ABSTRACT
The main purpose of carbon adsorption is the removal of soluble organic material that is difficult to remove by biological or physical/chemical treatment.
The wastewater passes through a container filled either with carbon granules or a carbon slurry. Organics are removed by adsorption onto the carbon when there is sufficient contact time.
A carbon system usually has several columns or basins used as contactors. Most contact chambers are either open concrete gravity-type systems, or steel pressure containers applicable to either upflow or downflow operation.
With use, the carbon loses its adsorptive capacity. The carbon must then be regenerated or replaced with fresh carbon.
Carbon used for adsorption at wastewater treatment plants may be in a granular form or in a powdered form.
Granular carbon adsorption is accomplished by passing the wastewater through beds of the carbon housed in columns. These carbon columns usually provide 20 to 40 minutes of contact time.
As headloss develops in carbon contactors, they are backwashed with clean effluent in much the same way the effluent filters are backwashed.
Powdered carbon is too fine to use in columns and is usually added to the wastewater and then later removed by coagulation and settling.
