Question

The pollutants like phenol and mercury can be removed from water by:
1. Sedimentation
2. Electro-dialysis
3. Filtration
4. Biological oxidation

Answer 1

Correct Answer - Option 3 : Filtration

The correct answer is Filtration.

• By the Filtration process, The pollutants like phenol and mercury can be removed from the water.
• Coagulation/filtration is a common treatment that uses AlSO₄that reacts with the mercury to form a solid which can precipitate out of the water.
  • The sludge then must be disposed of in a hazardous waste landfill.
  • This process is beneficial because it costs very little and is reliable.
• The phenolic compounds removal from water involves absorption and photocatalytic process, using synthetic or natural particles, such as carbon materials and clays.
  • Activated carbon (AC) is the most used in industry as an adsorbent.

• Sedimentation is the process of allowing particles in suspension in water to settle out of the suspension under the effect of gravity.
  • The particles that settle out from the suspension become sediment, and in water treatment is known as sludge.
  • When a thick layer of sediment continues to settle, this is known as consolidation.
• Electro Dialysis (ED) is a membrane process, during which ions are transported through a semi-permeable membrane, under the influence of an electric potential.
  • The membranes are cation or anion-selective, which basically means that either positive ions or negative ions will flow through.
  • This technique can be applied to remove ions from water. Particles that do not carry an electrical charge are not removed.
• Biological oxidation is the mechanism where microorganisms degrade organic matter contaminants of wastewater.
  • They feed on organic matter in the presence of oxygen and nutrients.