Read Essays on: 1. Essay on the Introduction to Water Pollution 2. Essay on the Nature of Water Pollutants 3. Essay on the Categories of Water Pollution 4. Essay on the Sources of Water Pollution 5. Essay on the Causes of Water Pollution 6.Essay on Water Pollution by Industrial Wastes 7.Essay on the Effects of Water Pollution 8. Essay on the Impact of Water Pollution on Public Health 9.Essay on the Methods for Water Pollution Control 10.Essay on the Suggested Approaches to Prevent Water Pollution. Compilation of essays on ‘Water Pollution’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Water Pollution’ especially written for school and college students. Also learn about: 1. Long Essay On Water Pollution 2. Short Essay On Water Pollution 3. Essay On Water Pollution For Class 5 6. Essay On Water Pollution And Its Prevention7. Water Pollution College Essay 8. Causes Of Water Pollution Essay
Essay on Water Pollution
Essay Contents:
- Essay on to Water Pollution [Introduction]
- Essay on the Nature of Water Pollutants
- Essay on the Categories of Water Pollution
- Essay on the Sources of Water Pollution
- Essay on the Causes of Water Pollution
- Essay on Water Pollution by Industrial Wastes
- Essay on the Effects of Water Pollution
- Essay on the Impact of Water Pollution on Public Health
- Essay on the Methods for Water Pollution Control
- Essay on the Suggested Approaches to Prevent Water Pollution
Essay # 1. Essay on Water Pollution [Long Essay on Water Pollution]:
It is a well-known fact that clean water is absolutely essential for healthy living. Adequate supply of fresh and clean drinking water is a basic need for all human beings, yet it has been observed that millions of people worldwide are deprived of this. Freshwater resources all over the world are threatened not only by over-exploitation and poor management but also by ecological degradation.
The main sources of freshwater pollution can be attributed to discharge of untreated waste, dumping of industrial effluents, and run-off from agricultural fields. Industrial growth, urbanization and the increasing use of synthetic organic substances have serious and adverse impacts on freshwater bodies.
It is a generally accepted fact that the developed countries suffer from problems of chemical discharge into the water sources mainly groundwater, while developing countries face problems of agricultural run-off in water sources. Polluted water like chemicals in drinking water causes problem to health and leads to water-borne diseases which can be prevented by taking measures even at the household level.
The quality of water is of vital concern for mankind since it is directly linked with human welfare. It is a matter of history that fecal pollution of drinking water caused water-borne diseases which wiped out entire populations of cities. At present, the menace of water-borne diseases and epidemics still looms large on the horizons of developing countries. Polluted water is the culprit in all such cases. The major sources of water pollution are domestic waste from urban and rural areas, and industrial wastes which are discharged into natural water bodies.
Water is one of our most important natural resources and there are many conflicting demands upon it. Skillful management of our water bodies is required if they are to be used for such diverse purpose as domestic and industrial supply, crop irrigation, transport, recreation, sport and commercial fisheries, power generation and waste disposal. Water pollution is most common associated with the discharge of effluents from sewers or sewage treatment plants, drains and factories to the water body of rivers, seas and marines.
Estimates suggest that nearly 1.5 billion people do not have access to safe drinking water. More than 2.2 million people, primarily in developing countries die each year from diseases caused by polluted water and filthy sanitary conditions. With over 70 per cent of the planet covered by oceans, people have long acted as if these very bodies of water could serve as a limitless dumping ground for wastes. Raw sewage, garbage and oil spills/slicks have begun to overwhelm the diluting capabilities of the oceans, and most coastal waters are now polluted.
Generally speaking, water pollution is a state of deviation from the pure condition, whereby its normal function and properties are affected. Knowledge of aquatic environmental chemistry is the key to the understanding of water pollution and its control. Water pollution can be best considered in the perspective of possible pollutant cycles throughout the environment. The major routes of pollutant interchange among the biotic, terrestrial, atmospheric and aquatic environments.
Any shift in the naturally dynamic equilibrium existing among the environmental segments – hydroshpere/atmosphere/lithosphere (sediment) give rise to the state of pollution. The signs of water pollution are obvious to all; bad taste of drinking water; offensive odours from lakes, rivers and ocean beaches; unchecked growth of aquatic weeds in water bodies; decrease in number of fish in fresh water, river water, sea water; oil and grease floating on water surfaces.
These disturb the normal use of water for:
(i) Public water supply,
(ii) Recreation and aesthetics,
(iii) Fish, other aquatic life and wildlife,
(iv) Agriculture, and
(v) Industry.
Thus, water quality characterization must take into account:
(a) The distribution dynamics of chemicals in the aqueous phase (soluble, colloidal or adsorbed on particulate matter);
(b) Accumulation and release of chemicals by the aquatic biota;
(c) Accumulation and release of bottom deposits; and
(d) Inputs from land and atmosphere, e.g., air-borne contaminants and land run-offs. In the present discussion, an attempt has been made to describe causes of water pollution and methods of minimizing their hazards.
Essay # 2. Nature of Water Pollutants:
There are diverse categories of water pollutants often encountered in nature. They are primarily high nutrients like PO4, NO3, CO3 or SO4; acidity or alkalinity of water, contamination of toxic metals, high particulates load, contamination with pathogenic microbes and pesticides, presence of oils, grease and other hydrocarbons etc.
These contaminants causing detrimental effects on aquatic biota or its consumption in any form cause serious health hazards. In addition, higher water temperature may also cause detrimental effects on aquatic biotic life too.
The eutrophication is a nutrient enrichment (mostly nitrate and phosphates) in water bodies. This is quite common in confined water bodies like lakes and reservoirs. The sign of eutrophication is manifested by a number of features viz., phytoplankton bloom, higher macrophyte growth and depletion of oxygen level of water.
The eutrophication is primarily caused by anthropogenic or cultural activities of mankind. Sewage contamination, waste dumping in water bodies or even agricultural run-off storage leads to eutrophication.
After the planktonic bloom or macrophysics growth nutrients are reduced due to plants uptake, then finally water bodies became much more less polluted. There is distinct loss of species diversity due to eutrophication of water bodies.
In lentic and lotic water bodies, there is an intimate relationship of nitrogen and phosphorus cycling and sunlight. For instance, if in a water body the ratio of phosphate to nitrate is 1:15, the aquatic plants will be able to use all phosphates but only about half of the nitrate i.e., the phosphate becomes limiting and nitrate in abundance.
But keeping the nitrate at the same level, if phosphate enrichment takes place say to 4:15 phosphate; nitrate level, then all nitrates will be used by plants and it becomes limiting. The acceptable level of total inorganic phosphate in water is 0.03 to 0.40 mg/l. In most of the lakes and rivers of topics where eutrophication is encountered, the principal cause is excessive enrichment of water by phosphate and nitrates.
In and around cities and industries, phosphate content has increased by 20 – 25 folds during the last 10-15 years. Formation of froths and foams in lentic and lotic waters are due to phosphate containing detergents now profusely used for washing clothes.
Essay # 3. Categories of Water Pollution:
Following are ten categories of water pollution. There are a great variety of ways to delineate types of pollution or its nature, but regardless of the manner chosen, those areas listed below represent the most relevant.
1. Oxygen-Demanding Wastes:
Oxygen is a basic requirement of almost all plant and animal life-forms in any given body of water. If an insufficient amount of oxygen is available to support life, damage to the ecosystem results.
All organic materials or wastes can be broken down or decomposed by bacterial and other biological activity (biodegradation). Although some inorganic substances are included in this category, most are organic compounds that can exhibit a biochemical oxygen demand (BOD) or also possibly a chemical oxygen demand (COD), because oxygen will be used or is required in the degradation process.
Typical sources include sewage from domestic and animal sources; industrial wastes from food processing, paper mills, tanning operations, meatpacking plants, etc.; natural decaying vegetation; and the decay of dead plant or animal life. Biological degradation takes place at all times in almost all environments.
This category of water pollution becomes a problem when the oxygen required for chemical oxidation or biological decomposition of the organic material present is greater than the available oxygen in the ecosystem. Natural systems do have a limited capability to accommodate self-purification through decomposition by employing a number of re-oxygenation processes. However, anthropogenic pollution often overwhelms the given system.
2. Disease-Causing Agents:
There are various types of pathogenic microorganisms that pass through their host species and may enter the aquatic ecosystem, for example, by way of contamination from human or animal waste. Through drinking water consumption or through various water-contact activities, the spread of diseases such as typhoid, cholera, hepatitis, etc. may occur.
Pathogens may be spread to water only sporadically, and once there, do not survive long, so testing for them is difficult. We usually use indicator species testing— e.g., coliform bacteria—as a means of identifying a problem.
In this category, we may also want to consider man’s activities resulting in the creation of an environment that fosters disease. Mosquito-breeding environments, with the mosquito as an agent for malaria, can be created, for example, by certain construction activities that may create stagnant water suitable for mosquito larvae.
3. Thermal Pollution:
The discharge of cooling water from industrial and commercial operations may artificially heat up the aquatic environment. Organisms may become physiologically stressed from exposure to heated water or can be directly killed if escape is not possible. Some can adapt to the point of dependency and suffer if the thermal source is suddenly removed.
If artificial heat loading is combined with natural seasonal warming of an aquatic system, the impact can be quite severe. Besides causing outright death, the problem also may result in the interference with natural life processes such as growth rates, respiration, reproduction, and distribution of species. However, thermal pollution primarily causes a decrease in oxygen content, which may directly kill aquatic species through asphyxiation.
4. Sediments and Debris:
Soils, sands, and silts washed from the surrounding lands naturally follow a progression of turning wetlands into dry land. Upland lakes and ponds eventually evolve into marshes, swamps, bogs, and finally into meadowlands. Man’s artificial manipulation of the environment adjacent to wetlands and water bodies, from such activities as clearing and development operations, may release weathered sediments through runoff.
These sediments may directly smother and kill aquatic life. Delicate ecosystems, such as coral reefs, are particularly vulnerable to this. Transported sediments can directly destroy habitats, precluding their use in fulfilling any one of a number of potential biological needs. The siltation of rivers with gravel bottoms directly destroys the spawning areas of salmon. Improper farming and mining techniques especially encourage erosion and sediment runoff.
As the origin of sediments is terrestrial, it is convenient to include the debris discarded by man into the aquatic environment. We have all seen pictures of marine life strangled by plastic six-pack holders, or of Dead Sea turtles that mistakenly swallowed a plastic bag instead of a jellyfish.
Autopsies performed on dead seals often show severe intestinal blockage. The presence of medical waste on our beaches from such sources as combined sewer overflows or direct illegal dumping may present a significant human health hazard besides the obvious aesthetic damage. The list of examples in this category is endless.
5. Plant Nutrients:
In this category, the primary focus is on fertilizing chemicals such as nitrates and phosphates. While important for plant growth, too much fertilization encourages the overabundance of plant life and can result in environmental damage called “eutrophication.” This can occur at both the microscopic level by algae (phytoplankton) or by macroscopic algae and aquatic plants. It is a normal process until man accelerates it and thereby creates a pollution situation.
Nitrates and phosphates are made available through natural means; however, anthropogenic sources such as sewage treatment plant effluents, the use of fertilizers, and a variety of point and non-point sources can create significant problems.
6. Petroleum Hydrocarbons:
Much oil seeps from the earth as a natural material; however, man’s activities pose an even greater threat to the environment. From crude oil through highly refined petroleum products including gasoline, the release of this material into aquatic systems is very detrimental.
Direct smothering, acute and chronic toxic effects, loss of habitat, etc., can all result. Recent events have greatly focused our attention on this form of pollution, particularly in the transport of the material, but daily wastewater discharges, leaching, recreational boating, bilge cleaning, and underground tank leaks are all factors.
On Long Island, New York, petroleum hydrocarbons, particularly from leaking underground storage tanks, are the single greatest threat to the drinking water supply. This is because Long Island is a “sole-source aquifer” and pollutants released at or near the land surface eventually find their way into the drinking water resources.
7. Inorganic Chemicals and Minerals:
This type of pollution is generally associated with various types of mining and industrial processing operations. The most common operations include processes that can release acids and heavy metals into sediments from leaching of raw or processed wastes or materials, or through direct discharges.
In particular, many problems have been associated with tailings, spoils, and direct leaching from wastes piles and stockpiles in mining operations. Acid rain and runoff not only threaten aquatic life directly through the effects of low pH, but also indirectly through leaching, which may increase the heavy metal burden on receiving water bodies.
8. Synthetic Organic Compounds:
Especially since World War II, the production of synthetic chemicals has risen at an overwhelming rate. Accidental and intentional discharges of these potentially hazardous materials have created many cases of serious pollution. As pure products, by-products, and waste products, they may have both a powerful and quick-acting “acute” effect and a long-term “chronic” effect on aquatic ecosystems. They include everything from plastics, plasticizers, solvents, detergents, pesticides, PCBs, pharmaceuticals, paints, and many other synthetically created compounds.
Because they are synthetic, these compounds may be resistant to biological breakdown and persist and accumulate in the environment. They may be directly toxic to aquatic life, or they may make objectionable tastes and odors in aquatic species taken for human consumption.
The potential for much more serious biological effects on humans is a primary concern, especially from low-level chronic exposure in drinking water supplies. Some of the more common contaminants include 1, 1, 1-trichloroethane, trichloroethylene (TCE), and tetrachloroethylene, also called per- chloroethylene (perc).
9. Radioactive Substances:
Radioactively unstable elements emit forms of radiation that can be highly injurious to aquatic organisms by affecting biological process such as reproduction, or can be directly lethal. Sources of such materials include the mining and processing of ores; nuclear weapons manufacturing and testing; the handling and disposal of nuclear fuels; the use of nuclear materials for medical, industrial, and research applications; and the legal and illegal discharge of radioactive wastes.
Russia has recently admitted to dumping radioactive wastes into the Baltic Sea. Contamination of the shallow groundwater aquifer has been confirmed at the nuclear repository at Han- ford, Washington, and at the Brookhaven National Laboratory on Long Island.
10. Biological Pollution:
The introduction of a non-indigenous species into an established environment by man very often has led to disastrous consequences. Sometimes the introduction has been intentional, such as for hunting; in other instances, species have accidentally been released or have escaped from man’s control.
In other circumstances, an activity of man has enabled a species to invade a habitat that geography or other conditions had precluded. The classic case of an aquatic species expanding its range through man’s activity is the sea lamprey.
To facilitate shipping, the Welland Canal was constructed to bypass Niagara Falls and associated rapids. This enabled the lamprey to penetrate the lakes beyond Lake Ontario. The result was the almost total destruction of the fishing industry, followed by 40 years of eradication efforts at high cost and only limited success.
The introduction of species on land also can have an effect on aquatic resources. In New Mexico, 125 years of introduced cattle ranching has in some places severely denuded and compacted the soil. Subsequent to a drought, heavy rains and runoff so clogged the existing small streams with sediment that many fish species were simply smothered to death.
These two examples are unfortunately only a few of the many situations that have occurred.
Essay # 4. Sources of Water Pollution:
1. Agricultural Run Off:
The use of land for agriculture and the practices followed in cultivation greatly affect the quality of groundwater. Intensive cultivation of crops causes chemicals from fertilizers (e.g., nitrate) and pesticides to seep into the groundwater, a process commonly known as leaching. 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 high nitrate content in ground water is mainly from irrigation run off from agricultural fields where chemical fertilizers have been used indiscriminately.
2. Industrial Effluents:
Waste water from manufacturing or chemical processes in industries contributes to water pollution. Industrial waste water usually contains specific and readily identifiable chemical compounds. During the last fifty years, the number of industries in India has grown rapidly. But water pollution is concentrated within a few sub-sectors, mainly in the form of toxic wastes and organic pollutants. Out of this a large portion can be traced to the processing of industrial chemicals and to the food products industry.
In fact, a number of large and medium-sized industries in the region covered by the Ganga Action Plan do not have adequate effluent treatment facilities. Most of these defaulting industries are sugar mills, distilleries, leather processing industries, and thermal power stations. Most of the major industries have treatment facilities for industrial effluents. But this is not the case with small-scale industries, which cannot afford enormous investments in pollution control equipment as their profit margin is very slender.
Essay # 5. Causes of Water Pollution [for college students]:
Water pollution is the changes in physical, chemical and biological characteristics of water.
Water pollution is the contamination of water bodies like lakes, rivers, oceans, aquifers and groundwater. This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.
Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, but also to the natural biological communities.
1. Point Source:
It refers to contaminants that enter a waterway from a single, identifiable source, such as a pipe or ditch. Examples are discharges from sewage treatment plant, storm drain, drain of construction site etc.
2. Non-Point Source:
It refers to water contamination that does not originate from a single discrete source. Non-Point Source (NPS) pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. Examples are, leaching out of nitrogen compounds from fertilized agricultural lands, contaminated water runoff and urban runoff etc.
3. Natural Substances:
Natural Substances like plant leaves, grass, dead and decayed animals, microorganisms etc. Aquatic bodies or the water organisms require dissolved oxygen. Because of water contamination, dissolved oxygen level decreases in water. This leads to the death of aquatic animals.
4. Organic, Inorganic and Macroscopic Contaminants:
a. Organic water pollutants include:
i. Detergents
ii. Disinfection by-products found in chemically disinfected drinking water, such as chloroform
iii. Food processing waste, which can include oxygen-demanding substances, fats and grease
iv. Insecticides and herbicides, a huge range of organo-halides and other chemical compounds
v. Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and lubricants (motor oil), and fuel combustion byproducts, from storm water runoff.
vi. Volatile organic compounds, such as industrial solvents, from improper storage.
vii. Chlorinated solvents, which are dense non-aqueous phase liquids, may fall to the bottom of reservoirs, since they don’t mix well with water and are denser.
viii. Polychlorinated biphenyl (PCBs).
ix. Trichloroethylene.
x. Various chemical compounds found in personal hygiene and cosmetic products.
xi. Drug pollution involving pharmaceutical drugs and their metabolites.
b. Inorganic water pollutants include:
i. Acidity caused by industrial discharges (especially sulfur dioxide from power plants)
ii. Ammonia from food processing waste
iii. Chemical waste as industrial by-products
iv. Fertilizers containing nutrients-nitrates and phosphates—which are found in storm water runoff from agriculture, as well as commercial and residential use
v. Heavy metals from motor vehicles and acid mine drainage
vi. Silt in runoff from construction sites, logging, slash and burn practices or land clearing sites.
c. Macroscopic Contaminants Include:
i. large visible items polluting the water – may be termed “floatables” in an urban storm water context, or marine debris when found on the open seas, and can include items such as – Trash or garbage (e.g. paper, plastic, or food waste) discarded by people on the ground, along with accidental or intentional dumping of rubbish, that are washed by rainfall into storm drains and eventually discharged into surface waters
ii. Shipwrecks, large derelict ships.
5. Thermal Pollution:
It is the rise or fall in the temperature of a natural body of water caused by human influence. Thermal pollution, unlike chemical pollution, results in a change in the physical properties of water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers.
Elevated water temperatures decrease oxygen levels, which can kill fish and alter food chain composition, reduce species biodiversity, and foster invasion by new thermophilic species. Urban runoff may also elevate temperature in surface waters.
6. Biological Pollutants:
There are microorganisms (bacteria, viruses, protozoa and helminthes) that are harmful to humans and other forms of life. Infectious diseases caused by biological pollutants, such as typhoid and cholera, are the most common and widespread public health risks associated with drinking water.
Microorganisms may get into water with dust from the air as rain falls, and when water passes through soil which is polluted with human and animal wastes. The contamination of water supplies with raw sewage (human and domestic wastes generated from residential areas) is the most common route for biological pollutants to enter water.
When contaminated river water moves downstream it is possible that any pollutant will be diluted as more water flows in and so increases the total volume of water in the river. This dilution may be enough to reduce the contaminants sufficiently to minimize the possible health effects but this process may not work for all pathogens.
Essay # 6. Water Pollution by Industrial Wastes [for class 5 students]:
Certain types of organic, inorganic and radioactive substances present in the industrial waste in minute suspended or colloidal form and microorganisms pollute the sources of water, where these are disposed off. The decomposition of the industrial wastes by microorganisms results in the products which are odoriferous or unacceptable in taste appearance as well as harmful to public health.
The organic impurities give odour, colour and taste to the water, whereas inorganic compounds give foaming, odour, turbidity etc. Various types of bacteria, viruses and plant life also grow in the trade wastes.
Various types of organic compounds such as proteins, carbohydrates, fats, soaps, resins, rubber, waxes, oils, coal, dyes, tar, synthetic, detergents, ketones, amines, acids, alcohols etc., present in the industrial wastes are objectionable.
Keratin from wool industries, proteins from egg- albumen, tannin from tanneries, gelatine from bones and animal tissues, case in from dairies fibroin from natural silk, gelatin from wheat etc., when discharged in the natural water sources from industrial wastes, undergo degradation by bacterial action resulting in compounds like putrescine, cadaverine, indole, skotole, lower aliphatic amines, indole-thylamine etc.
These all compounds impart most objectionable colour and pollute the water. The pollutants add colour, taste and odour in the receiving water, make the water oily, greasy, corrosive and unfit for industrial recreational or domestic use. They also impart hardness change pH-value, increase temperature and algae growth destroy the aquatic life and increase the insect nuisance.
When the organic pollution load is small and DO content of receiving water are high, the aerobic bacteria break down the organic matter into simple compounds, which are relatively harmless, stable and odourless.
If the DO is unable to cope with the load, the anaerobic bacteria decompose the organic load into compounds such as organic sulphate compounds, organic amines, hydrogen disulphide, phosphine etc., which are highly odoriferous.
Therefore, the discharge of such pollutants into the receiving water converts them into obnoxious mixture and objectionable matter should be removed for the utilization of the water for various purposes. It will be economical to control the oxygen-demand load of the inflowing wastes into the receiving waters, rather than the treatment of objectionable water at the later stage.
This method will also reduce the air pollution and surrounding land. Therefore, the industrial waste should be given proper treatments, before disposal in the water courses.
Essay # 7. Effects of Water Pollution:
As water is essential for human beings, animals and plants the effects of water pollution are also wide spread. Water pollution is harmful for where-ever it is used.
(i) Direct Effect on the Human Beings:
By drinking polluted water, much damage is caused to human body.
The diseases spread by polluted water are known as water born diseases:
a. Cholera, typhoid, diarrhoea, etc., bacterial diseases.
b. Hepatitis, jaundice etc., viral diseases.
c. Amoebiosis, stomach and intestinal infection etc., protozoa caused diseases.
d. Tape worm, ring worm, water caused diseases.
e. Due to contact with polluted water, skin diseases, eye infections and other secondary infections take place.
f. When there is excess of a chemical fluoride in water, it causes deformation of bones, staining and weakening of teeth and the disease is known as fluorosis.
g. Presence of some metal ions like, mercury, arsenic lead, cadmium make the water poisonous and unfit for drinking.
(ii) Effect on Aquatic Animals:
Pollution in water harms the aquatic life in a great way:
a. High level of pollution in water harms fish and aquatic life decreasing their population alarmingly.
b. Due to decrease in the amount of oxygen in polluted water, death of fish and other aquatic animals take place.
c. The oil pollution in ocean harms aquatic animals in the sea.
d. Due to thermal pollution loss of many aquatic lives.
(iii) Effect on other Animals:
a. Other than the aquatic animals, other cattle like cow, buffalos, sheep, goats, etc., drink the polluted water and suffer from intestinal diseases.
b. By drinking the water having excess of fluoride both pet and wild animals suffer from weakening of bones and teeth.
(iv) Effect on Vegetation:
Due to pollution in water vegetation of an area, is either damaged or some species are permanently missing from that area:
a. Water becomes, alkaline due to mixing of domestic waste water and detergents etc., in which many aquatic plants cannot survive.
b. In the agricultural effluents, there is excess of nitrates, phosphates etc., which enhances the growth of plants like blue green algae in a water body and due to excess spreading of this algae, all the other vegetation die.
c. Affecting genetic diversity of many water bodies.
d. In polluted water light penetration is less which slow-down the process of photosynthesis, diminishing the growth of the plants.
e. BOD and COD in polluted water is high.
Essay # 8. Impact of Water Pollution on Public Health
:
Drinking untreated water nowadays will have immediate reaction on the body. People may get a stomach ache at the least. Water-borne diseases account for the deaths of 3,575,000 people a year! That’s equivalent to a jumbo jet crashing every hour, and the majority of these are children.
Chemicals in the water also have negative effects on our health. Chemical pollutants usually occur in very low amounts in water supplies, but even at such low levels, they’re still dangerous to human health. Some of these compounds are, at the molecular level, very similar to human hormones and are called environmental estrogens or endocrine disruptors.
1. Pesticides – can damage the nervous system and cause cancer because of the carbonates and organophosphates that they contain. Chlorides can cause reproductive and endocrinal damage.
2. Nitrates – are especially dangerous to babies that drink formula milk. It restricts the amount of oxygen in the brain and cause the “blue baby” syndrome.
3. Lead – can accumulate in the body and damage the central nervous system. Over exposure of lead leads to lower IQ level in small kids.
4. Arsenic – causes liver damage, skin cancer and vascular diseases
5. Fluorides – in excessive amounts can make your teeth yellow and cause damage to the spinal cord and leads to skeletal fluorosis.
6. Petrochemicals – even with very low exposure, can cause cancer.
7. Metals- such as mercury, iron, and nickel, pollute water as well. Some of these metals wash into water during mining operations, whereas others, such as mercury, settle into water via the air after being emitted from industrial smokestacks. The small amounts of these metals that scientists measure in water supplies appear almost harmless.
Essay # 9. Methods for
Water Pollution Control:
Actually water pollution has become a global problem, partly because of the population explosion and partly due to the phenomenal advancement in industrialization. India has many localized areas where water pollution already creates situations not only hazardous to health but also adverse to the economy in several ways.
Water pollution problem can be minimized by adopting the following techniques:
1. Stabilization of the waste
2. Recycling of the waste
3. Waste treatment
4. Removal of pollutants.
1. Stabilization of the Waste:
It is the most relevant economical and wise way to control water pollution. The principles involved in this method include reduction of the waste at source, harvesting and removal of biomass, trapping of nutrients, fish management and aeration. It is a very economical method for the treatment of industrial effluent and domestic sewage.
Industrial and domestic wastes are stored in a dilute condition in shallow ponds called oxidation or stabilization ponds. After a week, microbes and algae start flourishing. The microbes decompose the organic wastes by oxidation, and water is purified. This water is rich in nitrogen, phosphorus, potassium and other nutrients. This method was devised by NEERI at Nagpur.
2. Recycling of the Waste:
Water pollution can be controlled to a certain extent by reutilizing the wastes, called recycling. In developed countries the waste water consisting of industrial effluents, domestic sewage, thermal pollutants, radioactive pollutants and municipal sullage etc. receive some sort of treatment before these get mixed into the water bodies.
Examples-
a. The dung of cattle can be reused for the production of gobar gas.
b. Sewage can be reused for irrigation and pisciculture after treatment in oxidation pond.
3. Waste Treatment:
Water pollution control by sewage treatment includes the following steps:
(a) Sedimentation
(b) Dilution, and
(c) Storage.
When sewage is allowed to stand, the suspended particles settle to the bottom. So by sedimentation the suspended particles are removed from sewage.
The sewage can be diluted with water. This increases the O2 contents and reduces BOD and CO2.
The dilution sewage is stored in a pond. This facilitates the growth of microbes. This renders further oxidation of sewage.
4. Removal of Pollutants:
Various techniques involved in the removal of biological, chemical and radioactive water pollutants may be adsorption, electro-dialysis, ion-exchange, reverse-osmosis etc.
The processes for the removal of various pollutants are:
(i) Removal of Phosphorus by Electrolysis:
In Norway, organic sewage is mixed with 10 to 15% sea water and subjected to electrolysis to remove phosphorus from sewage. The removal of phosphorus reduces the eutrophication of lake and rivers. Phosphorus compounds in the sewage get precipitated as calcium or magnesium phosphate.
These salts along with sludge and suspended particles adhere to Mg(OH)2 at the negative pole during electrolysis. Hydrogen gas liberated during electrolysis makes the phosphate and sludge to float on the surface as scum, which can be scraped off from the top layer. Chlorine produced at the positive pole can be used for disinfection at the outlet.
Placing an electrical potential difference across the waste water produces an electric current, making the cations to migrate toward the cathode and the anions to migrate toward the anode. Membranes (really ion-exchange resins in sheet form) permeable to only cations or only anions are used to control the migration of the ions and permit demineralized water to be taken out of the appropriate chambers. Organic molecules are not removed and they can collect on and clog the membranes.
(iii) Removal of Salts [Reverse Osmosis Technique]:
Various toxic substances and salts present in the water can be removed by reverse osmosis by forcing the waste water through a semipermeable membrane under a pressure exceeding the osmotic pressure. During the process, flow occurs in the reverse direction. The solvent is attracted while the solute is repelled. This method is commonly used to desalinate the brackish water and to purify water from sewage.
Process of reverse osmosis is the opposite phenomenon of osmosis and is produced by applying pressure to the more concentrated solution and thereby forcing water to the side of the membrane.
Reverse osmosis reduces both the organic and inorganic content of the waste water but some fouling of membranes may still occur. An experimental reverse osmosis plant at Pomona, California, led to reduction of 88% for total dissolved solids, 84% for COD, 98.2% for phosphate, 82% for NH3 and 67% for nitrate.
(iv) Ion-Exchange:
Ion exchange can be accomplished by the use of natural materials (Example — zeolite) and synthetic materials (such as ion-exchange resins). Cation- exchange resins exchange their H+ ions for metallic cations in the solution passing through the ion- exchange column, while ion-exchange resins exchange their OH– ions for chloride and other anions in the solution.
The resins can be regenerated by treatment with H2SO4 (for cationic resins) or NaOH (for anionic resins). Ion exchange is very effective and produces high quality effluents and it is possible to mix treated water with untreated water to produce effluent of any desired quality. At present the cost of this treatment has been fairly high. One natural zeolite, clinoptilolite, seems to adsorb both phosphate and NH4 ions and may prove to be of great value.
C.S.I.R., New Delhi, has devised several techniques for the removal of following pollutants in water:
a. Mercury:
Mercury can be removed from chloro-alkali effluent plants by applying mercury- selective ion exchange resin.
b. NH3:
It can be removed from waste water of chemical industries by ion-exchange technique as described above.
3. Sodium Salts:
The sodium salts can be removed from industrial effluents by reverse osmosis.
4. Phosphorus Compounds:
Phosphorus and its compounds can be removed from industrial effluents viz., reactor effluents by passage through beds of aluminium turning.
5. Phenolic Compounds:
By the polymeric absorbents, phenolic compounds from the waste water of pulp and paper mills, tanneries, petroleum refineries and resin plants can be recovered.
6. Decolourization of Water:
The brackish waste water from industries can be decolourized by electrolytic decomposition technique.
Essay # 10. Suggested Approaches to Prevent Water Pollution
:
The objective of all control legislation and management are the same, i.e., to achieve and maintain water quality at acceptable levels.
Some suggested approaches are:
1. Licencing of Discharging Effluents for Prevention of Water Pollution:
In developed industrialized countries, the system of administrative agreement for the release of effluents into aquatic bodies, considering technological and economic conditions, have been established. The system includes consent conditions, abatement requirements, enforcement methods and severe tax penalties for violating the rules of agreed limits. Discharge license has to be issued to any polluter by any competent authority or organization like water pollution control authority, a state government or a federal agency to avoid water pollution.
2. Economic Incentives for Control of Water Pollution:
Incentives can be applied to waste water discharges to maintain the desired quality in the receiving water. The incentive is principally based upon “pollute pays principle”.
3. Environmental Impact Assessment:
This scheme may enable to prevent environmental damage prior to the construction of industrial plant. The format will have to be prepared by environmentalists and scientists.
4. Set up of Water Pollution Control Boards:
Water Pollution Prevention and Control of Act, 1974, was adopted by 16 stages in India up to 1977 and they also constituted Water Pollution Control Boards. Central Water Pollution Control Board is set up in New Delhi to coordinate the work of State Boards and Union Territories.
The principal functions of a State Pollution Control Board are:
(i) To educate the water consuming industries for effective water pollution control.
(ii) To conduct seminars and workshops for water pollution control.
(iii) To evolve effective and efficient methods of disposal of sewage and industrial effluents.
(iv) To perform functions from time to time as suggested by the Central Pollution Control Board.
(v) To carry out sewages of aquatic bodies for classification for the beneficial uses of water.
(vi) To encourage, conduct and participate in investigations and research programmes related to water pollution and its prevention.
Prevention and Control of Water Pollution Act was implemented in 1974 and amended in 1988. Now the Central and State Pollution Control Boards have set up “National Implementation Programmes” which could be planned in each Five Year Plan for different industries.