Electrochemical reactivation of granular activated carbon: Impact of reactor configuration

The main objective of this paper was to compare different electrochemical reactor configurations for the reactivation of granular activated carbon (GAC). Laboratory experiments were conducted using phenol as adsorbate; three different GACs as adsorbents; and four different reactor configurations (divided-cell batch reactor, undivided-cell batch reactor, stainless steel column type reactor, and a simple batch reactor). The undivided-cell and divided-cell batch reactors were slightly more efficient than the simple batch reactor. The divided-cell reactor had slightly higher efficiencies than the undivided reactor, however, it had a number of disadvantages that countered the slightly better performance. The stainless steel column reactivation reactor did not perform as well as the batch reactors with a single layer of GAC particles, possibly due to the lower fraction of the GAC particles in direct contact with the cathode. However, the stainless steel column reactivation reactor performance was slightly better than the batch reactors with multi-layer of GAC. Reactivation of different numbers of layers of GAC particles showed a significant decrease in the reactivation efficiency with increasing number of the GAC layers demonstrating the benefit for closer contact between the GAC particles and the electrode.

► Membrane separation of the electrodes slightly improved reactivation.
► Electrolyte recirculation lowered the GAC reactivation efficiency.
► Flow direction and cathode location did not have a significant impact.
► Direct contact between the phenol-loaded GAC and the cathode is critical.
► The three different conductivity activated carbons behaved similarly.