摘要
随着社会现代化进程不断加快,大量挥发性有机化合物(VOCs)排入大气,严重危害生态环境和人体健康,VOCs排放控制与降解引起广泛关注。近年来,由于生物法降解VOCs具有成本低廉、净化效率高、操作简便、无二次污染等优点,研究应用较为广泛。然而,由于疏水性VOCs从气相到液相的低传质,导致生物反应器对VOCs的降解效率较低。从传质效率、微生物群落种类及填料性能3方面分析了生物降解疏水性VOCs的影响因素,探讨了真菌生物的应用、表面活性剂的添加、亲水性化合物的利用及新型生物降解技术等疏水性VOCs生物降解效率改进方法,并对未来生物降解疏水性VOCs研究方向进行了展望。改善污染物在生物反应器中的传质效率尤为重要,未来需加强疏水性VOCs在生物膜中的迁移和降解机理研究。随着环境变化,如水分减少、pH降低,接种的细菌对VOCs的降解效率下降。而真菌对环境变化耐受力较强。生物反应器中填料会影响微生物的附着和生物膜的形成,从而直接影响VOCs降解效率。选择和开发合适的填料能为微生物群落的生长、代谢以及生物膜的发育提供良好的生态环境,为反应器长期稳定运行提供保障。真菌具有气生菌丝的优势,有助于疏水性VOCs的吸收,从而提高疏水性VOCs的去除率,但目前能降解疏水性VOCs的真菌较少,未来应该致力于开发更多能降解疏水性有机化合物的真菌。表面活性剂可以通过将疏水有机污染物分配到表面活性剂胶束的疏水核心来增加其溶解度,提高疏水性VOCs的传质效率,相较于传统的化学表面活性剂,生物表面活性剂环保、毒性小、易生物降解,未来应加大对生物表面活性剂的研究。将亲水性化合物与疏水性VOCs混合,不同污染物之间可产生相互作用,提高疏水性VOCs的溶解度和生物利用度,但其机制有待研究。新型生物反应器能解决传统生物反应器对于疏水性VOCs降解效率较低的难题,如两相分配生物反应器(TPPBs)、膜生物反应器(MBR)及生物电化学系统(BESs)等,但成本和能耗都较高,需加强相关研究。
With the continuous acceleration of social modernization, a large number of volatile organic compounds(VOCs) are discharged into the atmosphere in industrial production and daily life, which seriously harms the ecological environment and human health. Therefore, the emission control and degradation of VOCs have attracted wide attention. In recent years, due to the advantages of low cost, high purification efficiency, simple operation and free secondary pollution, biodegradation of VOCs has been extensively studied and applied. However, because of the low mass transfer of hydrophobic VOCs from gas phase to liquid phase, the degradation efficiency of VOCs in bioreactor is low. The influencing factors of biodegradation of hydrophobic VOCs were analyzed from the aspects of mass transfer efficiency, microbial community types and packing performance. The methods to improve the biodegradation efficiency of hydrophobic VOCs, such as the application of fungi, the addition of surfactants, the utilization of hydrophilic compounds and new biodegradation technologies, were discussed, and the research direction of biodegradation of hydrophobic VOCs in the future was prospected. It is particularly important to improve the mass transfer efficiency of pollutants in bioreactors. In the future, researches on migration and degradation mechanism of hydrophobic VOCs in biofilms should be strengthened. The degradation efficiency of VOCs by the inoculated bacteria decreases with environmental changes, such as decreasing moisture and pH. The packing in the bioreactor can affect the attachment of microorganisms and the formation of biofilm, which directly affects the degradation efficiency of VOCs. The selection and development of suitable packing can provide a good ecological environment for the growth, metabolism and biofilm development of the microbial community, and provide guarantee for the long-term stable operation of the reactor. The advantage of aerial mycelia could help fungi to absorb hydrophobic VOCs which can improve the degradation efficiency of VOCs, so as to improve the removal rate of hydrophobic VOCs. However, few fungi that can degrade hydrophobic VOCs have been found so far, more fungi that can degrade hydrophobic organic compounds should be developed in the future. Surfactants can increase their solubility by partitioning hydrophobic organic pollutants into the hydrophobic core of surfactant micelles and improve the mass transfer efficiency of hydrophobic VOCs. Compared with traditional chemical surfactants, biosurfactants are natural compounds that are more environmentally friendly, less toxic, and more easily biodegradable. Future research should pay more attention to biosurfactants. Mixing hydrophilic compounds with hydrophobic VOCs can interact with different pollutants, which improves the solubility and bioavailability of hydrophobic VOCs, but the mechanism needs to be further studied. The new bioreactor can solve the problem of low degradation efficiency for hydrophobic VOCs, such as two-phase distribution bioreactors Reactors(TPPBs),membrane bioreactors(MBR),and bioelectrochemical systems(BESs),etc.,but the cost and energy consumption of the entire degradation process are high, relevant research needs to be strengthened.
作者
方翔
程凯
郭冀峰
FANG Xiang;CHENG Kai;GUO Jifeng(Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region,Ministry of Education,School of Water and Environment,Chang′an University,Xi′an 710054,China)
出处
《洁净煤技术》
CAS
北大核心
2022年第2期13-22,共10页
Clean Coal Technology
基金
国家重点研发计划资助项目(2021YFE0192600)
陕西省自然科学基金资助项目(2019JM-419)。
