Adsorption process with powdered activated carbon (PAC)
Elimination and reduction of micropollutants with the PAC process
Trace substances can be removed from wastewater with the help of powdered activated carbon (PAC), as the micropollutants adsorb to the activated carbon.
Powdered activated carbon is ground activated carbon. According to DIN 12903, at least 95 percent of the mass fraction must have a grain size of less than 150 µm. The average particle diameter of typical powdered activated carbons is approximately in the range of 10 µm to 50 µm.
For the elimination of micropollutants, the powdered activated carbon is added directly to the wastewater to be treated. The activated carbon can be added at different points in the wastewater treatment process (simultaneous process). In the "Ulm process", a separate adsorption tank is used after the biological stage. There, fresh activated carbon is added to the treated wastewater.
PAC
Powdered Activated Carbon
In principle, it is important that the process ensures sufficient contact time so that the trace substances can adsorb to the powdered activated carbon. The powdered activated carbon must then be separated from the treated wastewater. This is usually done after precipitant addition in a sedimentation tank, where some of the separated carbon is discharged as excess carbon together with the excess sludge and some is returned to the contact tank as return carbon. Due to the recirculation, the activated carbon remains in the wastewater treatment process for several days.
It is very important that the treated wastewater is free of activated carbon before it is discharged into the receiving water. The powdered activated carbon (PAC) should be separated as completely as possible from the treated wastewater. For this reason, a downstream filtration stage (polishing filter) is necessary that is able to retain any remaining fine carbon particles.
The HUBER Pile Cloth Media Filter RotaFilt® is an ideal product solution for this purpose. The polishing pile cloth filter reliably retains even the finest carbon slip that could not be separated in the sedimentation tank.
As an alternative to the pile cloth media filter, the HUBER Sandfilter CONTIFLOW® can be used as a proven and reliable polishing stage to retain the ultrafine activated carbon particles.
Products
HUBER Products for Powdered Activated Carbon Process
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