Real waste water, which resulted from the oxidative phenol synthesis and contained high amounts of organic peroxides (about 300 mmol l⁻¹ including 2000 mg l⁻¹ cumolhydroperoxide) was treated using one fluidized bed biofilm reactor (FBR) with granular activated carbon and two upflow suspended growth bioreactors (USB) containing either no support or powdered activated carbon (1%). The continuous operating reactors were employed to investigate the part of the activated carbon biofilm supports in the degradation of organic peroxides.

The peroxide containing waste water was degraded by the suspended bacteria in the USB very slowly (maximum degradation rate about 30 mg TOC l⁻¹ d⁻¹). Moreover, organic peroxides accumulated during the treatment. The biodegradation of the organic compounds was completely inhibited, if the peroxide concentration exceeded 15 mmol l⁻¹. The biocommunities in the biofilm reactors, however, continued to degrade the organic compounds almost completely up to a TOC loading of 1000 mg TOC l⁻¹ d⁻¹ without any accumulation of organic peroxides. This degradation rate was more than 45-fold higher than that obtained by the USB without a biofilm support and was shown to be caused by the action of the activated carbon biofilm support. The carrier material acted as a very effective catalyst for the disproportionation of the organic peroxides and the resulting products from the catalytic reaction were mineralized by the biocommunity within the biofilm. The transport of the toxic substrates to the catalytic active support without damaging the biofilm organisms was suggested to be mainly favored by the three-dimensional biofilm structure containing dense microcolonies and highly permeable channels.