【作者】 赵以轩；

【导师】 刘俊杰；

【作者基本信息】 天津大学 ， 供热、供燃气、通风及空调工程， 2010， 硕士

【摘要】 清洁的空气是人类维系健康与幸福生活的最基本需求。然而,目前的室内空气污染却在全球范围内对公共健康造成了非常严重的威胁。尽管近年来关于室内空气净化的改良技术和新兴技术层出不穷,但由于室内气态化学污染的特殊性与现有净化技术自身存在不足与局限性,至今仍不能满足改善室内空气品质的多方面要求。本课题针对室内环境中广泛存在的低浓度气态有机化学污染物,提出将经济环保的微生物降解技术引入室内气态有机化学污染物控制应用领域加以充分利用,并对该技术引入的可行性进行深入探讨。本课题的研究重点在于探讨室内环境中涉及的空气温度条件对微生物降解空气净化系统长期运行可能产生的影响。本课题选择了室内环境最广泛存在的甲醛作为研究的目标气体,根据固定化微生物填料自身特点,对过滤系统中微生物降解化学污染物的过程进行动力学分析,建立了可预测微生物过滤系统的在进气温度影响下运行性能的数学模型。不同的进气温度会通过影响气液相之间的物质传递过程和填料内微生物转化传入污染物的速率而最终影响过滤系统运行。理论模型计算结果显示,微生物过滤系统运行性能与进气温度呈负相关关系,当温度超过30℃后,过滤性能下降趋势加剧。分析认为温度升高导致气体在循环液中的溶解度降低是造成过滤系统性能下降的主要原因。同时,通过监测同一台过滤系统在不同进气工况下连续运行的过滤性能变化,系统地实验研究了进气温度对微生物过滤系统运行性能的影响。实验表明,气温在30℃左右时系统的净化性能最好,平均效率高于90%。当温度升高或降低后,净化效率略有下降,但基本可保持在75%-80%的可接受范围内。而且,从长期运行的性能来看,过滤系统在相对较高的进气温度条件下运行更加稳定。此外,当进口甲醛浓度低于0.6ppmv稳定运行时,系统在各进气温度条件下都可保证出口气体的甲醛浓度低于国家卫生标准规定的健康限值(0.1mg/m~3)。为了验证过滤系统中微生物降解的作用,实验将同一台过滤系统的填料替换为不含微生物的空白颗粒,在与温度影响研究相同的实验条件下对该系统的过滤性能进行了连续5天的监测。结果显示,由于缺少微生物降解的实质性去除作用,过滤系统在运行48h后开始出现过滤失效,位于反应器底部的填料层将率先出现向下游散发甲醛污染的情况。更多还原

【Abstract】 Clean air is considered to be a basic requirement of human health and well-being. However, air pollution continues to pose a significant threat to health worldwide, and air pollution in indoor environment has been one of the key threats. Despite there have been many improvement or emerging technologies come forth to improve indoor air quality (IAQ), there still has not one technology of air pollution control can remove gaseous chemical pollutants from indoor environment absolutely and meet various IAQ requirements in all dimensions, in respect to the particularity of those pollutants in physical or chemical properties, and deficiencies in these existing technologies.This research aiming at removal of low-concentrations gaseous organic chemical pollutants, which exist widely in indoor environment, through introduction of biodegradation technology into application of indoor air pollution control, and the feasibility of this suggestion has been discussed in depth. The focus of this research is on the potential impacts of inlet gas temperatures, which are tent to be involved in HVAC system of buildings, on long-term performance of biodegradation system for air purification.Formaldehyde was selected as the objective and typical gaseous chemical pollutant in this research. Based on the characteristic of immobilized-microorganisms packing and kinetic analysis about biodegradation process of gaseous chemicals in the trickling biofilters, a mathematical model was developed to predict the operational performance of the trickling biofilter with the effects of different inlet temperature. The inlet temperature influence the operation of biofiltration indirectly with the paths of Henry’s constant H(T) and bacterial specific grow rateμ(T). According to the predicted results, operational performance of the trickling biofilter represented negative correlations with inlet gas, less gaseous formaldehyde were removed by trickling biofilter when the inlet temperature was increased. Especially for the state that inlet temperature was higher than 30℃, degradation of operation performance was intensified. It is analyzed that decrease of gas solubility in circulating liquid caused by increase of temperature was the main reason.At the same time, through the method that continuous monitoring the periodical run of one trickling biofilter packed with immobilized-microorganisms packing under different inlet conditions, a series of systematic studies were carried out about the effect of inlet temperature on biofiltration. Experimental data presented that, the best biofiltration results, more than 90% of average removal efficiency, appeared if the inlet temperature were around 30℃, and the removal efficiency reduced as soon as temperature deviate from 30℃neither higher nor lower, but it still keep in acceptable range of 75~80%. Additionally, trickling biofilter would operate more stable at relatively higher inlet temperature from the long term. Furthermore when inlet cons of formaldehyde was under 0.6ppmv, that the cons of outlet were not exceeded the healthy limits stated by GB/T18883-2002 (0.1mg/m3) was achieved under every kind of operational condition. It was found that the trickling biofilter ceased to be effective after 48h run, because lack of substantive removal process by biodegradation, and the bottom packing stage was appeared to failure in filtration of formaldehyde at first.For the sake of validating action of biodegradation in trickling biofilters, the same trickling biofilter, of which packing was replaced by blank beads without bacterium, was investigated again for 5 days under the same experimental conditions with previous ones.更多还原