Water Pollution: In-Depth Notes

Water Pollution: Key Concepts

  • Potable Water

    • Definition: Water that is free of harmful chemicals, microorganisms, and other contaminants.
    • Importance: Safe for drinking and food preparation.

  • Global Water Distribution

    • 97.4% of Earth's water is saline (saltwater) found in oceans.
    • Only 2.6% is freshwater, primarily located in glaciers and groundwater.
    • Only 0.014% of freshwater is readily available for human use (in rivers, lakes, springs).

Sources and Challenges of Water

  • Surface Water

    • Characteristics: High flow, susceptible to contamination, high total suspended solids (TSS) and pathogens.
    • Vulnerability: Rivers and streams can dry up in dry seasons.

  • Groundwater

    • Characteristics: Lower flow, natural filtration capacity.
    • Issues: High in total dissolved solids (TDS), difficult to clean after contamination.

  • Seawater

    • Issues: Desalination (removal of salt) is costly and energy-intensive.
    • Technologies: Distillation, reverse osmosis, electrodialysis, ion exchange (most commonly used: multistage distillation, reverse osmosis).

Water Consumption Data

  • Average Water Consumption Rates:

    • Saudi Arabia: 275 LPCD (Liters per capita per day)
    • USA: 575 LPCD
    • UK: 150 LPCD
    • Rwanda: 20 LPCD

  • Factors Affecting Water Consumption:

    • Lifestyle (car wash, gardening)
    • Environmental awareness
    • Weather conditions
    • Availability of conservation programs
    • Social and cultural habits (bathing frequency, food festivals).

Water Pollution

  • Definition: Any chemical, biological, or physical change that makes water unfit for use.

  • Types of Pollutants:

    1. Point Source Pollution: Contaminants enter waterbodies through pipes, often from industrial and municipal sources.
    2. Nonpoint Source Pollution: Diffused pollution (urban runoff, agricultural runoff).

  • Common Water Pollutants:

    • Pathogenic Organisms: Disease-causing microorganisms (e.g., bacteria, viruses).
    • Oxygen-Demanding Substances: Organic materials that deplete oxygen levels when decomposed.
    • Nutrients: Phosphates and nitrates that cause eutrophication.
    • Toxic Organics and Inorganics: Harmful chemical substances.
    • Heavy Metals: Lead, mercury which have serious health effects.

Factors Leading to Water Pollution

  1. Domestic Sewage: Main source of pathogenic organisms.
  2. Agricultural Sources: Fertilizers, pesticides leading to excess nutrients in water.
  3. Industrial Waste: Contains toxic substances that can severely affect water quality.
  4. Oil Spills: Untreated oil pollution affects marine and coastal waters.

Parameters of Water Quality

  • Physical Parameters:

    • Turbidity, color, taste, odor, and total solids (suspended and dissolved).

  • Chemical Parameters:

    • pH (neutral ~ 7), hardness, alkalinity, presence of iron and manganese, nitrogen compounds.

  • Microbiological Quality:

    • Bacteria (total coliform, fecal coliform) as indicators of contamination.

Water Quality Standards

  • Standards: Include maximum allowable contaminant levels (MCLs) from sources like:
    • GSO 149:2014, EPA, WHO.

Conclusion

  • Importance of Water Quality Management: Affects both human health and the environment. Effective monitoring and treatment are crucial for sustainable water resources.