Production of Validamycins from Crude Substrates by Streptomyces hygroscopicus in an External-loop Airlift Bioreactor with a Low Height-to-Diameter Ratio

Fermentation experiments to produce validamycins from crude substrates by Streptomyces hygroscopicus were carried out in an external-loop airlift bioreactor (0.0115 m^3 ) with a low ratio of height to diameter of the riser of 2.9 and a ratio of riser to downcomer diameter of 6.6. The influences of gas flow rate and liquid volume on fermentation of validamycins were investigated. Comparisons of validamycin fermentation were made among the external-loop airlift bioreactor, a mechanically stirred tank bioreactor (0.010m^3 ) and shaking flasks. Under the same operation conditions including fermentation medium composition, inoculum ratio and culture temperature, the fermentation time in the external-loop airlift bioreactor (45 h) was shorter than that in the shaking flasks (100 h) and the same as that in the mechanically stirred tank bioreactor. After a total fermentation time of 45 h under optimized operation conditions, average validamycin concentration obtained in the external-loop airlift bioreactor was close to 19630 μg·ml^-1 validamycin concentration in the mechanically stirred tank bioreactor. It was demonstrated that the external-loop airlift bioreactor could substitute for the mechanically stirred tank bioreactor in production of validamycins from crude substrates with dregs by Streptomyces hygroscopicus.

Mass Transfer, Gas Holdup, and Kinetic Models of Batch and Continuous Fermentation in a Novel Rectangular Dynamic Membrane Airlift Bioreactor

Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.

Preliminary Study on Airlift Membran-Bioreactor

A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.

Growth Enhancement of Dunaliella salina by Microbubble Induced Airlift Loop Bioreactor (ALB)—The Relation between Mass Transfer and Growth Rate

The efficiency of a novel microalgal culture system (an airlift loop bioreactor [ALB] engaged with a fluidic oscillator to produce microbubbles) is compared with both a conventional ALB (producing fine bubbles without the fluidic oscillator) and non-aerated flask culture. The impact of CO2 mass transfer on Dunaliella salina growth is assessed, through varying the gas (5% CO2, 95% N2) dosing flow rate. The results showed that approximately 6 - 8 times higher chlorophyll content was achieved in the aerated ALB cultures than in the non-aerated flasks, and there was a 20% - 40% increase in specific growth rate of D. salina in the novel ALB with microbubbles when compared with the conventional ALB cultures. The increase in chlorophyll content was found to be proportional to the total amount of CO2 mass transfer. For the same dosing time and flow rate, higher CO2 mass transfer rate (microbubble dosing) resulted in a greater growth rate.

Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor

Removal of inorganic nitrogen （inorganic-N） from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor （AEC-MBR） was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/（m^3·d） helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen （DO） on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BODs/ammonia nitrogen （NH4＋-N） at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4^＋-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m^3, and the energy consumption was approximately 0.72 kWh/m^3 at the flux of 8 L/（m^2-h）.

COMPARISON OF TWO TYPES OF BIOREACTORS IN PLANT CELL SUSPENSION CULTURE

-In plant cell culture on large scale,we have studied two types of biore-actors-Airlift reactor and stirred tank reactor-under the same volume and work conditions. It shows that the value of volumetric oxygen transfer coefficient K1a in airlift is a little higher than that in stirred tank reactor at the aeration rate of 0.1~0.3vvm:the mixing time tm in both of them is small respect to the culture period.The shear stress in stirred tank reactor is higher than that in airlift reactor,but its influence is not negative at all. When the value or the shear stress in medium is low-er than a critical value,it will be favorable to the dispersion of cells and promotes the growth of cells.This result is verified in the experiment we have conducted in the airlift reactor and stirred tank reactor.

高效气提环流式生物脱氮反应器在污水厂扩建改造中的应用

西北某污水处理厂扩建改造一期工程处理规模为5000m^(3)/d,采用高效气提环流式生物脱氮反应器(DIAB)工艺,所用反应器基于厌氧-缺氧-好氧(AAO)推流式生物反应器与升流式厌氧污泥床(upflow anaerobic sludge bed,UASB)反应器特点进行改良,由多级环状结构构成,利用三相分离器结构设计实现水、气、污泥分离,利用曝气尾气作为动力来源,实现混合液的无动力回流。总水力停留时间为21 h,其中厌氧区、缺氧区和好氧区停留时间分别为1.5、8.5 h和11 h,混合液悬浮固体(MLSS)质量浓度为5500 mg/L,平均BOD5污泥负荷为0.1 kg BOD5/(kg MLSS·d),混合液回流比为300%。污水厂采用该工艺完成改造运行后实际出水水质可稳定达到一级A标准。扩建工程单位处理成本为0.454元/m^(3)、生物处理区占地面积为0.161 m^(2)/m^(3),与相似规模传统AAO工艺相比较处理成本和占地面积分别减少了24.3%和25.8%,在出水水质、运行成本方面均有明显改善,与相似规模循环式活性污泥(CASS)工艺相比较占地面积相似,但处理成本减少约20%,出水水质优于CASS工艺,尤其在脱氮方面表现出色。DIAB工艺脱氮效率及碳源利用率较高,脱氮效果好,碳源投加及回流设备用电电耗低,适用于土地、工期受限,以及进水低碳氮比条件下污水处理厂的扩建、应急建设。

利用稻谷壳水解液在气升式生物反应器中发酵生产单细胞蛋白

以稻谷壳水解液为原料 ,采用树状假丝酵母 AS1 .2 57( Candida arborea AS1 .2 57) ,在罐体高径比为 2 .9和上升管与下降管的直径之比为 6.6的外循环气升式生物反应器中发酵生产单细胞蛋白 .研究了通风量、装料量、空气喷嘴直径等工艺和结构参数对发酵的影响 ,得到了较佳的发酵操作参数 .在发酵前 2 4 h的通风量为 1 .1 m3/( m3· min) ,后 2 4 h的通风量为 1 .4m3/( m3· min)～ 1 .5m3/( m3· min) ,起始装料量为 8.5L～ 9.0 L,起始 p H为 4.5～ 5.0 ,发酵温度为 2 9± 1℃的操作条件下 ,经 48h的发酵 ,可得到较佳的结果 .在无筛板 ,带一块筛板和带二块筛板的外循环气升式生物反应器中 ,发酵 48h后的干基粗蛋白含量分别为 61 .3%、62 .9%、64.5% ,发酵液中干物质重分别为 2 0 .8mg/ml、2 1 .2 mg/ml、2 1 .3mg/ml,总糖利用率分别为 78.2 %、83.9%、81 .4% ,均高于机械搅拌生物反应器 ,气升式生物反应器内加装筛板可提高发酵得率 .

序批式气提生物反应器(SABR)处理氯苯胺类有机废水好氧污泥颗粒化研究

研究了序批式气提生物反应器(SABR)处理氯苯胺类(CAs)有机废水过程中好氧污泥的颗粒化.SABR运行15d后,反应器内出现细小污泥颗粒,通过缩短循环时间与污泥沉降时间,并逐步提高COD与CAs进水负荷,SABR运行48 d后污泥颗粒化明显;反应器在循环时间为12 h、污泥沉降时间为6 min、表面气速为2 4 cm·s-1、COD负荷为1.0～3.6 kg·m-3·d-1、CAs负荷逐步提升至800 g·m-3·d-1的条件下继续运行50d,SABR污泥颗粒化趋于成熟,COD、CAs去除率稳定在90%、99.9%以上.根据污泥形态、最小沉降速率、SVI和目标污染物降解性能的变化,好氧污泥颗粒化过程可分为启动期、颗粒污泥形成期、生长期和成熟期.成熟好氧颗粒污泥粒径为0.9～2.5 mm,平均颗粒密度为64 g·L-1(以MLVSS计),污泥最小沉降速率为68.4 m·h-1,SOUR为167 mg·g-1·h-1;颗粒污泥外形为圆形或椭圆形,呈橙黄色,结构较致密,颗粒内外分布有丰富的类球菌、类短杆菌,与胞外多聚物交织共存.

利用气升式内环流生物反应器培养青蒿毛状根生产青蒿素

利用自制的气升式内环流生物反应器进行青蒿（ArtemisiaannuaL．）毛状根多层培养生产青蒿素。毛状根培养物在培养过程中均匀分布在生物反应器的筛网间，或以不锈钢网为附着点向四周生长，在25℃和12h／d光照周期下，经20d分批培养获得生物量干重22．57g／L，青蒿素产量374．4mg／L，并对培养过程中蔗糖、磷酸盐、硝酸盐和氨盐消耗的动力学进行了分析。

气升式生物反应器在杂交瘤细胞培养中的应用

在前述研究工作基础上,设计开发了10L规模的动物细胞培养用气升式生物反应器。应用该生物反应器悬浮培养杂交瘤细胞,通过平行试验,考察了该反应器设计的合理性和可靠性。结果显示该反应器不存在限制细胞生长、代谢和产物生成的因素,而且细胞破损被彻底消除,表明该气升式生物反应器给细胞生长、代谢和产物生成提供了理想的培养环境,其设计是成功的。

气升式反应器结构参数优化设计CFD仿真研究

气升式反应器是生物发酵生产过程中的重要设备,工业生产过程中要求反应器内保持较高的气含率和循环液速,从而提高气液传质效率。由于气升式反应器的导流筒直径对气含率和循环液速有决定性影响,研究其结构参数优化设计具有重要意义;文章利用计算流体力学仿真软件研究了气升式反应器内的流动状态,给出了不同导流筒直径下气含率和循环液速的变化趋势,发现了该结构参数存在最佳设计范围。

改进型气升式内环流硝化反应器氧传递特性的研究

在废水处理领域，气升式内环流硝化反应器有着较好的应用前景；但其氧传递性能有待进一步改善。通过调整导流简直径以及导流简内静态混合元件的个数，试验了反应器结构对氧传递特性的影响。研究发现，当导流简直径取5．5cm，并在导流简内安装13个静态混合元件时，这种改进型硝化反应器的氧传递能力显著提高。在表观气速为5．05～23．80cm·s^-1。的条件下，测得氧传递系数为0．151～0．778min^-1，充氧能力为7．84～42．80g O2·h^-1，容积供氧能力为2．00-10．93kg O2·m^-3·d^-1，氧转移效率为39．2％～48．1％，氧转移动力效率为3．2～4．0kg O2·（kW·h）^-1,相对于普通气升式内环流硝化反应器，改进型内环流硝化反应器的氧传递系数、充氧能力、氧转移效率和氧转移动力效率都提高72.5％。根据Higbie渗透模型和Kolmogoroff各向同性理论，建立了氧传递系数与相关参数的关联式，预测值与试验结果相吻合，两者的相对误差为9．15％。

环流反应器生化处理皂化废水研究

以17L的环流反应器为曝气设备,研究了皂化废水的生物降解过程。环流反应器可高效处理皂化废水,水力停留时间仅6h,皂化废水的生物降解过程满足一级宏观动力学,最佳活性污泥质量浓度范围为5～9g/L;活性污泥系统连续运行稳定,出水化学需氧量稳定在100mg/L左右。扫描电镜显示驯化污泥相较接种污泥有较大变化,微生物的活性提高,种类更为丰富。

外循环气升式生物反应器气含率及其用于井冈霉素发酵的研究

对外循环气升式生物反应器的气含率进行了试验研究 ,得出了气含率与操作条件之间的关联式。在此基础上 ,进行了井冈霉素发酵试验 ,并与 10 L 机械搅拌生物反应器进行了比较 ,实验结果表明 :当外循环气升式生物反应器的空气喷嘴直径为 1.5和 3.0 mm时 ,井冈霉素的发酵效价分别为 19975和 1895 0 u/ml,而 10 L机械搅拌生物反应器的井冈霉素发酵效价为 196 30 u/ ml。因此 ,将气升式生物反应器应用于井冈霉素的发酵是一项值得研究的工作。

10升气升环流式生物反应器培养紫草细胞

本文采用自行设计研制的10升气升环流式生物反应器培养紫草细胞，培养周期34d．前14d为细胞生长培养，细胞生长呈正常的S型曲线，细胞增长到原细胞接人量的4倍．后20d为紫草色素生产培养，细胞增长到32倍。整个周期每升培养液可生产紫草色素0．6g，在反应器中，培养液pH值的变化与细胞生长呈正相关，与紫草色素的形成呈负相关，pH值变化规律可用于监测紫草细胞在生物反应器的生长和色素形成．

内循环气升式生物反应器培养甘草细胞

自行设计研制了７Ｌ，９Ｌ及２５Ｌ内循环气升式生物反应器，并应用于甘草细胞的放大培养研究。在接种量为８％（Ｗ／Ｖ）通气率为０．２—０．２５ｖｖｍ的条件下，甘草细胞在反应器中生长迅速。其中在９Ｌ反应器中生长最好，最高生物量达１６．２５ｇ／Ｌ，生长速率达０．９ｇ／Ｌ．ｄ，均高于摇瓶培养。培养过程中ｐＨ值、溶氧状况通过电极自动显示记录，说明设计的气升式生物反应器适合于甘草细胞的大规模培养。

固定化解脂耶氏酵母间歇式处理油脂废水研究

固定化解脂耶氏酵母菌（Yarrowia lipolytica）在气升式反应器中处理色拉油浓度为2 000 mg/L、COD为3 000 mg/L的高COD油脂废水。结果表明,固定化菌对废水的最佳处理时间为6 d,可间歇式处理9批次高COD油脂废水,重复处理废水后,其对油脂的降解均在85%以上,对COD的降解在70%以上,降解后的排出水pH稳定在3.6~3.8。且处理动力学方程属于一级生化方程。结果进一步表明,固定化解脂耶氏酵母菌在气升式反应器中适于处理高COD含油脂的污水。

内置筛板外循环气升式生物反应器中液相循环时间的研究

在上升管与下降管直径之比为６．６，罐体高径比为２．９的内置筛板外循环气升式生物反应器内，以羧甲基纤维钠水溶液为模拟介质，测定了反应器内液相循环时间与操作参数的关系，用均匀设计考察了操作参数对液相循环时间的影响程度，结果表明介质粘度对循环时间影响最大。

气升式一体化A/O生物膜反应器的硝化和反硝化过程

构建了新型气升式一体化A/O生物膜反应器并于生活污水的脱氮处理,研究了反应器挂膜启动后硝化和反硝化反应形成的过程.试验结果表明,由于反应器构造独特,能够形成具有不同溶解氧浓度的好氧区、缓冲区和缺氧区,并利用曝气推动力实现硝化液在各区间的循环.通过对进水方式的调节,反应器内能够形成良好的硝化和反硝化过程,硝化率和反硝化率分别达到89.49%和97.86%.