Activated carbon regeneration methods

Activated carbon regeneration is one of the most important measures that must be taken into account in the process of wastewater treatment. Activated carbon is used in industrial wastewater treatment due to its high surface absorption property for additional treatment and removal of wastewater color. The economic use of carbon in activated carbon filters depends on the existence of an efficient method for the regeneration of activated carbon after completing its absorption capacity. Granular activated carbon can be regenerated by oxidizing its organic materials in the furnace and separating them from the carbon surface. It can also be done by chemical and biological methods. In the following, we will examine the types of activated carbon regeneration methods.

Activated carbon recovery by heating

One of the oldest and most common methods for reviving active carbon and removing the materials accumulated on it is the heating method. This regeneration method is performed in multi-floor furnaces. Some of the carbon (about 5%) is lost during the regeneration process and must be replaced with new active carbon. In order to prevent activated carbon from igniting, it is heated to 800 degrees Celsius. Although this method is widely used and also regenerates carbon well, it has two main disadvantages: the need for significant investment. In multiple furnaces with a capacity greater than 6 tons per day and relatively high carbon losses.

Regeneration of activated carbon with steam

In addition to placing activated carbon in the dry environment of the furnace, it is possible to clean the existing pollutants accumulated on their surface with water vapor. In this method, the carbons are passed over water vapor and the regeneration process is performed. One of the disadvantages of this method is the inability to completely remove pollutants. All types of pollutants cannot be removed with water vapor, and for this reason, it is necessary to carry out regeneration for a long period of time, which will lead to a reduction in carbon volume and an increase in economic costs. This method is currently not widely used in the industry.

Activated carbon regeneration by chemical method

Another common method to remove materials accumulated in the pores of activated carbon is to use chemicals and wash the carbon with various solvents. In this method, many pollutants on the surface of carbon can be removed in contact with solvents such as enanol, methanol, carboxylic acids, and all kinds of esters and amines. One of the most important advantages of this method is the complete removal of pollutants on carbon. Unlike the heating method, we will not waste carbon. One of the disadvantages of this method is the high cost of buying chemicals, which will not be cost-effective for reviving a large volume of activated carbon.

Biological regeneration of activated carbon

Among other methods of active carbon regeneration, we can mention the biological method of active carbon regeneration. In this method, the volume of activated carbon is placed in a very resistant net chamber and kept for several days in bioreactors with a high volume of microorganisms and activated sludge. In this way, the organic and inorganic substances in the carbon pores are consumed by microorganisms and the carbon surface is cleaned. One of the most important advantages of this method is its high efficiency in removing pollutants and not wasting carbon. The main disadvantage of this method is its time-consuming nature, which is not economically justified for high-tonnage activated carbon regeneration.

Important points in choosing the activated carbon regeneration method

Due to the fact that nowadays the use of activated carbon to achieve a higher quality of treated wastewater has become very common, so choosing the right method for its regeneration is also suggested. In order to choose the right method, the following should be considered:

• The amount of active carbon that should be regenerated. This issue is especially important for the heating method.
• The amount of carbon loss in each of the methods
•  The time of the removal process of pollutants on the activated carbon surface and the efficiency of the processes
• Economic costs of setting up an active carbon recovery unit, purchasing chemicals, etc.