Transformation And Degradation Of Tetrabromobisphenol A In Enhanced Biological Nitrogen And Phosphorus Removal Processes

Tetrabromobisphenol A (TBBPA) is a flame retardant, and threats the ecology and human’s health after releasing into the environment. TBBPA has been frequently reported in the sewage treatment plant, but few studies have been focused on the transformation of tetrabromobisphenol A in biological nitrogen and phosphorus removal processes. By suing sequencing batch reactors (SBRs) where biological nitrogen and phosphorus removal was achieved, TBBPA transformation was examined in long-term operation, typical SBR operation cycles, and nitrification and denitrification processes. The sorption characteristics of TBBPA on activated sludge was investigated using batch experiments, effects of contact time, pH and SS were determined. By using enhanced nitrification SBR system, TBBPA transformation was examined in long-term operation.(1) The SBR system which TBBPA was added could maintain stable levels of VSS, and nitrogen and phosphorus removal efficiency was high as the control SBR system, demonstrated TBBPA has no toxicity in activated sludge. TBBPA concentration as high as20mg-L-1has no effect on nitrification activity.(2) The long-term experiment showed that the removal percentage of TBBPA was48.4%, with the biological process contributing to44.4%. BPA was not detected in any experiment, TBBPA was not converted to BPA, or BPA was degraded in the SBR process.(3) The concentration of TBBPA decreases during the anaerobic stage and increased during the aerobic stage. Concentration of TBBPA in typical SBR operation cycles was highly affected by pH.(4) Removal of TBBPA during nitrification was mainly contributed by the biological process, while removal of TBBPA during denitrification was mainly due to adsorption.(5) TBBPA was absorbed well on activated sludge and the adsorption rate was rapid. The pH value is an important parameters affecting sorption behavior, within the range of pH7.5-9.0, the amounts of TBBPA adsorbed declined with pH rose.(6) TBBPA was examined in enhanced nitrification SBR system long-term operation showed that the removal percentage of TBBPA was31.6%, which was contributed by the biological process.