Phenol removal and biofilm response in coupling of visible-light-driven photocatalysis and biodegradation: Effect of hydrothermal treatment temperature

• Intimate coupling of visible-light-responsive photocatalysis and biodegradation (VPCB) was realized.
• VPCB performed greater phenol degradation efficiency than photocatalysis alone.
• Photocatalytic activity of photocatalyst determined microbial responses.
• Biomass at carriers' exterior detached most but well protected at the interior.
• Extracellular polymeric substances content was mainly related to inhibitory level.

Intimate coupling of visible-light-responsive photocatalysis and biodegradation (VPCB) provides novel insights into removal of inhibitory pollutants. Under these reactions, microbes are prone to photocatalytic activity. In this study, microbial responses to photocatalytic activity in VPCB used for phenol degradation were investigated. VPCB was conducted with Er3+:YAlO3/TiO2 photocatalysts prepared at heat-treatment temperatures [HT] of 110 °C, 130 °C, and 150 °C to evaluate photocatalytic activities. The highest phenol removal rate (71.6%) was observed in photocatalysis [HT] 130, and particular microbial responses were elicited in VPCB [HT] 130. Dehydrogenase activity exhibited the highest decrease (90.7%) in VPCB [HT] 130. In this treatment, large amounts of biofilm were detached from the exterior of the carrier but the biofilm remained well protected in the interior. Extracellular polymeric substances with decreases of 65.6% and 31.4% in protein and polysaccharide levels, respectively, were not stimulated in VPCB [HT] 130 but were evidently stimulated in the other two protocols, which could be due to lower phenol inhibition. These results indicated that the most efficient removal rates of phenol and dissolved organic carbon reached 99.8% and 67.1%, respectively, in VPCB [HT] 130.