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# How can I calculate granular activated carbon (GAC) usage rates?

Our carbon vendors generally don't care to share the equations involved in calculating GAC usage. Can anyone give me a simple breakdown of the process of calculating this? As far as compounds go, I typically only use carbon with PCE or TCE laden sites. Thank you in advance for any insight you can offer!

Your water treatment response was great; but I should clarify that I'm interested in a vapor application (VGAC) and I'd like to know how to calculate carbon adsorption (for PCE and/or TCE) taking pressure, temperature, and flow rates into account. Please help if you can, and thank you in advance!

### 3 Answers

- 10 years agoFavorite Answer
If this is a water treatment question one would use isotherm data for reference as to adsoption capacity of PCE/TCE based upon concentration and temperature. If the flow is 10,000 GPD and PCE/TCE is 10-PPM then the calculation is as follows as an example:

10,000 GPD = 37,800 liters per day. 10-PPM = 10 mg/l concentraion and at 37,800 liters/day the total PCE/TCE is 378,000 mg. 378,000mg / 1000 = 3,780 g/day of TCE/PCE. 3,780 grams /454 = 8.32-lbs/day. If carbon capacity is 50% by weight then carbon usage rate is 2 X 8.32 = 16.64 lbs. of carbon per day. Since isotherm data are lab results under ideal conditions, one usually adds a fudge factor of 15-20% to reflect real world conditions so in this case the carbon usage rate would be about 20-lbs. per day.

Source(s): Carbon experience. - Anonymous6 years ago
i want to calculate quantity of activated carbon required for removal of oil from air in service of pneumatic conveying line . flow rate of air is 10.2 Nm3 while oil is 10ppm , line dia is 1/2" .

carbon specs given by vendor are

carbon tetra chloride activity is 60min

iodine no. 900 - 1000

apparent density 0.51.

kindly suggest me how can i calculate the quantity of carbon required for this ?

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But it's not a water treatment question, is it?