Study On The Treatment Of Bromoamine Acid Wastewater By The Bioaugmented Membrane Bioreactor

The purpose of this dissertation is to investigate the degradability and characteristics of activated sludge, the physiological state and the structure of microbial community in the membrane bioreactor (MBR) bioaugmented with the strain sphingomonas xenophaga QYY treating bromoamine acid (BAA) wastewater. And the possible metabolic pathway of BAA in the system is tried to be presumed. Finally, the inherent relationship between the macroscopical characteristics and the microcosmic structure is tried to gain to provide the theoretical evidence for the actual industrial wastewater.The MBR with activated sludge is used to treat BAA wastewater. The characteristics during the phases of acclimation, stable operation, pre-bioaugmentation are studied, respectively. The results show that during the acclimation phase, the concentration of activated sludge decreases, the dehydrogenase activity declines and keeps at a low level, however the protein and carbohydrate concentrations in the extracellular polymeric substances (EPS) both increase. After the acclimation, the removals of BAA and COD reach 90% and 50%, respectively. Ribosomal intergenic sequence analysis (RISA) shows that there are dynamic changes in the microbial community and the genetic diversity of the activated sludge community is declined. During the stable phase, with the increase of the influent concentration, the effluent presents a product with yellow color, which results in a decline of decolorazation rate of BAA. The decolorazation rates of supernatant and the effluent are 50% and 65%, respectively. And the corresponding COD removals are about 25% and 50%, respectively. The dehydrogenase activity and the concentrations of protein and carbohydrate in EPS both decrease first and then increase. Pre-bioaugmentation is carried out on the basis above. The results show that after inoculation, the decolorization rate and the COD removal are similar to those of the system before bioaugmentation with the influent load increase. The dehydrogenase activity and the concentrations of protein and carbohydrate in EPS fluctuate slightly after inoculation, and then come back to the previous level after a period of operation. RISA shows that the inoculated strain QYY can steadily survive in the system and does not affect the indigenous populations of the microbial community.The characteristics of startup phase, the effects of various operational parameters on the system are investigated in the continuous bioaugmented MBR. The results indicate that bioaugmentation can accelerate startup of the MBR and maintain relatively stable operation.During the startup phase, the concentration of activated sludge decreases, the settle and flocculation ability are becoming better, the dehydrogenase activity declines and keeps at a low level, and the concentrations of protein and carbohydrate in EPS increase. At the end of the startup phase, the decolorazation rate of BAA is over 90%, and the COD removal is over 50%. RISA shows that the genetic diversity of the microbial community decreases. The BAA degrading functional community is developed. The optimal operation conditions are gained by studing the influence of operational parameters on the system: BAA concentration 350 mg/L, without temperature control, aeration amount 0.8 L/min, HRT 14.5 h, pH=7. RISA shows that the dynamic changes of the community structure are appeared as the operational parameters changing, which can well explain the corresponding changes of macroscopical characteristics.Through the analysis on the degradative mechanism of the continuous operation, the sequncing operational mode is put forward aim at the polymerization of the products. The bioaugmanted sequncing MBR (SMBR) can also startup rapidly and operate stably. When the BAA concentration is up to 350 mg/L, the decolorization rates of supernatant and effluent are both more than 90% and no yellow product is found. And the corresponding COD removals are 52% and 62%, respectively. The settle and flocculation ability are becoming better. The dehydrogenase activity declines and keeps stable. And the concentrations of protein and carbohydrate in EPS are increased and tend to stable too. RISA shows that the community in SMBR changes a lot and has a similar trend as the continuous MBR. The genetic diversity of the microbial community finally appeared in the SMBR declines.The metabolic pathway of BAA degradation by the bioaugmented MBR is investigated by UV-VIS, HPLC-MASS, etc. The results show that the microbial community has a more complex degradative mechanism than that of the strain QYY. Under the sequncing operational mode or the continuous mode with low influent concentration, the anthraquinone ring of BAA is cleaved, the portion without substituent is mineralized, and the products with the structure of a benzene ring with groups of amino, Br and sulfonic hydroxyl or other small molecules are produced. However, the products tent to polymerize under the continuous mode with high concentration of influent.The effluent is treated by the combined photocatalysis and ozonation (TiO2/UV7O3) process. The results show that the products can nearly be mineralized completely by the TiO2/UV/O3 process. An appropriate process combined of bioaugmented MBR, photocatalysis and ozonation is proposed for treatment of BAA wastewater.