The treatment of wastewater containing nitrotoluene by photocatalytic oxidation-immobilized microbials technology

The wastewater containing nitrotoluene was degraded by integrated photocatalytic oxidation and immobilized microbials technology. The biodegradability of wastewater was studied when the concentration of nanometer titania was 0.1 g/L, the concentration of hydrogen peroxide was 0.1 ml/L, the pH was 3, and the reaction time was 4 hours, which were the optimum photocatalytic conditions. The results showed that, the biodegradability of wastewater was increased from 0.04 to above 0.3, when the photocatalytic reaction time was 3 hours. The effluent from photocatalytic reactor was degraded by immobilized microbials technology continually. When the hydraulic detention time was 4 hours and the stable operational time of the bioreactors was 40 days, the removal rate of 2, 6-DNT, 4-MNT and the COD were above 90%, 90% and 60%. With SEM technology, the surface morphology of immobilized microorganisms on the surface of carrier was observed.