Process Research Of Biodegradation Of Reactive Brilliant Red By Sequencing Batch Reactor

Wastewater discharged from textile industries is high in quantity, color salinity and COD. In this paper, Sequencing Batch Reactor was used to treat synthetic wastewater containing Reactive Brilliant Red X-3B, glucose was applied as the co-substrate, and the reactor operated in anaerobic-aerobic condition. We investigated the start of the system, the optimization of operation condition, and the effects of electron donor and electron acceptor on X-3B degradation. Finally, some improvement actions were stated for SBR. The paper provided the theory basis for the system application in textile wastewater treatment.In the startup stage, seed sludge was obtained from a settling tank; glucose was applied as the co-substrate. We enhanced COD and X-3B concentration gradually. After 50 days, COD removal rate reached 94%, and X-3B degradation efficiency reached 93%, and the biological treatment system operated stably at this time. The steady system could tolerate COD and X-3B shock. The seed sludge concentration was high initially, but it decreased subsequently. It may be due to the reason that the seed sludge needs time to match its new surroundings. And then, the sludge concentration increased to 3200~3300 mg/L. In the anaerobic stage, the solution pH decreased as the hydrolysis acidification of glucose, which was degraded to some volatile fatty acids. The addition of alkali was required.X-3B and COD could be removed effectively by the reactor. When the anaerobic stage was 40 h, and the aerobic stage was 4 h, X-3B removal rate could reach 92.8%, it was degraded to aromatic amine, which further degraded by aerobic digestion. The removal rate of X-3B decreased with the increase of X-3B concentration as X-3B is noxious to aerobic microorganisms. The system have been running well as MLSS maintained at 4500 mg/L. Because X-3B contributes very low COD content, the COD removal rate was under 90% when MLSS was low. The acid condition had a adverse effect on COD removal and it had negligible effect on the anaerobic treatment stage. UV-vis spectrum showed that the azobenzene group was destroyed during the anaerobic treatment, and the products were aromatic amine, which were degraded by following aerobic microorganism.Effects of electron donor on X-3B removal was studied, we found that when sodium acetate, glucose and starch were used as the co-substrate, X-3B removal rates were 94.6%, 93.2% and 63.1% in 44 h, respectively. Technical pure glucose could be applied in actual treatment for its low price. Sulfate ion had negligible effect on decolorization. When sulfate concentration was 800 mg/L, the decolorization rate decreased to 85.3%. The products included sulfide, which is noxious to aerobic microorganisms and it might be oxidized to sulfate again. Nitrate has a adverse effect on X-3B decolorization, when nitrate concentration increased from 100 mg/L to 500 mg/L, the decolorization rate decreased about 20% in 44 h. Denitrifying bacteria has strong ability completing for electrons. The dissolved oxygen could inbibit the decolorization process. When the aeration intensity was 0.02 Nm3/h in the anaerobic treatment stage, the decolorization rate reduced 10%. As a result, the dissolved oxygen content should be controled below 0.5 mg/L during anaerobic treatment.