Model studies on granular activated carbon adsorption in fixed bed filtration

Area of Science:

• Environmental Science
• Water Treatment Engineering
• Adsorption Science

Background:

• Natural organic matter (NOM) removal is crucial for water purification.
• Granular activated carbon (GAC) is a common adsorbent for NOM.
• Understanding adsorption kinetics and modeling is essential for optimizing GAC performance.

Purpose of the Study:

• To evaluate the efficiency of GAC in removing NOM from water.
• To compare the performance of different GAC materials (KI-6070 and KI-8085).
• To assess the applicability of various adsorption models (Adams-Bohart, Bed-Depth-Service-Time, Clark) for NOM removal.

Main Methods:

• Continuous flow fixed bed column experiments were conducted.
• Two types of GAC with different surface areas were utilized.
• Adsorption data were fitted using Adams-Bohart, Bed-Depth-Service-Time, and Clark models.
• The impact of empty bed contact time (EBCT) on adsorption was investigated.

Main Results:

• Adsorption of NOM onto GAC was a complex process involving multiple rate-limiting steps.
• Critical bed depths for KI-6070 and KI-8085 were determined to be 0.24 m and 0.3 m, respectively.
• The Clark model provided a better simulation of the adsorption breakthrough process compared to the Adams-Bohart model.
• Shorter EBCT (15 minutes) showed a better fit with the Clark Model.

Conclusions:

• GAC is effective for NOM removal, but the process is complex.
• The Clark model is a suitable tool for simulating GAC adsorption of NOM.
• Optimizing EBCT is important for enhancing the predictive accuracy of adsorption models and improving GAC filtration efficiency.