A pilot-scale study of in situ granular activated carbon regeneration via ozone micro-nano bubbles oxidation for long-lasting micropollutant purification in water

In the study, a novel in situ regeneration technology of granular activated carbon (GAC) via ozone micro-nano bubbles (OMNBs) was proposed for efficient, economical and sustainable water deep decontamination. The regeneration performance was evaluated via long-term running of the pilot unit (10 m³/h) with GAC1 (coconut shell-based GAC) and GAC2 (coal-based GAC) for comparison. Overall, the regeneration of GAC by OMNBs was effective in maintaining its adsorption capacity. The average permanganate index (PI) removal increased by 6.0 % and 6.3 % for GAC1 and GAC2, respectively. Additionally, OMNBs technology was powerful in organic micropollutants (OMPs) degradation. The OMNBs regeneration process induced an increase in the specific surface areas of GAC1 and GAC2, which benefits the adsorption. Apart from this, OMNBs regeneration barely affects the morphological and chemical characteristics of GAC over the study period. To provide a comprehensive comparison, the direct OMNBs oxidation and GAC adsorption (OMNBs/GAC) were combined, and it showed high performance (more than 76 %) for various OMPs removal. During the long-lasting water decontamination, the OMNBs-regenerated process reduced the production costs by approximately 70 % compared to the OMNBs/GAC process. The successful application of this proposed regeneration technology in the long-term pilot process provides a new treatment model for deeply improving the quality of drinking water.