Effective Combination of Low-Thermal and Ozone as a Method for Regenerating Spent GAC Saturated with Phenol.

Activated carbon adsorption technology is widely used in wastewater treatment, however, efficient regeneration of spent granular activated carbon (SGAC) at low energy consumption has become a challenge in this technology area. In this study, the thermal + ozone oxidation regeneration (LTO) was proposed for the first time. Technical feasibility is explored and mechanisms are analyzed in detail. According to the analysis of the LTO test, when the regeneration temperature was 350℃, the time was 1 h, the ozone addition time as 40 min, the SGAC regeneration efficiency was as high as 95%, which was 34% higher than thermal regeneration. The regeneration efficiency of SGAC decreased slightly after the three adsorption-regeneration cycles, but it was still able to reach 81.8% almost no carbon loss. During the low-thermal regeneration stage, phenol could desorb physically by the change of temperature and opened the pores for ozone to enter the inside of GAC. In the ozone regeneration phase, the chemisorbed phenol is desorbed and oxidized through the oxidizing power of ozone itself and hydroxyl radicals. This study helps to reduce the regeneration temperature for conventional thermal regeneration and the amount of oxidant used for ozone regeneration, which has practical engineering implications. [ABSTRACT FROM AUTHOR]

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