2/15/2011

WATER POLLUTION TYPES & RESOURCES

Submitted to: Sir Zaheer Abbas

Submitted by: Muhammad Khuram (2007-chem-45)Usman Ashraf (2007-chem-63)AbaidUllah (2007-chem-47)Tahir Haroon (2007-chem-105)

Environmental Engineering

Water Pollution

Water pollution can be defined as "any biological, chemical, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses."In the United States, approximately 44% of lakes, 37% of rives, and 32% of estuaries are unsafe for recreation due to toxic water pollution.Pollutants fall into three main categories: 1) biological, such as bacteria or viruses; 2) chemical, including heavy metals, nutrients, pesticides, and wastes; 3) physical, such as sediment, radioactive material, and heat.

Types of water pollution There are various types of water pollution based on different types of pollutants. Types of water pollutions are

Physical PollutionChemical PollutionBiological Pollution

I) Chemical Pollution

When various chemicals are mixed into the water then chemical water pollution causes. The following chemicals are the most common water pollutants:

Crude oil and various petroleum (including gasoline, diesel fuel, kerosene, motor and lubricating oils, jet fuel). These compounds are lighter than water and thus always sit on top of water forming sheens of “free product”. However, part of these compounds dissolve in water and, even in small amounts may be harmful and at the same time may remain unnoticeable by the eye. Fertilizers (including nitrates and phosphates) – while small amounts are useful to life, higher amounts of nitrates and phosphates in water are only benefic to algae and harmful microorganisms and are poisonous to human and aquatic life. These contaminants cannot be seen themselves in water (as they do not form sheens or color the water), but their effects can. The typical effect of water pollution by fertilizers (usually through agricultural runoff) is the fast and abundant water growth. Chlorinated solvents (including TCE, PCE, 1,1,1-TCA, carbon tetrachloride, Freons) which sink in water (are denser than water) and are quite persistent and to 558 xic. These compounds thus, cannot be seen by the eye, in contrast with petroleum products that are easily seen as sheens on top of water surface.

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FIGURE 1

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Petroleum solvents (including benzene, toluene, xylenes, ethylbenzene)

Organic water pollutants are:

Food processing waste, including pathogens Insecticides and herbicides, a huge range of organohalide and other

chemicals Tree and brush debris from logging operations Bacteria from sewage or livestock operations

Inorganic water pollutants are:

pre-production industrial raw resin pellets

heavy metals including acid mine drainage

silt in surface runoff due to logging, slash and burn practices, construction sites or land clearing sites

Antibiotics and other pharmaceutical productsPer chlorate – perchlorate salts are used in rocket fuels, as well as many other applications such as fireworks, explosives, road flares, inflation bags, etc. This contaminant is usually associated with military bases, construction sites (when explosives are used). However, natural formation in arid areas may account for perchlorate in water, too (e.g., in Chile, Texas or California where natural formation of per chlorate has been observed).Trihalometanes – these are usually byproducts of water chlorination and may pollute groundwater and surface water via leaking sewer lines and discharges. Examples of such compounds are: chloroform, bromoform, dichlorobromomethane; Metals and their compounds – of higher health risk are the organo-metal co 558 mpounds which may form when metals from water react with organic compounds from water. Common examples include Hg, As, and Cr poisoning of water. Thus, if water is polluted with both metals and organic compounds the health risk is higher. And so is the effect of water pollution on aquatic life. Heavy metals represent a common type of chemical pollution in water. They can be found naturally in bedrock and sediment or they may be introduced into water from industrial sources and household chemicals. Heavy metals harm humans through direct ingestion of contaminated water or through accumulation in the tissues of other organisms that are eaten by humans. The following are some common heavy metals found in water:

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FIGURE 2

Environmental Engineering

Mercury (Hg): Enters the environment through the leaching of soil due to acid rain, coal burning, or industrial, household, and mining wastes. Causes damage to nervous system, kidneys, and vision. Lead (Pb): Sources include paint, mining wastes, incinerator ash, water from lead pipes and solder, and automobile exhaust. Causes damage to kidneys, nervous system, learning ability, ability to synthesize protein, and nerve and red blood cells. Cadmium (Cd): Sources include electroplating, mining, and plastic industries,

as well as sewage. Causes kidney disease.

Example of Chemical water Pollution:

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Arsenic in BangladeshThe presence of arsenic in tube wells in Bangladeshbecause of natural contamination from underground geologicallayers was first confirmed in 1993. Ironically, theUnited Nations Children’s Fund had introduced the wellsin the 1960s and 1970s as a safe alternative to water contaminatedwith microbes, which contributed to a heavydiarrheal disease burden. Estimates indicate that 28 millionto 35 million people of Bangladesh’s population of130 million are exposed to arsenic levels exceeding50 micrograms per liter, the prescribed limit for drinkingwater in Bangladesh (Kinniburgh and Smedley 2001).This number increases to 46 million to 57 million if theWHO guideline level of 10 micrograms per liter is used.The most common sign of arsenic poisoning inBangladesh is skin lesions characterized by hyperkeratosisand melanosis. Other effects reported, but not epidemiologicallyconfirmed, include cancer (particularly of theskin, lungs, and bladder); liver damage; diabetes; hypertension;and reproductive effects (spontaneous abortionsand stillbirths). Cancer and vascular effects are the dominatingeffects in other arsenic-polluted areas (WHO2001).Source: Authors.

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Physical Pollutants

Sediment, solid fragments of inorganic or organic material that do not dissolve in water, represents the most significant source of water pollution, physical or otherwise.

Sources of sediment include erosion, deforestation, and agricultural and hydroelectric projects. Sediment chokes and fills lakes, reservoirs, harbors, and other aquatic environments, reducing photosynthesis and disrupting aquatic food webs. Sediment may also carry pesticides, bacteria, and other harmful substances,

and it can destroy the feeding and spawning grounds of fish. Heat is another physical water pollutant. Excessive heat in water results when large quantities of water are used for cooling of electric power plants. Each year, almost half of the water withdrawn in the United States is used for such cooling. Thermal pollution in water lowers dissolved oxygen levels and makes aquatic species more susceptible to disease, parasites, and toxic chemicals. Thermal shock occurs when an organism adapted to a certain temperature range is suddenly exposed to a temperature outside of that range. Thermal pollution results in death for many aquatic species.

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FIGURE 3

Environmental Engineering

Physical Pollution is measured in NTU (Nephelometric Turbidity Units) Normal levels: 1-50 NTUDrinking Water: 0.5-1 NTUVisible: >5 NTUHigher during storms

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FIGURE 4

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Biological Pollutants

Water pollution which is caused by bacteria, and harmful microorganisms is called biological water pollution.

Pathogens are another type of pollution that prove very harmful.  They can cause many illnesses that range from typhoid and dysentery to minor respiratory and skin diseases.  Pathogens include such organisms as bacteria, viruses, and protozoan.  These pollutants enter waterways through untreated sewage, storm drains, septic tanks, runoff from farms, and particularly boats that dump sewage.  Though microscopic, these pollutants have a tremendous effect evidenced by their ability to cause sickness. 

Each year, about 1.5 million Americans become ill as a result of bacterial contamination in drinking water. Other examples of biological pollutants include viruses, protozoa, and parasitic worms. These infectious agents enter the environment from human and animal wastes, and they cause a variety of serious diseases. The United States Environmental Protection Agency uses the number of coli form bacteria per 100 milliliters of a water sample in order to determine the severity of biological pollution in water. The EPA recommends that drinking water contain zero colonies per 100 milliliters, and that swimming water contain no more than 200 colonies per 100 milliliters.

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FIGURE 5

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Oxygen-Demanding Waste Dissolved OxygenAdded by: turbulent water and photosynthesis. Removed by: Increased temperature (exsolution) and respiration/decompositionGood: > 6 ppm (mosquitoes can survive in 1 ppm) (also measured in % of maximum - Good = 60-80%)

Water quality

FIGURE 6

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WaterQuality

Good 8-9

Do (ppm) at 20˚C

Slightlypolluted

Moderatelypolluted

Heavilypolluted

Gravelypolluted

6.7-8

4.5-6.7

Below 4.5

Below 4

Environmental Engineering

Point Resources – including any localized source such as an industrial process, mining activity, etc. These sources are usually regulated and thus their effect may be predicted and of low impact. However, an exception related to accidental leaks and spills. Point-source pollutants in surface water and groundwater are usually found in a plume that has the highest concentrations of the pollutant nearest the source (such as the end of a pipe or an underground injection system) and diminishing concentrations farther away from the source.

Non-point Resources – include un-localized sources from which pollutants are carried away by water discharges and runoffs. Thus, non-point pollution may involve a broad range of pollutants usually at lower amounts than the point sources.

Point and Nonpoint Sources

Water consumption

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FIGURE 7

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Worldwide, agriculture accounts for 70% of all water consumption, compared to 20% for industry and 10% for domestic use. In industrialized nations, however, industries consume more than half of the water available for human use. Belgium, for example, uses 80% of the water available for industry.Freshwater withdrawals have tripled over the last 50 years. Demand for freshwater is increasing by 64 billion cubic meters a year (1 cubic meter = 1,000 liters) The world’s population is growing by roughly 80 million people each year. Changes in lifestyles and eating habits in recent years are requiring more water consumption per capita. The production of biofuels has also increased sharply in recent years, with significant impact on water demand. Between 1,000 and 4,000 liters of water are needed to produce a single litre of biofuel. Energy demand is also accelerating, with corresponding implications for water demand. Almost 80% of diseases in so called "developing" countries are associated with water, causing some three million early deaths. For example, 5,000 children die every day from diarrhoea, or one every 17 seconds.

Water consumption Country vice

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Conclusion

Water demand is increasing in the world and resources are going to be scarce. There will come a time in near future when drinking water will not be available due to increasing pollution in the water. Experts say that the third world war will be due to water and it will be final. Increasing water pollution is a threat to life on earth and directly or indirectly every human being is involved in it. New and dangerous diseases are taking place due to water pollution. Every kind of life is facing the serious effects of water pollution on earth.

We should try to reduce our activities that may contaminate water. Government environmental protection agencies should emphasize chemical industries not to throw heavy chemicals in the river or lakes.

Reference:

http://www.environmentalpollutioncenters.org (Retrieved on 12/02/2011)

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Environmental Engineering

http://library.thinkquest.org/04oct/01590/pollution/pollutants.html (Retrieved on 12/02/2011)

http://www.waterencyclopedia.com/Po-Re/Pollution-Sources-Point-and-Nonpoint.html#ixzz1Dq24LRVj ( Retrieved on 12/02/2011)

http://www.defra.gov.uk/evidence/statistics/environment/inlwater/kf/iwkf11.htm ( Retrieved on 12/02/2011)

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