A TiO2 modified abiotic-biotic process for the degradation of the azo dye methyl orange

To investigate the feasibility of titanium dioxide (TiO2) employed as a modifier in the sodium alginate immobilization system, the degradation of methyl orange with the strain Delftia sp. A2(2011) (STT01) was carried out using a TiO2 modified sodium alginate system (TiO2/SA) and a non-TiO2 modified sodium alginate system (SA). It was found that the decolorization of methyl orange was enhanced from 76.5% to 100%, and the chemical oxygen demand (COD) removal was increased from 35.6% to 52.7%. The results further revealed that the TiO2 played a crucial role in the cell immobilization system, and the potential modification mechanisms of dye sensitization and TiO2-SA complex-mediated photocatalysis were investigated. Additionally, the intrinsic bright color of the bacterial strain STT01 could be ingeniously employed as an indicator for the degradation efficiency. This work not only presents a promising opportunity for developing novel cell immobilization techniques but also affords a direct and visually observed treatment for azo dye wastewater.