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931.
Kleerebezem R 《Applied biochemistry and biotechnology》2003,109(1-3):3-13
Operational practice of high-rate anaerobic bioreactors such as upflow anaerobic sludge bed (UASB) reactors is generally based
on maximization of the biomass concentration and, in the case of more than one reactor compartment, operation in parallel.
In this article, a modeling approach is used to postulate that the treatment performance of anaerobic bioreactors can be improved
by simple operational measures. To achieve minimized effluent soluble substrate concentrations, operation of two reactors
in series combined with active exchange of biomass between both reactors is suggested. In this way, substrate concentrations
lower than the minimum achievable concentration in a completely mixed reactor can be achieved. It is furthermore suggested
that maximized biomass concentrations (and solid retention times [SRTs]) do not necessarily lead to minimized effluent concentrations
of organic material. At elevated SRTs, the soluble microbial products resulting from biomass turnover are shown to represent
the main fraction of soluble organic material in the effluent of the reactor, limiting treatment efficiency. 相似文献
932.
Goksungur Y Mantzouridou F Roukas T Kotzekidou P 《Applied biochemistry and biotechnology》2004,112(1):37-54
The effect of aeration rate and agitation speed on β-carotene production from molasses by Blakeslea trispora in a stirred-tank fermentor and optimization of the production of the pigment in a bubble column reactor were investigated.
In addition, a central composite design was employed to determine the maximum β-carotene concentration at optimum values for
the process variables (aeration rate, sugar concentration, linoleic acid, kerosene). By image analysis of the morphology of
the fungus, a quantitative characterization of the hyphae and zygospores formed was obtained. The hyphae were differentiated
to intacthyphae, vacuolated hyphae, evacuated cells and degenerated hyphae. An increased proportion of zygospores was correlated
to high β-carotene production. In the stirred-tank fermentor, the highest concentration of the carotenoid pigment (92.0 mg/L)
was obtained at an aeration rate of 1.5 vvm and agitation speed of 60 rpm. In the bubble column reactor, the aeration rate
and concentration of sugars, linoleic acid, kerosene, and antioxidant significantly affected the production of β-carotene.
In all cases, the fit of the model was found to be good. Aeration rate, sugar concentration, linoleic acid, and kerosene had
a strong positive linear effect on β-carotene concentration. Moreover, the concentration of the pigment was significantly
influenced by the negative quadratic effects of the given variables and by their positive or negative interactions. Maximum
β-carotene concentration (360.2 mg/L) was obtained in culture grown in molasses solution containing 5% (w/v) sugar supplemented
with linoleic acid (37.59 g/L), kerosene (39.11 g/L), and antioxidant (1.0 g/L). 相似文献
933.
Koji Sode Minoru Honda Yoichi Mikami Tsuyoshi Yanagimoto Isao Kargbe 《Applied biochemistry and biotechnology》1988,19(2):209-220
Microbial conversion of 4-oxoisophorone (OIP) by thermophilic bacteriumThermomonospora curvata was attempted in a continuous process.
The correlation between cell growth and microbial conversion was first examined in a batch culture. The results indicated
that this microbial conversion was strongly dependent upon cell growth. In a continuous microbial conversion of OIP using
a continuous stirred tank reactor, the cell density in the reactor seemed to be the limiting factor in the OIP conversion.
Therefore, we developed an air-bubbling hollow fiber reactor to achieve a high density culture. By using this bioreactor,
more than 3.3 times higher productivity was achieved. In addition, during the process, only a slight cell contamination to
the product was observed. Therefore, this bioreactor is suitable for the continuous microbial conversion, considering further
downstream processes and high productivity. 相似文献
934.
Kalyuzhnyi S Sklyar V Epov A Arkhipchenko I Barboulina I Orlova O Kovalev A Nozhevnikova A Klapwijk A 《Applied biochemistry and biotechnology》2003,109(1-3):77-94
This article summarizes the results obtained during the laboratory and pilot development of integrated biologic and physicochemical
treatment and reuse of diluted pig manure streams. The application of a straw filter was an effective means to separate the
solid and liquid fractions of raw wastewater and resulted in the removal of a significant part of the dry matter, total nitrogen,
and phosphorus (65, 27, and 32%, respectively). From the filtrate generated, 60–80% of the total chemical oxygen demand (COD)
was removed in an upflow anaerobic sludge bed reactor operating at 15–30°C. Ammonia was efficiently eliminated (>99%) from
the anaerobic effluents using Ural laumantite as an ion exchanger. However, the nitrogen-content of the zeolite was too low
to consider this method of ammonia removal economically feasible. The phosphate precipitation block, consisting of stripper
of CO2 and fluidized-bed crystallizator, was able to decrease the concentration of soluble phosphate in the anaerobic effluents
up to 7–15 mg of phosphate/L. The application of aerobic/anoxic biofilter as a sole polishing step was acceptable from an
aesthetic point of view (the effluents were transparent and almost colorless and odorless) and elimination of biochemical
oxygen demand (the resting COD was hardly biodegradable). However, the effluent nutrient concentrations (especially nitrogen)
were far from the current standards for direct discharge of treated wastewater. We discuss the approaches for further improvement
of effluent quality. Finally, we provide an outline of a full-scale system that partially implements the laboratory- and pilot-scale
results obtained. 相似文献
935.
Hlroshi Ooshima Yoshiharu Yamane Yozo Nakamura Hideki Sakashita Masayuki Azuma Jyoji Kato 《Applied biochemistry and biotechnology》1998,73(1):51-58
A highly efficient spray-cycle reactor for oxygen supply was developed. A typical arrangement of the reactor consists of a
spray column fitted with a nozzle and a coaxal tube, and a reservoir vessel. The culture broth was circulated between the
column and vessel by a peristaltic pump. The volumetric oxygen-transfer coefficient, k1a was evaluated as a parameter for oxygen supply. The liquid circulation rate in the spraycycle reactor was represented in
terms of the number of circulations. The k1a value increased as the number of circulations increased, reaching 208 h-1 at 4.4 min-1 of circulation numbers. This value was 1.8 times higher than that in a 1500-mL stirred-tank reactor under the agitation of
20.7g and the aeration of 1.0 volume per min.
The spray-cycle reactor was applied to riboflavin production by an aerobic microorganism. The riboflavin production increased
as k1a values increased and the maximal riboflavin production was 161 mg/L at 208 h-1 of k1a. These results suggest that the spray-cycle reactor is useful to oxygen-demanding fermentation because of the high k1a value in comparison with the stirred-tank reactor. 相似文献
936.
固定床反应器——科学、技术和艺术 总被引:1,自引:0,他引:1
本文是关于固定床反应器现状及可能发展的综述。作为一种传统的反应器,固定床反应器在模型理论上已相当完善。但是由于模型和模型参数的不确定性,要通过模型化来实现优化操作几乎是不可能的。因而从科学方法的观点提出了基于状态估计和参数估计的动态优化方法。固定床反应器的一种可能发展趋势是与有关的一种(或几种)技术结合,最有可能的是与膜技术结合或与催化剂设计技术结合,实现反应一分离的综合日标。最后,本文叙述了组合已有的化学工程的原理和技术,使固定床反应器在降低能耗、提高收率等方面取得的进展。 相似文献
937.
Randall A. LaViolette Ray A. Berry Robert McGraw 《Plasma Chemistry and Plasma Processing》1996,16(2):249-264
We present a new and general application of the method of moments for modeling the nucleation of condensates in a steady-state supersonic nozzle flora generated in a plasma-quench reactor. A closed set of growth/evaporation rate equations has been employed to propagate the moments of the particle size distribution without invoking the usual coarse-graining or truncation approximations of conventional binning approaches. The method has been employed to calculate the nucleation rates, particle number density, and the particle-size distribution for 11 elemental metals (Ag, Al, Be, Ce, Cr, Fe, Gd, Ti, Th, U, and Zr) condensing in a model argon nozzle flow. We have identified the regions in the nozzle of maximum nucleation rate, and have shown how different particle-size distributions can develop in different regions. 相似文献
938.
In a previous publication, we described a continuous production ofd-fructose from enzymatic hydrolysis of inulin with immobilized permeabilized cells (1).Kluyveromyces fragilis ATCC 12424 have been shown to possess inulase activity. The half life of the reactor was at least 1300 h, but productivity
was relatively low (around 40 g/L/day).
A selection of 50 mutants was tested on liquid medium for a possible increase of productivity.
In relation to the improvement of the reactor, the most important factor is intracellular inulase activity, and this activity
was increased with the KF 28 mutant.
Productivity reached 2000 g/L/day with the increase (of the productivity), proportional to the increase of intracellular inulase
activity. 相似文献
939.
在内径98mm的鼓泡浆态反应器内,考察了工艺参数对浸没表面与浆液间的传热系数的影响。浆态反应器轴向装有一个外径20mm,长120mm的测量传热膜系数用的铜制元件。为了模拟浆态FT合成反应系统,三相系统由N2、液体石蜡和石英砂(平均粒径53μm、110μm、180μm)或63μm以下的Fe2O3组成。工艺参数变化范围如下:表观气速0.005m/s~0.08m/s, 温度353K~453K, 压力0.1MPa~0.8MPa,固体的质量分数0~20%,初始液位高度625mm~1240mm。本研究使用单孔板、多孔板、烧结金属板三种气体分布器类型。结合实验数据,应用最小二乘法求得各个参数值,得到的无因次传热系数关联式为St=0.179(ReFr)-0.25Pr-0.66,相关指数0.98,最大偏差18%。该关联式可应用于气-液和粒径小于100μm的气-液-固体系。 相似文献
940.
Zheng-hong Luo Yi Zheng Zhi-kai Cao Shao-hua Wen 《高分子科学》2007,(4):365-377
The estimation of the amount of reactive impurities in a loop reactor is of strategic importance to the propylene polymerization industry. It is essential to investigate the level of impurities in order to develop reliable monitoring and control strategies. This paper described one approach based on generation function technique with the following two steps. First, a new mechanism for propylene polymerization was proposed by considering the effects of the reactive impurities in the material on the propylene polymerization. Second, a series of equations of population balance for the propylene polymerization in loop reactors were established based on the proposed mechanism. Accordingly, the equations were transformed into the mathematic matrix through the generation function technique to investigate the effects of the reactive impurities on the propylene polymerization. Significant effects of the reactive impurities were analyzed through computational simulation. The results show that the concentration of active centre on catalysts and the polymerization conversion both decrease with the increase of the initial concentration of any reactive impurity; hydrogen concentration decreases with the increase of the initial concentration of ethylene or butylenes, whereas, it increases with the increase of the initial concentration of propadiene; the simulated weight average molecular weight and the molecular weight distribution index of polymer resins both increase with the increase of the initial concentration of ethylene or butylenes. They decrease with the increase of the initial concentration of propadiene. 相似文献