Water Pollution

Step 1: Understanding Non-Biodegradable Waste
Non-biodegradable waste refers to materials that do not decompose naturally and persist in the environment for a long time, causing pollution. These include plastics, heavy metals, industrial chemicals, and fly ash.

Step 2: Analyzing the Given Industries
1. Cotton mills: Incorrect. Cotton mills primarily generate biodegradable waste, such as natural fiber residues.\ 2. Paper mills: Incorrect. Paper waste is mostly biodegradable and recyclable.
3. Thermal power plants: Correct. These plants generate large amounts of non-biodegradable waste such as fly ash, bottom ash, and heavy metal residues, which contribute to environmental pollution.
4. Textile factories: Incorrect. Textile waste can include biodegradable materials like natural fibers, though synthetic fibers may persist longer. Step 3: Evaluating the Given Options
- Option (1): Incorrect, as cotton waste is biodegradable.
- Option (2): Incorrect, as paper is mostly biodegradable.
- Option (3): Correct, as thermal power plants generate non-biodegradable industrial waste.
- Option (4): Incorrect, as textile waste varies, but most of it is biodegradable.
Thus, the correct answer is

Option (3).

Step 1: Definition of Methemoglobinemia

• Methemoglobinemia (sometimes called “blue baby syndrome”) arises when hemoglobin is oxidized to methemoglobin, which cannot effectively carry oxygen.

Step 2: Role of Nitrates

• High nitrate levels in drinking water, especially in infants, lead to the formation of methemoglobin in the blood.
• Sulphates, fluorides, or lead do not typically trigger methemoglobinemia; they cause other disorders.

Hence, excess nitrate in drinking water is the primary cause of methemoglobinemia.