Activated carbon offers excellent adsorption capacity for a wide range of organic compounds as well as certain inorganic substances such as heavy metals.
In addition, it can effectively remove some oxidizing agents, including chlorine.

However, the performance of activated carbon is difficult to predict, as it depends on various factors, including:

• The type of compound to be removed
• The concentration of the compound to be removed
• The presence of other organic substances
• The pH value of the wastewater stream

The following tables show the relative adsorption capacity of different compounds in water.
They provide a quick way to assess whether activated carbon is likely to be an effective technology for removing a particular substance.

Adsorption Capacity Ratings

• Very high adsorption capacity
• Good adsorption capacity
• Moderate adsorption capacity – activated carbon is effective only in specific cases
• Low or unlikely effectiveness – activated carbon is generally not effective but may be applicable in certain situations, such as low flow rates or low concentrations

The classification also indicates whether the respective compound is listed in the EU Directives on hazardous discharges (Directives 76/464/EEC and 86/280/EEC).

Compounds such as chlorine and chloramines are removed catalytically by activated carbon.