Topic 3: Activated Carbon

Description

Activated carbon is an important treatment technology for removing dissolved organic contaminants from drinking water. Unlike filtration processes that remove particles, activated carbon targets substances that are dissolved in water and cannot be removed mechanically.

It is mainly used to improve taste, odor, and overall water quality, especially when trace organic contaminants are present. With increasing environmental pollution, activated carbon is also used for emerging micropollutants at very low concentrations.

Typical contaminants include:

  • taste- and odor-causing compounds
  • pesticides and herbicides
  • pharmaceutical residues
  • industrial organic pollutants
  • natural organic matter
  • algal by-products
  • trace micropollutants

Because of its versatility, activated carbon is widely used in modern drinking water treatment systems.

How It Works

Activated carbon is produced from carbon-rich materials such as coal, wood, or coconut shells and has an extremely porous structure.

This structure provides a very large internal surface area. When water flows through the carbon bed, dissolved substances are removed by adsorption, meaning they attach to the carbon surface.

Process steps:

  • contaminants come into contact with carbon
  • organic molecules are attracted to the surface
  • substances attach to internal pores
  • treated water flows through

Over time, adsorption sites become saturated. The carbon must then be replaced or regenerated.

Types of Activated Carbon

Granular Activated Carbon (GAC)

Granular activated carbon is used in fixed filter beds. Water flows continuously through the media, allowing long contact times.

Typical applications:

  • municipal treatment plants
  • surface water treatment
  • taste and odor control
  • micropollutant removal

Powdered Activated Carbon (PAC)

Powdered activated carbon is dosed directly into the water and later removed during subsequent treatment steps.

Typical applications:

  • seasonal pollution events
  • algae-related taste and odor problems
  • emergency treatment situations

Advantages

  • highly effective for organic contaminants
  • strong improvement of taste and odor
  • proven and widely used technology
  • flexible application options
  • compatible with many treatment processes
  • relatively simple operation
  • improves consumer acceptance

Disadvantages

  • limited adsorption capacity (requires replacement or regeneration)
  • not effective for most salts and minerals
  • performance depends on contact time and water quality
  • requires regular monitoring
  • operating costs increase over time

Typical Applications

  • surface water treatment plants
  • pesticide and herbicide removal
  • micropollutant control
  • taste and odor improvement
  • pharmaceutical residue removal
  • polishing step after filtration
  • advanced treatment systems

Key Takeaway

Activated carbon is a highly effective solution for removing dissolved organic contaminants that cannot be eliminated by filtration.

Its strength lies in its large internal surface area, which enables adsorption of a wide range of substances affecting taste, odor, and water quality.

However, because its capacity is limited, it must be carefully monitored and regularly replaced or regenerated to maintain reliable performance.

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