High-efficient biosorption of dye wastewater onto aerobic granular sludge and photocatalytic regeneration of biosorbent by acid TiO2 hydrosol.

In present study, aerobic granular sludge (AGS) was applied as a high-efficient biosorbent for dye wastewater treatment. The feasibility of acid TiO2 hydrosol as self-clean eluent for the regeneration of dye-loaded AGS and subsequently photo-catalytic degrade desorbed dyes was investigated. Acid TiO2 hydrosol was successfully synthesized and characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Batch sorption experiments suggested that methyl orange (MO) and crystal violet (CV) sorption onto AGS were both fitted well with Langmuir model, and the maximum adsorbed capacities of AGS for MO and CV were 741.6 and 323.6 mg/g, respectively. Biosorbent regeneration experiment indicated that adsorbed dyes were successfully desorbed from dye-loaded AGS and subsequently degraded by a self-cleaning acid TiO2 hydrosol (pH at 2.0). It was found that the photodegradation times for MO and CV were 240 and 300 min, respectively. Moreover, the AGS retained more than 50 and 70% of its original MO and CV adsorption capacity after the fourth cycle. The result implied that the integration of biosorption with self-cleaning desorption and photocatalytic degradation process could be applied as a feasible technique for dye wastewater practical treatment.