These all impurities are macroscopic and cause turbidity in the water. The concentration of suspended matter in water is measured by its turbidity. The size of suspended impurities ranges from 0 to 10-3mm.

Dissolved Impurities

•Some impurities are dissolved in water when water flows over the rocks, soils etc. Solids, liquids and gases are dissolved in natural water. This dissolved impurities may contain organic compounds, inorganic salts and gases.

•The concentration of total dissolved solids is usually expressed in ‘ppm’ and is obtained by weighing the residue after evaporation of the water sample from a filtered sample.

Colloidal Impurities

•It is very finely divided dispersion of particles in water. This particles are so small that these can not be removed by ordinary filters and are not  visible to the naked eye.

•Most of the color of the water is due to colloidal impurities. Their quantity is determined by color tests. The size of colloidal particles is between ‘1 micron to 1 milli-micron’.

Characteristic properties of natural water in hydrologic cycle.
1. Sea Water	Salts
2. Precipitation	Gases, vapours, particulates, salts nuclei, radio active fall out
3. Surface runoff	Particulates, organic matter, nitrates, phosphates, biocides
4. Ground water	Carbonates, chlorides and sulphates of calcium and magnesium, iron etc
5. Lake water	Algae, odours, tastes
6. Swamp water	Odours, tastes, color
7. River water	Particulates, organic matter, waste water

 Potable water

The water which is suitable for drinking is known as potable water.

The potable water should have the following qualities:

1.It should be odourless and colorless.

2.It should be free from suspended solids and turbidity.

3.It should be free from toxic substances.

4.It should be free from pathogenic organisms.

5.It should be moderately soft.

6.It should be aesthetically pleasant, i.e cool and fresh.

7.Having pH preferably between 7 & 8.5.

Types of water.

•Pure form of water : in the from of H2O, also known as distilled water.

•Mineral water :  water with acceptable limits of minerals specified by potable water standards.

•Tap water :  water supplied by the concerned authority available at home.

•Polluted water :  water containing impurities not suitable for drinking.

•Contaminated water : water containing harmful impurities, not suitable for any purpose nor even can be thrown in water bodies.  

HARMS OF WATER POLLUTION

•Virtually all types of water pollution are harmful to the health of humans and animals. Water pollution may not damage our health immediately but can be harmful after long term exposure.

    Different forms of pollutants affect the health of animals in different ways:

•Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. 

•Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them.

•Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water.

 WATER BORNE DISEASES AND THEIR CONTROL:

Water borne diseases are those diseases which spread primarily through contaminated waters. Water borne diseases are caused by pathogenic organisms.(bacteria, viruses, protozoa) carried by water containing sewage contamination.

  The important water borne diseases are :

•Typhoid fever.

•Paratyphoid fever.

•Cholera.

•Dysenteries.

•Gastro- enteritis.

•Infectious hepatitis, etc. 

The water borne diseases may be grouped in four heads:

1)Bacterial diseases.

2)Virus diseases.

3)Protozoan diseases.

4)Worm(helminthic) diseases.