Degradation of Wastewater Containing Nitrobenzene by High Gravity-Ultrasonic/Ozonation/Electrolysis Technology

The integrated high gravity-ultrasonic/ozonation/electrolysis technology was applied in the pretreatment of wastewater containing nitrobenzene. The effect of pH value, high gravity factor, liquid flow-rate and electric current density on removal of COD and nitrobenzene compounds was investigated. Experimental results have determined the optimal process regime involving a high gravity factor of 100, an electric current density of 20 mA/cm(2), a liquid flow-rate of 100 L/h, and an initial liquid pH value of 11. After the wastewater had been treated for 180 min, the degradation of nitrobenzene and COD reached 99% and 80%, respectively, with the biochemical coefficient (BOD/COD) equating to 0.64, and the subsequent treatment of wastewater could be carried out by conventional biochemical means. Compared with traditional aeration-ozone contactors, a rotating packed bed with high mass transfer characteristics could be used to increase the ozonation treatment efficiency.