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Cultivation of aerobic granular sludge in a conventional, continuous flow, completely mixed activated

Xi CHEN,Linjiang YUAN,Wenjuan LU,Yuyou LI,Pei LIU,Kun NIE

《环境科学与工程前沿(英文)》 2015年 第9卷 第2期   页码 324-333 doi: 10.1007/s11783-014-0627-3

摘要: Aerobic granules were formed in a conventional, continuous flow, completely mixed activated sludge system (CMAS). The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen (DO) of the reactor were 2 h and 4.2 mg·L , respectively. The reactor was agitated by a stirrer, with a speed of 250 r·min , to ensure good mixing.The granular sludge had good settleability, and the sludge volume index (SVI) was between 50 and 90 mL·g . The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope (SEM) investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Sequencing analysis indicated the dominant species were α, β, and γ- , , and . The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.

关键词: aerobic granular sludge     completely mixed activated sludge system (CMAS)     continuous flow     shear force     filamentous bacteria     polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)    

Estimation of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

《环境科学与工程前沿(英文)》 2014年 第8卷 第5期   页码 683-692 doi: 10.1007/s11783-014-0680-y

摘要: In this paper the photolysis half-lives of the model dyes in water solutions and under ultraviolet (UV) radiation were determined by using a continuous-flow spectrophotometric method. A quantitative structure-property relationship (QSPR) study was carried out using 21 descriptors based on different chemometric tools including stepwise multiple linear regression (MLR) and partial least squares (PLS) for the prediction of the photolysis half-life ( ) of dyes. For the selection of test set compounds, a K-means clustering technique was used to classify the entire data set, so that all clusters were properly represented in both training and test sets. The QSPR results obtained with these models show that in MLR-derived model, photolysis half-lives of dyes depended strongly on energy of the highest occupied molecular orbital ( ), largest electron density of an atom in the molecule ( ) and lipophilicity (log ). While in the model derived from PLS, besides aforementioned and descriptors, the molecular surface area ( ), molecular weight ( ), electronegativity ( ), energy of the second highest occupied molecular orbital ( ) and dipole moment ( ) had dominant effects on logt values of dyes. These were applicable for all classes of studied dyes (including monoazo, disazo, oxazine, sulfonephthaleins and derivatives of fluorescein). The results were also assessed for their consistency with findings from other similar studies.

关键词: dye     photolysis half-life     quantitative structure-property relationship     continuous-flow     stepwise multiple linear regression     partial least squares    

Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by

Rusen Zhou, Renwu Zhou, Xianhui Zhang, Kateryna Bazaka, Kostya (Ken) Ostrikov

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 340-349 doi: 10.1007/s11705-019-1798-z

摘要: Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N and air plasmas treatments, O plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma treated solution, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.

关键词: continuous removal     dye-containing wastewater     dielectric barrier discharge     plasma water bed     activated carbon adsorption    

Continuous flow pyrolysis of virgin and waste polyolefins: a comparative study, process optimization

《化学科学与工程前沿(英文)》 doi: 10.1007/s11705-024-2429-x

摘要: Under optimal process conditions, pyrolysis of polyolefins can yield ca. 90 wt % of liquid product, i.e., combination of light oil fraction and heavier wax. In this work, the experimental findings reported in a selected group of publications concerning the non-catalytic pyrolysis of polyolefins were collected, reviewed, and compared with the ones obtained in a continuously operated bench-scale pyrolysis reactor. Optimized process parameters were used for the pyrolysis of waste and virgin counterparts of high-density polyethylene, low-density polyethylene, polypropylene and a defined mixture of those (i.e., 25:25:50 wt %, respectively). To mitigate temperature drops and enhance heat transfer, an increased feed intake is employed to create a hot melt plastic pool. With 1.5 g·min–1 feed intake, 1.1 L·min–1 nitrogen flow rate, and a moderate pyrolysis temperature of 450 °C, the formation of light hydrocarbons was favored, while wax formation was limited for polypropylene-rich mixtures. Pyrolysis of virgin plastics yielded more liquid (maximum 73.3 wt %) than that of waste plastics (maximum 66 wt %). Blending polyethylenes with polypropylene favored the production of liquids and increased the formation of gasoline-range hydrocarbons. Gas products were mainly composed of C3 hydrocarbons, and no hydrogen production was detected due to moderate pyrolysis temperature.

关键词: waste plastics     polyolefins     chemical recycling     pyrolysis     alternative fuels     waste-to-energy    

Hydrogen production from co-gasification of coal and biomass in supercritical water by continuous flow

YAN Qiuhui, GUO Liejin, LIANG Xing, ZHANG Ximin

《能源前沿(英文)》 2007年 第1卷 第3期   页码 327-330 doi: 10.1007/s11708-007-0048-0

摘要: Hydrogen is a clean energy carrier. Converting abundant coal sources and green biomass energy into hydrogen effectively and without any pollution promotes environmental protection. The co-gasification performance of coal and a model compound of biomass, carboxymethylcellulose (CMC) in supercritical water (SCW), were investigated experimentally. The influences of temperature, pressure and concentration on hydrogen production from co-gasification of coal and CMC in SCW under the given conditions (20–25 MPa, 650vH, 15–30 s) are discussed in detail. The experimental results show that H, CO and CH are the main gas products, and the molar fraction of hydrogen reaches in excess of 60%. The higher pressure and higher CMC content facilitate hydrogen production; production is decreased remarkably given a longer residence time.

关键词: carboxymethylcellulose     temperature     co-gasification performance     Hydrogen     residence    

Continuous deacylation of amides in a high-temperature and high-pressure microreactor

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1818-1825 doi: 10.1007/s11705-022-2182-y

摘要: The deacylation of amides, which is widely employed in the pharmaceutical industry, is not a fast reaction under normal conditions. To intensify this reaction, a high-temperature and high-pressure continuous microreaction technology was developed, whose space-time yield was 49.4 times that of traditional batch reactions. Using the deacylation of acetanilide as a model reaction, the effects of the temperature, pressure, reaction time, molar ratio of reactants, and water composition on acetanilide conversion were carefully studied. Based on the rapid heating and cooling capabilities, the kinetics of acetanilide deacylation at high temperatures were investigated to determine the orders of reactants and activation energy. This microreaction technology was further applied to a variety of other amides to understand the influence of substituents and steric hindrance on the deacylation reaction.

关键词: amide deacylation     microreactor     flow chemistry     reaction intensification    

Experimental and theoretical study of microwave enhanced catalytic hydrodesulfurization of thiophene in a continuous-flow

Hui Shang, Pengfei Ye, Yude Yue, Tianye Wang, Wenhui Zhang, Sainab Omar, Jiawei Wang

《化学科学与工程前沿(英文)》 2019年 第13卷 第4期   页码 744-758 doi: 10.1007/s11705-019-1839-7

摘要: Hydrodesulfurization (HDS) of thiophene, as a gasoline model oil, over an industrial Ni-Mo/Al O catalyst was investigated in a continuous system under microwave irradiation. The HDS efficiency was much higher (5%‒14%) under microwave irradiation than conventional heating. It was proved that the reaction was enhanced by both microwave thermal and non-thermal effects. Microwave selective heating caused hot spots inside the catalyst, thus improved the reaction rate. From the analysis of the non-thermal effect, the molecular collisions were significantly increased under microwave irradiation. However, instead of being reduced, the apparent activation energy increased. This may be due to the microwave treatment hindering the adsorption though upright S-bind (η ) and enhancing the parallel adsorption (η ), both adsorptions were considered to favor to the direct desulfurization route and the hydrogenation route respectively. Therefore, the HDS process was considered to proceed along the hydrogenation route under microwave irradiation.

关键词: thiophene     microwave irradiation     hydrodesulfurization     non-thermal microwave effect    

瑞德西韦核碱基单元的连续流合成 Article

郭永兴, 刘敏杰, 姜梅芬, 陶媛, 程荡, 陈芬儿

《工程(英文)》 2023年 第21卷 第2期   页码 92-100 doi: 10.1016/j.eng.2021.07.029

摘要:

本研究通过五步连续流合成了抗病毒药物瑞德西韦的核碱基单元7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺。采用间歇式合成化学方法,利用广泛可用且廉价的起始原料吡咯,通过顺序流动操作成功生产了7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺。在最佳流动条件下,7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺的分离收率为14.1%,总停留时间为79 min,通量为2.96 g∙h−1,总停留时间明显短于批处理程序中消耗的总时间(大于26.5 h)。在流动中,有利地促进了涉及危险和不稳定的中间体的高度放热的Vilsmeier-Haack 和N-胺化反应、氧化液-液双相转化及需要严格低温条件的溴化反应。这种合成方法的显著特点是,通过部署专用设备和分离单元,将后处理程序完全集成到反应序列中,从而形成一个精简的连续流系统,最大限度地提高整个过程的效率。该方法是一种更环保、更可持续的高效、安全地制备核碱基单元的方法。

关键词: 流动化学     连续多步合成     微反应技术     反应分离集成    

八步连续流全合成维生素B1工艺研究 Article

姜梅芬, 刘敏杰, 李伟剑, 夏应奇, 陈芬儿

《工程(英文)》 2024年 第32卷 第1期   页码 226-232 doi: 10.1016/j.eng.2023.01.016

摘要:

维生素B1作为一种抗利尿和抗氧化剂被广泛应用于医疗保健和食品行业,以维持神经传导、心脏和胃肠道的正常功能。本研究报道了由市售2-氰基乙酰胺进行的维生素B1的八步连续流全合成工艺。本研究提出的连续流工艺基于化学、工程和设备设计的创新基础,与间歇釜式工艺相比,生产的性能和安全性均有所提高。本文使用各种微通道流反应器、微混合器、连续分离设备和连续过滤器等装置,对连续流合成工艺中的问题和挑战进行了精确的研究和控制,包括混合、意外堵塞、溶剂切换、放热反应和避免副反应等。维生素B1全合成的连续流工艺总停留时间约为3.5小时,产品纯度高,分离产率为47.7%。该八步连续流动技术方案至少涉及绿色化学的六个关键准则。因此,连续流技术的应用对于提高生产安全性、减少废物污染,尤其是提高批量操作的生产效率至关重要。

关键词: 维生素B1     连续流合成     微反应器     连续制造    

Response of bioaerosol cells to photocatalytic inactivation with ZnO and TiO impregnated onto Perlite and Poraver carriers

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-020-1335-9

摘要:

•ZnO/Perlite inactivated 72% of bioaerosols in continuous gas phase.

关键词: Immobilized catalysts     Continuous flow     Photocatalysis     Bioaerosols     Cytotoxicity     Inactivation mechanism    

Strain and process engineering toward continuous industrial fermentation

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1336-1353 doi: 10.1007/s11705-022-2284-6

摘要: Most current biotechnology industries are based on batch or fed-batch fermentation processes, which often show low productivity and high production costs compared to chemical processes. To increase the economic competitiveness of biological processes, continuous fermentation technologies are being developed that offer significant advantages in comparison with batch/fed-batch fermentation processes, including: (1) removal of potential substrates and product inhibition, (2) prolonging the microbial exponential growth phase and enhancing productivity, and (3) avoiding repeated fermentation preparation and lowering operation and installation costs. However, several key challenges should be addressed for the industrial application of continuous fermentation processes, including (1) contamination of the fermentation system, (2) degeneration of strains, and (3) relatively low product titer. In this study, we reviewed and discussed metabolic engineering and synthetic biology strategies to address these issues.

关键词: continuous fermentation     productivity     contamination     strain degeneration     metabolic engineering    

A review of research progress on continuous cropping obstacles REVIEW

《农业科学与工程前沿(英文)》 2024年 第11卷 第2期   页码 253-270 doi: 10.15302/J-FASE-2024543

摘要:

Due to the increasing global population and limited land resources, continuous cropping has become common. However, after a few years of continuous cropping, obstacles often arise that cause soil degeneration, decreased crop yield and quality, and increased disease incidence, resulting in significant economic losses. It is essential to understand the causes and mitigation mechanisms of continuous cropping obstacles (CCOs) and then develop appropriate methods to overcome them. This review systematically summarizes the causes and mitigation measures of soil degradation in continuous cropping through a meta-analysis. It was concluded that not all continuous cropping systems are prone to CCOs. Therefore, it is necessary to grasp the principles governing the occurrence of diseases caused by soilborne pathogens in different cropping systems, consider plant–soil-organisms interactions as a system, scientifically regulate the physical and chemical properties of soils from a systems perspective, and then regulate the structure of microbial food webs in the soil to achieve a reduction in diseases caused by soilborne pathogens and increase crop yield ultimately. This review provides reference data and guidance for addressing this fundamental problem.

关键词: Continuous cropping obstacles     rhizosphere regulation     soil microecological environment    

Ant colony optimization in continuous problem

YU Ling, LIU Kang, LI Kaishi

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 459-462 doi: 10.1007/s11465-007-0079-6

摘要: Based on the analysis of the basic ant colony optimization and optimum problem in a continuous space, an ant colony optimization (ACO) for continuous problem is constructed and discussed. The algorithm is efficient and beneficial to the study of the ant colony optimization in a continuous space.

关键词: beneficial     algorithm     efficient     continuous     ACO    

连续铸钢前沿技术的工程化

干勇

《中国工程科学》 2002年 第4卷 第9期   页码 12-18

摘要:

论述了具有我国自主知识产权的高效连铸和薄板坯连铸工程化关键技术的特点;介绍了连续铸钢领域轻压下、液压非正弦振动、电磁连铸等前沿技术的开发现状;阐述了传统连铸技术超高效率、高品质化及近终形连铸、电磁连铸开发的研发方向。

关键词: 连续铸钢     高效连铸     薄板坯连铸     轻压下     电磁连铸    

天然气水合物浆液流变学研究综述 Perspective

Ahmad A.A. Majid, David T. Wu, Carolyn A. Koh

《工程(英文)》 2018年 第4卷 第3期   页码 321-329 doi: 10.1016/j.eng.2018.05.017

摘要:

天然气水合物是固体包裹化合物,由三维的氢键网络组成,可以用来捕获气体小分子,比如甲烷和二氧化碳。了解溶液中天然气水合物晶体的流变性能对于许多能源方面的应用至关重要,包括天然气在海底和陆地上的运输,以及气体分离、脱盐或封存等方面的技术应用。人们已经对水合物浆体流变学进行了多次实验和模型模拟;然而,理论与实验之间的联系并不明确。本文讲述了对高、低压流变仪的研究以及在高压流动环境下,一系列不同的过冷度(ΔTsub = TequilTexp)和流体条件的水合物浆体黏度测量技术的现状(包括水和油的连续系统)。本文介绍了天然气水合物泥浆相对黏度的理论模型,还讨论了实验和理论之间的联系。

关键词: 相对黏度     流动保障     流变仪     连续油    

标题 作者 时间 类型 操作

Cultivation of aerobic granular sludge in a conventional, continuous flow, completely mixed activated

Xi CHEN,Linjiang YUAN,Wenjuan LU,Yuyou LI,Pei LIU,Kun NIE

期刊论文

Estimation of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

期刊论文

Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by

Rusen Zhou, Renwu Zhou, Xianhui Zhang, Kateryna Bazaka, Kostya (Ken) Ostrikov

期刊论文

Continuous flow pyrolysis of virgin and waste polyolefins: a comparative study, process optimization

期刊论文

Hydrogen production from co-gasification of coal and biomass in supercritical water by continuous flow

YAN Qiuhui, GUO Liejin, LIANG Xing, ZHANG Ximin

期刊论文

Continuous deacylation of amides in a high-temperature and high-pressure microreactor

期刊论文

Experimental and theoretical study of microwave enhanced catalytic hydrodesulfurization of thiophene in a continuous-flow

Hui Shang, Pengfei Ye, Yude Yue, Tianye Wang, Wenhui Zhang, Sainab Omar, Jiawei Wang

期刊论文

瑞德西韦核碱基单元的连续流合成

郭永兴, 刘敏杰, 姜梅芬, 陶媛, 程荡, 陈芬儿

期刊论文

八步连续流全合成维生素B1工艺研究

姜梅芬, 刘敏杰, 李伟剑, 夏应奇, 陈芬儿

期刊论文

Response of bioaerosol cells to photocatalytic inactivation with ZnO and TiO impregnated onto Perlite and Poraver carriers

期刊论文

Strain and process engineering toward continuous industrial fermentation

期刊论文

A review of research progress on continuous cropping obstacles

期刊论文

Ant colony optimization in continuous problem

YU Ling, LIU Kang, LI Kaishi

期刊论文

连续铸钢前沿技术的工程化

干勇

期刊论文

天然气水合物浆液流变学研究综述

Ahmad A.A. Majid, David T. Wu, Carolyn A. Koh

期刊论文