Water Pollution | Sources, Quality parameters, Effects, Control measures

Water is essential for the survival of all living organisms. It acts as a universal solvent, allowing plants to absorb essential nutrients in dissolved form. However, when harmful substances—whether organic, inorganic, chemical, or microbial—enter water bodies in excessive quantities, they alter its natural composition and lead to water pollution.

🔬 What is Water Pollution?

Water pollution refers to the addition of any substance to water that changes its physical, chemical, or biological properties, making it unfit for its intended use—whether for drinking, agriculture, industry, or recreation.

Water is never 100% pure, but when its natural balance is disrupted due to pollutants, it becomes turbid, smelly, unpleasant, and often dangerous to health.

🚱 Sources of Water Pollution

Water pollution originates from various natural and human-made sources, such as:

1. Sewage and Domestic Waste

• Contains human excreta, soaps, detergents, food waste, cloth, and paper.
• Improperly dumped waste from rural and urban households clogs rivers, lakes, and ponds.
• Accumulation reduces water’s self-purification ability.

2. Industrial Effluents

• Industries like tanneries, paper mills, dye factories, breweries, and chemical plants release toxic effluents.
• These may include acids, phenols, dyes, heavy metals, oils, plastics, and more—many of which are non-biodegradable.

3. Agricultural Runoff

• Fertilizers and pesticides like DDT, herbicides, and fungicides enter nearby water bodies.
• Phosphates in detergents also promote algal blooms, reducing oxygen for aquatic life.

4. Thermal Pollution

• Hot water from coal-fired thermal plants is released into rivers, raising water temperature.
• This disrupts aquatic ecosystems.

5. Oil Pollution

• Oil spills from tankers and offshore drilling are a major source of marine pollution.
• Oil reduces oxygen levels and harms marine mammals, fish larvae, and plankton.

6. Radioactive Waste

• Nuclear power plants, medical and research institutions discharge radioactive materials.
• Improper disposal can lead to long-term contamination of water bodies.

7. Oceanic Pollution

• Oceans cover 70% of Earth and play a key role in nutrient cycling.
• Plastic waste, shipping, and offshore mining contribute heavily to marine pollution.
• Ocean currents often bring pollutants back to shorelines.

✅ Water Quality Parameters

To safeguard public health, water quality standards are enforced. The United States Public Health (USPH) has set upper limits for key water parameters.

Key Water Quality Indicators:

1. Dissolved Oxygen (DO)
   • Measured using oxygen probes or Winkler’s method.
   • Indicates the oxygen available for aquatic life.
2. Biochemical Oxygen Demand (BOD)
   • Measures the amount of oxygen microbes need to decompose organic matter.
   • Higher BOD = more pollution.
3. Chemical Oxygen Demand (COD)
   • Measures oxygen needed to chemically oxidize organic substances.
   • COD is always higher than BOD.
4. Turbidity
   • Indicates cloudiness or dirtiness of water.
   • Measured using a Jackson Candle Turbidimeter.
5. Total Solids
   • Residue left after evaporating water at 103°C.
   • Includes suspended and dissolved solids.

⚠️ Effects of Water Pollution

Water pollution impacts not just humans but all forms of life. Here are some major consequences:

1. High BOD Levels
   • Household sewage may have 200–400 ppm BOD.
   • High BOD leads to oxygen depletion in water, killing aquatic life.
2. Reduced Dissolved Oxygen
   • Oil spills block sunlight, affect photosynthesis, and reduce oxygen, impacting marine food chains.
3. Arsenic Poisoning
   • Affects millions in West Bengal.
   • Causes hair loss, brittle nails, skin lesions, and respiratory issues.
4. Minamata Disease (Mercury Poisoning)
   • Found in Japan and Sweden due to mercury-contaminated fish.
   • Causes neurological disorders and death.
5. Fluorosis
   • Results from drinking water with high fluoride (>1 ppm).
   • Causes bone deformities, stiff joints, and spine problems.
6. Selenium Toxicity
   • Affects animals grazing on selenium-accumulating plants.
   • Leads to stunted growth, hair loss, and digestive issues.
7. Lead Poisoning
   • From leaded gasoline and industrial waste.
   • Accumulates in food chains causing anemia, kidney damage, mental retardation.
8. Oxalic Acid
   • Excess leads to kidney stones (renal calculi).
9. Ganga River Pollution
   • Once a symbol of purity, now heavily polluted by industrial and human waste.

🛡️ Control Measures

While biodegradable wastes contribute to pollution, non-biodegradable pollutants (plastics, heavy metals, pesticides) pose even greater threats.

Effective Water Pollution Control Strategies:

1. Ecosystem Stabilization
   • Reduce waste inflow, manage fish population, increase aeration, and trap nutrients.
2. Waste Recycling
   • Reuse of domestic and industrial waste where feasible.
3. Pollutant-Specific Removal Techniques
   • Ammonia: Removed using ion exchange (can be reused as fertilizer).
   • Mercury: Removed from effluents using mercury-selective resin.
   • Phenolics: Removed using polymeric absorbents.
   • Water Color: Treated using electrolysis techniques.
   • Salts: Removed via reverse osmosis.

🧾 Legal Framework

• Water (Prevention and Control of Pollution) Act, 1974 was the first significant legal step in India.
• Later, the Water Cess Act, 1977 aimed to fund pollution control through a levy system.

✅ Conclusion

Water is life—but it’s under threat. From industrial waste to household garbage, our water bodies are bearing a toxic load. Effective pollution management, waste treatment, policy enforcement, and public awareness are the only ways forward to ensure clean water for all.

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