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Chapter: Environmental Science and Engineering

Classification of Pollution

Classification of Pollution ü Air pollution ü Water pollution ü Soil pollution ü Marine pollution ü Noise pollution ü Thermal pollution and ü Nuclear hazards

Types of pollutants


1.   Bio degradable pollutants - decompose rapidly by natural processes.

2. Non- degradable pollutants - do not decompose or slowly decompose in the environment.


Classification of Pollution

ü   Air pollution

ü   Water pollution

ü   Soil pollution

ü   Marine pollution

ü   Noise pollution

ü   Thermal pollution and

ü   Nuclear hazards





The presence of one or more contaminants like dust, smoke, mist and odor in the atmosphere which are injurious to human beings, plants and animals.


1 Sources of air pollution


Natural pollution - volcanic eruptions, forest fires, biological decay.

Man – made activities – Thermal power plants, agricultural activities.

2 Classification


§    Primary pollutant – these are those emitted directly in the atmosphere in harmful form like CO, NO.


§    Secondary pollutant – these may react with one another or with the basic components of air to form new pollutants.



3 Control Measures

2.     Source control

v Use only unleaded petrol

v Use petroleum products and other fuels that have low sulphur and ash content

v Plant trees along busy streets because they remove particulates and carbon monoxide and absorb noise.


v Industries and waste disposal sites should be situated outside the city centre. v Use catalytic converters to help control the emissions of carbon monoxide and




2.     Control measures in Industrial centers

v   Emission rates should be restricted to permissible levels


v   Incorporation of air pollution control equipments in the design of the plant lay out.





o   It may be defined as “the alteration in physical, chemical and biological characteristics of water which may cause harmful effects on human and aquatic life.


1 Types, effects and sources of water pollution


1.     Infectious agents: Bacteria, viruses, protozoa and parasitic worms.

Sources: Human and animal wastes.

Effects: Variety of diseases.


2.     Oxygen demanding wastes: Animal manure and plant debris that can be decomposed by aerobic bacteria.


Sources: Sewage, paper mills, and food processing facilities.


Effects: Wastes can degrade quality by depleting water of dissolved oxygen.


3.     In organic Chemicals: Water soluble inorganic chemicals. Compounds of toxic metals such as lead, arsenic and selenium. Salts such as Nacl in ocean water.


Effects: Genetic mutations, birth defects and certain cancers.


4.     Thermal pollution (Heat) Example: Excessive heat.


5.     Human source


·        Water cooling of electric power plants and some types of industrial plants. Almost all of all water withdrawn in United States for cooling electric power plants.


2 Effects


ü   Lowers dissolved oxygen levels and makes aquatic organisms more vulnerable to disease and toxic chemicals


ü   When a power plant first opens or shuts down for repair, fish and other organisms adapted to a particular temperature range can be killed b the abrupt change in water temperature known as thermal shock.


3 Control measures of water pollution


·        The administration of water pollution should be in the hands of state or central government.


·        Industrial plants should be based on recycling operations, because it will not only stop the discharge of industrial wastes into natural water sources but by products can be extracted from the wastes.


·        Plants, trees and forests control pollution and they acts as natural air conditioners.


·        Highly qualified and experienced persons should be consulted from time to time for effective control of water pollution.


·        Basic and applied research in pubic health engineering should be encouraged.





It may be defined as “the contamination of soul by human and natural activities which may cause harmful effects on living beings”.


1 Types


1. Industrial wastes


Sources and effects: Pulp and paper mills, chemical industries, oil refineries, sugar factories. These pollutants affect and alter the chemical and biological properties of soil. As a result, hazardous chemicals can enter into human food chain from the soil; disturb the bio chemical process and finally lead to serious effects.


2. Urban wastes


Sources and effects: Plastics, Glasses, metallic cans, fibers, papers, rubbers, street sweepings, and other discarded manufactured products. These are also dangerous.


2. Agricultural practices


Sources and effects: Huge quantities of fertilizers, pesticides, herbicides, and weedicides are added to increase the crop yield. Apart from these farm wastes, manure, slurry, are reported to cause soil pollution.


4. Radioactive pollutants


Sources and effects: These are resulting from explosions of nuclear dust and radio active wastes penetrate the soil and accumulate there by creating land pollution.


5. Biological agents


Sources and effects: Soil gets large quantities of human, animal and birds excreta which constitute the major source of land pollution by biological agents.



2 Control measures of soil pollution

The pressure on intensification of farm activities increases for two reasons


ü   Population growth


ü   Decrease of the available farm land due to urbanization


ü   Forestry and  farm practices


ü   Proper dumping of unwanted materials


ü   Production of natural fertilizers


ü   Proper Hygienic condition


ü   Public awareness


ü   Recycling and Reuse of wastes


ü   Ban on Toxic chemicals.





It may be defined as “the discharge of waste substances into the sea resulting in harm to living resources hazards to human health, hindrance to fishery and impairment of quality for use of sea water”.


Source of marine pollution


The coastal zones contain rich heritage, coral reefs, wetlands, and sea grass beds.


1 Effects of marine pollutants


Ø   The presence of heavy metals and organic pollutants cause more damage in birds as thinning of eggshell and tissue damage of egg.

Ø   Oil spilling causes abnormally low body temperature in birds resulting in hypothermia.


Ø   Oil films are able to retard significantly the rate of oxygen uptake by water.


2 Control measures of marine pollution


v   Plants for conserving marine biodiversity must be taken into account of human needs.


v   People should be educated about marine ecosystems and the benefits offered by them.


v   Local communities must be involved in protecting and managing their coastal resources. Social and economic incentives must be offered for conserving and sustainable use of marine resources.


v   Governments must manage their own water while extending cooperation to the neighboring states.






It may be defined as “the unwanted, unpleasant or disagreeable sound that causes discomfort for all living beings”


1 Types of noise


§    Industrial noise


§    Transport noise


§    Neighborhood noise


2 Effects of Noise pollution


ü   This affects human health, comfort and efficiency.


ü   It causes muscles to contract leading to nervous breakdown, tension.


ü   It affects health efficiency and behavior.


ü   In addition to serious loss of hearing due to excessive noise, impulsive noise also causes psychological and pathological disorders.


ü   Brain is also adversely affected by loud and sudden noise as that of jet and aero plane noise.


3 Control and preventing measures


v   Source control – acoustic treatment to machine surface, design changes, limiting the operational timings.


v   Transmission path intervention- the source inside a sound insulating enclosure, construction of a noise barrier or provision of sound absorbing materials.

v   Oiling – Proper oiling will reduce the noise from the machines.






It may be defined as the “addition of excess of undesirable heat to water that makes it harmful to man, animal or aquatic life or otherwise causes significant departures from the normal activities of aquatic communities in water”


1 Sources of thermal pollution


ü   Nuclear power plants


ü   Coal fired power plants


ü   Industrial effluents


ü   Domestic sewage


ü   Hydro – electric power.


2 Effects of thermal pollution


§    Reduction in dissolved oxygen


§    Increase in Toxicity


§    Interference with biological activities


§    Interference with reproduction


§    Direct mortality


§    Food storage for fish.


3 Control measures of thermal pollution


Ø   Cooling towers - This is used as a coolant wet cooling tower, dry cooling tower.


Ø   Cooling ponds and spray ponds.


Ø   Artificial lakes – The heated effluents can be discharged into the lake at one end and the water for cooling purposes from the other end.



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