生物滤器处理海水养殖水过程中亚氮积累与影响因素

实验研究了竹环填料曝气生物滤器在处理高盐度、低氨氮负荷的海水养殖水体过程中NO2--N的积累现象,考察了进水有机负荷、NH4+-N负荷、温度、pH值和溶解氧等运行条件以及反硝化作用对NO2--N积累的影响.结果表明,在进水有机负荷为0.65~0.75kg/(m3·d)、NH4+-N负荷为0.058~0.077kg/(m3·d)、温度为20.9~22.2℃、pH值为7.50~8.14和溶解氧为7.43~9.73mg/L条件下,生物滤器内较低的溶解氧(0.91~1.36mg/L)是NO2--N积累的主要原因.同时,研究了反硝化过程中低溶解氧、不同碳氮比(C/N)及碳源类型等因素对NO2--N积累的影响,查明了生物滤器内含氮化合物的浓度变化与反硝化细菌的数量和功能,验证了反硝化过程对NO2--N积累的影响,明确了反硝化作用对NO2--N积累的促进作用.     

DG-DGGE分析除臭生物滤池微生物多样性及富集后的种群结构差异

以细菌的通用引物PCR扩增16SrRNA基因的V3可变区,结合应用双梯度变性梯度凝胶电泳(DGDGGE)技术分析除臭生物滤池中不同空间层次的微生物种群的基因多样性,以及富集前后的微生物种群结构变化,初步了解可培养细菌的情况,并回收主要的DNA片段进行序列分析.结果表明,在滤池的不同层次上呈现出明显的空间分布多样性差异,并且培养前后及不同培养基富集培养的微生物种群的多样性及特异性有很大的差别.序列比对显示,硫氧化细菌在除臭过程中占有优势地位,为进一步的菌种分离提供有益的指导,也为更好地处理恶臭气体提供可靠的科学支持.图4表2参18     

生物滴滤床降解有机废气净化效率的理论模型

将生物膜滴滤塔内的多孔填料简化为壁面覆盖有生物膜的平行平板通道,建立了一个净化低浓度有机废气的理论模型.该模型首先运用两相流理论获得了通道内液膜厚度,然后通过污染物在气相、液相的质量组分方程,结合生物膜内的传质与不考虑氧限制的生化反应动力学方程,获得了污染物在液相和生物膜中浓度分布的近似分析解,最终得到污染物在气相中沿塔高的浓度分布及废气净化效率.模型的理论预测值与生物膜滴滤塔净化低浓度甲苯废气的实验结果基本吻合.     

两级滴滤去除硫化氢和甲硫醇混合恶臭气体

把氧化硫硫杆菌(T. thiooxidans)、排硫硫杆菌(T. thioparus)组成的自养菌群和黄单胞菌(Xanthomonas)为主的异养菌群分别接种在两个生物滴滤反应器中,将其依次串联净化处理硫化氢(H₂S)、甲硫醇(MT)混合臭气.一级反应器(A^#)的复合自养菌在酸性环境下对负荷为7～8g/(m³h)的H₂S平均去除率可达94%,且不受混合气体中MT含量的影响.二级反应器(B^#)适于中性环境,对负荷为4～5g/(m^{3h)的MT平均去除率为83%.若H₂S在混合气体中浓度过高,经A#处理后的浓度仍高于50mg/m3,可导致后反应器酸化,使MT脱臭效率显著下降.}     

生物法处理高浓度H2S废气的现场试验

生物法处理废气的现场中试研究可为工业放大装置的设计和运行提供依据.采用规模为18 m³/h的中试装置现场处理某制药厂污水站含H₂S浓度238.2～891.5 mg/m³的废气,研究对比了生物滤床(BF)和生物滴滤床(BTF)2种工艺对废气中H₂S的去除效果和运行情况.试验表明,当气体空床停留时间(EBRT)为28 s时,在上述浓度范围内,BF和BTF均可几乎完全去除废气中的H2S,且运行稳定;BF的去除率随进口浓度的增加而减小,当EBRT为15 s,进口浓度从243.6 mg/m³增加到584.1 mg/m3时,去除率从95.2%下降到86.3%;BTF的去除率受进口浓度变化的影响较小,当EBRT为9 s时,在试验的浓度范围内,去除率达95%以上;BF和BTF的最大去除负荷分别为138 g/(m³.h)和205 g/(m³·h).床内生物膜中的菌落分析表明,BTF和BF填料表面的微生物都以细菌为主,但前者微生物生长密度高于后者.因此,综合考虑去除性能和运行控制等因素,工业放大装置宜采用BTF工艺.     

理生物滤池-活性污泥法处理生物质煤气废水的工程应用

将生物滤池与活性污泥池串联形成一个生化处理系统,生物质煤气洗涤废水经过预处理后,采用ASBRO和AO1O2两种联合工艺进行处理,着重考察了系统对生物质煤气洗涤废水CODCr、NH+4N的降低效果。采用ASBRO工艺,CODCr的去除率平均达到85.4%,NH+4N平均去除率为33.5%;采用AO1O2工艺,CODCr的去除率平均达到78.2%。NH+4N平均去除率为22.7%。     

Biodegradation of mixture of VOC''''s in a biofilter

IntroductionDeterioratingatmosphericairqualityhasresultinginmorestringentregulationsarebeingenforcedtocontrolairpollutants .Volatileorganiccompounds(VOCs)areamongthenewclassofaircontaminantsgeneratedfromavarietyofindustrialsources .Effortstocontroltheemis…     

Mathematical modeling of biofiltration in activated pine-bark charge of a biofilter

Aim, Scope and Background Human economic activities cause emissions of various pollutants of an organic nature: butanol, butyl acetate, methanol, formaldehyde, phenol, benzene, toluene, xylene, etc. These compounds are emitted to atmosphere by various enterprises of food, chemistry, wood processing industries, from transportation means, agricultural enterprises, etc. Therefore, when purifying air from these pollutants, it is necessary to apply efficient and inexpensive air purification methods. In this dimension, the biological air purification is chosen from all possible air cleaning methods. An experimental biofilter with the activated charge of pine bark was developed at the Department of Environment Protection of the Vilnius Gediminas Technical University. In the course of the experimental investigation, it was determined that this air purification method is efficient. Filter efficiency, when purifying air of volatile organic compounds (butanol, butyl acetate and xylene), to a great extent, depending on the nature and concentrations (up to 100 mg/m3) of pollutants injected, might go up to 70-98%. The mathematical model of the biofilter was developed based on the research results and fully taking into consideration physical, chemical, and biological processes going on during its operations. Main Features The aim of this article is to determine biodegradation constant , absorption capacity , and half empiric expressions of filter efficiency. Knowing this, it is possible to find out the dependence of the filter efficiency on the operational parameters of the filter (i.e. on the concentrations and the height of biocharge of the initial pollutants (butanol, butyl acetate, xylene) fed through it). Conclusions With the help of mathematical modeling, the biodegradation constants and absorption capability of volatile organic compounds (butanol, butyl acetate, and xylene) fed into the biofilter charged with the activated pine bark and used for the cleaning of volatile organic compounds, as well as the efficiency of the biofilter in half empiric expression, have been established. It has been discovered that the constant of pollutant biodegradation is a value inverse to the time during which the amount of pollutants in the filter becomes times higher. It is rather complicated to carry out theoretical calculation of the biodegradation constant at a molecular level, therefore this constant has been established based on the results obtained in the course of research. The equations describing pollutant dynamics in the filter charge and the air cleaning processes going on in it have been derived from diffusion equations in a mobile medium. The modeling helped to find out the absorption capacity of the examined pollutants, which by its numeric value is equal to the volume unit of the absorbed gas amount. The latter factor, the same as the biodegradation constant, was determined basing on the experimental results. Mathematical modeling brought a range of formulas expressing dependences of each pollutant's efficiency on its initial concentrations and filter charge height. Recommendation /Outlook. Based on the experimental data, a mathematical model has been developed which will allow the measuring of the filter efficiency not only with regard to the absorption and biodegradation of the pollutants under examination, but also with regard to other pollutants and their compounds, etc., having an impact on the filter performance. The results of the mathematical modeling have revealed that the modeling of processes going on in the filter is much simpler than isthe performance of long and costly experiments. The developed mathematical model makes it possible to measure the filter efficiency at the present moment.     

Performance of rotating drum biofilter for volatile organic compound removal at high organic loading rates

Uneven distribution of volatile organic compounds （VOCs） and biomass, and excess biomass accumulation in some biofilters hinder the application of biofiltration technology. An innovative multilayer rotating drum biofilter （RDB） was developed to correct these problems. The RDB was operated at an empty bed contact time （EBCT） of 30 s and a rotational rate of 1.0 r/min. Diethyl ether was chosen as the model VOC. Performance of the RDB was evaluated at organic loading rates of 32,1, 64.2, 128, and 256 g ether/（m^3·h） （16.06 g ether/（m^3·h） ≈ 1.0 kg chemical oxygen demand （COD）/（m^3·d））. The EBCT and organic loading rates were recorded on the basis of the medium volume. Results show that the ether removal efficiency decreased with an increased VOC loading rate. Ether removal efficiencies exceeding 99% were achieved without biomass control even at a high VOC loading rate of 128 g ether/（m^3·h）. However, when the VOC loading rate was increased to 256 g ether/（m^3·h）, the average removal efficiency dropped to 43%. Nutrient limitation possibly contributed to the drop in ether removal efficiency. High biomass accumulation rate was also observed in the medium at the two higher ether loading rates, and removal of the excess biomass in the media was necessary to maintain stable performance. This work showed that the RDB is effective in the removal of diethyl ether from waste gas streams even at high organic loading rates. The results might help establish criteria for designing and operating RDBs.     

焦炭填料生物滤床净化VOC研究

采用焦炭为填料的生物滤床降解苯乙烯废气，试验过程中对焦炭进行循环挂膜，发现焦炭对苯乙烯这样的挥发性有机物（VOC）初期以吸附作用为主，随着生物膜的长成生物降解作用逐渐占有优势，表现为对苯乙烯的去除效率稳定在35％－55％左右。