BIRMINGHAM — In Water Technology’s October article, “Activated carbon software programs improve operations: Part one,” Henry Nowicki, Ph.D., a contributing author, writes about available software programs designed for activated carbon (AC) users and manufacturers in this special two-part feature, helping to enhance productivity and quality.

In the article Nowicki explains a few factors municipalities keep in mind with regards to purchasing granular activated carbon (GAC). “Municipal drinking water plants often purchase [GAC ] based on: Mean particle diameter, effective size and uniformity coefficient. Specifications are designed to obtain water gravity flow through GAC beds.”

He continues by highlighting the following terms in greater detail:

  • Mean particle diameter is the property of AC that influences pressure drop. MPD is the weighted average particle size in millimeters, of a granular adsorbent, which is computed by multiplying the percent retained in a size fraction by the respective mean sieve opening, then summing these values and dividing by 100.
  • Effective sizeis the particle size in millimeters, which corresponds to 10 percent finer on the cumulative particle size distribution curve.
  • Uniformity coefficientis the ratio of the particle diameter corresponding to 60 percent finer on the cumulative particle size distribution curve to the particle diameter corresponding to 10 percent finer on the same distribution curve.

“Knowing the GAC particle size distribution is necessary in order to provide proper contact of gases or liquids in packed AC beds,” he says. “Changes in particle size distribution can affect the pressure drop through bed depth and the rate of adsorption in a bed of a given size. Smaller particles provide faster kinetics and sharper mass transfer zones with higher AC loading capacity at equilibrium.”

You can find part one of this feature on AC software programs here.