Water Pollution

What is water pollution?

Any physical, biological, or chemical change in water quality that harms living organisms or makes water unsuitable for its intended uses.

What is the difference between a point source and a non-point source of water pollution?

• Point Source: Comes from a single, identifiable location (e.g., a factory pipe or sewer outfall). Easy to monitor.

• Non-Point Source: Comes from multiple, diffuse locations (e.g., agricultural runoff, urban stormwater). Difficult to monitor and control.

What are the two most common pollutants from non-point sources?

Sediment and nutrients (like fertilizers).

What human activity is a major source of river pollution in Malaysia?

Residues from palm oil and rubber manufacturing, and erosion from logging.

What is eutrophication?

The process where excess nutrients (like nitrogen and phosphorus) cause algal blooms. When the algae die and decompose, oxygen is depleted, suffocating fish and other aquatic life.

What are some human health effects of water pollution?

Diseases like cholera and typhoid, diarrhea, skin lesions, cancer, nervous system disorders, and "blue baby syndrome" from high nitrate levels.

What do physical parameters of water quality measure?

Characteristics that respond to the senses, like sight, touch, taste, or smell (e.g., suspended solids, temperature, colour, turbidity).

What is turbidity and what is it measured with?

The cloudiness of water caused by suspended solids.
Secchi disk: Used in deep, slow-moving water.

Turbidimeter: Measures light scattering in Nephelometric Turbidity Units (NTU).

Why is high water temperature a problem?

It reduces the amount of dissolved oxygen (DO) water can hold and increases the metabolic rates of aquatic organisms, leading to oxygen depletion.

What is the key difference between BOD and COD?

BOD (Biochemical Oxygen Demand): Measures oxygen used by microbes to break down biodegradable organic matter. Takes 5 days.

COD (Chemical Oxygen Demand): Measures oxygen required to chemically oxidize all organic matter (both biodegradable and non-biodegradable). Takes 3 hours.

What is water hardness primarily caused by?

The concentration of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.

What is the problem with high levels of nitrate (NO₃⁻) in drinking water?

It can cause methemoglobinemia, or "blue baby syndrome," which limits the blood's ability to carry oxygen. It also contributes to eutrophication.

What is a beneficial level of fluoride in drinking water and what happens if there is too much?

Beneficial: ~1 mg/L prevents dental cavities.

Too Much: >2 mg/L causes dental fluorosis (tooth mottling); >5 mg/L causes skeletal fluorosis.

What are pathogens?

Disease-causing microorganisms, including bacteria, viruses, protozoa, and fungi.

What is the role of algae in a water body?

They are photosynthetic organisms that produce oxygen during the day. However, overgrowth (algal blooms) can cause taste, odour, and light penetration problems, and lead to oxygen depletion at night.

What is the main environmental law for controlling water pollution in Malaysia?

The Environmental Quality Act (EQA) 1974.

What is the primary purpose of the coagulation and flocculation process in water treatment?

To clump together fine suspended particles into larger, heavier particles called "floc" so they can be easily removed by sedimentation.

What is the final, crucial step in both water and wastewater treatment to ensure public safety?

Disinfection (e.g., using chlorine or UV light) to kill harmful pathogens.

What is the main goal of secondary treatment in a wastewater plant?

To use microorganisms in an aeration tank to biologically remove dissolved organic material from the wastewater.

How does water pollution directly impact Sustainable Development Goal 6 (SDG 6)?

It undermines targets for safe drinking water (6.1), improving water quality by reducing pollution (6.3), and protecting water-related ecosystems (6.6).