【作者】 徐超；

【导师】 杨春平；

【作者基本信息】 湖南大学 ， 环境科学与工程， 2013， 硕士

【摘要】 苯、甲苯、乙苯及二甲苯(BTEX)等单环芳烃类是重要的工业溶剂,每年都世界各地有大量的BTEX蒸气排放到大气中,势必会影响大气环境和人类健康。目前,生物净化法是去除这类污染物的有效方法之一。与传统的处理方法相比,如活性炭吸附、液体洗涤、浓缩、燃烧和催化燃烧等,对于低浓度的BTEX气体,生物净化法具有设备简单、投资运行费用低、无二次污染等多项优点。对于使用生物法处理苯、甲苯和二甲苯气体的研究,国内外已有报道,但对乙苯净化的报道所见不多,本文即对乙苯的生物法净化进行实验研究。生物过滤由于其良好的成本效益和环境友好性已经成为控制挥发性有机化合物(VOCs)含量和气味气体排放的常规技术。营养物质的均匀分布,生物膜,介质床内的气体流是成就一个性能优良的生物过滤器至关重要的因素。而由本实验室开发的管式生物过滤器(TBFs)已经证明了这种优势。本实验的管式生物过滤器以聚氨酯海绵作为填料,研究了在不同有机负荷、气体停留时间(EBCT)、进气量和表面活性剂等条件下乙苯废气的去除效率(RE)。实验同时记录了管式生物过滤器启动阶段的表现。初期使附着在填料上的微生物暴露在浓度为40mg·m-3的乙苯废气中40天,此时的气体停留时间为15秒,使微生物慢慢适应并逐步降解乙苯废气。然后连续地控制管式生物过滤器的入口乙苯浓度为40,80,120和160mg·m-3,以使有机负荷逐步升高。结果表明,乙苯去除效率随着有机负荷的增大而逐步减小。当气体停留时间从15秒增加到30秒和60秒而有机负荷控制在38.60g·m-3·h-1时,乙苯废气去除效率略微增加。此外,随着进气量的增大乙苯废气的最大平均去除效率有所下降而此时的降解容量增大,这个过程中乙苯进气浓度保持不变。结果进一步说明了,在营养液中加入聚乙二醇辛基苯基醚这种表面活性剂可以提高乙苯废气的去除效率除此之外实验结果证明了：用本生物过滤器进行乙苯废气的处理,具有填料使用寿命长,易于控制,去除效率高,去除能力大等优点。因此,此方法降解VOCs具有广阔的应用前景。另外在长达238天的实验期间,此管式生物过滤器在未进行反冲洗的条件下,能够长期稳定运行对低浓度乙苯废气有较强降解能力。更多还原

【Abstract】 The monocyclic aromatic such as benzene, toluene, ethylbenzene and xylene(BTEX), is an important industrial solvent. Every year a lot of BTEX vapor emissionsare exhausted into the atmosphere around the word, which will inevitably affect theatmospheric environment and human health. At present, biotechnology is one of theeffective methods to purify this kind of material. Compared with traditionalpurification method, such as activated carbon adsorption, washing liquid,concentration, and catalytic combustion, etc., biological method has some advantagessuch as simple equipment, low investment processing cost, no secondary pollution, etcto the low concentration and large volume of BTEX steam. Biological purificationmethod of benzene, toluene, xylene, has been reported at home and abroad, but reportsof ethylbenzene purification are rare. This article studied the biological purification ofethylbenzene.Biofiltration is becoming an established technology for the control of volatileorganic compounds (VOCs) and odor emissions from waste gas streams due to itscost-effectiveness and environmental friendliness. Even distribution of nutrientsolutions, biofilms, and gas streams within the medium bed is critical to a betterperformance of a biofilter. Tubular biofilters (TBFs) developed in this laboratory haveshown this advantage.In this investigation, performances of tubular biofilters packed with polyurethanesponge media were evaluated for ethylbenzene removal from waste gas streams undervarious ethylbenzene loading rates, gas empty bed contact time (EBCT) and differentgas flow rates. The performances of the TBFs have also been monitored at the start-upperiod. Microbial acclimation to ethylbenzene was achieved by exposing the biofilterbed to an inlet ethylbenzene concentration of40mg·m-3and an EBCT of15s for40days. Then the TBFs was operated continuously at inlet ethylbenzene concentration of40,80,120and160mg·m-3. Results showed that the ethylbenzene removal efficiency(RE) decreased with an increased ethylbenzene loading rate. When EBCT increasedfrom15s to30s and60s at a constant VOC loading rate of38.60gethylbenzene·m-3h-1, and the ethylbenzene RE increased slightly. In addition, themaximum average removal efficiency was decreased while the elimination capacityincreased with increased gas flow rate at a constant inlet ethylbenzene concentration. Results also showed that Surfactant Triton X-100in the nutrient solution led to ahigher RE.Experimental results also show that This method has many advantages such aslong service life of the packing, easy to control, high removal efficiency and removalability, etc. Therefore, this method has broad application prospects. In addition, duringthe long period the tubular biological filter under the condition of not reverse flushinghas strong degradation ability to degrade ethylbenzene waste gas in low concentration.更多还原