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An Assignment On Water Pollution Submitted To: Dr. ShrabantiDev Assistant Professor Pharmacy Discipline Khulna University, Khulna. Submitted By: 151115 151116 151117 151118 151119
Water The importance of water for sustenance of life cannot be overemphasized. Whether it isin use of running water in our homes, rearing cattle and growing crops in our farms, or theincreased uses in industry, remain immeasurable. It is important therefore, to not thatdepletion of this commodity either through contamination, or careless use results in seriousconsequences. 71% from earth surface. 97% salt water (sea) 3% fresh water 87% ice and glaciers, underground, air. 13% surface water (0.4% total water).
70% total human body wt. • 30 – 40% bone mass. • Body functions: • Absorption of oxygen at alveoli. • Control of body temperature. • Blood component. • Digestion in kidneys and intestine. • Alteration of 10% body content – health problem. • Alteration of 20% body content – death.
Water Pollution! Water is considered polluted if some substances or condition is present to such a degree that the water cannot be used for a specific purpose. Water pollution is intended as water quality degradation caused by the introduction of substances that alter its physicochemical characteristics and impede its normal use. These substances having either a solid, liquid or gaseous origin have different effects according to their amount and potential danger and fragility of the environments where they are released.The three main types of pollution are: Land Pollution, Air Pollution and Water Pollution. Both for the purpose of this assignment, emphasis are on water pollution and control.
Water Pollution Parameters Water may be called polluted when the following parameters stated below reach beyond a specified concentration in water. i) Physical parameters: Color, odor, turbidity, taste, temperature and electrical conductivity constitute the physical parameters and are good indicators of contamination. For instance, color and turbidity are visible evidences of polluted water while an offensive odor or a bitter and difference than normal taste also makes water unfit for drinking.
ii) Chemical parameters: These include the amount of carbonates, sulphates, chlorides, fluorides, nitrates, and metal ions. These chemicals form the total dissolved solids, present in water. iii) Biological parameters: The biological parameters include matter like algae, fungi, viruses, protozoa and bacteria. The life forms present in water are affected to a good extent by the presence of pollutants. The pollutants in water may cause a reduction in the population of both lower and higher plant and animal lives. Thus, the biological parameters give an indirect indication of the amount of pollution in water.
Water Pollutants • Infectious Agents Bacteria, Viruses, Protozoa, Parasitic Worms • Oxygen-Demanding Waste Organic debris & waste + aerobic bacteria • Inorganic Chemicals Acids, Metals, Salts • Radioactive Materials Iodine, radon, uranium, cesium, thorium
Plant Nutrients Nitrates, Phosphates, • Organic Chemicals Oil, Gasoline, Plastics, Pesticides, Solvents, detergents • Eroded Sediment Soil, Silt • Free oils and emulsifiers • Suspended solids • Heat, acids and strong bases
SOURCES OF WATER POLLUTION Water pollution in Nigeria according to Gbamanija (1998) arises from various activities, among which are: (i) Sewage leakages (ii) High population density (iii) oil spillage (іv) Industrial waste dumped into our waters (v) Pollution of ground water through drilling activities (vi) Radioisotopes
(vii)Heavy metal (viii) Combustion (ix) Toxic waste disposal at sea (x) Mineral processing plant (e.g. coal production) (xi) Eroded sediments (xii) Deforestation (xiii) Mining (xiv) Littering (xv) Pesticides
Causes of water Pollution • Marine dumping • Industrial wastage • sewage • Mainly from households • Nuclear waste • Oil pollution • Underground storage leakage • Agricultural
Acid Rain is one the causes of Water Pollution: Acid rain has many ecological effects, but none is greater than its impact on lakes, streams, wetlands, and other aquatic environments. Acid rain makes waters acidic, and causes them to absorb the aluminum that makes its way from soil into lakes and streams. Pollutants that cause acid rain: H₂O + SO₂ = H₂SO₄ H₂SO₄ ↔H⁺ + HSO₄⁻ ↔ 2H⁺ + SO₄⁻⁻ Sulfur dioxide reacts with water to form sulfuric acid in the atmosphere which dissociates into sulfates and hydrogens ions. And hydrogen ion makes a solution acidic.
Another reaction; NOₓ + H₂O → HNO₃ HNO₃ ↔ H⁺ + NO₃⁻ Nitrogen oxides reacts with water to form Nitric acid, which also dissociates into hydrogen and nitrate ions.
Types of Water Pollution Fresh water pollution may be classified into two types: surface water pollution and ground water pollution. Surface Water Pollution • When pollutants enter a stream, river or lake these gives rise to surface water pollution. The surface water pollution has a number of sources. These can categorized as: • Point and Non-point Sources • Natural and Anthropogenic Sources
(i) Point and Non-point Sources • The well-defined sources that emits pollutants or effluents directly into different water bodies of fresh water are called point sources. (ii) Natural and Anthropogenic Sources • An increase in the concentration of naturally occurring substances is also termed pollution. The sources of such an increase are called natural sources. Siltation (which includes soil, sand and mineral particles) is one such natural source. The human activities that result into the pollution of water are called anthropogenic.
Other Types of Water Pollution • Sewage • Disease-causing agents • Sediment pollution • Inorganic plant and algal nutrients • Organic compounds • Inorganic chemicals • Thermal pollution
Effects of Water Pollution The effects of water pollution are varied and depend on what chemicals are dumped and in which locations. Many water bodies near urban areas (cities and towns) are highly polluted. This is the result of both garbage dumped by individuals and dangerous chemicals legally or illegally dumped by manufacturing industries, health centers, schools and market places. Effects: • Death of aquatic animals • Disruption of the food chain • Diseases • Destruction of ecosystem
Death of Aquatic Animals The main problem caused by water pollution is that it kills life that depends on these water bodies. Dead fish, crabs, birds and sea gulls, dolphins, and many other animals often wind up on beaches, killed by pollutants in their habitat (living environment).
Disruption of Food Chain Pollution disrupts the natural food chain as well. Pollutants such as lead and cadmium are eaten by tiny animals. Later, these animals are consumed by fish and shellfish, and the food chain continues to be disrupted at all higher levels.
Diseases Eventually, humans are affected by this process as well. People can get diseases such as hepatitis by eating seafood that has been poisoned. In many poor nations, there is always outbreak of cholera and diseases as a result of poor drinking water treatment from contaminated waters
Destruction of Ecosystem Ecosystems (the interaction of living things in a place, depending on each other for life) can be severely changed or destroyed by water pollution. Many areas are now being affected by careless human pollution, and this pollution is coming back to hurt humans in many ways.
Pollution management and Control There are many approaches that could be adopted in water pollution control and management. It could be through prevention, practice efforts or join a project/program; Regulation and monitoring or engaging in control measures by reducing or minimizing waste. (i) Wash your car far away from any storm water drains. (ii) Don’t throw trash, chemicals or solvents into sewer drains (iii) inspects your septic system every 3 – 5 years
(iv) avoid using pesticides and fertilizers that can run off into water systems (v) sweep your driveway instead of hosing it down (vi) always pump your waste-holding tanks on your boat (vii) use non-toxic cleaning materials (viii) clean up oil and other liquid spills with kitty litter and sweep them up (ix) don’t wash paints brushes in the sink. Regulation and monitoring is an effective way of pollution management.
Pollution control means to control the emissions and effluents into the air, water and land or soil. Without pollution control, the waster products from consumptions, heating, agriculture, mining, manufacturing, transportation and other human activities, whether they accumulate or disperse, will degrade the environment. Pollution prevention and waste minimization are more desirable than pollution control. However, pollution could be minimize by adopting these practices • by recycling (ii) by reusing (iii) waste minimization (iv) by mitigating (v) by preventing (vi) by compost.
Water Treatment The treatment of this waste water is carried out in the following three stages: (i) Primary treatment (ii) Secondary treatment, and (iii) Tertiary treatment Primary Treatment: When the waste water is to be dumped off into a river or flowing steam, the treatment is carried out by sedimentation, coagulation and filtration. This is known as primary treatment. If the water is required for drinking purposes, it has to undergo further treatment called secondary and tertiary treatments. The following steps are performed to do primary treatment of water:
Sedimentation: This step is carried out in large tanks specially built for this purpose in sewage treatment plant. The polluted water is allowed to settle so that silt, clay and other matter settle to be bottom and water is slowly allowed to move out. Fine particles do not settle and are thus required to be removed in the next step.
Coagulation: Fine particles and colloidal suspension are combined into large particles by a process called coagulation. This step is carried out by the addition of special chemicals called coagulants (flocculants) such as potash alum. The large particles either settle to the bottom or are moved in the next step.
Filtration: Suspended particles, flocculants, bacteria and other organisms are filtered by passing the water through a bed of sand or finely divided coal or through some fibrous materials. The total impurities collected in these steps are called sludge. It is used as a valuable fertilizer. On composting (i.e. the action of anaerobic bacteria), it releases sludge gas. It consists mainly of methane gas which is used for cooking purposes.
Secondary or Biological Treatment: The water after primary treatment is not fit for drinking purposes and has to undergo further treatment. This is done through secondary or biological treatment. A commonly used method is to allow polluted water to spread over a large bed of stones and gravel so that the growth of different microorganisms needing nutrients and oxygen is encouraged. Over a period of time a fast moving food chain is set up. For example, bacteria consume organic matter from the polluted water; protozoa live on bacteria. Every form of life including algae and fungi help in the cleaning up process. This is called secondary treatment of water. It involves the following processes
Softening : By this treatment undesirable cations of calcium and magnesium are removed from hard waters. Either water is treated with lime and soda ash to precipitate Ca2+ ions as carbonates or it is passed through cation exchangers. This makes water soft.
Aeration: In this process, soft water is exposed to air by forcing air through it to add oxygen to water. This encourages bacterial decomposition of organic matter into harmless products such as carbon dioxide and water. The addition of oxygen reduces carbon dioxide, sulphideetc.. The water is as yet not fit for drinking purposes. The pathogenic and other microorganisms need to be killed. This is done in the next treatment.
Tertiary Treatment : The tertiary treatment is actually disinfecting water. Chlorine is the most commonly used disinfectant used for killing bacteria. However, chlorine also reacts with traces of organic matter present in water and forms undesirable chlorinated hydrocarbons (toxic and potentially carcinogenic). It is therefore desirable to reduce the organic matter in water before passing chlorine gas. Other methods of disinfection such as ultraviolet radiation, ozone gas treatment or reverse osmosis are preferred over chlorine treatment. But these methods are more expensive.
Sewage is one of the major causes of water borne diseases and therefore the treatment of sewage is one of the important tasks. For a long time treatment of municipal waste in the form of sewage involved mainly of the removal of suspended solids, oxygen demanding materials and harmful bacteria. Now the disposal of the solid residue from sewage has been improved by applying municipal treatment processes. Septic tanks Primary (physical) sewage treatment Secondary (biological) sewage treatment Urban sewage treatment (Clean Water Act)
Conclusion The problems associated with water pollution have the capabilities to disrupt life on our planet to a great extent. Congress has passed laws to try to combat water pollution thus acknowledging the fact that water pollution is, indeed, a serious issue. But the government alone cannot solve the entire problem. It is ultimately up to us, to be informed, responsible and involved when it comes to the problems we face with our water. We must become familiar with our local water resources and learn about ways for disposing harmful household wastes so they don't end up in sewage treatment plants that can't handle them or landfills not designed to receive hazardous materials. In our yards, we must determine whether additional nutrients are needed before fertilizers are applied, and look for alternatives where fertilizers might run off into surface waters. We have to preserve existing trees and plant new trees and shrubs to help prevent soil erosion and promote infiltration of water into the soil
