Assessing the engineering aspects of azo dye decolorization in aerobic granular reactors

• Published in: Chemical engineering research & design 2024-11, Vol.211, p.152-159
• Main Authors: Oliveira Júnior, José Kleber Sousa, Rollemberg, Silvio Luiz de Sousa, dos Santos, André Bezerra, da Silva, Marcos Erick Rodrigues, Firmino, Paulo Igor Milen
• Format: Article
• Language: English
• Subjects: Aerobic granular sludge; AQDS; Color removal; Redox mediators
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2024.09.040

This investigation evaluated the impact of the azo dye Reactive Black 5 (RB5) (50 mg·L−1) on the formation and stability of aerobic granular sludge (AGS). Additionally, the effects of the reactor configuration (conventional and simultaneous fill/draw), use of pre-granulated sludge, and addition of the redox mediator anthraquinone-2,6-disulfonate (AQDS) (25 and 50 µM) on the removal of C, N, P, and color were assessed. Although granulation was achieved, the AGS grown in the presence of RB5 showed lower concentration, worse settleability, and smaller size. Nevertheless, the dye did not compromise C, N, and P removals (above 90 %, 75 %, and 35 %, respectively). However, color removal was considered low (∼50 %). Neither the reactor configuration nor the use of pre-granulated sludge significantly affected N, P, and color removals. Therefore, except for C removal, using an AGS previously grown in dye presence is not a prerequisite. Finally, AQDS addition increased RB5 decolorization (from 48 % to 64 % at 50 µM). However, unexpectedly, it had a slight negative impact on N removal. [Display omitted] •Different conditions were tested with AGS treating dye-containing effluent.•RB5 negatively affected granule formation but not C, N, and P removal.•Reactor configuration and pre-granulated sludge did not influence decolorization.•AQDS increased RB5 decolorization from 48 % to 64 % at 50 µM.