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Essay on Water Pollution: Top 6 Essays Water Pollution

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Here is a compilation of essays on ‘Water Pollution’ for class 6, 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Water Pollution’ especially written for school and college students.

Essay on Water Pollution


Essay Contents:

  1. Essay on the Meaning of Water Pollution
  2. Essay on the Classification of Water Pollutants
  3. Essay on the Sources of Water Pollution
  4. Essay on the Measurement of Water Pollution
  5. Essay on the Effects of Water Pollution
  6. Essay on the Control of Water Pollution


1. Essay on the Meaning of Water Pollution:

Water pollution is the contamination of water bodies like lakes, rivers, oceans, aquifers and groundwater. Water pollution is a major global problem, that requires evaluation and revision of water resource policy at all levels.

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Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without any treatment or removal of harmful compounds. Contaminated and polluted water now kills more people than all forms of violence including wars. Natural phenomena such as volcanoes, algal blooms, storms and earthquakes also cause major changes in water quality and the ecological status of water.

The specific contaminants leading to pollution in water are various organic and inorganic chemicals, wide spectrum of pathogens especially bacteria, fungus spore, cyanobacteria, actinomycetes, etc., and physical or sensory changes such as elevated temperature and discoloration.

Pathogens can produce waterborne diseases in either human or animal hosts. Coliform bacteria are a commonly used bacterial indicator of water pollution, although not an actual cause of disease. Other microorganisms such as Burkholderia pseudomallei, Cryptosporidium parvum, Giardia lamblia, Salmonella, Novovirus and other viruses Parasitic worms sometimes found in surface waters which have caused human health problems.

Some of the pollutants like lead (Pb), arsenic (As), mercury (Hg), chromium (Cr) specially hexavalent chromium, nickel (Ni), barium (Ba), cadmium (Cd), cobalt (Co), selenium (Se),vanadium (V), oils and grease, pesticides, etc. are very harmful, toxic and poisonous even in PPB (parts per billion) range.

Many of the chemical substances are occurring naturally like calcium, sodium, iron, manganese, etc. that regulated the quality of water. High concentrations of naturally occurring substances may have negative impacts on aquatic flora and fauna. Many of the chemical substances are toxic too. Alteration of water’s physical/chemistry property includes acidity (change in pH), electrical conductivity, temperature, and eutrophication.

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Eutrophication is an increase in the concentration of chemical nutrients in an ecosystem to an extent that increases in the primary productivity of the ecosystem. Depending on the level of eutrophication, subsequent negative environmental effects such as anoxia (oxygen depletion) and severe reductions in water quality may occur, affecting fish and other animal populations.

There are some organic compounds like cyanides, thiocyanides, phenolic compounds, fluorides, radioactive substances, etc. which are harmful for humans as well as animals. Organic water pollutants include detergents, disinfection byproducts found in chemically disinfected drinking water, such as chloroform, food processing waste, which can include oxygen-demanding substances, fats and grease, insecticides and herbicides, a huge range of organic halides and other chemical compounds petroleum hydrocarbons, including fuels, gasoline, diesel fuel, jet fuels, and fuel oil and lubricants, motor oil and fuel combustion by products etc.

Besides these various chemical compounds found in personal hygiene and cosmetic products like volatile organic compounds (VOCs), polychlorinated biphenyl (PCBs),trichloroethylene, perchlorate etc., are industrial solvents, from improper storage, chlorinated solvents, which are dense non-aqueous phase liquids (DNAPLs), may fall to the bottom of reservoirs, since they don’t mix well with water and are denser.

The most polluting of them are the city sewage and industrial waste discharged into the rivers. Due to this, pollutants enter groundwater, rivers, and other water bodies. Such water, which ultimately ends up in our households, is often highly contaminated and carries disease-causing microbes.

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Routine applications of fertilizers and pesticides for agriculture and indiscriminate disposal of industrial and domestic wastes are increasingly being recognized as significant sources of water pollution. The use of land for agriculture and the practices followed in cultivation greatly affect the quality of groundwater.

The high nitrate content in groundwater is mainly from irrigation run-off from agricultural fields where chemical fertilizers have been used indiscriminately Intensive cultivation of crops cause chemicals from fertilizers (e.g. nitrate) and pesticides to seep into the groundwater, a process commonly known as leaching. Agricultural run-off, or the water from the fields that drains into rivers, is another major water pollutant as it contains fertilizers and pesticides.


2. Essay on the Classification of Water Pollutants:

Water pollutants may be classified into following categories:

(A) Chemical,

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(B) Physical,

(C) Physiological,

(D) Biological, and 

(E) Radioactive.

(A) Chemical Pollutants:

Chemical materials discharged into a receiving water may be broadly classified as Organic, and Inorganic pollutants. Undesirable results from the discharge of inorganic materials include changes in the pH of the water caused by soluble salts and toxicity caused by heavy metals or other toxic materials.

Inert insoluble inorganics such as clay create sludge deposits on the bottom of the river and adversely affect the biological life. The major consideration with respect to organic materials is the depletion of dissolved oxygen. Oils will form surface films, phenols will affect the taste and odor of water and refractory organics will cause death of fish and other aquatic life.

(B) Physical Pollutants:

Physical pollutants include:

(i) Colour,

(ii) Turbidity,

(iii) Temperature,

(iv) Suspended solids,

(v) Foam, and 

(vi) Radio-activity.

Colour though not necessarily harmful, is obviously undesirable in drinking water. Turbidity is primarily caused by either colloidal or very finely divided suspended matter which settles slowly and with difficulty. Turbidity caused by the hydrous oxides of Fe and Mn is quite objectionable in domestic water and may require special treatment for removal.

Temperature increase (due to the use of water as cooling media in power generation) has only recently been considered as a water pollutant. Suspended materials may go in water from erosion processes or by various waste discharges. The resultant foam produced in many waters from detergents manufacturing industries may be objectionable from an aesthetic stand point.

(C) Physiological:

Undersirable taste and odor present in water used for drinking or food processing is objection­able to the consumer. Taste and odor of water can easily change if chlorophenols or H2S is present in it, even in very small quantities.

(D) Biological:

It is most important of all water pollution problem. In fact, the single most important process in the water treatment plant is disinfection, which helps insure the absence of pathogenic organisms in the drinking water. Biological pollutants cause bacterial bone diseases, amoebic dysentery, cholera etc.

(E) Radioactive:

Radioactive pollution is the discharge of a radioactive waste material into a receiving body.


3. Essay on the Sources of Water Pollution:

Water, after being used for the following purposes, when drained out in a bigger and clean source of water, creates pollution problems over there:

1. Domestic life,

2. Industry,

3. Agriculture,

4. Wild life watering,

5. Propagation of fish and other aquatic life,

6. Swimming and bathing pools,

7. Boating ponds/lakes,

8. Water power generation, and 

9. Transport etc.


4. Essay on the Measurement of Water Pollution:

Waste water sampling and flow data are the two most important factors of any water pollution control program. Proper selection of sampling points assures samples that will yield representative and reliable data. Samples of water may be taken at plant outfalls, branch streams to main drain etc. Once the drain discharge and sample points have been established it is necessary to determine the type of sample to be collected at each point.

Samples are either grab or composite:

A grab sample is a single sample, while the composite is one composed of a series of samples col­lected over a period of time and blended for analysis. Waste water streams can be continuously and automatically monitored and analyzed by reliable on-stream effluent monitoring equipment.

A wide variety of instrumental methods for the chemical analysis of water constituents exist such as:

(i) Atomic Absorption Spectrophotometry.

(ii) Infrared Absorption Spectrophotometry.

(iii) Electrochemical Analysis.

(iv) Chemical Spectrophotometry.

(v) Molecular Absorption Spectrophotometry.


5. Essay on the Effects of Water Pollution:

Water pollution is very harmful to humans, animals and water life. The effects can be catastrophic, depending on the kind of chemicals, concentrations of the pollutants and where there is polluted. Water pollution is not only effects to people but also to animals, fish, and birds.

Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It reduced the quality of lakes and rivers. More seriously, contaminated water destroys aquatic life and reduces its reproductive ability. Eventually, it is a hazard to human health. Nobody can escape the effects of water pollution. The effects of water pollution are varied.

They include poisonous drinking water, poisonous food animals (due to these organisms having bio-accumulated toxins from the environment over their life spans), unbalanced river and lake ecosystems that can no longer support full biological diversity, deforestation from acid rain, and many other effects.

These effects are, of course, specific to the various contaminants. When toxic substances enter into lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bottom. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.

When fresh water is artificially supplemented with nutrients, it results in an abnormal increase in the growth of water plants. This is known as eutrophication. The discharge of waste from industries, agriculture, and urban communities into water bodies generally stretches the biological capacities of aquatic systems.

Oxygen depleting substances may be natural materials, such as plant matter (e.g. leaves and grass) as well as man-made chemicals (pollutants).One of the most important water pollution facing the world today is the level of mercury in the oceans. Inorganic mercury is a common byproduct of a number of industrial processes.

The level of mercury in fish is mostly dangerous for small children and women, who might become pregnant, are pregnant or are nursing. Mercury has been found to interfere with the development of the central nervous system in fetuses and young children, which could potentially lead to a large amount of long-term side effects.

Pollutants such as lead and cadmium are eaten by tiny animals. These animals are consumed by fish and shellfish, and the food chain continues to be disrupted at all higher levels.

Each successive step up the food chain causes a stepwise concentration of pollutants such as heavy metals (e.g. mercury) and persistent organic pollutants such as DDT. This is known as bio-magnification, which is occasionally used interchangeably with bioaccumulation.

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

1. 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. Heavy metals can slow development; result in birth defects and some are carcinogenic.

2. Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some of the toxins in industrial waste may only have a mild effect whereas other can be fatal. They can cause immune suppression, reproductive failure or acute poisoning.

3. Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water. Microbial water pollution is a major problem in the developing world, with diseases such as cholera and typhoid fever being the primary cause of infant mortality.

4. Organic matter and nutrients causes an increase in aerobic algae and depletes oxygen from the water column. This causes the suffocation of fish and other aquatic organisms.

5. Sulphates particles from acid rain can cause harm the health of marine life in the rivers and lakes it contaminates, and can result in mortality.

6. Suspended particles in freshwater reduces the quality of drinking water for humans and the aquatic environment for marine life. Suspended particles can often reduce the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms.

Biochemical Oxygen Demand (BOD):

BOD is the amount of oxygen required by micro-organisms to decompose the organic substances in sewage. The amount of organic material that can rot in the sewage is measured by the biochemical oxygen demand. Dissolved oxygen is an important factor that determines the quality of water in lakes and rivers.

Water with the higher the concentration of dissolved oxygen has the better the water quality. When sewage enters a water bodies, micro-organisms begin to decompose the organic materials. Oxygen is consumed by micro-organisms in their metabolism.

The main organic materials are food and vegetable waste, plant nutrient come from chemical soaps, washing powders, etc. Domestic sewage is also very likely to contain disease causing microbes. Thus, disposal of domestic waste water is a significant technical problem.

 

Biochemical Oxygen Demand

Impact of Heavy Metals:

(a) Cadmium (Cd):

Cd is very toxic, 50 mg may cause vomiting, diarrhoea, abominal pains, loss of consciousness. It takes 5-10 years for chronic Cd intoxication. During first phase, discolouration of teeth, loss of sense of smell, mouth dryness occurs.

Afterwards it may cause decrease of red blood cells, impairment of bone marrow, lumber pains, disturbance in calcium metabolism, softening of bones, fractures, skeletal deformations, damage, of kidney, hypertension, tumor formation, heart disease, impaired reproductive function, genetic mutation, etc.

(b) Mercury (Hg):

Mercury is very toxic. Excess mercury in human body (more than 100 mg) may cause headache, abdominal pain, diarrhoea, destruction of haemoglobin, tremors, very bad effect on cerebral functions and central nervous system, paralysis, inactivates functional proteins, damage of renal tissues, hyper coagulability of blood, mimamata disease, and even death.

It may cause impairment of vision and muscles and even coma. It disturbs reproductive and endocrine system. Also causes isomnia, memory loss, gum inflammation, loosening of teeth, loss of appetite, etc.

(c) Lead (Pb):

More than 400 mg of lead in human body can cause brain damage, vomiting, loss of appetite, convulsions, uncoordinated body movements, helepessly amazed state, coma. It is retained in liver, kidney, brain, muscle, soft tissues, bones.

Leads to high rate of miscarriages, affects skin, and respiratory system, damages kidney, liver and brain cells. Disturbs endocrine system, causes anaemia, and long term exposure may cause even death.

(d) Arsenic (As):

Poisonous to fishes, animals and humans. Greater than 25 mg of arsenic causes vomiting, diarrhoea, nausea, irritation of nose and throat, abdominal pain, skin eruptions inflammations and even death. It binds globulin of blood haemoglobin in erythrocytes. May cause cancer of skin, lungs and liver, chromosomal aberration and damage, gangrene, loss of hearing, injury to nerve tissue, liver and kidney damage. Minor symptoms of as poisoning, weight loss, hair loss, nausea, depression, fatigue, white lines across toe nails and finger nails.

(e) Vanadium (V):

It is very toxic, may cause paralysis.

(f) Silver (Ag):

Causes pathological change in kidney, liver and may even damage kidney. May cause Argyria (discolouration of skin). Effects mucous membranes and eyes. In high doses, it may be fatal to humans.

(g) Radioactive Materials/Metals/Substances:

There generally cause ‘Gene’ mutation, ionization of body fluids, chromosomnal mutations and cancers. Destroy body cell tissue, adversely effects reproductive system. When mother is exposed to radiation during pregnancy, it causes severe mental retardation and leukaemia in infants. Radioactive metals like heavy metals are nephrotoxic and damage kidneys.

(h) Fluoride:

Excess fluoride intake in body results in progressive crippling scourge (sponging)/fluorosis of bones, teeth. May causes metabolic alternations in soft tissues and their functional mechanism.


6. Essay on the Control of Water Pollution:

In order to maintain satisfactory water quality, effluents containing excessive amounts of objectionable materials must be treated to remove the offensive matter prior to the discharge of the effluent into a receiving water. In order to define the various processes available for water pollution control, it is necessary to categorically describe the process in generalized terms.

The various phases of waste treatment are usually described as follows:

(i) Pretreatment.

(ii) Primary treatment.

(iii) Secondary treatment.

(iv) Tertiary treatment.

(i) Pre-Treatment:

It includes processes to remove larger aggregates of floating and suspended solid matter, grit and also much of the oil and grease content. It may also include flow measurement and sometimes prechlorination to prevent odors from emanating from the subsequent processes.

The most common methods of removing large solid particles are passing the waste effluent through screens consisting of spaced metal bars or using comminutors to grind the solids into small pieces which subsequently settle out in the primary sedimentation tanks.

(ii) Primary Treatment:

It consists of the pretreatment processes plus tank sedimentation and usually chlorination prior to discharge into a receiving water. A primary treatment plant will often include the sludge digester, in which the solids removed from the sedimentation tank are subjected to anaerobic fermentation i.e., stabilisation in the absence of free oxygen.

(iii) Secondary Treatment:

It is a biological process following primary treatment. The most common biological process in use today is probably either the activated sludge process or an aerated lagoon. Activated sludge process consists of maintaining an active floe in a tank well supplied with oxygen in such a way that maximum contact is made between the incoming waste water and the organisms in the floe. Another secondary treatment process is Trickling Filtration.

This process is identical to activated sludge process, except that the microorganisms working to stabilize the organic waste material are attached to a fixed bed rather than being of a floating and suspended nature. The waste water is distributed from rotary nozzles over the bed which gives support to the biological film. The material in the waste is oxidized after assimilation by the bacteria, and then released in a more stable form.

(iv) Tertiary Treatment:

If the effluent from a secondary treatment plant is not considered satisfactory, tertiary treatment may be required.

Tertiary treatment may consist of many different processes including:

a. Coagulation,

b. Filtration,

c. Co-precipitation,

d. Membrane separation processes, and 

e. Adsorption etc.

Coagulation may be defined operationally as the reactions that take place upon the addition of a coagulant (e.g., inorganic metal salts’ and organic polymers) to water and result in the formation of insoluble products of reaction between the coagulant and the impurity to be removed.

Membranes have been used to concentrate and separate soluble ions and molecules, colloidal species, particulates and microorganisms in waste water. The capabilities of membranes to exclude species by virtue of their size (dialysis and membrane filtration) and to adsorb or exclude due to specific chemical interactions (ion exchange and osmosis) have been utilized.

In Co-precipitation an ion is removed from the solution phase with a precipitate (carrier), even though its solubility is not exceeded. The two principal mechanisms for this process are Adsorption, in which the ion co-precipitating is adsorbed onto the surface of the primary precipi­tate; and occlusion, in which the ion is found in the interior of the primary precipitate, this category includes both solid solution formation and ion entrapment.

The most common type of water treatment, except disinfection, is filtration. This was almost the only form of treatment practised prior to the advent of chlorination. Today, almost all water supplies are filtered as an integral part of the purification process.

Filtration should be done after coagulation as most of the filters will not remove colloidal impurities by themselves. Filters a may be made up of sand, anthracite coal or diatomaceous earth.


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Water pollution

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Raw sewage and industrial waste in the New River as it passes from Mexicali to Calexico , California

By-products of copper color this stream blue.

Water pollution is the pollution of bodies of water, such as lakes , rivers , seas, the oceans , as well as groundwater . It occurs when pollutants reach these bodies of water, without treatment. Waste from homes, factories and other buildings get into the water bodies.

Water pollution is a problem for the species and ecosystems there. It affects plants and organisms living in the water. In almost all cases the effect is damaging not only to individual species and populations, but also to the wider biological communities . The colour is usually green or brown but normal water can be blue.

Agriculture is one of the major sources of water pollution, because the fertilizers given to the crops for better growth are washed into rivers and lakes, which in large amounts pollute the water.

There are many chemicals that are naturally found in these bodies of water but today it is polluted by nitrates, phosphates, oil, acid from acid rain, and debris like sediments, fallen logs and so on. and hence it creates diseases to human and other living organisms e.g they drink water from rivers which are mixed with poisonous chemicals which can affect them. Aquatic organisms in rivers are also effected and then humans who consume this fishes can also have serious health problems.

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