entrapped cell

  • 文章类型: Journal Article
    三氯卡班(TCC)已用于消费品,是市政污水处理系统中的广泛污染物,最终会积聚在自然接收水和土壤中。这项工作旨在应用一种创新的混合移动截留珠活性污泥反应器(名为“HyMER”),该反应器集成了截留的TCC降解微生物和自由悬浮的活性污泥来处理TCC污染的废水。应用了先前分离的TCC降解细菌(荧光假单胞菌菌株MC46,称为MC46)和海藻酸钡包埋。合成TCC污染的废水处理(TCC浓度为10mg/L)使用20个循环的分批进料反应器操作进行,进料时间为12和24h,循环时间为13和25h。结果表明,HyMER有效地将化学需氧量降低了80%和95%,将TCC降低了53%和83%,分别,进料时间为12和24h。发现了三种TCC降解中间产物-3,4-二氯苯胺,4-氯苯胺,还有苯胺.扫描电子显微镜分析显示,较短的细胞和细菌附件的发育是针对TCC及其中间体的细胞适应。活/死试验表明,在毒性条件下,截留的MC46的存活率很高,高达84%的活细胞。基于计算流体动力学分析,反应器中没有显示出截留的细胞团聚,表明了HyMER在实际废水处理中的潜在应用。这些结果表明了HyMER的可行性及其在未来有毒废水处理中的适用性。
    Triclocarban (TCC) has been used in consumer products and is a widespread contaminant in municipal wastewater treatment systems that ultimately accumulates in natural receiving water and soil. This work aims to apply an innovative hybrid moving entrapped bead activated sludge reactor (named \"HyMER\") that integrates entrapped TCC-degrading microbes and freely suspended activated sludge to treat TCC-contaminated wastewater. A previously isolated TCC-degrading bacterium (Pseudomonas fluorescens strain MC46, called MC46) and barium alginate entrapment were applied. The synthetic TCC-contaminated wastewater treatment (with TCC concentration of 10 mg/L) was performed using 20-cycle fed-batch reactor operation with feeding times of 12 and 24 h and cycle times of 13 and 25 h. The results indicated that the HyMER effectively reduced chemical oxygen demand by up to 80 and 95 % and TCC by up to 53 and 83 %, respectively, with feeding times of 12 and 24 h. Three TCC degradation intermediate products were found-3,4-dichloroaniline, 4-chloroaniline, and aniline. Scanning electron microscopic analysis revealed shorter cells and bacterial appendage development as cell adaptations against TCC and its intermediates. The live/dead assay indicated high survival of entrapped MC46 in toxic conditions, with up to 84 % viable cells. Based on computational fluid dynamic analysis, no entrapped cell agglomeration showed in the reactor, indicating the potential application of HyMER for real wastewater treatment. These results exhibit the feasibility of HyMER and its applicability for future toxic wastewater treatment.
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  • 文章类型: Case Reports
    A surgical case of a benign notochordal cell tumor of the lung is reported. The patient was an asymptomatic 41-year-old man, who was incidentally found to have a small tumor in the subpleural region of the left lingular segment. Since wedge resection of the tumor, the patient has been free from recurrence. The tumor measured 12 mm in diameter and showed a central cystic change. It consisted of a diffuse proliferation of polygonal cells with abundant, uni- or multi-vacuolated cytoplasm and bland nuclei. The tumor did not show a lobular architecture and lacked a myxoid or fibrous connective tissue containing blood vessels. In the peripheral region of the tumor, a small number of alveolar epithelial cells were entrapped. The nuclei of tumor cells were immunoreactive for brachyury, and the cytoplasm was positive for cytokeratin and S-100 protein. The entrapment of alveolar epithelial cells suggests infiltrative growth of the tumor, and the almost complete absence of blood vessels within the tumor may have restricted tumor growth and induced a cystic change in the central region.
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  • 文章类型: Journal Article
    Oxygen-limiting and/or free ammonia (FA)-accumulating conditions are two common operating strategies for partial nitrification in wastewater. Controlling either bulk dissolved oxygen (DO) or free ammonia (FA) concentration to maintain partial nitrification can be challenging due to the strong interdependency between these two parameters as substrates for ammonia oxidation. In this study, DO/FA ratio is proposed as a controlling parameter for partial nitrification by entrapped-cell-based reactors. At DO/FA >1.5, both ammonia and nitrite oxidation proceeded without inhibition leading to complete oxidation of ammonia to nitrate. An effluent containing nitrate as the main nitrogen species can be produced at these ratios. At a DO/FA ratio range of 0.2-1.5, ammonia oxidation proceeded without efficiency deterioration, while nitrite oxidation decreased with decreasing DO/FA ratio. At the ratios of 0.2-0.6, an effluent containing mainly nitrite can be generated. At DO/FA <0.2, both ammonia oxidation and nitrite oxidation were inhibited and the effluent with nearly equal molar of ammonia and nitrite was obtained. By controlling DO/FA ratio, effluents with different proportions of nitrogen species can be produced allowing the entrapped-cell-based system to be adaptable as an initial reactor for various nitrogen removal approaches.
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  • 文章类型: Journal Article
    A novel entrapped cells-based-anaerobic forward osmosis membrane bioreactor (E-FOMBR) was developed. Its performance and fouling were investigated in comparison with suspended cells-based-anaerobic forward osmosis membrane bioreactor (S-FOMBR). E-FOMBR and S-FOMBR were operated under the same conditions with two widely used draw solutions (NaCl and (NH4)2SO4). The membrane fouling especially irreversible fouling in S-FOMBR was more severe than that in E-FOMBR regardless of the type of draw solution. The permeate flux of E-FOMBR were 1.79 and 1.85 LMH while those of S-FOMBR were 1.49 and 1.14 LMH with NaCl and (NH4)2SO4 as draw solutions, respectively. More deterioration of biological activity (suggested by lower organic removal) due to accumulation of salt was observed in S-FOMBR compared to E-FOMBR. Proteobacteria dominated in both FOMBRs but was more abundant in E-FOMBR than S-FOMBR. The superiority of E-FOMBR over S-FOMBR included higher and stable system performance, higher flux, and longer operation time.
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  • 文章类型: Journal Article
    An entrapment of nitrifiers into gel matrix is employed as a tool to fulfill partial nitrification under non-limiting dissolved oxygen (DO) concentrations in bulk solutions. This study aims to clarify which of these two attributes, inoculum type and DO concentration in bulk solutions, is the decisive factor for partial nitrification in an entrapped-cell based system. Four polyvinyl alcohol entrapped inocula were prepared to have different proportions of nitrite-oxidizing bacteria (NOB) and nitrite-oxidizing activity. At a DO concentration of 3 mg l(-1), the number of active NOB cells in an inoculum was the decisive factor for partial nitrification enhancement. However, when the DO concentration was reduced to 2 mg l(-1), all entrapped cell inocula showed similar degrees of partial nitrification. The results suggested that with the lower bulk DO concentration, the preparation of entrapped cell inocula is not useful as the DO level becomes the decisive factor for achieving partial nitrification.
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