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关键词： Gas-liquid fermenter agitators   gas-liquid bioreactor agitators   fermenter agitator   bioreactor agitator   agitator development   agitator design   agitator construction   agitator maintenance   agitator principles   agitator implementation  

ISBN: (数字)9781119650546 ISBN: (纸本)9781119650492

摘要： This book is concise reference to designing mechanically sound agitation systems that will perform the process function efficiently and economically. Currently, all the books on bioreactor and fermenter design do not focus specifically on agitation. Sections cover agitator fundamentals, impeller systems, optimum power and air flow at peak mass transfer calculations, optimizing operation for minimum energy per batch, heat transfer surfaces and calculations, shaft seal considerations, mounting method, mechanical design, and vendor evaluation.

关键词： Ethinylestradiol   Micropollutants   Advanced oxidative process   Membrane   Wastewater treatment   Economic evaluation  

摘要： Synthetic hormone 17 alpha-ethinylestradiol (EE2) is not completely removed by conventional wastewater treatment plants and therefore is often detected in surface and groundwater, sludge and sediments. Due to its persistence in the environment and its estrogenic potential, a high removal of EE2 from wastewaters before its disposal has become a concern from an environmental point of view, particularly when considering urban reuse applications. This work investigated the application of advanced processes to treat synthetic municipal wastewater containing EE2 after treatment in a membrane bioreactor (MBR). Two advanced processes were assessed: the first is advanced oxidation process (AOP), using hydrogen peroxide (H2O2) and ultraviolet (UV) light (mute MBR-AOP) and the second, reverse osmosis (RO), in this case using UV/H2O2 to treat the retentate from RO (route MBR-RO). EE2 concentration in final effluent was one order of magnitude lower in mute MBR-AOP than in route MBR-RO. Implications for disposal or water reuse were discussed considering the importance of other water quality parameters as well. Economic estimates for CAPEX, OPEX and total cost were made. The introduction of the oxidative step (UV/H2O2) after MBR caused an increase in the total cost of US$ 0.39/m(3). In turn, mute MBR-RO increased the total process cost by US$ 0.86/m(3), showing that reduction of volume to be treated by UV/H2O2 in this route did not offset the cost associated with the acquisition and operation of RO. The total cost was estimated at US$ 2.47/m(3) for MBR-AOP and US$ 2.94/m(3) for MBR-RO for a design flow of 10 m(3)/h.

摘要： The last author's name was incorrectly captured in the initial online publication. The original article has been corrected.

关键词： Membrane fouling mitigation   Microbial diversity   Endogenous respiration   16S rRNA gene sequencing   Dissolved organic carbon  

摘要： The aimof this study was to evaluate the contribution of dissolved organic carbon (DOC) and microbial community dynamics to membrane fouling development in membrane bioreactor (MBR). We operated laboratory-scale anoxic/oxic-MBRs under prolonged starvation conditions in different seasons and the dynamics and diversity of the microbial communitieswere investigated. Although fouled-MBRs showed DOC accumulation in the activated sludge (AS), the fouling-mitigated MBR suggested that dissolved oxygen was consumed and DOC of the sludge supernatant was degraded. 16S rRNA genes analysis of AS in the MBRs revealed that Chitinophagaceae and Candidatus Promineofilum specifically increased in the fouling-mitigated MBR, suggesting that they played important roles in membrane fouling mitigation;high microbial diversity in the reactor also contributed to fouling mitigation. In the fouled reactor, enrichment of Xanthomonadaceae might be related to fouling causing substances formation leading to membrane fouling development;lower microbial diversity also contributed to fouling development in the fouled MBR. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Anaerobic digestion   AnMBR   Municipal wastewater   Sludge yield   Suspended solids   Membrane fouling  

摘要： Sludge yield and suspended solid are important factors concerned in the anaerobic treatment of municipal-wastewater. In this study, a large pilot-scale anaerobic membrane bioreactor (AnMBR) was constructed for effectively treating real municipal wastewater at an ambient temperature of 25 degrees C. The sludge yield and the degradation of influent suspended solidswere evaluated during the long-term operation of the AnMBR. This reactorwith 5.0 m(3) effective volume is the largest one-stage submerged AnMBR that has ever been used to treat municipalwastewater. During the long-termoperation of 217 days, this AnMBR obtained excellent CODand BOD5 removal efficiency over 90%. Stable biogas production was also successfully obtained from treating municipal wastewater. The sludge yield of the AnMBR was approximately 0.19-0.26 gMLSS g(-1) COD removed for the treatment of realmunicipal wastewater. The shortest SRT of the AnMBR was calculated as 29 days for an HRT of 6 h at an empirical MLSS of 10 g L-1. While theinfluent suspended solid (SS) contained in themunicipalwastewaterwas completely removed by the AnMBR, only 57%-66% of the influent SS was degraded. The rest of influent SS was directly converted to MLSS instead of being degraded. The AnMBR maintained a stable membrane filtration using a hollowfiber membrane with a total area of 72 m(2), realizing a flux of 2.75-17.83 LMH, and the mean transmembrane pressure (TMP) was 0.9-23.5 kPa. An online chemical backwash cleaning systemhelped to lower the TMP timely using sodium hypochlorite and citric acid when the TMP increased rapidly and reached the rated limit of membrane. This is the first report on demonstrating the successful operation and detailed performance of a large pilotscale AnMBR applied to the treatment of real municipal wastewater. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Temporary Immersion Systems   Micropropagation   SETIS bioreactor   Large-scale propagation   Vanilla planifolia  

摘要： Temporary immersion systems (TIS) are extensively used for the in-vitro regeneration of plants. These systems have been proposed as a suitable technique for propagating vanilla (Vanilla planifolia Jacks) for commercial purposes. This study compares three different culture systems for the micropropagation of vanilla: semi-solid (SS), liquid medium under partial immersion (PI), and temporary immersion (TI) using the SETIS (TM) bioreactor. In all cases, the culture systems included the Murashige and Skoog culture medium (MS) added with 30 g L-1 sucrose and 9.55 mu M benzyladenine (BA). The number of shoots per explant, as well as shoot length, number of leaves per shoot, fresh weight, dry weight, stomatal index, and chlorophyll content were recorded after four weeks of culture. Also, the ex-vitro survival rate was estimated for all the culture systems investigated. The highest values of shoot proliferation and development were observed in TI (11.41 shoots/explant), followed by PI (6.53), and SS (3.76);the highest fresh and dry weights were obtained in TI, followed by PI, and SS. A higher synthesis of chlorophyll was observed in PI relative to TI and SS. Stomata showed a similar distribution and morphology in leaves of plants under the different culture systems. T1 showed peak values of the percentage of closed stomata and stomatal index. The highest percent survival during acclimatization was observed in TI (98%), followed by PI (85%), and SS (75%). At the end of the micropropagation process, 227 plants of V. planifolia were obtained in SS, 500 plants in PI and 3026 in TI. In conclusion, the SETIS (TM) bioreactor improves the physiological conditions of in-vitro development and is an alternative for the propagation of V. planifolia at large scale.

关键词： Nitrite-free ammonium-rich wastewater   anammox process   hybrid technology   16S rRNA sequencing   Candidatus Brocadia species  

摘要： This study presents effective ammonium removal from nitrite-free ammonium-rich synthetic wastewater through combined partial nitrification (PN) and anammox processes in a multi-zone hybrid airlift bioreactor (BioCAST). Removal efficiencies of ammonia-nitrogen and total nitrogen up to 85.6% and 81.2%, respectively, were achieved shortly after the start-up of bioreactor treating the nitrite-free ammonium-rich synthetic wastewater with ammonium concentrations of 10-350 mg/L. The hybrid (containing suspended and attached biomass) and multi-zone design of the bioreactor with different dissolved oxygen levels, along with the inoculation with anammox-containing sludge were the main factors in the successful start-up of the bioreactor. Nitrate accumulation problem due to the fast growth of nitrite-oxidizing bacteria in the bioreactor was controlled by two operating strategies including lowering the HRT from 4 days to 2 days and controlling the dissolved oxygen concentration in the aerobic zone of the bioreactor between 0.9 and 1.2 mg/L. Moreover, the 16S rRNA gene analysis confirmed that the partial nitrification of ammonia to nitrite occurred by Nitrosomonas sp. primarily in the suspended biomass in the aerobic zone, while the conversion of nitrite to N-2 occurred by Candidatus Brocadia species in the anoxic zone. This study showed the effective removal of ammonium from a nitrite-free wastewater by providing a proper HRT, controlling the DO concentration between 0.9 and 1.2 mg/L in the aerobic zone, and preventing biomass loss using both suspended and attached microbial cultures in different zones of the bioreactor.

关键词： AMD   Bioremediation   Iron-oxidizing bacteria   HYTEC   Reactive transport modeling  

摘要： Natural attenuation in acid mine drainage (AMD) due to biological iron and arsenic oxidation offers a promising strategy to treat As-rich AMD in passive bioreactors. A reactive transport model is developed in order to identify the main controlling factors. It simulates batch and flow-through experiments that reproduce natural attenuation in a high-As AMD. The 2-D model couples second-order microbial kinetics (Fe- and As- oxidation) and geochemical reactions to hydrodynamic transport. Oxidation only occurrs in the biofilm with an oxygen transfer from the air through the water column. The model correctly simulates the Fe(II)-Fe(III) and As(III)-As(V) concentrations in the outlet waters and the precipitates, over hydraulic retention times from 30 min to 800 min. It confirms that the natural attenuation at 20 degrees C is driven by the fast Fe(II) oxidation and slow As(III) oxidation that favors arsenite trapping by schwertmannite over amorphous ferric arsenate (AFA) formation. The localization of iron oxidation in the biofilm limits the attenuation of arsenic and iron as the water column height increases. The change in the composition of the bacterial iron-oxidizer community of the biofilm at the lowest pH boundary seems to control the Fe(II) oxidation kinetic rate besides the bacterial concentration.

关键词： Dissolved air flotation   yeast   polyacrylamide   microtoxicity   BAF  

摘要： In this work, the performance of a bench-scale integrated system for oilfield wastewater was investigated. This system contained dissolved air flotation (DAF), yeast bioreactor, up-flow anaerobic sludge blanket reactor (UASB), and biological aerated filter. Under the optimized conditions, the overall removal efficiencies of chemical oxygen demand, suspended solids, oil, and polyacrylamide were 95.7%, 88.8%, 99.6%, and 97.0%, respectively. DAF removed most of the oil components, and the residual oil was efficiently degraded by yeast bioreactor. The biodegradability of the effluent was enhanced by UASB. The final effluent can meet the grade I national wastewater discharge standard of China.

关键词： 硝胺废水   Fenton氧化   紫外光化   生物降解菌  

摘要： 在含能硝胺类化合物的生产过程中,会产生高盐度高毒性废水,无法采用传统的生物法直接处理。因此采用紫外光化与Fenton催化氧化进行预处理,对实际生产废水中的硝胺化合物先进行初步分解,然后将出水进入膜生物反应器,并筛选了六株高耐盐降解细菌与两株高耐盐降解真菌作为降解菌进行复合,最终实现废水的达标排放。由研究结果可知,Fenton催化氧化的最佳条件为:n(H_(2)O_(2))∶n(COD)=2.5∶1,n(H_(2)O_(2))∶n(Fe^(2+))=5∶1,pH=3.0。Fenton氧化工艺COD的去除率可以达到54%。筛选的特异降解菌株对硝胺类特征污染物具有较强的转化能力,转化率在70%以上,运行24 h后出水硝胺化合物的质量浓度≤0.1 mg/L。本研究为硝胺生产废水的处理提供了有效工艺,优化了相关参数并筛选了特异性降解菌,实现了废水的达标排放。