UV-生物过滤联合降解苯乙烯废气的研究

实验采用主波长为185 nm的低压汞灯为紫外光源,泥炭、棕纤维、多孔活性炭为填料的UV-生物过滤塔联合装置净化苯乙烯废气.苯乙烯进气浓度控制在320~583 mg·m-3之间,稳定后去除率能维持在95%以上.UV光解苯乙烯形成醇、醛、羧酸等水溶性较好的可生物降解的物质,能改善生物过滤塔的运行性能.稳定运行阶段,当总停留时间(total residence time,TRT)较长时,进气浓度的变化基本不影响去除率,随着TRT减少,进气浓度对去除率的影响逐渐显现.TRT为102 s时,联合装置的去除负荷随进气负荷的增加而线性增加,去除率达95%以上.TRT为68 s时,进气负荷较低时,去除负荷的变化也遵循上述规律,但当进气负荷大于30 g·(m3·h)-1时,去除负荷逐渐偏离直线并趋于某一定值.若仅考虑苯乙烯浓度的增减,UV光解对苯乙烯的去除贡献率高于生物过滤塔,而系统关停10 d后重启,苯乙烯的去除效果在第4 d就能恢复.

Degradation of Styrene by Coupling Ultraviolet and Biofiltration

Purification of styrene by ultraviolet (UV)-biofiltration was studied in this paper. The light source and the biofilm carrier were ozone producing lamp at 185 nm and the peat, palm fiber, porous acticarbon, respectively. Styrene inlet concentration was controlled between 320-583 mg·m^-3, and the removal efficiency remained above 95% after stabilization. The UV converted styrene into more soluble and biodegradable intermediates, such as alcohol, aldehyde and acid, thus the performance of biofilter can be improved. In the stable operation stage, the variation of inlet concentration did not affect the removal efficiency when the total residence time (TRT) was long, however, the inlet concentration obviously affected the removal efficiency when the TRT decreased. The removal load of coupling system increased linearly with increasing inlet load, and the removal efficiency was higher than 95% under a TRT of 102 s. When TRT was 68 s and the inlet load was low, the variation of removal load complied with the law described above, but it gradually deviated from the straight line and tended to stabilized at a certain value when the inlet load became higher than 30 g·(m³·h)^-1. If considering the fluctuation of styrene concentration only, the contribution rate of ultraviolet photolysis to styrene removal was greater than that of the biofilter, and the removal effect could be restored on the fourth day, after closing the system for ten days and restarting.