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Adav S.S.,National Taiwan University | Lin J.C.-T.,National Taiwan University | Yang Z.,Tsinghua University | Whiteley C.G.,Microbiology | And 3 more authors.
Biotechnology Advances | Year: 2010

This review addresses the introduction of fluorescent molecular tags into exo-enzymes and extra polymeric substances of bioaggregates and the use of confocal laser scanning microscopy (CLSM) to map their role, purpose and quantitative description of the biological processes they undertake. Multiple color staining coupled with CLSM and fluorescent in situ hybridisation (FISH) and flow cytometry have identified the individual polymeric substances, whether they are proteins, lipids, polysaccharides, nucleic acids or antibodies, as well as the microorganisms in the bioaggregate. Procedures are presented for simultaneous multicolor staining with seven different fluorochromes - SYTOX Blue for nucleic acids; Nile red for lipids; Calcofluor white [CW] for β-polysaccharides; concanavalin A [Con A] for α-poly-saccharides; fluorescein-isothiocyanate [FITC] for proteins; SYTO 63 for live microbial cells and Calcium Green for monitoring calcium levels in the microbial cells. For the distribution of certain microbial strains, metabolic enzymes and extrapolymeric substances to be quantitatively described the generated colored images are converted into digital forms under specific predefined criteria. Procedures and computer software programs (Amira; MATLAB) are presented in order to quantitatively establish grid patterns from the CLSM images. The image is digitized using a threshholding algorithm followed by a reconstruction of the image as a volumetric grid for finite element simulation. The original color image is first converted to a grey followed by resizing, detection and modification of bilevel images and finally a total reversal of the image colors. The grid file is then used by specific computer software (Gambit, Fluent) for further numerical studies incorporating chemical reactions, transport processes and computational fluid dynamics including intra-bioaggregate fluid flow, and heat and mass transfer within the bioaggregate matrix. © 2009 Elsevier Inc. All rights reserved.


Show K.-Y.,University Tunku Abdul Rahman | Zhang Z.-P.,Beijing Enterprises Water Group Ltd | Tay J.-H.,Nanyang Technological University | Liang D.T.,Nanyang Technological University | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2010

Production of biohydrogen using dark fermentation has received much attention owing to the fact that hydrogen can be generated from renewable organics including waste materials. The key to successful application of anaerobic fermentation is to uncouple the liquid retention time and the biomass retention time in the reactor system. Various reactor designs based on biomass retention within the reactor system have been developed. This paper presents our research work on bioreactor designs and operation for biohydrogen production. Comparisons between immobilized-cell systems and suspended-cell systems based on biomass growth in the forms of granule, biofilm and flocs were made. Reactor configurations including column- and tank-based reactors were also assessed. Experimental results indicated that formation of granules or biofilms substantially enhanced biomass retention which was found to be proportional to the hydrogen production rate. Rapid hydrogen-producing culture growth and high organic loading rate might limit the application of biofilm biohydrogen production, since excessive growth of fermentative biomass would result in washout of support carrier. It follows that column-based granular sludge process is a preferred choice of process for continuous biohydrogen production from organic wastewater, indicating maximum hydrogen yield of 1.7 mol-H 2/mol-glucose and hydrogen production rate of 6.8 L-H 2/L-reactor h. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.


Meng T.-T.,Beijing Enterprises Water Group Ltd. | Meng T.-T.,Beijing Beihuaqingchuang Environmental Science and Technology Co. | Meng T.-T.,CAS Institute of Botany | Wang H.,Northwest Agriculture and Forestry University | And 10 more authors.
Biogeosciences | Year: 2015

Dynamic global vegetation models (DGVMs) typically rely on plant functional types (PFTs), which are assigned distinct environmental tolerances and replace one another progressively along environmental gradients. Fixed values of traits are assigned to each PFT; modelled trait variation along gradients is thus driven by PFT replacement. But empirical studies have revealed "universal" scaling relationships (quantitative trait variations with climate that are similar within and between species, PFTs and communities); and continuous, adaptive trait variation has been proposed to replace PFTs as the basis for next-generation DGVMs.

Here we analyse quantitative leaf-trait variation on long temperature and moisture gradients in China with a view to understanding the relative importance of PFT replacement vs. continuous adaptive variation within PFTs. Leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC) and nitrogen content of dry matter were measured on all species at 80 sites ranging from temperate to tropical climates and from dense forests to deserts. Chlorophyll fluorescence traits and carbon, phosphorus and potassium contents were measured at 47 sites. Generalized linear models were used to relate log-transformed trait values to growing-season temperature and moisture indices, with or without PFT identity as a predictor, and to test for differences in trait responses among PFTs.

Continuous trait variation was found to be ubiquitous. Responses to moisture availability were generally similar within and between PFTs, but biophysical traits (LA, SLA and LDMC) of forbs and grasses responded differently from woody plants. SLA and LDMC responses to temperature were dominated by the prevalence of evergreen PFTs with thick, dense leaves at the warm end of the gradient. Nutrient (N, P and K) responses to climate gradients were generally similar within all PFTs. Area-based nutrients generally declined with moisture; Narea and Karea declined with temperature, but Parea increased with temperature.

Although the adaptive nature of many of these trait-climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits. Finally, models should take account of the diversity of trait values that is found in all sites and PFTs, representing the "pool" of variation that is locally available for the natural adaptation of ecosystem function to environmental change. © Author(s) 2015. CC Attribution 3.0 License.


Shi X.,Tsinghua University | Lin J.,Beijing Enterprises Water Group Ltd | Zuo J.,Tsinghua University | Li P.,Tsinghua University | And 2 more authors.
Journal of Environmental Sciences (China) | Year: 2016

The effect of free ammonia on volatile fatty acid (VFA) accumulation and process instability was studied using a lab-scale anaerobic digester fed by two typical bio-wastes: fruit and vegetable waste (FVW) and food waste (FW) at 35°C with an organic loading rate (OLR) of 3.0kg VS/(m3·day). The inhibitory effects of free ammonia on methanogenesis were observed due to the low C/N ratio of each substrate (15.6 and 17.2, respectively). A high concentration of free ammonia inhibited methanogenesis resulting in the accumulation of VFAs and a low methane yield. In the inhibited state, acetate accumulated more quickly than propionate and was the main type of accumulated VFA. The co-accumulation of ammonia and VFAs led to an "inhibited steady state" and the ammonia was the main inhibitory substance that triggered the process perturbation. By statistical significance test and VFA fluctuation ratio analysis, the free ammonia inhibition threshold was identified as 45mg/L. Moreover, propionate, iso-butyrate and valerate were determined to be the three most sensitive VFA parameters that were subject to ammonia inhibition. © 2016.


Lin J.,Tsinghua University | Lin J.,Beijing Enterprises Water Group Ltd | Zuo J.,Tsinghua University | Chen X.,Tsinghua University | And 2 more authors.
Tongji Daxue Xuebao/Journal of Tongji University | Year: 2012

An intelligent algorithm rule-based on expert library for high-solid anaerobic digestion process was developed and applied in a pilot-scale continuous stirred-tank reactor (CSTR) treating fruit and vegetable waste and food waste. The intelligent control system includes a quick-start model, an efficient and stable operation model and a potential model. The CSTR was automatically controlled by the intelligent control system over 260 d. The pH value was stable at 7.8. The volatile solid organic loading rate and biogas production rate were 2.25 kg·(m3·d)-1and 1.8 m3·(m3·d)-1(standard condition), respectively.


Guo W.-Q.,Harbin Institute of Technology | Meng Z.-H.,Harbin Institute of Technology | Meng Z.-H.,China North Municipal Engineering Design Institute | Ren N.-Q.,Harbin Institute of Technology | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2011

The optimization of process conditions for the production of hydrogen by Ethanoligenens harbinense W1 was investigated using response surface methodology (RSM). Three parameters namely inoculum to substrate ratio, initial pH value and temperature were chosen as variables. The adequately high R2 value (99.4%) indicated the statistical significance of the model. The optimum process conditions for hydrogen production rate were determined by analyzing the response surface three-dimension surface plot and contour plot and by solving the regression model equation with Design Expert software. The central composite design (CCD) was used to optimize the process conditions, which showed that an inoculum to substrate ratio of 14%, initial pH value of 4.32 and the experimental temperature of 34.97 °C were the best conditions. Under the optimized conditions, the maximum specific hydrogen production rate (SHPR) was 35.74 mL/g-CDW.h based on cell dry weight. The results were further verified by triplicate experiments. The batch reactors were operated under an optimized condition of the inoculum to substrate ratio of 14%, initial pH value of 4.3 and the experimental temperature of 35 °C. The maximum SHPR was estimated at 35.57 mL/g-CDW.h, which further verified the practicability of this optimum strategy. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.


Xue X.,Beijing Enterprises Water Group Ltd | Liu Y.,Jianghan University | Shao Y.,Beijing Enterprises Water Group Ltd | Deng N.,Wuhan University
Advanced Materials Research | Year: 2011

This study investigated the decolorization of Rhodamine B by the UV/Fe(III)-Oxalate and UV/Fe(III)-Penicillamine process under neutral pH. Fe(III)-Penicillamine complexes showed much higher photoactivity than that of Fe(III)-Oxalate complexes. The efficiency for decolorization of Rhodamine B at pH 5.0 was 59% and 88% in Fe(III)-Oxalate and Fe(III)-Penicillamine complexes aqueous solution after 60 min irradiation, respectively, whereas, 35% and 57% was achieved at pH 7.0. Compared to the Fe(III)/Oxalate system, the kinetic constants k app (min -1) for Rhodamine B decolorization in Fe(III)/Penicillamine system increased 2.4 and 2.0 times at pH 5.0 and 7.0, respectively. According to the obtained results, it was quite reasonable to conclude that penicillamine should play a similar role in Fe(III)-Penicillamine aqueous solution as oxalate did in Fe(III)-Oxalate solution. The results obtained indicated that the UV/Fe(III)-Penicillamine process was probably an alternative method to treat dye pollutant at neutral pH condition. © (2011) Trans Tech Publications.

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