第四讲 废气生物处理技术

2. 生物滤过(biofiltration)
生物滤过采用是固态介质
* 生物滤池(biofilters)
* 生物滴滤池(biotrickling filters)
表3
工艺类型比较
技术名称
生物滤器 生物滴滤
化合物浓度
低 低－中 低－中
化合物溶解度
低 低－高 中－高
生物净化器
Biofilters Biofilters can be described as biochemical fixed bed reactors where the waste gas is treated while passing a biofilter bed. Microorganisms settle on its surface and form a biofilm in which the airborne substances are absorbed. An important criterion for biofilter media is to provide optimum environments for the microorganisms, thus an essential property is the ability to store water. Additional criteria are a low pressure drop to assure an even air distribution and a large specific surface for the mass transfer and the microorganisms to settle on.
7 污染气体的生物处理
第一节 废气的生物反应器处理 第二节 恶臭的原位处理
废气主要来源
人类生产及生活中的燃料燃烧 ； 生产活动，例如化工、冶金、生物制品、 屠宰、污水处理及垃圾处理等工厂所产
生的废气。
废气的处理
废气处理是环境污染控制的一个重要方面。
废气处理方法： ①理化法：目前主要采用的方法，如燃烧、 吸附、吸收和还原等。工艺或设备较复杂， 运行费用较高；用于处理某些恶臭废气时， 效果不甚理想。 ②生物法：具有处理效率较高、适应性较广、 工艺较简单以及费用较省等优点。
第一节 废气的生物反应器处理
一、废气生物处理的特点
二、废气生物处理的基本形式 三、生物法处理废气的机理 四、处理废气的微生物 五、废气生物处理的基本条件
第一节 废气的生物反应器处理
废气的微生物处理于1957年在美国获得专利，但
到 1970 年代才开始引起重视，直到 1980年代才
在德国、日本、荷兰等国家有相当数量工业规模
甲烷气（厂区最高浓度） 5
我国规定的恶臭污染物排放标准 (GBl4554-93)
表2 臭气强度表示方法
适宜处理的污染气体应具有的特点：
1.

水溶性强 兼具有蒸汽压低、亨利定律常数低的特点， 向介质表面微生物膜扩散速率高；

Hale Waihona Puke Baidu
主要有无机物如H2S和NH3等、醇类、醛类、 酮类以及简单芳烃(如BTEX)等有机物。
◆设备实图：
In bioscrubbers and biotrickling filters, the microorganisms generally are suspended in a scrubbing liquid but may additionally be immobilised on packing material. The most important component of these devices is the absorption column where the mass transfer between gaseous and aqueous phase takes place, and thus the airborne substances are made available to the microorganisms. Usually packing materials are installed to enhance the contact surface of both phases. In most applications the gaseous and the aqueous phases are distributed in counter flow to each other. However, if no packing materials are installed, cross-flow systems often are used.
1．生物滤池
Frequently used biofilter media are compost, peat, root wood, bark, wood chips (normally used as
bulking agent) and different kinds of combination.
2.
易降解
分子被吸附在生物膜上必需被降解，否则将导
致污染物浓度增高，毒害生物膜或影响传质，
降低生物滤器效率，或使处理完全失败。
除臭系统组成图
二、废气生物处理的基本形式
根据介质性质不同，分为：
1. 生物洗涤(bioscrubbing)
生物洗涤器(bioscrubber)内是液态介质。
2. 去除效率高
一般的空气污染物去除效率超过90％。
3. 投资少，运行费用低


不需要投入额外的化学品;
化学法则需加催化剂和氧化剂等，如次氯酸盐、 过氧化氢、二氧化氯等。
4. 污染少

生物处理的产物是生物量，很容易处理。
5. 耗能低
生物反应在常温常压下进行，能量来自微生物利用VOCs成分
本身产生的能量。
的各类生物净化装置投入运行。
废气生物反应器处理对许多一般性的空气污染物
的去除率可达到90％以上。
Biological waste gas treatment systems rely on the activity of microorganisms, which are able to degrade organic contaminants from the air stream. The microorganisms feed on odorous substances and oxidise them, at best to CO2 and H2O or other odourless products. Thus, biological systems sustainably reduce odorous emissions and do not shift the problem to other media like scrubbing liquids or adsorbents, which remain as problematic residues. Furthermore, if at all, few chemical agents have to be added and energy costs are relatively low, as they are operated at atmospheric pressure and ambient temperatures. Accordingly, investment and operational costs for biological waste gas treatment systems are comparably low .
优点： 充填有机材料，利用介质表面的可溶化学物质和微 生物净化气体，反应器内部条件佳，合理维护，去除 滤可达95％或以上。 缺点：
水浸导致处理效率降低。
Traditionally, biofilters were used to treat off-gases from sewage treatment plants, composting facilities and rendering plants, which mainly contain biological intermediate degradation products. In recent years, further applications have been opened to this technology including in food and tobacco producing and processing industries, as well as the treatment of waste gases containing industrial solvents and other volatile organic compounds . Problematic substances regarding biofiltration are sulphurous and nitrogenous organic or inorganic compounds, as they cause acidification of the biofilter media due to their oxidisation products, sulphuric and nitric acid. For these applications, a combination with other treatment processes should be considered. Applicable filter loads usually range between 40 and 150 m3 m-3 biofilter material per hour (up to 500 m3 m-3 h-1 ).
One of the key parameters of biofiltration is the moisture content of the biofilter material. The optimal range for biologically active organic media is between 40% and 60%. To avoid drying of the filter media, the waste gas should be saturated with water vapour. Usually the air is humidified using wet scrubbers or even bioscrubbers. Both the dry air streams and a high microbial activity can cause drying of the biofilter material. That is why even if the waste gas initially is saturated with water, the biofilter media may still dry out. An additional irrigation system for the filter may be installed to ensure the optimal moisture content. Anyway, adding too much water should be avoided as it results in clogging and consequently in an increasing pressure drop, a limitation of the mass transfer, and possibly in anaerobic zones. Biofilter beds are up to 2 m deep.
滤料的选择
① 堆肥
原料常用污水处理厂污泥、有机垃圾和畜粪 以及植物凋落物。 须筛选，滤层要均匀、疏松，空隙率>40％，滤料 须保持湿润，滤层含水量不低于40％，但不能有积 水。滤层保持适当的温度。
② 土壤 腐殖土为好，其它土质需要改良，有效厚度 不应小于50cm，土壤水分40％~70％。 ③ 草炭 其通气性能良好，适于微生物生长，除臭效 果比用土壤好。
一、废气生物处理的特点
1.
废气或尾气(waste gas，off-gas)在生物反应器内进
行。
挥发性有机化合物 (volatile organic compounds，VOCs)以 及其它有毒或有臭味的气体，如NH3和H2S等。 化工、制药、电镀、喷漆、印刷等行业产生的有害污染物 (hazardous air pollutants，HAPs)以及废水处理厂、堆肥厂、 垃圾填埋厂产生恶臭(odor)等。
生物处理法消耗的动力只是污染气体进入处理系统时所消耗
的能量(正压送风或负压引风)。
表1 臭气浓度控制参考值
序号 1 2 3 4 5 6 7 控制项目 氨 硫化氢 甲硫醇 甲硫醚 臭气浓度（倍数） 氯气 一级标准 二级标准 1.5 0.06 0.007 0.07 20 0.4 4.0 0.32 0.02 0.55 60 5 0.6