生物滴滤塔净化含低浓度苯乙烯废气的研究

Purification of styrene in low concentration by biotrickling filters

利用菌丝体热解炭作为填料,采用两座相同实验室规模的生物滴滤塔,分别填装热解炭-木屑混合填料和木屑单一填料,并联操作,进行微生物净化含苯乙烯废气的实验,研究并对比了两座生物滴滤塔的净化性能.结果表明,由于热解炭具有比表面积大、孔隙率高等特点,热解炭-木屑混合作为生物滴滤塔填料,比单一的木屑填料挂膜速度快,净化效果好,停运恢复能力强.适宜操作条件为:入口气体浓度50～450mg·m-3,停留时间21.6～43.2s,气液比110.7～55.3,净化效率92%～100%,最大去除负荷可达153.1g·m-3·h-1.整个实验过程中,系统的压降始终维持在0～255Pa,动力消耗小.研究发现,循环液中氨氮(NH+4-N)浓度只需能够保证微生物正常的生命活动即可,不宜过量或不足.生物滴滤塔循环液的紫外吸光度(UV254)与苯乙烯去除率具有一定的相关性,可通过测定循环液UV254,了解生物滴滤塔的运行状况.

In this study, sawdust and the mixture of mycelium pyrolytic carbon and sawdust were used as loading materials of biotrickling filter to purify styrene. The removal capability of styrene was calculated as well. The results showed that, as mycelium pyrolytic carbon could provide high surface areas and porosity, the biofilm formation speed, purifying efficiency and recovery capability of the mixture were higher than those with sawdust as the single loading material of biotrickling filter. The styrene removal load was up to 153.1 g·m^-3 h ^-1 and the styrene removal efficiency was from 92% to 100% in the inlet gas concentration of 50～450 mg·m^-3, the retention time of 21.6 ～ 43.2s, and the ratio of gas/liquid of 110.7 -55.3. The pressure drop was retained within 0 to 255 Pa with a small power loss. To ensure biological activities, NH_4^＋ -N in a proper concentration was needed. The biological trickling filter can be monitored through the UV254 value of the circulating fluid, as there is a positive correlation between the styrene removal rate and the UV254 value.