好氧反硝化菌的分离及应用研究进展

好氧反硝化菌是好氧或兼性好氧的异养微生物中的一类,由于它的生长特性以及具有同步异养硝化好氧反硝化的功能,这就为环境的生物脱氮提供了一个崭新的技术思路。文章综述了好氧反硝化菌的种类、特性、反硝化作用机制和影响因素,介绍了好氧反硝化菌在废水治理以及大气治理方面的应用。     

好氧反硝化生物脱氮机理分析及研究进展

传统生物脱氮包括好氧硝化和缺氧反硝化两个过程。针对传统生物脱氮工艺存在的不足,提出好氧反硝化技术优点,初步探讨了好氧反硝化的机理,并从不同角度做了理论分析。同时阐述了有关好氧反硝化脱氮的研究进展,对好氧反硝化的应用前景作了展望,提出了好氧反硝化今后的研究方向应重点放在对好氧反硝化菌的筛选和驯化上,并深入了解其反硝化特性,以对好氧反硝化生物脱氮提供有力的技术支持。(哈尔滨工业大学市政环境工程学院,哈尔滨150090)     

硝化菌与反硝化菌混合培养生物脱氮的研究

从污泥中筛选得到了脱氮效率较高的硝化菌、亚硝化菌和反硝化菌,测定了其在含氮溶液中的生长曲线,计算得到其反硝化或硝化强度。将所得菌种在好氧条件下于模拟污水中进行混合培养,研究了脱氮效率及影响因素,并与用传统生物序列法进行硝化与反硝化培养脱氮的效果进行了比较。结果表明:混合培养硝化菌、亚硝化菌和反硝化菌过程中不会累积中间产物,生物脱氮率可达76.7%,较传统序列式脱氮法有显著提高,混合培养过程受pH值和温度的影响较小,是一种简易可行、高效和无污染的生物脱氮方法。     

在SBBR中接种硝化菌时SND特性及机理

通过加硝化菌与未加硝化菌的对比试验,对序批式生物膜法(SBBR)中户斤表现出来的脱氮特性进行了试验分析,研究探讨生物膜法SND脱氮的机理：好氧情况下生物膜的吸附作用为反硝化菌提供碳源和能源;SND反应主要发生在好氧生物膜层和兼性生物膜分界内;在深层的反硝化菌利用生物膜中储存的有机物作为有机碳源,将好氧生物膜中产生的N03^ 3-N转化为N2。同时加入一定量的硝化菌能较好地提高硝化,脱氮率。     

好氧微生物颗粒污泥脱氨机理

好氧颗粒污泥应用于生物脱氮,机理为如下几种.第一种为常规硝化-反硝化途径.第二种为亚硝化-反硝化途径,颗粒污泥的外部为好氧的硝化区,通过适当的控制,使硝化过程停留在亚硝化阶段,直接进入内层进行反硝化.第三种为硝化-厌氧氨氧化途径,通过外层的硝化和内层的厌氧氨氧化作用实现脱氮.第四种为硝化-反硝化聚磷方式,颗粒污泥内部在反硝化的同时聚磷,实现好氧颗粒污泥同步脱氮除磷.第五种脱氮的途径为好氧反硝化.在不同的条件下,某一种脱氮的途径可能占主导地位.     

好氧微生物颗粒污泥脱氮机理

好氧颗粒污泥应用于生物脱氮，机理为如下几种。第一种为常规硝化-反硝化途径。第二种为亚硝化-反硝化途径，颗粒污泥的外部为好氧的硝化区．通过适当的控制．使硝化过程停留在亚硝化阶段．直接进入内层进行反硝化。第三种为硝化-厌氧氨氧化途径．通过外层的硝化和内层的厌氧氨氧化作用实现脱氮。第四种为硝化-反硝化聚磷方式．颗粒污泥内部在反硝化的同时聚磷，实现好氧颗粒污泥同步脱氮除磷。第五种脱氮的途径为好氧反硝化。在不同的条件下．某一种脱氮的途径可能占主导地位。     

城市污水连续流A/O系统富氧条件下脱氮特征

基于添加流离填料的连续流A/O生物膜反应器,研究城市污水生物脱氮特征。系统在富氧条件（溶解氧大于1.5 mg·L^-1）下连续运行113 d,氨氮和总氮去除率均稳定在50%。系统稳定运行阶段好氧区和出水均无亚硝酸盐或硝酸盐积累现象,表现出良好的同步硝化反硝化特征。16S rDNA分析表明,实现这一现象的主要功能细菌为好氧区存在的好氧反硝化菌;FISH分析表明,不同好氧区的好氧反硝化菌的活性和相对数量不同。结果证明系统内发生的同步硝化反硝化主要由好氧反硝化作用实现,硝化反应产生的硝酸盐类物质得到去除。根据试验结果与微生物学分析,提出了在富氧水环境中通过同步硝化反硝化途径脱氮的生物膜模型。     

好氧反硝化细菌研究及应用进展

好氧反硝化菌是一类可利用好氧反硝化酶,在有氧条件下进行反硝化作用的细菌。综述了好氧反硝化作用机理及其酶系统,重点阐述了好氧反硝化菌筛选方法以及已分离获得的好氧反硝化菌类群及生长特性,并介绍了好氧反硝化实际工艺应用情况。同时,归纳总结出相关研究及应用中存在的问题,提出了好氧反硝化的研究方向。     

好氧颗粒污泥同步除磷脱氮研究的新进展

结合近年来国内外除磷脱氮的最新研究成果,对好氧颗粒污泥除磷脱氮的机理及工艺进行了探讨和研究。研究表明通过适当的SBR定向培养,可以在颗粒污泥中培养出不同的微生物菌群(硝化菌、反硝化菌、聚磷菌、反硝化聚磷菌等),使其能够实现同步除磷脱氮,从而为污水生物除磷脱氮工艺研究提供了一个新思路。     

一体化复合式生物反应器的脱氮研究

利用自制的一体式缺氧/好氧(A/O)复合式生物反应器(HBR),对高浓度氨氮废水进行了脱氮研究.结果表明,当进水COD浓度在950～1100 mg·L-1、氨氮浓度增加到150 mg·L-1时系统COD、氨氮去除率开始下降;在好氧区内检测到大量的NO-2-N积累,表明HBR的脱氮作用部分是通过短程硝化-反硝化途径实现的.且复合式生物反应器填料内部存在多种多样的微环境类型以及缺氧/好氧内循环,造成反应器缺氧、好氧区都发生了同步硝化-反硝化反应.     

酒精酵母固定化的研究

海藻酸钙固定化酵母球形颗粒经过Al~(3+)处理后,其机械强度提高一倍。用拉西环陶瓷填料作隐蔽及支撑物,海藻酸钙固定化酵母颗粒的机械强度即为拉西环陶瓷填料本身的机械强度,反应器的乙醇生产能力只降低了27％。本文考察了海藻酸钙固定化酵母与聚乙烯醇固定化酵母的连续乙醇发酵行为。     

Optimization of pullulan production using Ca‐alginate‐immobilized Aureobasidium pullulans by response surface methodology

BACKGROUND: The production of pullulan from synthetic medium by Aureobasidium pullulans P56 immobilized in Ca‐alginate beads was investigated using batch and repeated batch fermentation systems. RESULTS: The highest pullulan concentration (19.52 ± 0.37 g dm^?3) was obtained with 2.0‐2.4 mm beads prepared from 2% sodium alginate solution. Pullulan production was mainly accomplished by immobilized fungal cells since leaked cells in the fermentation medium comprised 17.4% of the total fungal population at the end of fermentation. The pullulan proportion was 84.5% of the total polysaccharide in the fermentation medium. Response surface methodology was used to investigate the effects of three fermentation parameters (initial pH, agitation speed and incubation time) on the concentration of pullulan. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum pullulan concentration of 21.07 ± 0.48 g dm^?3 was obtained at the optimum concentrations of process variables (pH 7.31, agitation speed 191.5 rpm, incubation time 101.2 h). The gel beads produced pullulan under the optimized conditions for six consecutive batch fermentations without marked activity loss and deformation. CONCLUSION: The results of this study suggest that the immobilization of A. pullulans cells in Ca‐alginate gel beads is suitable for batch and repeated batch production of pullulan. Copyright © 2007 Society of Chemical Industry     

海藻酸凝胶性质对蛋白质扩散的影响

通过观察冷冻干燥海藻酸凝胶的断面扫描电镜(SEM)照片与卵清蛋白从海藻酸凝胶中的释放试验,分析了海藻酸凝胶性质对蛋白质在凝胶中扩散的影响。凝胶的SEM照片可见,海藻酸钙的冷冻干燥颗粒内为较大的圆孔,海藻酸锌凝胶内为较小的长孔,表明海藻酸锌高分子链在凝胶颗粒中的体积分率相对较大同时刚性较强;卵清蛋白从海藻酸凝胶颗粒中释放的试验结果表明,由于上述海藻酸锌凝胶的特性,导致海藻酸锌对卵清蛋白扩散阻滞作用相对较强;根据试验数据计算得卵清蛋白在海藻酸钙、海藻酸锌凝胶颗粒中的扩散系数分别为1.19×10-7、0.07×10-7cm2/s,利用阻滞模型计算得海藻酸锌高分子链在凝胶颗粒中体积分率约为海藻酸钙高分子链在凝胶颗粒中体积分率的1.7倍。     

Modeling of the Substrate and Product Transfer Coefficients for Ethanol Fermentation

The transfer phenomena of the substrate and product for ethanol fermentation with immobilized biocatalyst were investigated. Fermentation was carried out with a biocatalyst consisting of Ca‐alginate gel in the form of two‐layer spherical beads in anaerobic conditions. The determination of kinetic parameters was achieved by fitting bioreaction progress curves to the experimental data. The calculation of the diffusion coefficients was performed by numerical methods for experimental conditions. Finally, the glucose and ethanol transfer coefficients are defined and determined, using the effective diffusion coefficients.     

Controlled release study of carbaryl insecticide from calcium alginate and nickel alginate hydrogel beads

In this study, controlled release formulations for reducing environmental impact of pesticides have been produced by encapsulating as a model pesticide carbaryl (Carb) in the alginate beads. The various hydrogel bead formulations were prepared by the ionotropic crosslinking of sodium alginate (NaAlg) with calcium and nickel ions. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as carbaryl entrapment efficiency, particle size, equilibrium swelling degree, and carbaryl release kinetics, were determined. The effects of the bead preparation conditions such as crosslinker concentration and type, carbaryl/sodium alginate (Carb/NaAlg) ratio and percentage of NaAlg on the carbaryl release from the calcium alginate (Ca‐Alg) and nickel alginate (Ni‐Alg) beads were investigated in distilled water at 25°C. It was observed that carbaryl release from the Ca‐Alg beads was slower than that of Ni‐Alg beads. The release results indicated that carbaryl release from both of the Ca‐Alg and Ni‐Alg beads decreases with the increasing crosslinker concentration, Carb/NaAlg ratio and percentage of NaAlg. The highest carbaryl release was found to be 100% for the Ni‐Alg beads at 3 days whereas the lowest carbaryl release was found to be 67% for the Ca‐Alg beads at 21 days. The swelling measurements of the beads were also in consistent with the carbaryl release results. The carbaryl release from most of the bead formulations followed Case II transport. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

pH‐sensitive uniform gel beads for DNA adsorption

Uniform gel beads 3 mm in diameter were obtained by the suspension polymerization of an amine functionalized monomer, N‐3‐(dimethyl amino)propylmethacrylamide (DMAPM). The polymerization of DMAPM in the form of uniform droplets could be achieved at room temperature in an aqueous dispersion medium by using Ca–alginate gel as the polymerization mold. In this preparation, potassium persulfate/tetramethyl ethylenediamine and sodium alginate/calcium chloride were used as the redox initiator and the stabilizer systems, respectively. The crosslinked DMAPM gel beads exhibited pH‐sensitive, reversible swelling–deswelling behavior. The uniform gel beads were also obtained by the copolymerization of DMAPM and acrylamide (AA) in the same polymerization system. Although copolymer gel beads with higher pH sensitivities were obtained with increasing feed concentration of DMAPM, the total monomer conversion decreased. Crosslinked DMAPM and DMAPM–AA copolymer gel beads were utilized as sorbents for DNA adsorption. The gel beads produced with higher DMAPM feed concentration exhibited higher equilibrium DNA adsorption capacity. The DNA equilibrium adsorption capacities up to 50 mg DNA/g dry gel could be achieved with the crosslinked DMAPM gel beads. This value was reasonably higher relative to the previously reported adsorption capacities of known sorbents. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3154–3161, 2000     

固定化氧化亚铁硫杆菌对Fe2+的氧化

用Ca(NO3)2凝固聚乙烯醇(PVA)、海藻酸钠和氧化亚铁硫杆菌复合水溶胶,并把成形后的颗粒置低温冷冻,从而形成固定化颗粒。用该颗粒填充固定床生物反应器进行连续操作,考察了不同稀释率下固定床生化反应器氧化Fe2+ 的情况,在温度31 ℃、pH值1.8、稀释率0.5 h—1条件下,Fe2+最大氧化速率达2.90 g/(L•h)。系统即使在没有灭菌的情况下,稳定性保持良好,具有较好的应用前景。     

Direct Generation of Mn‐Doped ZnS Quantum Dots/Alginate Nanocomposite Beads Based on Gelation and In Situ Synthesis of Quantum Dots

Herein, a concise and novel method is developed to directly generate Mn‐doped ZnS QDs/alginate nanocomposite beads. In this method, the ionic gelation of alginate is employed to produce alginate gel beads in a solution of Zn²⁺ and Mn²⁺ ions. Subsequently, the gel beads serve as the reaction support for in situ synthesis of Mn‐doped ZnS QDs in the beads through the reaction of sodium sulfide with Zn²⁺ and Mn²⁺ ions. The method has many benefits such as the simple preparation, the environmentally friendly process, the mild conditions, and the easy post‐treatment for the beads. The resulting QDs/alginate beads are homogeneous and stable gel spheres which show clear fluorescence. TEM images demonstrate that Mn‐doped ZnS QDs are homogeneously distributed within the QDs/alginate nanocomposite, and their average size is 2.4 ± 0.3 nm. Potentially, the QDs/alginate beads can be utilized for fluorescence bioimaging, as well as fluorescence detection toward metal ions.     

Modelling of phenol biodegradation by Candida tropicalis immobilised in alginate gel beads

Phenol‐degrading yeast Candida tropicalis were immobilised in alginate gel beads and photographed by scanning electron microscopy. Batch phenol biodegradation experiments were done in shaking flasks under varying conditions such as initial phenol concentrations and bead loadings. A mathematical model was proposed to simulate the batch phenol biodegradation process in the immobilised system, which took into account the internal and external mass transfer resistances of phenol and oxygen and the double‐substrate phenol–oxygen intrinsic kinetics. The validation of this model was done by the comparison between the model simulations and the experimental measurements of phenol concentration profiles in the main liquid phase. Moreover, the time and radius courses of phenol, oxygen, and cell concentration profiles within the alginate gel beads were reasonably predicted by the proposed model.     

Optimization of lactic acid production from whey by L casei NRRL B‐441 immobilized in chitosan stabilized Ca‐alginate beads

The production of lactic acid from whey by Lactobacillus casei NRRL B‐441 immobilized in chitosan‐stabilized Ca‐alginate beads was investigated. Higher lactic acid production and lower cell leakage were observed with alginate–chitosan beads compared with Ca‐alginate beads. The highest lactic acid concentration (131.2 g dm^?3) was obtained with cells entrapped in 1.3–1.7 mm alginate–chitosan beads prepared from 2% (w/v) Na‐alginate. The gel beads produced lactic acid for five consecutive batch fermentations without marked activity loss and deformation. Response surface methodology was used to investigate the effects of three fermentation parameters (initial sugar, yeast extract and calcium carbonate concentrations) on the concentration of lactic acid. Results of the statistical analysis showed that the fit of the model was good in all cases. Initial sugar, yeast extract and calcium carbonate concentrations had a strong linear effect on lactic acid production. The maximum lactic acid concentration of 136.3 g dm^?3 was obtained at the optimum concentrations of process variables (initial sugar 147.35 g dm^?3, yeast extract 28.81 g dm^?3, CaCO₃ 97.55 g dm^?3). These values were obtained by fitting of the experimental data to the model equation. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in lactic acid production using alginate–chitosan‐immobilized cells. Copyright © 2005 Society of Chemical Industry