课程文献中心 更多>>

关键词： Bacteria resistance   Degradation by-products   Emerging contaminants   Micropollutants   Removal mechanisms  

摘要： Membrane bioreactors (MBRs) are one of the treatment technologies with the potential to remove emerging compounds from wastewater. The present work evaluated the efficiency of an MBR pilot system in removing amoxicillin from synthetic wastewater using a continuous flow pre-denitrification MBR (A/O-MBR) pilot unit. The system operated in three phases: (1) synthetic wastewater and hydraulic retention time (HRT) of 40 h;(2) adding amoxicillin 100 mu g L-1 to the influent, and (3) varying flowrate to HRT of 20 h. Liquid chromatography coupled to high resolution mass spectrometry analysis confirmed the presence of five amoxicillin degradation by-products in the effluent. The addition of amoxicillin did not affect chemical oxygen demand (COD) or dissolved organic carbon (DOC) removal efficiencies. Respirometry showed that amoxicillin level did not inhibit heterotrophic bacteria metabolism. The change in HRT reduced the DOC removal (from 84% to 66%) but did not influence COD ( > 94%) or total nitrogen (> 72%). The amoxicillin and by-products removal decreased from 80% to 54% with HRT change. Adsorption and biodegradation represented the largest removed fraction of the antibiotic in the A/O-MBR system (68%). Ecotoxicity assays showed P. fluorescens was more resistant and E. coli less resistant to amoxicillin residues at effluent sample matrix.

关键词： 电化学技术   膜生物反应器   膜污染  

摘要： 传统膜生物处理工艺存在膜污染严重以及成本高的问题,这是限制膜-生物反应器(Membranebioreactor,MBR)推广应用的主要原因。电化学MBR是近年来发展起来的新型污水处理技术,其主要利用电化学的作用原理提高MBR的过滤性能与抗污染性能。本文综述了电化学MBR的原理、影响因素和国内外相关研究与应用现状。

关键词： AnAOB   Biological nitrogen removal   Nitrification   Nutrient removal and recovery   Sludge reject water   Packed-bed biofilm reactor  

摘要： Anammox, the oxidation of ammonium with nitrite, is a key microbial process in the nitrogen cycle. Under mesophilic conditions (below 40 degrees C), it is widely implemented to remove nitrogen from wastewaters lacking organic carbon. Despite evidence of the presence of anammox bacteria in high-temperature environments, reports on the cultivation of thermophilic anammox bacteria are limited to a short-term experiment of 2 weeks. This study showcases the adaptation of a mesophilic inoculum to thermophilic conditions, and its characterization. First, an attached growth technology was chosen to obtain the process. In an anoxic fixed-bed biofilm bioreactor (FBBR), a slow linear temperature increase from 38 to over 48 degrees C (0.05-0.07 degrees C d(-1)) was imposed to the community over 220 days, after which the reactor was operated at 48 degrees C for over 200 days. Maximum total nitrogen removal rates reached up to 0.62 g N L-1 d(-1). Given this promising performance, a suspended growth system was tested. The obtained enrichment culture served as inoculum for membrane bioreactors (MBR) operated at 50 degrees C, reaching a maximum total nitrogen removal rate of 1.7 g N L-1 d(-1) after 35 days. The biomass in the MBR had a maximum specific anammox activity of 1.1 +/- 0.1 g NH4+-N g(-1) VSS d(-1), and the growth rate was estimated at 0.075-0.19 d(-1). The thermophilic cultures displayed nitrogen stoichiometry ratios typical for mesophilic anammox: 0.93-1.42 g NO2--N-removed g(-1) NH4+-N-removed and 0.16-0.35 g NO3--N-produced g(-1) NH4+-N-removed. Amplicon and Sanger sequencing of the 16S rRNA genes revealed a disappearance of the original "Ca. Brocadia" and "Ca. Jettenia" taxa, yielding Planctomycetes members with only 94-95% similarity to "Ca. Brocadia anammoxidans" and "Ca. B. caroliniensis", accounting for 45% of the bacterial FBBR community. The long-term operation of thermophilic anammox reactors and snapshot views on the nitrogen stoichiometry, kinetics and microb

关键词： 污水处理   膜生物反应器   能量消耗  

摘要： MBR主要由活性污泥反应器和横流膜组件组成,二者之间采用创新的结构。结果表明,横流膜组件和低循环流量具有能耗低、抗膜污染能力强等优点。整个系统的总能耗测试为1.97±0.74 kW·h/m^3(渗透),采用净化水定期反冲洗和混合液每日反冲洗,与淹没式膜生物反应器相同,能耗为2.4 kW·h/m^3(渗透)。系统能耗分析表明,膜组件比泵、曝气、管道系统和污泥回流速度损失四部分能耗高,占总能耗的37.66-52.20%。该系统的出水可满足中国灰水回用的要求,具有广阔的应用前景。

关键词： 开孔陶粒   同步硝化/反硝化   淡水养殖   脱氮  

摘要： 为了在常规淡水养殖条件下实现同步硝化/反硝化(SND)脱氮,研究了自制陶粒组建SND生物反应器的脱氮能力。结果表明,在陶土中添加1.5%(质量分数)纸纤维,900℃烧蚀6h,可制得内部具有丰富开孔孔隙结构的多孔陶粒;利用该陶粒构建SND生物反应器,在常规淡水养殖条件下,可顺利启动SND反应,亚硝态氮在第2天时开始显著积累,氨氮质量浓度在第6天起即可从15mg/L降至检测限以下;开孔陶粒借助内部孔隙形成好氧/厌氧微环境,抑制亚硝酸盐氧化细菌(NOB)生长并促使氨氧化细菌(AOB)成为优势菌,同时陶粒对溶液中氨氮具有选择吸附能力,促进了SND生物反应器的脱氮作用。

关键词： Osteochondral regeneration   Umbilical cord mesenchymal stem cell   Exosome   3D culture  

摘要： Animal and clinical studies have shown that mesenchymal stem cells (MSCs) play an important role in cartilage repair. The therapeutic effect of mesenchymal stem cells based therapies has been increasingly demonstrated to exosome-mediated paracrine secretion. Here, we investigated the cellular processes and mechanism of exosomes produced by conventional 2D culture (2D-Exos) and exosomes produced from 3D culture (3D-Exos) of umbilical MSCs (U-MSCs) in a hollow-fiber bioreactor for the treatment of cartilage repair. We found that the yield of 3D-Exos was 7.5-fold higher than that of 2D-Exos. The in vitro experiments indicated that both 2D-Exos and 3D-Exos can stimulate chondrocyte proliferation, migration, and matrix synthesis, and inhibit apoptosis, with 3D-Exos exerting a stronger effect than 2D-Exos. This effect was partly attributed to the activation of transforming growth factor beta 1 and Smad2/3 signaling. The injection of 2D-Exos and 3D-Exos showed enhanced gross appearance and attenuated cartilage defect;however, 3D-Exos showed a superior therapeutic effect than 2D-Exos. In summary, our study provides novel insights into the chondroprotective effects of exosomes produced from 3D culture of U-MSCs in a hollow-fiber bioreactor. Because of its promising biological function and high yield, 3D-Exos may become a promising therapeutic method for the treatment of cartilage defects.

关键词： Sugarcane vinasse   Biodegradation   Decolorization   Fungal biomass   Air-lift bioreactor   Ligninolytic enzymes  

摘要： This work evaluated the degradation of sugarcane vinasse with the production of biomass by Pleurotus sajor-caju CCB020, considering the combination of temperature and pH effects, using surface response methodology (RSM). A 2(2) complete central factorial composite experiment was used to analyze the results. The optimum temperature and pH values were respectively 27 degrees C and 5.6 for maximum decolorization yield and 20 degrees C and 6.8 for maximum biomass production. In parallel, scale-up experiments under conditions of 30 degrees C and initial pH 5.0 were evaluated in two different air-lift bioreactors of 7.0 L Under these conditions, reductions of 53% and 58% in chemical oxygen demand (COD) and 71% and 58% in biological oxygen demand (BOD) were obtained respectively with the concentric tube type air-lift bioreactor with an increased degassing zone and without an increased degassing zone. Under these conditions, this study concluded that the systematic combination of P. sajor-caju and vinasse can be applied in the biodegradation process of refractory compounds contained in vinasse, concomitant to obtaining biomass and laccase and manganese peroxidase enzymes. Due to the good performance of the air-lift bioreactors, they can be used in scale studies in future industrial vinasse applications, besides it is possible to emphasize that different configurations in the bioreactor can affect the efficiency of the process. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： membrane bioreactor   nutrients enrichment   reverse salt flux   salinity   fouling   simulation  

摘要： The effects of reverse salt diffusion through a forward osmosis membrane were studied in a microfiltration osmotic membrane bioreactor. The reactor was used to treat and simultaneously concentrate nutrients from wastewater. The system was operated at different draw solution concentrations, leading to varying salinity conditions. A relatively low, yet stable forward osmosis flux was observed regardless of increasing draw solution conductivities from 10 to 50 mS cm(-1). A substantial increase in sludge conductivity from 5.7 to 19.8 mS cm(-1) was observed during the operation. Batch transmembrane pressure-step experiments showed a decline in sludge filtration properties with increasing salinity buildup in sludge due to increasing deflocculation and associated release of protein and carbohydrate fractions of extracellular polymeric substances. Mathematical simulations showed that accumulation of total dissolved solids could mainly be attributed to reverse flux of salts from the draw solution rather than by the enrichment of incoming nutrients when forward osmosis membrane's salt permeability was high and water permeability low. Ideally, salt permeability below 0.010 L m(-2) h(-1) and effective water permeability above 0.13 L m(-2) h(-1) bar(-1) are crucial to ensure enhanced nutrient enrichment and reduce sludge osmotic pressure, microbial inactivation, sludge deflocculation and membrane fouling.

摘要： 783

关键词： Biological nutrient removal   Membrane bioreactor   IFAS   Membrane fouling   Respirometry  

摘要： The present paper investigated an Integrated Fixed Film Activated Sludge (IFAS) Membrane BioReactor (MBR) system monitored for 340 days. In particular, the short-term effects of some operational parameters variation was evaluated. Results showed a decrease of the removal rates under low C/N values. Respirometry results highlighted that activated sludge was more active in the organic carbon removal. Conversely, biofilm has a key role during nitrification. The major fouling mechanism was represented by the cake deposition (irreversible).