Environmental Management (0680) | Managing pollution of fresh water

🌊 Managing Pollution of Fresh Water: Your IGCSE Study Guide 🌊

Hello future Environmental Manager! This section is all about one of our most precious resources: fresh water. We rely on rivers, lakes, and groundwater for survival, but human activities often pollute these sources.

In these notes, we will look at how we can clean up our water and, crucially, how we can stop people from getting sick from water-related diseases like cholera and malaria. This topic connects directly to human health and sustainable living, making it super important for your exams!

Key Syllabus Focus: Why We Need Management

Pollution often comes from three main sources (which you learned previously):

• Domestic waste (sewage, garbage)
• Industrial processes (toxic chemicals)
• Agricultural practices (fertilisers and pesticides)

Effective management means addressing these sources to ensure water is safe (potable).

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4.9 Strategies for Improving Water Quality

Improving water quality involves both immediate clean-up actions and long-term planning to reduce the flow of pollutants into rivers and lakes.

1. Improved Sanitation

Sanitation refers to the provision of facilities and services for the safe disposal of human urine and faeces (sewage).

In many developing regions (rural areas especially), lack of sanitation means sewage often ends up directly in rivers or groundwater, contaminating drinking water.

Action Points for Improved Sanitation:

• Building Toilets and Latrines: Ensuring all settlements have proper systems for waste collection, rather than open defecation.
• Separating Water Sources: Making sure sewage pipes or septic tanks are far away from wells and boreholes used for drinking.

Analogy: Think of improved sanitation as giving your whole neighbourhood a proper, modern plumbing system, ensuring waste goes where it should and doesn't mix with clean supplies.

2. Treatment of Sewage (Wastewater)

Sewage treatment is a vital process, especially in urban areas, to remove pollutants before wastewater is released back into the environment.

Don't worry if this seems technical—we can break the process down into three main stages:

1. Primary Treatment (Physical): This is the 'screening' stage.
   

   Wastewater flows through screens and tanks, allowing large solids (like rags, grit, and stones) to be filtered out or settle at the bottom (forming sludge).

2. Secondary Treatment (Biological): This is the 'eating' stage.
   

   The remaining liquid is mixed with air (oxygen) and beneficial bacteria. These bacteria naturally feed on and break down the remaining organic matter (waste). This significantly reduces the Biological Oxygen Demand (BOD) of the water, making it less harmful when released.

3. Tertiary Treatment (Chemical/Advanced): This is the 'polishing' stage.
   

   Special treatments may be applied to remove fine particles, phosphorus, or nitrogen (which cause eutrophication). Finally, the water is disinfected, usually using chlorine or UV light, to kill remaining pathogens (disease-causing microbes).

3. Pollution Control and Legislation

Laws and rules are essential tools used by governments to prevent pollution in the first place.

• Legislation: Governments pass laws that set limits on the amount and type of pollutants that industries can discharge into rivers (Discharge Licenses).
• Fines and Penalties: Companies that break these laws are fined heavily. This gives them a strong economic incentive to install treatment plants themselves.
• Quality Standards: Setting strict national standards for water quality (e.g., acceptable pH levels, maximum pesticide concentration) ensures that water bodies are protected.
• Agricultural Controls: Implementing rules on the timing and quantity of fertiliser and pesticide application to reduce run-off into fresh water sources.

Key Takeaway for 4.9: Improving water quality is a mix of infrastructure (sanitation and sewage plants) and regulatory control (laws and standards) to tackle pollution at its source.

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4.10 Managing Water-Related Diseases

Polluted fresh water is the primary cause of many infectious diseases globally. These diseases fall into two main categories based on how they spread:

• Waterborne Diseases: Spread when people drink or wash with contaminated water (e.g., Cholera, Typhoid).
• Vector-Borne Diseases: Spread by insects (vectors) that breed or live near water (e.g., Malaria, Dengue).

1. Controlling Cholera and Waterborne Diseases

Cholera is a severe bacterial infection causing extreme dehydration, spread primarily through water or food contaminated by human faeces.

Strategies to Control Cholera:

1. Safe Drinking Water Supply: Providing communities with clean, treated water (potable water) from protected sources like deep wells or treated reservoirs.
2. Boiling: This is the simplest and most effective household method. Heating water to boiling point (100°C) for several minutes kills the cholera bacteria and other pathogens.
3. Chlorination: Adding a small amount of chlorine (or chlorine compounds) to water. Chlorine acts as a powerful disinfectant, killing bacteria and viruses rapidly.

   Did you know? This is the technique used in most municipal water treatment plants worldwide.

4. Improved Sanitation: As discussed above, preventing sewage from mixing with drinking water is the most crucial long-term control measure.

2. Controlling Malaria and Vector-Related Diseases

Malaria is caused by a parasite, spread by the bite of the Anopheles mosquito (the vector). Mosquitoes breed in stagnant (still) fresh water, making water management critical.

Understanding the Malaria Parasite Life Cycle (Simplified):

You need to describe the basic life cycle to understand control points:

1. Infected Mosquito Bites Human: The mosquito, carrying the parasite, injects it into the human bloodstream.
2. Parasite Multiplies: The parasite travels to the liver and then multiplies in red blood cells, causing illness (fever, chills).
3. Human Becomes Reservoir: Another mosquito bites the infected human, picking up the parasite.
4. Cycle Repeats: The newly infected mosquito is ready to infect another person.

The key to management is breaking this cycle at various points (human, parasite, or mosquito).

Strategies to Control Malaria:

Control strategies target the human host (treatment) or the vector (prevention/eradication).

1. Antimalarial Drugs:
   

   Used both as a preventative measure (prophylaxis) and to treat people who are already infected, killing the parasite within the human body.

2. Vector Control: Reducing the population of the mosquito vector.
   • Habitat Elimination: Draining stagnant water (like puddles, ditches, and open containers) where mosquitoes breed.
   • Larvicides: Chemical or biological agents applied to water bodies to kill mosquito larvae before they develop into flying adults.
   • Insecticides: Spraying interior walls of houses with residual insecticides to kill mosquitoes that land there.
   • Bed Nets: Using insecticide-treated nets (ITNs) while sleeping, which physically prevents bites and kills the mosquitoes that touch the netting.
3. Eradication:
   

   This is the most ambitious goal—aiming to completely eliminate the parasite or the vector from a specific area or globally (though this is extremely difficult in practice).

Key Takeaway for 4.10: Cholera is controlled by cleaning the water (boiling/chlorination). Malaria is controlled by treating people (drugs) and managing the stagnant water environment (vector control) where mosquitoes breed.