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Removal of taste and odour

Short answer

Taste and odour are removed by aeration (volatile gases), activated carbon adsorption (most effective for organics), break-point chlorination or ozone/permanganate oxidation, copper sulphate for algae, and coagulation–filtration.

Describe briefly the methods of removal of tastes and odour in water.

Taste and odour in water are caused by dissolved gases (H2_2S, CO2_2), decaying vegetation and algae, industrial wastes, phenols, and iron, manganese and chlorine compounds. The methods of removal are as follows.

  1. Aeration: the water is exposed to air (cascade, spray, diffusion), which drives out H2_2S, CO2_2 and volatile organics and oxidises Fe and Mn.
  2. Activated carbon adsorption: powdered activated carbon (PAC) 5 to 50 mg/l is added before the filters, or granular (GAC) is used in a filter bed. It adsorbs organic compounds, phenols and chlorine tastes. It is the most effective method.
  3. Chlorination: break-point chlorination and chlorine dioxide oxidise organic compounds and ammonia, and destroy taste-causing algae and bacteria.
  4. Oxidation by potassium permanganate or ozone: ozone and KMnO4_4 destroy odour-producing organic substances.
  5. Copper sulphate (CuSO4_4) dosing (0.3 to 0.5 mg/l) in storage reservoirs to kill algae which cause the taste and odour.
  6. Coagulation, sedimentation and filtration: remove colloids and algae together with the floc; micro-straining removes algae.
  7. Prevention at source: protect the catchment from pollution and avoid stagnant, stratified water.

✓ Answer checked by Claude Opus 5.5 (high effort)

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