Powdered Activated Carbon
Powdered activated carbon (PAC) is finely ground carbon with many small pores. These pores provide a large internal surface on which molecules can attach.
The attachment of dissolved compounds to these surfaces is called adsorption. The raw material and pore distribution determine which compounds the carbon can retain and to what extent.
Technical Specifications
| Physical form | Finely pulverized powder |
|---|---|
| Feedstock types | Coal, wood and coconut shell |
| Iodine number | 656–978 mg/g |
| Moisture | 8.8% |
| Ash content | 12.1% |
| Passing US 200 mesh | 95% |
| Passing US 325 mesh | 65–78.3% |
| Molasses number | 210 |
Application and use
- PAC is dosed to reduce taste and odor compounds such as geosmin and MIB in drinking water.
- The dose can be adjusted as seasonal loading changes; spent carbon must be separated downstream.
- Suitable grades reduce color in liquid processes and are then removed by filtration.
- Choose the dosing point based on required contact time and the available mixing arrangement.
Frequently asked questions
Is iodine number enough to select PAC?
No. It is one test result; trial the carbon against the target compound in the actual feed.
Can PAC be used before a GAC bed?
Yes, if PAC is removed before reaching the bed. This may protect GAC during some contaminant-load spikes.
PAC or GAC?
Consider PAC where dosing can be adjusted and spent carbon separated. Compare a GAC bed for continuous treatment.
Can I take the PAC dose from a catalog?
No. Set the dose through a trial using the actual feed, outlet target and contact time.
Does backwashing restore spent PAC?
No. Spent PAC is removed through solids separation; backwashing does not restore its adsorption capacity.