Comparison study of dyestuff wastewater treatment by the coupled photocatalytic oxidation and biofilm process

Degradation of Rhodamine B (RhB) and COD by means of the coupled photocatalytic oxidation (PCO) and biofilm systems has been studied. The coupled PCO-biofilm systems were divided into two operation systems. The one (R1) consisted of a pre-PCO and a post-biofilm reactor system and the other (R2) was a pre-biofilm and a post-PCO reactor system. In a batch experiment, the order of initial decolorization rate was photocatalytic oxidation > adsorption > photolysis. The color removal rate of RhB was decreased with an increase of the initial COD concentration. In a continuous experimental study, almost all color was removed in the PCO reactor. During 180 days, the color and COD removal efficiencies in the R2 (pre-biofilm + post-PCO) system were higher than those in the R1 (pre-PCO + post-biofilm) system. In our experimental ranges, the PCO process was superior to Fenton oxidation in the color and COD removal.