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Sample records for autotrophic nitrifying bioreactor

  1. Fate of 14C-labeled microbial products derived from nitrifying bacteria in autotrophic nitrifying biofilms

    OpenAIRE

    Okabe, Satoshi; Kindaichi, Tomonori; Ito, Tsukasa

    2005-01-01

    The cross-feeding of microbial products derived from 14C-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [14C] bicarbonate, biofilm samples were incubated with and without NH4+ as a sole energy source for 10 days. The transfer of 14C originally incorporated into nitrifying b...

  2. Autotrophic growth of nitrifying community in an agricultural soil

    OpenAIRE

    Xia, Weiwei; Zhang, Caixia; Zeng,Xiaowei; Feng, Youzhi; Weng, Jiahua; Lin, Xiangui; Zhu, Jianguo; Xiong, Zhengqin; Xu, Jian; Cai, Zucong; Jia, Zhongjun

    2011-01-01

    The two-step nitrification process is an integral part of the global nitrogen cycle, and it is accomplished by distinctly different nitrifiers. By combining DNA-based stable isotope probing (SIP) and high-throughput pyrosequencing, we present the molecular evidence for autotrophic growth of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and nitrite-oxidizing bacteria (NOB) in agricultural soil upon ammonium fertilization. Time-course incubation of SIP microcosms indicated t...

  3. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    OpenAIRE

    B. Veuger; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J.S.; Middelburg, J. J.

    2013-01-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC in the presence and absen...

  4. [Performance of internal-loop air-lift nitrifying bioreactor].

    Science.gov (United States)

    Lin, Feng-Mei; Zheng, Ping; Zhao, Yang-Yang; Hu, Bao-Lan; Chen, Jian-Song

    2002-07-01

    The performance of internal-loop air-lift nitrifying bioreactor was good with strong tolerance to influent ammonia concentration (78.49 mmol/L), high volume converting rate (163.18 mmol/L.d) and obvious working stability (ammonia removal > 94.42%). During operation of internal-loop air-lift bioreactor, the nitrifying activated sludge was granulated. The nitrifying granular activated sludge began to appear on day 45. Its average diameter was 0.83 mm, settling velocity was 55.53 m/h and specific ammonia removal rate was 0.95 mmol (NH4(+)-N)/g (VS).d. The nitrifying granular activated sludge had the activity for anaerobic ammonia oxidation with ammonia oxidation rate of 0.23 mmol (NH4(+)-N)/g(VS).d and nitrite reduction rate of 0.24 mmol (NO2(-)-N)/g(VS).d. PMID:12385250

  5. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Science.gov (United States)

    Veuger, B.; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J. S.; Middelburg, J. J.

    2013-03-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon) in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate) in combination with compound-specific stable isotope (13C) analysis of bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41-221 nmol N L-1 h-1). Ammonium assimilation was always substantially lower than nitrification - with nitrification on average contributing 89% (range 73-97%) to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27-95 %). The inhibitor-sensitive 13C-PLFA (phospholipid-derived fatty acid) pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance (16S rRNA and amoA (ammonia monooxygenase)). These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance measurements only, in order to

  6. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Directory of Open Access Journals (Sweden)

    B. Veuger

    2013-03-01

    Full Text Available Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate in combination with compound-specific stable isotope (13C analysis of bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41–221 nmol N L−1 h−1. Ammonium assimilation was always substantially lower than nitrification – with nitrification on average contributing 89% (range 73–97% to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27–95 %. The inhibitor-sensitive 13C-PLFA (phospholipid-derived fatty acid pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance (16S rRNA and amoA (ammonia monooxygenase. These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance

  7. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Directory of Open Access Journals (Sweden)

    B. Veuger

    2012-11-01

    Full Text Available Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate in combination with compound-specific stable isotope (13C analysis of bacterial- and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41–221 nmol N l−1h−1. Ammonium assimilation was always substantially lower than nitrification with nitrification on average contributing 89% (range 73–97% to total ammonium consumption.

    13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27–95%. The inhibitor-sensitive 13C-PLFA pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. Cell-specific 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance. These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance

  8. Incidence of plant cover over the autotrophic nitrifying bacteria population in a fragment of Andean forest

    International Nuclear Information System (INIS)

    It was determined the incidence of plant cover (forest vs. pasture), on the autotrophy nitrifying bacteria, through the effect of biotic factors (radical exudate) and abiotic factors (temperature, ph and humidity), in a high mountain cloud forest fragment. The site of study was located near La Mesa (Cundinamarca) municipality. The temperature of soil was measured in situ, and soil samples were collected and carried to the laboratory for pH and humidity percentage measurements. Serial soil dilution method was used for plating samples on a selective culture medium with ammonium sulphate as nitrogen source, in order to estimate the autotrophic nitrifying bacteria population levels. Grown colonies were examined macro and microscopically. The quantity of nitrates produced by bacteria cultured in vitro was determined spectra-photometrical. In relation to the abiotic factors, there was no significant differences of pH between both plant covers, but there were significant for soil humidity and temperature (p<0.05). There were highly significant differences with respect to the bacteria population levels (p<0.0001) and with respect to nitrate production. This suggests a higher bacterial activity in the under forest cover. The radical exudate from both types of plant cover reduced the viability of bacteria in vitro, from 1:1 to 1:30 exudate bacteria proportions. In the soils physical and chemical analysis, it was found a higher P and Al concentrations, and a higher CIC and organic matter content under the forest cover. It is suggested the importance of this functional group in this ecosystem

  9. Two-step nitrification in a pure moving bed biofilm reactor-membrane bioreactor for wastewater treatment: nitrifying and denitrifying microbial populations and kinetic modeling.

    Science.gov (United States)

    Leyva-Díaz, J C; González-Martínez, A; Muñío, M M; Poyatos, J M

    2015-12-01

    The moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) is a novel solution to conventional activated sludge processes and membrane bioreactors. In this study, a pure MBBR-MBR was studied. The pure MBBR-MBR mainly had attached biomass. The bioreactor operated with a hydraulic retention time (HRT) of 9.5 h. The kinetic parameters for heterotrophic and autotrophic biomasses, mainly nitrite-oxidizing bacteria (NOB), were evaluated. The analysis of the bacterial community structure of the ammonium-oxidizing bacteria (AOB), NOB, and denitrifying bacteria (DeNB) from the pure MBBR-MBR was carried out by means of pyrosequencing to detect and quantify the contribution of the nitrifying and denitrifying bacteria in the total bacterial community. The relative abundance of AOB, NOB, and DeNB were 5, 1, and 3%, respectively, in the mixed liquor suspended solids (MLSS), and these percentages were 18, 5, and 2%, respectively, in the biofilm density (BD) attached to carriers. The pure MBBR-MBR had a high efficiency of total nitrogen (TN) removal of 71.81±16.04%, which could reside in the different bacterial assemblages in the fixed biofilm on the carriers. In this regard, the kinetic parameters for autotrophic biomass had values of YA=2.3465 mg O2 mg N(-1), μm, A=0.7169 h(-1), and KNH=2.0748 mg NL(-1). PMID:26264139

  10. Extraction and structural characteristics of extracellular polymeric substances (EPS), pellets in autotrophic nitrifying biofilm and activated sludge.

    Science.gov (United States)

    Liang, Zhiwei; Li, Wenhong; Yang, Shangyuan; Du, Ping

    2010-10-01

    The composition and the distribution of extracellular polymeric substances (EPS) and pellets of autotrophic nitrifying biofilm and activated sludge were investigated in this work. Fourier-transform Infrared Spectroscopy, fluorescent in situ hybridization and fluorescence staining were used to examine proteins, carbohydrates, humic substances and DNA being present in the biofilms and the sludge samples. To investigate extraction efficiency and its effect on characterization of tightly bounded EPS, four extraction methods (ethylenediamine tetraacetic acid (EDTA), NaOH, cationic exchange resin (CER), ultrasound) were compared. EDTA and ultrasound showed more effective extraction ability than NaOH and CER. NaOH and ultrasound extraction led to high activity of glucose-6-phosphate dehydrogenase from cell lysis, which was confirmed by fluorescence staining analysis. Ultrasound and NaOH extraction yielded 18% and 11% of dead cells in biofilm, respectively, whereas they obtained 11% and 9% of dead cells in activated sludge, respectively. Four layers of extractible products were separated from autotrophic nitrifiering flocs. The extraction results indicated that extraction yield in different layers varied in a wide range: 3-6% of soluble EPS, 5-10% of loosely bound EPS, 34-67% of tightly bound EPS and 30-60% of pellets. PMID:20655088

  11. Activated sludge filterability improvement by nitrifying bacteria abundance regulation in an adsorption membrane bioreactor (Ad-MBR).

    Science.gov (United States)

    Sun, Fei-yun; Lv, Xiao-mei; Li, Ji; Peng, Zhong-yi; Li, Pu; Shao, Ming-fei

    2014-10-01

    Autotrophic nitrifying bacteria have its intrinsic properties including low EPS production, dense colonial structure and slow-growth rate, favoring the sludge filterability improvement. An adsorption-MBR (Ad-MBR) was developed to enrich nitrifier abundance in the MBR chamber by inlet C/N regulation, and its possible positive effect on sludge filterability and underlying mechanisms were investigated. By DNA extraction, PCR amplification and Illumina high-throughput pyrosequencing, the abundance of nitrifying bacteria was accurately quantified. More than 8.29% nitrifier abundance was achieved in Ad-MBR sludge, which was above three times of that in conventional MBR. Regulated C/N ratio and thereafter nitrifier abundance enrichment improved sludge filterability by altering sludge mixture and its supernatant properties, reflected by a good sludge settleability, a low supernatant viscosity and turbidity, a low supernatant organic substances concentration, and a small amount of strong hydrophobic fractional components, thus to profoundly improve sludge filterability and decelerate membrane fouling. PMID:25146315

  12. Microbial community structure in autotrophic nitrifying granules characterized by experimental and simulation analyses

    DEFF Research Database (Denmark)

    Matsumoto, S.; Katoku, M.; Saeki, G.;

    2010-01-01

    the bacterial distribution obtained by fluorescence in situ hybridization analysis, as well as the measured oxygen, nitrite, nitrate and ammonium concentration profiles. Results of this study are important because they show that a combination of simulation and experimental techniques can better......This study evaluates the community structure in nitrifying granules (average diameter of 1600 mu m) produced in an aerobic reactor fed with ammonia as the sole energy source by a multivalent approach combining molecular techniques, microelectrode measurements and mathematical modelling...... groups also became evident from a 16S rRNA clone library. Microprofiles of NH4+, NO2-, NO3- and O-2 concentrations measured with microelectrodes showed good agreement with the spatial organization of nitrifying bacteria. One- and two-dimensional numerical biofilm models were constructed to explain the...

  13. The effect of clay particles on the activity of suspended autotrophic nitrifying bacteria and on the performance of an air-lift reactor

    OpenAIRE

    Vieira, M. J.; Pacheco, A. P.; I. A. Pinho; Melo, L. F.

    2001-01-01

    Clay minerals have some properties, namely a high surface area and the ability of ion exchange that may exert some effects on microbial systems. It is often difficult to know the way the clay is exerting its influence and whether its presence improves a given metabolic process The present work concerns the study of the effect of the addition of Powdered kaolin to autotrophic nitrification systems, and includes the study of the effects of the particles on the activity of a suspended nitrifying...

  14. Autotrophic ammonia removal from landfill leachate in anaerobic membrane bioreactor.

    Science.gov (United States)

    Suneethi, S; Joseph, Kurian

    2013-01-01

    Anaerobic ammonium oxidation (ANAMMOX) process, an advanced biological nitrogen removal, removes ammonia using nitrite as the electron acceptor without oxygen. In this paper, ANAMMOX process was adopted for removing NH4+-N from landfill leachate having low COD using anaerobic membrane bioreactor (AnMBR). The AnMBR was optimized for nitrogen loading rate (NLR) varying from 0.025 to 5 kg NH4+-N/m3/d with hydraulic retention time (HRT) ranging from 1 to 3d. NH4+-N removal efficacy of 85.13 +/- 9.67% with the mean nitrogen removal rate of 5.54 +/- 0.63 kg NH4+-N/m3/d was achieved with NLR of 6.51 +/- 0.20kg NH4+-N/m3/d at 1.5 d HRT. The nitrogen transformation intermediates in the form of hydrazine (N2H4) and hydroxylamine (NH2OH) were 0.008 +/- 0.005 and 0.006 +/- 0.001 mg/l, respectively, indicating co-existence of aerobic ammonia oxidizers and ANAMMOX. The free ammonia (NH3) and free nitrous acid (HNO2) concentrations were 26.61 +/- 16.54 mg/l and (1.66 +/- 0.95) x 10(-5) mg/l, preventing NO2(-)-N oxidation to NO3(-)-N enabling sustained NH4+-N removal. PMID:24617075

  15. Nitrifying treatment of wastewater from fertilizer production in a three-phase flow airlift loop bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Jianping, W.; Lei, P.; Xiaojing, X.; Zhiyong, Z. [Department of Biochemical Engineering, College of Chemical Engineering, Tianjin University, Tianjin 300072 (China)

    2003-06-01

    A 12-L gas-liquid-solid three-phase flow airlift loop bioreactor, in which biological membranes replace the activated sludge, was used in the nitrifying treatment of a real effluent in a Nanjing chemical fertilizer plant. The influences of temperature, pH, air flow rate and HRT on ammonia nitrogen reduction were investigated and discussed. The optimum operating conditions, such as temperature of 30-35 C, pH value of 7-8, air influx of 0.3 m{sup 3}/h, and hydraulic residence time (HRT) of 8 hours, were found. Under optimum operating conditions, the average removal efficiencies of COD and NH{sub 4}-N are higher than 95 % and 99 %, corresponding to the effluent COD < 50 mg/L and NH{sub 4}-N < 5 mg/L, which is far below the primary discharge standard for the chemical fertilizer industry of P.R. China - COD < 150 mg/L and NH{sub 4}-N < 60 mg/L (GWPB4-1999). In addition, the radial and axial positions have little influence on the local profiles of COD and NH{sub 4}-N. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  16. The effect of hydroxylamine on the activity and aggregate structure of autotrophic nitrifying bioreactor cultures

    DEFF Research Database (Denmark)

    Harper, W.F.; Terada, Akihiko; Poly, F.;

    2009-01-01

    by qPCR results showing that the copy numbers of amoA and nxrA genes gradually decreased by LIP to an order-of-magnitude. Longer term NH2OH addition damaged the active biomass. This research clarifies the effect of NH2OH on nitrification and demonstrates the need to incorporate NH2OH-related dynamics...

  17. 自养硝化污泥除磷能力研究%Study on the capacity of phosphorus removal of autotrophic nitrifying sludge

    Institute of Scientific and Technical Information of China (English)

    南亚萍; 袁林江; 赵倩; 李扬扬; 王晓昌

    2011-01-01

    The phosphorus uptake by autotrophic nitrifying bacteria was studied. The nitrifying bacteria phosphorus uptake ability discussed was fed with different nutrient with ammonia, inorganic carbon and ammonia, inorganic carbon when cultured under anaerobic/aerobic condition. Results indicated that in the condition similar to EBPR of phosphate accumulating organisms, phosphorus could not be removed by the nitrifying bacteria. Cell dyeing displayed that they had no PHB granules or poly-P granules. The nitrifying bacteria had no clear phosphorus removal ability cultured in the traditional mode of phosphorus removal of phosphate accumulating bacteria. The phenomenon and the reasons caused by energy utilization,nutritional type and culture conditions were discussed.%采用静态试验对自养硝化污泥的除磷特性进行研究.分别提供氨、无机碳源和氨、无机碳源三种营养条件,考察了厌氧—好氧交替环境下硝化细菌摄取磷酸盐的情况.结果表明:在与聚磷菌的运行模式相对应的条件下,硝化污泥无除磷效果;通过染色观察,硝化细菌体内几乎没有PHB颗粒及异染颗粒;按照传统聚磷菌除磷模式培养的硝化细菌未表现出明显的除磷特性.论文从能量利用、营养类型及培养条件等方面对该现象和产生的原因进行了分析.

  18. Drinking Water Denitrification using Autotrophic Denitrifying Bacteria in a Fluidized Bed Bioreactor 

    Directory of Open Access Journals (Sweden)

    Abdolmotaleb Seid-mohammadi

    2013-02-01

    Full Text Available Background and Objectives: Contamination of drinking water sources with nitrate may cause adverse effects on human health. Due to operational and maintenance problems of physicochemical nitrate removal processes, using biological denitrification processes have been performed. The aim of this study is to evaluate nitrate removal efficiency from drinking water using autotrophic denitrifying bacteria immobilized on sulfur impregnated activated carbon in a fluidized bed bioreactor. Materials and Methods: After impregnating activated carbon by sulfur as a microorganism carriers and enrichment and inoculation of denitrifying bacteria, a laboratory-scale fluidized bed bioreactor was operated. Nitrate removal efficiency, nitrite, turbidity, hardness and TOC in the effluent were examined during the whole experiment under various conditions including constant influent nitrate concentration as 90 mg NO3--N/l corresponding to different HRT ranging from 5.53 to 1.5 hr. Results: We found that  the denitrification rates was depended on the hydraulic retention time and the nitrate removal efficiency was up to 98%  and nitrite concentration was lower than 1mg/l at optimum HRT=2.4 hr respectively. Moreover, there was no difference in hardness between influent and effluent due to supplying sodium bicarbonate as carbon source for denitrifying bacteria.  However pH, TOC, hardness, and turbidity of the effluent met the W.H.O guidelines for drinking water.  Conclusion: This study demonstrated that an innovative carrier as sulfur impregnated activated carbon could be used as both the biofilm carrier and energy source for treating nitrate contaminated drinking water in the lab-scale fluidized bed bioreactor.

  19. Thaumarchaeotes abundant in refinery nitrifying sludges express amoA but are not obligate autotrophic ammonia oxidizers

    OpenAIRE

    Mußmann, M; Brito, I.; A. Pitcher; Hatzenpichler, R.; Richter, A; Nielsen, J. L.; Nielsen, P. H.; Daims, H.; MÜller, A.; Wagner, M.; Head, I.M.

    2011-01-01

    Nitrification is a core process in the global nitrogen cycle that is essential for the functioning of many ecosystems. The discovery of autotrophic ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota has changed our perception of the microbiology of nitrification, in particular since their numerical dominance over ammonia-oxidizing bacteria (AOB) in many environments has been revealed. These and other data have led to a widely held assumption that all amoA-encoding members of the...

  20. Thaumarchaeotes abundant in refinery nitrifying sludges express amoA but are not obligate autotrophic ammonia oxidizers

    OpenAIRE

    Mußmann, Marc; Brito, Ivana; Pitcher, Angela; Sinninghe Damsté, Jaap S.; Hatzenpichler, Roland; Richter, Andreas; Nielsen, Jeppe L.; Nielsen, Per Halkjær; Müller, Anneliese; Daims, Holger; WAGNER, MICHAEL; Head, Ian M.

    2011-01-01

    Nitrification is a core process in the global nitrogen cycle that is essential for the functioning of many ecosystems. The discovery of autotrophic ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota has changed our perception of the microbiology of nitrification, in particular since their numerical dominance over ammonia-oxidizing bacteria (AOB) in many environments has been revealed. These and other data have led to a widely held assumption that all amoA-encoding members of the...

  1. The effect of clay particles on the activity of suspended autotrophic nitrifying bacteria and on the performance of an air-lift reactor.

    Science.gov (United States)

    Vieira, M J; Pacheco, A P; Pinho, I A; Melo, L F

    2001-02-01

    Clay minerals have some properties, namely a high surface area and the ability of ion exchange that may exert some effects on microbial systems. It is often difficult to know the way the clay is exerting its influence and whether its presence improves a given metabolic process. The present work concerns the study of the effect of the addition of powdered kaolin to autotrophic nitrification systems, and includes the study of the effects of the particles on the activity of a suspended nitrifying bacteria consortium and on the performance of an air-lift biofilm reactor used for tertiary nitrification. Concerning the suspended culture, kaolin particles produced stimulation on the specific endogenous and exogenous respiration rates of the bacteria, probably due to a nutritional effect supplied by the clay. This effect was more pronounced for the ammonia oxidation rates, although nitrite oxidation was also enhanced but to a lesser extent. In respect to the presence of kaolin particles in the air-lift reactor, the results obtained indicate that the clay particles become incorporated in the biofilm pellets, but do not change significantly their thickness or their shape. However, nitrate production decreased when the concentration of particles increased. The low adsorption of ammonia by the kaolin indicated that the clay particles embedded in the biofilm did not probably retain the ions. Although it was not proved, precipitation of salts may have occurred. PMID:11349371

  2. Nitrous oxides reduction pathways induced during nitrified leachate recirculation in bioreactor landfill; Voies de reduction des oxydes d'azote lors de leur injection dans un massif de dechets menagers et assimiles: contribution a l'etude de la recirculation de lixiviat nitrifie dans une installation de stockage de dechets menagers et assimiles bioactive

    Energy Technology Data Exchange (ETDEWEB)

    Vigneron, V.

    2005-12-15

    Nitrified leachate recirculation in bioreactor landfill has been proposed to avoid ammonium accumulation. We worked on the identification of nitrous oxides reduction pathways induced when nitrified leachate is recirculated during waste degradation. Batch reactors (1.1 liter, 40 g of reconstituted Municipal Solid Waste, MSW) were operated at 35 deg C and saturated with leachate. Injections of 250 mg N-NO{sub x}.10{sup -1} were performed during different phases of waste biodegradation. Nitrate reduction during acido-genic and active methanogenic phases, with an easily available carbon source in leachate, was mainly attributed to heterotrophic denitrification. However, H{sub 2}S concentration up to 0.7 % in the biogas (corresponding to 0.5 mmol of free H{sub 2}S per liter of leachate) led to prevalent DNRA (Dissimilatory Nitrate Reduction to Ammonium) over denitrification. This reaction hindered the release of nitrogen outside of the system. This observation was confirmed with experiments performed with {sup 15}N enriched nitrate. During late methanogenic phase, without any available carbon source in leachate, nitrate was reduced by autotrophic denitrification with sulfide as an electron donor. No free metal was detected in the leachate. N{sub 2}O transient accumulation was detected during both DNRA and autotrophic denitrification. A second set of experiments was conducted in a MSW pilot scale column (0.2 m{sup 3}, 80 kg of reconstituted waste) in methanogenic phase. 113 % and 203 % of nitrate were converted into N{sub 2} when a synthetic KNO{sub 3} solution (280 mg N.day{sup -1} during 77 days) or nitrified leachate (61 mg N.day{sup -1} during 54 days) were respectively injected into the system. The downward movement of a denitrification front passing through the waste mass was followed using 3 redox probes inserted at different levels of the pilot. Even if N{sub 2}O was never detected, a small production of this gas could not be totally excluded. It was established

  3. Management of microbial community composition, architecture and performance in autotrophic nitrogen removing bioreactors through aeration regimes

    DEFF Research Database (Denmark)

    Mutlu, A. Gizem

    Completely autotrophic nitrogen removal from nitrogen-rich wastewaters through the nitritation -plus- anaerobic ammonium oxidation processes can greatly reduce operational energy costs compared to traditional nitrogen removal processes. The footprint can be further reduced by process intensificat......Completely autotrophic nitrogen removal from nitrogen-rich wastewaters through the nitritation -plus- anaerobic ammonium oxidation processes can greatly reduce operational energy costs compared to traditional nitrogen removal processes. The footprint can be further reduced by process...... some of the collateral impacts could be isolated, increasing process understanding. It was demonstrated that aeration strategy can be used as a powerful tool to manipulate the microbial community composition, its architecture and reactor performance. We suggest operation via intermittent aeration with...

  4. 生物膜内自养硝化菌与异养菌竞争关系的研究进展%Progress on Competition between Autotrophic Nitrifying Bacteria and Heterotrophic Bacteria in Biofilm

    Institute of Scientific and Technical Information of China (English)

    殷峻; 徐恒娟

    2013-01-01

    As one of efficient technologies in biological removal of organic matter and nitrogen,biofilm technology has been widely applied to the industrial and domestic wastewater treatment in the past decades.But during the practical wastewater treatment,insufficient and instable nitrogen removal often occurs.At present,many research mainly focused reactor performance,biofilm formation,hydrodynamics,mass transfer and reaction kinetics in the biofilm reactor.However,the competition between different microorganisms directly affects morphology,stability and conversion efficiency of biofilm.In this paper,the affecting factors were discussed,especially competition between autotrophic nitrifying bacteria and heterotrophic bacteria.Future issues were also proposed.%生物膜工艺作为一种高效的生物除碳脱氮技术,近20年来被广泛应用于工业废水和城市生活污水的生物处理.但在实际污水处理过程中,生物膜系统往往会出现脱氮效果不稳定的情况.目前大量的研究工作主要集中在系统的处理效率、生物膜形成、流体力学、传质以及反应动力学特性等方面.而生物膜内微生物之间的竞争关系直接影响到生物膜的形态、稳定性以及转化效率.本文针对生膜工艺及其影响因素对生物膜中自养硝化菌和异养菌竞争的研究进展进行了综述,并提出了值得进一步研究的内容.

  5. Bioreactor

    Science.gov (United States)

    1996-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues currently being cultured in rotating bioreactors by investigators

  6. Bioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Jamaleddine, E. [McGill Univ., Montreal, PQ (Canada). Dept. of Bioresource Engineering

    2010-07-01

    Composting is once again gaining interest among ecological engineers in view of greener industrial and residential activities. Uniform composting is needed to ensure decomposition and to keep the whole system at the same composting stage. A homogeneous temperature must be maintained throughout the media. A bioreactor design consisting of a heater core made of copper tubing was designed and tested. Two four-inch holes were made at the top and bottom of the barrel to allow air to flow through the system and promote aerobic composting. Once composting began and temperature increased, the water began to flow through the copper piping and the core heat was distributed throughout the medium. Three thermocouples were inserted at different heights on a 200 litre plastic barrel fitted with the aforementioned apparatus. Temperature variations were found to be considerably lower when the apparatus was operated with the heat redistribution system, enabling uniform composting, accelerating the process and reducing the risks of pathogenic or other contaminants remaining active in the barrels.

  7. Nitrification in brackish water recirculating aquaculture system integrated with activated packed bed bioreactor.

    Science.gov (United States)

    Rejish Kumar, V J; Joseph, Valsamma; Philip, Rosamma; Bright Singh, I S

    2010-01-01

    Recirculation aquaculture systems (RAS) depend on nitrifying biofilters for the maintenance of water quality, increased biosecurity and environmental sustainability. To satisfy these requirements a packed bed bioreactor (PBBR) activated with indigenous nitrifying bacterial consortia has been developed and commercialized for operation under different salinities for instant nitrification in shrimp and prawn hatchery systems. In the present study the nitrification efficiency of the bioreactor was tested in a laboratory level recirculating aquaculture system for the rearing of Penaeus monodon for a period of two months under higher feeding rates and no water exchange. Rapid setting up of nitrification was observed during the operation, as the volumetric total ammonia nitrogen removal rates (VTR) increased with total ammonia nitrogen (TAN) production in the system. The average Volumetric TAN Removal Rates (VTR) at the feeding rate of 160 g/day from 54-60th days of culture was 0.1533+/-0.0045 kg TAN/m(3)/day. The regression between VTR and TAN explained 86% variability in VTR (P<0.001). The laboratory level RAS demonstrated here showed high performance both in terms of shrimp biomass yield and nitrification and environmental quality maintenance. Fluorescent in-situ Hybridization analysis of the reactor biofilm ensured the presence of autotrophic nitrifier groups such as Nitrosococcus mobilis lineage, Nitrobacter spp and phylum Nitrospira, the constituent members present in the original consortia used for activating the reactors. This showed the stability of the consortia on long term operation. PMID:20150717

  8. Effects of Cr(III) and CR(VI) on nitrification inhibition as determined by SOUR, function-specific gene expression and 16S rRNA sequence analysis of wastewater nitrifying enrichments

    Science.gov (United States)

    The effect of Cr(III) and Cr(VI) on ammonia oxidation, the transcriptional responses of functional genes involved in nitrification and changes in 16S rRNA level sequences were examined in nitrifying enrichment cultures. The nitrifying bioreactor was operated as a continuous react...

  9. Autotrophic nitrogen removal in one lab-scale vertical submerged biofilm reactor

    Science.gov (United States)

    Liang, Zhiwei; Chen, Yingxu; Li, Wenhong; Yang, Shangyuan; Du, Ping

    In this study, the process performance of a new vertical submerged biofilm reactor for complete autotrophic ammonia removal was investigated using synthetic wastewater. The main objectives of this study were to evaluate the flexibility of the reactor, achieve partial autotrophic nitrification with influent ammonium nitrogen ranging from 40 to 280 mg L -1, and achieve a stable half partial autotrophic nitrification by controlling hydraulic retention time (HRT) and alkalinity. A very low concentration of nitrate was observed in the effluent during nitrification. Then autotrophic denitrification revealed Anammox bacteria were present and active in the central anaerobic parts of the bioreactor which was inoculated with a mixed microbial consortium from activated sludge. The results of this study demonstrated that autotrophic denitrification processes can coexist with heterotrophic denitrifying processes in the same environment even if Anammox bacteria were less competitive than heterotrophic denitrifying bacteria.

  10. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers.

    Science.gov (United States)

    Anderson, I C; Levine, J S

    1986-05-01

    Biogenic emissions of nitric and nitrous oxides have important impacts on the photochemistry and chemistry of the atmosphere. Although biogenic production appears to be the overwhelming source of N(2)O, the magnitude of the biogenic emission of NO is very uncertain. In soils, possible sources of NO and N(2)O include nitrification by autotrophic and heterotrophic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. The availability of oxygen determines to a large extent the relative activities of these various groups of organisms. To better understand this influence, we investigated the effect of the partial pressure of oxygen (pO(2)) on the production of NO and N(2)O by a wide variety of common soil nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The production of NO per cell was highest by autotrophic nitrifiers and was independent of pO(2) in the range tested (0.5 to 10%), whereas N(2)O production was inversely proportional to pO(2). Nitrous oxide production was highest in the denitrifier Pseudomonas fluorescens, but only under anaerobic conditions. The molar ratio of NO/N(2)O produced was usually greater than unity for nitrifiers and much less than unity for denitrifiers. Chemodenitrification was the major source of both the NO and N(2)O produced by the nitrate respirer Serratia marcescens. Chemodenitrification was also a possible source of NO and N(2)O in nitrifier cultures but only when high concentrations of nitrite had accumulated or were added to the medium. Although most of the denitrifiers produced NO and N(2)O only under anaerobic conditions, chemostat cultures of Alcaligenes faecalis continued to emit these gases even when the cultures were sparged with air. Based upon these results, we predict that aerobic soils are primary sources of NO and that N(2)O is produced only when there is sufficient soil moisture to provide the anaerobic microsites

  11. Activated packed bed bioreactor for rapid nitrification in brackish water hatchery systems.

    Science.gov (United States)

    Kumar, V J Rejish; Achuthan, Cini; Manju, N J; Philip, Rosamma; Singh, I S Bright

    2009-03-01

    A packed bed bioreactor (PBBR) was developed for rapid establishment of nitrification in brackish water hatchery systems in the tropics. The reactors were activated by immobilizing ammonia-oxidizing (AMONPCU-1) and nitrite-oxidizing (NIONPCU-1) bacterial consortia on polystyrene and low-density polyethylene beads, respectively. Fluorescence in situ hybridization demonstrated the presence of autotrophic nitrifiers belong to Nitrosococcus mobilis, lineage of beta ammonia oxidizers and nitrite oxidizer Nitrobacter sp. in the consortia. The activated reactors upon integration to the hatchery system resulted in significant ammonia removal (P systems. With spent water the reactors could establish nitrification with high percentage removal of ammonia (78%), nitrite (79%) and BOD (56%) within 7 days of initiation of the process. PBBR is configured in such a way to minimize the energy requirements for continuous operation by limiting the energy inputs to a single stage pumping of water and aeration to the aeration cells. The PBBR shall enable hatchery systems to operate under closed recirculating mode and pave the way for better water management in the aquaculture industry. PMID:19039611

  12. Modelling cometabolic biotransformation of organic micropollutants in nitrifying reactors.

    Science.gov (United States)

    Fernandez-Fontaina, E; Carballa, M; Omil, F; Lema, J M

    2014-11-15

    Cometabolism is the ability of microorganisms to degrade non-growth substrates in the presence of primary substrates, being the main removal mechanism behind the biotransformation of organic micropollutants in wastewater treatment plants. In this paper, a cometabolic Monod-type kinetics, linking biotransformation of micropollutants with primary substrate degradation, was applied to a highly enriched nitrifying activated sludge (NAS) reactor operated under different operational conditions (hydraulic retention time (HRT) and nitrifying activity). A dynamic model of the bioreactor was built taking into account biotransformation, sorption and volatilization. The micropollutant transformation capacity (Tc), the half-saturation constant (Ksc) and the solid-liquid partitioning coefficient (Kd) of several organic micropollutants were estimated at 25 °C using an optimization algorithm to fit experimental data to the proposed model with the cometabolic Monod-type biotransformation kinetics. The cometabolic Monod-type kinetic model was validated under different HRTs (1.0-3.7 d) and nitrification rates (0.12-0.45 g N/g VSS d), describing more accurately the fate of those compounds affected by the biological activity of nitrifiers (ibuprofen, naproxen, erythromycin and roxithromycin) compared to the commonly applied pseudo-first order micropollutant biotransformation kinetics, which does not link biotransformation of micropollutants to consumption of primary substrate. Furthermore, in contrast to the pseudo-first order biotransformation constant (k(biol)), the proposed cometabolic kinetic coefficients are independent of operational conditions such as the nitrogen loading rate applied. Also, the influence of the kinetic parameters on the biotransformation efficiency of NAS reactors, defined as the relative amount of the total inlet micropollutant load being biotransformed, was assessed considering different HRTs and nitrification rates. PMID:25150522

  13. Development of a microbiological ammonium to nitrate recycling bioreactor for space capsules

    International Nuclear Information System (INIS)

    Since 1988, the Expertise group of Molecular and Cellular Biology (MCB) is an important partner in the development of the Micro-Ecological Life Support System Alternative (MELiSSA). The MELiSSA was designed to allow a small crew to survive on an Antarctic, lunar or Mars outpost, and is a joint research project currently fostered by the European Space Agency, ESA. The MELiSSA functions through a series of five interconnected compartments, of which four are microbial bioreactors and was engineered to degrade organic waste, regenerate the outpost's atmosphere and water, and provide the crew with an additional vegetarian diet. The bioreactor of the third compartment provides the edible cyanobacteria and plants of the fourth compartment with nitrate instead of ammonium as a source of nitrogen. The two bacteria responsible for the biological transformation of ammonium to nitrate (nitrification) are Nitrosomonas europaea and Nitrobacter winogradskyi. Since all MELiSSA-reactors are to be relied on for a period of several years, reactor operation is to be studied exhaustively to allow optimal process- and reactor performance. Therefore, a pilot reactor for the third compartment was engineered and constructed at the Universitat Autonoma de Barcelona (UAB), where the pilot plant of the MELiSSA is installed. The reactor was able to perform nitrification with high efficiency for the entire trial period of nearly five years and was the subject of this study. Collaboration between the unit of MCB and researchers at Universitat Autonoma de Barcelona (UAB) allowed the development and validation of a mathematical model for the third compartment of the MELiSSA. A mathematical model will allow optimizing reactor operation and reactor performance even further. A Real-Time Quantitative Polymerase Chain Reaction (Q-PCR) was developed at MCB that allowed the quantitative assessment of the relative distribution of the two autotrophic nitrifying bacterial species along the reactor's packed

  14. Effect of carrier fill ratio on biofilm properties and performance of a hybrid fixed-film bioreactor treating coal gasification wastewater for the removal of COD, phenols and ammonia-nitrogen.

    Science.gov (United States)

    Rava, E; Chirwa, E

    2016-01-01

    The purpose of this study was to determine the effect different biofilm carrier filling ratios would have on biofilm morphology and activity and bacterial diversity in a hybrid fixed-film bioreactor treating high strength coal gasification wastewater (CGWW) for the removal of chemical oxygen demand (COD), phenols and ammonia-nitrogen. Results showed that a carrier fill of 70% formed a 'compact' biofilm, a 50% fill formed a 'rippling' biofilm and a 30% fill formed a 'porous' biofilm. The highest microbial activity was obtained with a 50% carrier fill supporting a relatively thin biofilm. The highest level of biofilm bound metals were aluminium, silicon, calcium and iron in the 'compact' biofilm; nitrogen, magnesium, chloride, sodium and potassium in the 'rippling' biofilm, and copper in the 'porous' biofilm. The bioreactor improved the quality of the CGWW by removing 49% and 78% of the COD and phenols, respectively. However, no significant amount of ammonia-nitrogen was removed since nitrification did not take place due to heterotrophic bacteria out-competing autotrophic nitrifying bacteria in the biofilm. The dominant heterotrophic genera identified for all three carrier filling ratios were Thauera, Pseudaminobacter, Pseudomonas and Diaphorobacter. PMID:27191568

  15. NASA Bioreactor

    Science.gov (United States)

    1996-01-01

    Close-up view of the interior of a NASA Bioreactor shows the plastic plumbing and valves (cylinders at center) to control fluid flow. A fresh nutrient bag is installed at top; a flattened waste bag behind it will fill as the nutrients are consumed during the course of operation. The drive chain and gears for the rotating wall vessel are visible at bottom center center. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  16. Enhancing the formation and shear resistance of nitrifying biofilms on membranes by surface modification

    DEFF Research Database (Denmark)

    Lackner, Susanne; Holmberg, Maria; Terada, Akihiko; Kingshott, P.; Smets, Barth F.

    2009-01-01

    Polypropylene (PP) membranes and polyethylene (PE) surfaces were modified to enhance formation and shear resistance of nitrifying biofilms for wastewater treatment applications. A combination of plasma polymerization and wet chemistry was employed to ultimately introduce poly(ethyleneglycol) (PEG...... structure might be possible explanations of the superiority of the -PEG-NH2 modification. The success of the-PEG-NH2 modification was independent of the original surface and might, therefore, be used in wastewater treatment bioreactors to improve reactor performance by making biofilm formation more stable...

  17. NASA Bioreactor

    Science.gov (United States)

    1998-01-01

    The heart of the bioreactor is the rotating wall vessel, shown without its support equipment. Volume is about 125 mL. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  18. Bioreactor principles

    Science.gov (United States)

    2001-01-01

    Cells cultured on Earth (left) typically settle quickly on the bottom of culture vessels due to gravity. In microgravity (right), cells remain suspended and aggregate to form three-dimensional tissue. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  19. Nitrification and Autotrophic Nitrifying Bacteria in a Hydrocarbon-Polluted Soil

    OpenAIRE

    Deni, Jamal; Penninckx, Michel J.

    1999-01-01

    In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate bu...

  20. Biodegradation of tetramethylammonium hydroxide (TMAH) in completely autotrophic nitrogen removal over nitrite (CANON) process.

    Science.gov (United States)

    Chen, Shen-Yi; Lu, Li-An; Lin, Jih-Gaw

    2016-06-01

    This study conducted a completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous anoxic upflow bioreactor to treat synthetic wastewater with TMAH (tetramethylammonium hydroxide) ranging from 200 to 1000mg/L. The intermediates were analyzed for understanding the metabolic pathway of TMAH biodegradation in CANON process. In addition, (15)N-labeled TMAH was used as the substrate in a batch anoxic bioreactor to confirm that TMAH was converted to nitrogen gas in CANON process. The results indicated that TMAH was almost completely biodegraded in CANON system at different influent TMAH concentrations of 200, 500, and 1000mg/L. The average removal efficiencies of total nitrogen were higher than 90% during the experiments. Trimethylamine (TMA) and methylamine (MA) were found to be the main biodegradation intermediates of TMAH in CANON process. The production of nitrogen gas with (15)N-labeled during the batch anaerobic bioreactor indicated that CANON process successfully converted TMAH into nitrogen gas. PMID:26879202

  1. Kinetic evaluation of nitrification performance in an immobilized cell membrane bioreactor.

    Science.gov (United States)

    Güven, D; Ubay Çokgör, E; Sözen, S; Orhon, D

    2016-01-01

    High rate membrane bioreactor (MBR) systems operated at extremely low sludge ages (superfast membrane bioreactors (SFMBRs)) are inefficient to achieve nitrogen removal, due to insufficient retention time for nitrifiers. Moreover, frequent chemical cleaning is required due to high biomass flux. This study aims to satisfy the nitrification in SFMBRs by using sponge as carriers, leading to the extension of the residence time of microorganisms. In order to test the limits of nitrification, bioreactor was run under 52, 5 and 2 days of carrier residence time (CRT), with a hydraulic retention time of 6 h. Different degrees of nitrification were obtained for different CRTs. Sponge immobilized SFMBR operation with short CRT resulted in partial nitrification indicating selective dominancy of ammonia oxidizers. At higher CRT, simultaneous nitrification-denitrification was achieved when accompanying with oxygen limitation. Process kinetics was determined through evaluation of the results by a modeling study. Nitrifier partition in the reactor was also identified by model calibration. PMID:27332835

  2. Cyanate as an energy source for nitrifiers.

    Science.gov (United States)

    Palatinszky, Marton; Herbold, Craig; Jehmlich, Nico; Pogoda, Mario; Han, Ping; von Bergen, Martin; Lagkouvardos, Ilias; Karst, Søren M; Galushko, Alexander; Koch, Hanna; Berry, David; Daims, Holger; Wagner, Michael

    2015-08-01

    Ammonia- and nitrite-oxidizing microorganisms are collectively responsible for the aerobic oxidation of ammonia via nitrite to nitrate and have essential roles in the global biogeochemical nitrogen cycle. The physiology of nitrifiers has been intensively studied, and urea and ammonia are the only recognized energy sources that promote the aerobic growth of ammonia-oxidizing bacteria and archaea. Here we report the aerobic growth of a pure culture of the ammonia-oxidizing thaumarchaeote Nitrososphaera gargensis using cyanate as the sole source of energy and reductant; to our knowledge, the first organism known to do so. Cyanate, a potentially important source of reduced nitrogen in aquatic and terrestrial ecosystems, is converted to ammonium and carbon dioxide in Nitrososphaera gargensis by a cyanase enzyme that is induced upon addition of this compound. Within the cyanase gene family, this cyanase is a member of a distinct clade also containing cyanases of nitrite-oxidizing bacteria of the genus Nitrospira. We demonstrate by co-culture experiments that these nitrite oxidizers supply cyanase-lacking ammonia oxidizers with ammonium from cyanate, which is fully nitrified by this microbial consortium through reciprocal feeding. By screening a comprehensive set of more than 3,000 publically available metagenomes from environmental samples, we reveal that cyanase-encoding genes clustering with the cyanases of these nitrifiers are widespread in the environment. Our results demonstrate an unexpected metabolic versatility of nitrifying microorganisms, and suggest a previously unrecognized importance of cyanate in cycling of nitrogen compounds in the environment. PMID:26222031

  3. Freshwater autotrophic picoplankton: a review

    Directory of Open Access Journals (Sweden)

    John G. STOCKNER

    2002-02-01

    Full Text Available Autotrophic picoplankton (APP are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. They often form the base of complex microbial food webs, becoming prey for a multitude of protozoan and micro-invertebrate grazers, that effectively channel APP carbon to higher trophic levels including fish. In this review we examine the existing literature on freshwater autotrophic picoplankton, setting recent findings and current ecological issues within an historic framework, and include a description of the occurrence and distribution of both single-cell and colonial APP (picocyanobacteria in different types of lakes. In this review we place considerable emphasis on methodology and ecology, including sampling, counting, preservation, molecular techniques, measurement of photosynthesis, and include extensive comment on their important role in microbial food webs. The model outlined by Stockner of an increase of APP abundance and biomass and a decrease of its relative importance with the increase of phosphorus concentration in lakes has been widely accepted, and only recently confirmed in marine and freshwater ecosystems. Nevertheless the relationship which drives the APP presence and importance in lakes of differing trophic status appears with considerable variation so we must conclude that the success of APP in oligotrophic lakes worldwide is not a certainty but highly probable.

  4. Cyanate as energy source for nitrifiers

    DEFF Research Database (Denmark)

    Palatinszky, Marton; Herbold, Craig; Jehmlich, Nico;

    2015-01-01

    Ammonia- and nitrite-oxidizing microorganisms are collectively responsible for the aerobic oxidation of ammonia via nitrite to nitrate and have essential roles in the global biogeochemical nitrogen cycle. The physiology of nitrifiers has been intensively studied, and urea and ammonia are the only...... recognized energy sources that promote the aerobic growth of ammonia-oxidizing bacteria and archaea. Here we report the aerobic growth of a pure culture of the ammonia-oxidizing thaumarchaeote Nitrososphaera gargensis1 using cyanate as the sole source of energy and reductant; to our knowledge, the first...... cyanase is a member of a distinct clade also containing cyanases of nitrite-oxidizing bacteria of the genus Nitrospira. We demonstrate by co-culture experiments that these nitrite oxidizers supply cyanase-lacking ammonia oxidizers with ammonium from cyanate, which is fully nitrified by this microbial...

  5. Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Ruscalleda, Maël; Terada, Akihiko;

    bacterial granules or biofilms. In this sense, completely autotrophic nitrogen removal from high ammonium strength wastewater was achieved in a Membrane-Aereated Biofilm Reactor (MABR) in a single step. Here, a biofilm containing nitrifiers (Aerobic Ammonium and Nitrite Oxidizing Bacteria, AOB and NOB......Due to the necessity of a source of nitrite, most of the processes involving Anaerobic Ammonium Oxidation (Anammox) are based on a separated two-step process with a previous partial-nitritation reactor. However, these two processes can occur simultaneously in the same reactor by taking advantage of......, respectively) and Anaerobic Ammonium Oxidizing Bacteria (AnAOB) is grown on bubbleless aeration membranes to remove ammonium. Since oxygen permeates through the membrane-biofilm interface while ammonium diffuses into the biofilm from the biofilm-liquid interface, oxygen gradients can be established across the...

  6. Bioreactor landfill

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; XING Kai; Anthony Adzomani

    2004-01-01

    Following the population expansion, there is a growing threat brought by municipal solid waste (MSW) against environment and human health. Sanitary landfill is the most important method of MSW disposal in China. In contrast to the conventional landfill, this paper introduces a new technique named bioreactor landfill (BL). Mechanisms, operation conditions as well as the advantages and disadvantages of BL are also discussed in this paper.

  7. Autotrophic ammonia oxidation by soil thaumarchaea

    OpenAIRE

    Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

    2010-01-01

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, bu...

  8. Hydrodynamic characteristics of airlift nitrifying reactor using carrier-induced granular sludge

    Energy Technology Data Exchange (ETDEWEB)

    Jin Rencun [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Department of Environmental Science, Hangzhou Normal University, Hangzhou 310036 (China); Zheng Ping [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)], E-mail: pzheng@zju.edu.cn; Mahmood, Qaisar; Zhang Lei [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)

    2008-09-15

    Since nitrification is the rate-limiting step in the biological nitrogen removal from wastewater, many studies have been conducted on the immobilization of nitrifying bacteria. A laboratory-scale investigation was carried out to scrutinize the effectiveness of activated carbon carrier addition for granulation of nitrifying sludge in a continuous-flow airlift bioreactor and to study the hydrodynamics of the reactor with carrier-induced granules. The results showed that the granular sludge began to appear and matured 60 and 108 days, respectively, after addition of carriers, while no granule was observed in the absence of carriers in the control test. The mature granules had a diameter of 0.5-5 mm (1.6 mm in average), settling velocity 22.3-55.8 m h{sup -1} and specific gravity of 1.086. The relationship between the two important hydrodynamic coefficients, i.e. gas holdup and liquid circulation velocity, and the superficial gas velocity were established by a simple model and were confirmed experimentally. The model also could predict the critical superficial gas velocity for liquid circulation and that for granules circulation, with respective values of 1.017 and 2.662 cm min{sup -1}, accurately.

  9. Hydrodynamic characteristics of airlift nitrifying reactor using carrier-induced granular sludge

    International Nuclear Information System (INIS)

    Since nitrification is the rate-limiting step in the biological nitrogen removal from wastewater, many studies have been conducted on the immobilization of nitrifying bacteria. A laboratory-scale investigation was carried out to scrutinize the effectiveness of activated carbon carrier addition for granulation of nitrifying sludge in a continuous-flow airlift bioreactor and to study the hydrodynamics of the reactor with carrier-induced granules. The results showed that the granular sludge began to appear and matured 60 and 108 days, respectively, after addition of carriers, while no granule was observed in the absence of carriers in the control test. The mature granules had a diameter of 0.5-5 mm (1.6 mm in average), settling velocity 22.3-55.8 m h-1 and specific gravity of 1.086. The relationship between the two important hydrodynamic coefficients, i.e. gas holdup and liquid circulation velocity, and the superficial gas velocity were established by a simple model and were confirmed experimentally. The model also could predict the critical superficial gas velocity for liquid circulation and that for granules circulation, with respective values of 1.017 and 2.662 cm min-1, accurately

  10. Osmotic stress on nitrification in an airlift bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin Rencun [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Zheng Ping [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Mahmood, Qaisar [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Hu Baolan [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)]. E-mail: blhu@zju.edu.cn

    2007-07-19

    The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L{sup -1} and hydraulic retention time at 20.7 h, with gradual increase in osmotic pressure from 4.3 to 18.8 x 10{sup 5} Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2 x 10{sup 5} Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2 x 10{sup 5} Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization.

  11. Osmotic stress on nitrification in an airlift bioreactor

    International Nuclear Information System (INIS)

    The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L-1 and hydraulic retention time at 20.7 h, with gradual increase in osmotic pressure from 4.3 to 18.8 x 105 Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2 x 105 Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2 x 105 Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization

  12. Influence of biofilm thickness on micropollutants removal in nitrifying MBBRs

    OpenAIRE

    Torresi, Elena; Andersen, Henrik Rasmus; Smets, Barth F.; Plósz, Benedek G.; Christensson, M.

    2015-01-01

    The removal of pharmaceuticals was investigated in nitrifying Moving Bed Biofilm Reactors (MBBRs) containing carriers with different biofilm thicknesses. The biofilm with the thinnest thickness was found to have the highest nitrification and biotransformation rate for some key pharmaceuticals. Microbial analysis revealed a different relative abundance of nitrifying guilds in the different carriers, suggesting the importance of nitrite oxidizing bacteria in removal of micropollutants.

  13. Cometabolism of trihalomethanes by mixed culture nitrifiers.

    Science.gov (United States)

    Wahman, David G; Henry, Andrea E; Katz, Lynn E; Speitel, Gerald E

    2006-10-01

    Three mixed-culture nitrifier sources degraded low concentrations (25-450 microg/L) of four trihalomethanes (THMs) (trichloromethane (TCM) or chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM) or bromoform) commonly found in treated drinking water. Individual THM rate constants (k1THM) increased with increasing THM bromine-substitution with TBM>DBCM>BDCM>TCM and were comparable to previous studies with the pure culture nitrifier, Nitrosomonas europaea. A decrease in temperature resulted in a decrease in both ammonia and THM degradation rates with ammonia rates affected to a greater extent than THM degradation rates. The significant effect of temperature indicates that seasonal variations in water temperature should be a consideration for technology implementation. Product toxicity, measured by transformation capacity (T(c)), was similar to that observed with N. europaea. Because both rate constants and product toxicities increase with increasing THM bromine-substitution, a water's THM speciation is an important consideration for process implementation during drinking water treatment. Even though a given water is kinetically favored, the resulting THM product toxicity may not allow stable treatment process performance. PMID:16970971

  14. Role of exopolymeric protein on the settleability of nitrifying sludges.

    Science.gov (United States)

    Martínez, Felipe; Lema, Juan; Méndez, Ramón; Cuervo-López, Flor; Gómez, Jorge

    2004-08-01

    The relationship of exopolymeric substances and the sludge volume indexes (SVI) of two nitrifying sludge were studied over a period of time (30 d) in two different types of reactors: (1) a stirred tank aerated nitrifying reactor (SANR) and (2) an air-lift nitrifying reactor (ALNR). Concentrations of lipids, carbohydrates and proteins of the EPS were determined in both reactors. The variation in lipids and carbohydrates was low (air-lift reactor. The variations in the SVI were mainly due to the changes in the molecular weight of the exopolymeric proteins resulting in the modification of the sludge settleability characteristics. PMID:15081485

  15. Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios.

    Science.gov (United States)

    Bassin, J P; Abbas, B; Vilela, C L S; Kleerebezem, R; Muyzer, G; Rosado, A S; van Loosdrecht, M C M; Dezotti, M

    2015-09-01

    In this study, the impact of COD/N ratio and feeding regime on the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors was addressed. Based on DGGE analysis of 16S rRNA genes, the influent COD was found to be the main factor determining the overall bacterial diversity. The amoA-gene-based analysis suggested that the dynamic behavior of the substrate in continuous and pulse-feeding reactors influenced the selection of specific ammonium-oxidizing bacteria (AOB) strains. Furthermore, AOB diversity was directly related to the applied COD/N ratio and ammonium-nitrogen load. Maximum specific ammonium oxidation rates observed under non-substrate-limiting conditions were observed to be proportional to the fraction of nitrifiers within the bacterial community. FISH analysis revealed that Nitrosomonas genus dominated the AOB community in all reactors. Moreover, Nitrospira was found to be the only nitrite-oxidizing bacteria (NOB) in the fully autotrophic system, whereas Nitrobacter represented the dominant NOB genus in the organic carbon-fed reactors. PMID:26025351

  16. Bioreactors Addressing Diabetes Mellitus

    OpenAIRE

    Minteer, Danielle M.; Gerlach, Jorg C; Marra, Kacey G.

    2014-01-01

    The concept of bioreactors in biochemical engineering is a well-established process; however, the idea of applying bioreactor technology to biomedical and tissue engineering issues is relatively novel and has been rapidly accepted as a culture model. Tissue engineers have developed and adapted various types of bioreactors in which to culture many different cell types and therapies addressing several diseases, including diabetes mellitus types 1 and 2. With a rising world of bioreactor develop...

  17. Performance and Biofilm Activity of Nitrifying Biofilters Removing Trihalomethanes

    Science.gov (United States)

    Nitrifying biofilters seeded with three different mixed-culture sources degraded trichloromethane (TCM) and dibromochloromethane (DBCM). In addition, resuspended biofilm degraded TCM, bromododichloromethane (BDCM), DBCM, and tribromomethane (TBM) in backwash batch kinetic tests,...

  18. Influence of biofilm thickness on micropollutants removal in nitrifying MBBRs

    DEFF Research Database (Denmark)

    Torresi, Elena; Andersen, Henrik Rasmus; Smets, Barth F.;

    The removal of pharmaceuticals was investigated in nitrifying Moving Bed Biofilm Reactors (MBBRs) containing carriers with different biofilm thicknesses. The biofilm with the thinnest thickness was found to have the highest nitrification and biotransformation rate for some key pharmaceuticals. Mi....... Microbial analysis revealed a different relative abundance of nitrifying guilds in the different carriers, suggesting the importance of nitrite oxidizing bacteria in removal of micropollutants....

  19. p-Cresol mineralization by a nitrifying consortium

    International Nuclear Information System (INIS)

    Nitrification and denitrification processes are considered economically feasible technologies for nitrogen removal from wastewater. Knowledge of the toxic or inhibitory effects of cresols on the nitrifying respiratory process is still insufficient. The aim of this study was to evaluate the kinetic behavior and oxidizing ability of a nitrifying consortium exposed to p-cresol in batch cultures. Biotransformation of p-cresol was investigated by identifying the different intermediates formed. (Author)

  20. Discrepant membrane fouling of partial nitrification and anammox membrane bioreactor operated at the same nitrogen loading rate.

    Science.gov (United States)

    Niu, Zhao; Zhang, Zuotao; Liu, Sitong; Miyoshi, Taro; Matsuyama, Hideo; Ni, Jinren

    2016-08-01

    In this study, two times more serious membrane fouling was found in anammox membrane bioreactor, compared to partial nitrification membrane bioreactor (PN-MBR) operated at the same nitrogen loading rate. By protein, polysaccharide, amino acids and functional groups analysis, it was found that the discrepancy in membrane fouling was virtually due to the difference in microbial products of nitrifiers and anammox bacteria. Protein and polysaccharide were main foulants on membrane surface; meanwhile theirs content and ratio in the EPS, supernatant and membrane surface were significantly different in PN-MBR and anammox-MBR. The anammox metabolism products contained much more hydrophobic organics, hydrophobic amino acids, and hydrophobic functional groups than nitrifiers. A mass of anammox bacteria as well as hydrophobic metabolism products deposited on the hydrophobic membrane surface and formed serious fouling. In further, hydrophilic modification is more urgently needed to mitigate membrane fouling when running anammox-MBR, than PN-MBR. PMID:27209455

  1. Denitrification in Membrane Bioreactors

    OpenAIRE

    Fonseca, Anabela Duarte

    1999-01-01

    Three membrane bioreactors, a low flux filter (LFF), a diafilter (DF), and an ion-exchange (IE) membrane bioreactor were used to treat water polluted with 50 ppm-N nitrate. The three systems were compared in terms of removal efficiency of nitrate, operational complexity, and overall quality of the treated water. In the low flux filter (LFF) membrane bioreactor an hemo-dialysis hollow fiber module was used and operated continuously for 29 days with a constant flux of permeate. The perform...

  2. Characterization of the start-up period of single-step autotrophic nitrogen removal in a sequencing batch reactor

    Institute of Scientific and Technical Information of China (English)

    GUO Jin-song; QIN Yu; FANG Fang; YANG Guo-hong

    2008-01-01

    The characteristics of the start-up period of single-step autotrophic nitrogen removal process were investigated. The autotrophic nitrogen removal process used a sequencing batch reactor to treat wastewater of medium to low ammonia-nitrogen concentration, with dissolved oxygen (DO), hydraulic retention time (HRT) and temperature controlled. The experimental conditions were temperature at (30(2) (C, ammonia concentration of (60 to 120) mg/L, DO of (0.8 to 1.0) mg/L, pH from 7.8 to 8.5 and HRT of 24 h. The rates of nitrification and nitrogen removal turn out to be 77% and 40%, respectively, after a start up period going through three stages divided according to nitrite accumulation: sludge domestication, nitrifying bacteria selection and sludge adaptation. It is demonstrated that dissolved oxygen is critical to nitrite accumulation and elastic YJZH soft compound packing is superior to polyhedral hollow balls in helping the bacteria adhere to the membrane.

  3. Membrane biofouling in a wastewater nitrification reactor: microbial succession from autotrophic colonization to heterotrophic domination

    KAUST Repository

    Lu, Huijie

    2015-10-22

    Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.

  4. Sulfide removal by simultaneous autotrophic and heterotrophic desulfurization-denitrification process

    International Nuclear Information System (INIS)

    An anaerobic attached-growth bioreactor (AAGBR) of 3.52 L was operated for 510 days to treat sulfide-laden organic wastewater where nitrate and nitrite were introduced as electron acceptors. When the influent sulfide was kept at 200 mg S2--S/L and organic carbon was increased from 20 to 33.6 mg C/L, and the hydraulic retention time decreased from 41.4 to 2.67 h, the removal rates of sulfide and organic carbon reached 99.9% and 91.8% at the loading rates of 1800 mg S2--S/(L d) and 302.4 mg C/(L d), respectively. Simultaneously, the introduced electron acceptors of nitrate and nitrite were, respectively, removed by 99.9% and 99.9% at the loading rates of 472.5 mg NO3--N/(L d) and 180 mg NO2--N/(L d). Inside the AAGBR, both autotrophic and heterotrophic denitrification processes were noted to take place. When the influent organic carbon was increased from 20 to 33.6 mg C/L, the nitrate and nitrite consumed for heterotrophic denitrification accounted for 27.3% and 48.5%, respectively. This simultaneous autotrophic and heterotrophic desulfurization-denitrification process has provided a demonstration of the possibility to eliminate sulfide and organic carbon with the presence of nitrate and nitrite

  5. NASA Bioreactor Demonstration System

    Science.gov (United States)

    2002-01-01

    Leland W. K. Chung (left), Director, Molecular Urology Therapeutics Program at the Winship Cancer Institute at Emory University, is principal investigator for the NASA bioreactor demonstration system (BDS-05). With him is Dr. Jun Shu, an assistant professor of Orthopedics Surgery from Kuming Medical University China. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Credit: Emory University.

  6. Clostridium difficile is an autotrophic bacterial pathogen.

    Directory of Open Access Journals (Sweden)

    Michael Köpke

    Full Text Available During the last decade, Clostridium difficile infection showed a dramatic increase in incidence and virulence in the Northern hemisphere. This incessantly challenging disease is the leading cause of antibiotic-associated and nosocomial infectious diarrhea and became life-threatening especially among elderly people. It is generally assumed that all human bacterial pathogens are heterotrophic organisms, being either saccharolytic or proteolytic. So far, this has not been questioned as colonization of the human gut gives access to an environment, rich in organic nutrients. Here, we present data that C. difficile (both clinical and rumen isolates is also able to grow on CO2+H2 as sole carbon and energy source, thus representing the first identified autotrophic bacterial pathogen. Comparison of several different strains revealed high conservation of genes for autotrophic growth and showed that the ability to use gas mixtures for growth decreases or is lost upon prolonged culturing under heterotrophic conditions. The metabolic flexibility of C. difficile (heterotrophic growth on various substrates as well as autotrophy could allow the organism in the gut to avoid competition by niche differentiation and contribute to its survival when stressed or in unfavorable conditions that cause death to other bacteria. This may be an important trait for the pathogenicity of C. difficile.

  7. Nitrogen removal in the bioreactor landfill system with intermittent aeration at the top of landfilled waste

    International Nuclear Information System (INIS)

    High ammonia concentration of recycled landfill leachate makes it very difficult to treat. In this work, a vertical aerobic/anoxic/anaerobic lab-scale bioreactor landfill system, which was constructed by intermittent aeration at the top of landfilled waste, as a bioreactor for in situ nitrogen removal was investigated during waste stabilization. Intermittent aeration at the top of landfilled waste might stimulate the growth of nitrifying bacteria and denitrifying bacteria in the top and middle layers of waste. The nitrifying bacteria population for the landfill bioreactor with intermittent aeration system reached between106 and 108 cells/dry g waste, although it decreased 2 orders of magnitude on day 30, due to the inhibitory effect of the acid environment and high organic matter in the landfilled waste. The denitrifying bacteria population increased by between 4 and 13 orders of magnitude compared with conventional anaerobic landfilled waste layers. Leachate NO3--N concentration was very low in both two experimental landfill reactors. After 105 days operation, leachate NH4+-N and TN concentrations for the landfill reactor with intermittent aeration system dropped to 186 and 289 mg/l, respectively, while they were still kept above 1000 mg/l for the landfill reactor without intermittent aerobic system. In addition, there is an increase in the rate of waste stabilization as well as an increase of 12% in the total waste settlement for the landfill reactor with intermittent aeration system

  8. Structure, composition, and strength of nitrifying membrane-aerated biofilms

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Smets, Barth F.

    2014-01-01

    achieve full nitrification revealed a significantly different structure of nitrifying MABR biofilms with respect to its co-diffusion counterparts reported in the literature (up to now assumed to have similar properties). Different levels of shear stress and oxygen loadings during MABR operation also...

  9. Bioreactor rotating wall vessel

    Science.gov (United States)

    2001-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells.

  10. Stimulating accumulation of nitrifying bacteria in porous carrier by addition of inorganic carbon in a continuous-flow fluidized bed wastewater treatment reactor.

    Science.gov (United States)

    Jun, B H; Tanji, Y; Unno, H

    2000-01-01

    Porous polyurethane carrier particles have been successfully applied for microbial immobilization to simultaneously remove carbonaceous and nitrogenous substances from wastewater by a fill-and-draw operation. This reactor system was extended to a continuous-flow operation mode, by which inorganic carbon (IC) was supplemented in order to stimulate the growth of autotrophic nitrifying bacteria. By addition of sodium bicarbonate, the ammonia oxidation reaction proceeded remarkably in the porous particle fluidized bed reactor, while a small increase in the nitrification was observed in a reactor with suspended microbes. Dissolved oxygen profile was obtained using an oxygen microelectrode to measure the microbial consumption of oxygen in the porous carrier. The size of ammonia-oxidizing bacterial populations in the carrier was proportional to the volume of the aerobic region of the carrier. The aerobic region decreased with the increase in sodium bicarbonate concentration, which improved the ammonia-oxidizing activity of retained nitrifiers in the carrier. The maximum ammonia oxidation rate was up to 55.6 gN/m3/h within the aerobic region of the carrier under the following feed conditions: 100 mg/l of total organic compound, 55 mg/l of ammonium concentration and 48 mg/l of inorganic carbon. PMID:16232755

  11. Tapered bed bioreactor

    Science.gov (United States)

    Scott, Charles D.; Hancher, Charles W.

    1977-01-01

    A vertically oriented conically shaped column is used as a fluidized bed bioreactor wherein biologically catalyzed reactions are conducted in a continuous manner. The column utilizes a packing material a support having attached thereto a biologically active catalytic material.

  12. Development of biological platform for the autotrophic production of biofuels

    Science.gov (United States)

    Khan, Nymul

    of the current status of metabolic engineering of chemolithoautotrophs is carried out in order to identify the challenges and likely routes to overcome them. This is presented in Chapter 3 of this dissertation. The initial metabolic engineering and bioreactor studies was carried out using a number of gene-constructs on R. capsulatus and R. eutropha. The gene-constructs consisted of Plac promoter followed by the triterpene synthase genes (SS or BS) and other upstream genes. A comparison of the production of triterpenes were done in the different growth modes that R. capsulatus was capable of growing---aerobic heterotrophic, anaerobic photoheterotrophic and aerobic chemoautotrophic. Autotrophic productivity could likely be improved much further by increasing the available mass-transfer of the reactor. These efforts are presented in Chapter 4 of this dissertation. (Abstract shortened by UMI.).

  13. Microelectrode measurements of the activity distribution in nitrifying bacterial aggregates

    OpenAIRE

    Beer, de, VHJ Vincent; Heuvel, van den, J.; Ottengraf, SPP Simon

    1993-01-01

    Microelectrodes for ammonium, oxygen, nitrate, and pH were used to study nitrifying aggregates grown in a fluidized-bed reactor. Local reactant fluxes and distribution of microbial activity could be determined from the microprofiles. The interfacial fluxes of the reactants closely reflected the stoichiometry of bacterial nitrification. Both ammonium consumption and nitrate production were localized in the outer shells, with a thickness of approximately 100 to 120 μm, of the aggregates. Under ...

  14. Biodiesel from microalgae Chlorella protothecoides growing at autotrophic and heterotrophic metabolisms in a new symbiotic bioreactor

    OpenAIRE

    Santos, Carla A.; Reis, Alberto

    2013-01-01

    Biodiesel is an alternative energy to fossil fuels, and is produced from biomass, therefore provides lower CO2 emissions. Currently, biodiesel is produced from plant oils, animal fats and used oils. These sources are low-yield which is a limitation to the production of biodiesel in large quantities. On the contrary, microalgae present a very high yield and can be produced in large amounts. The bio-refinery of microalgae oil must have a strategy of taking advantage of all by-products to make ...

  15. Management of microbial community composition, architecture and performance in autotrophic nitrogen removing bioreactors through aeration regimes

    OpenAIRE

    Mutlu, A. Gizem; Smets, Barth F.; Sin, Gürkan

    2015-01-01

    Fuldstændig autotrof fjernelse af kvælstof (der består af delvis nitrifikation koblet med anaerob ammonium oxidation) fra spildevand med et højt kvælstof indhold kan i høj grad minimere omkostninger i form af energibesparelse sammenlignet med den konventionelle behandling af spildevand. Dette forbrug kan reduceres yderligere ved en intensivering af processen, hvor begge processer kører i samme reaktor. Dette kan lade sig gøre i systemer med biofilmdannelse eller bioaggregater, der skaber de n...

  16. Mannitol in six autotrophic stramenopiles and Micromonas.

    Science.gov (United States)

    Dittami, Simon M; Aas, Hoai T N; Paulsen, Berit S; Boyen, Catherine; Edvardsen, Bente; Tonon, Thierry

    2011-08-01

    Mannitol plays a central role in brown algal physiology since it represents an important pathway used to store photoassimilate. Several specific enzymes are directly involved in the synthesis and recycling of mannitol, altogether forming the mannitol cycle. The recent analysis of algal genomes has allowed tracing back the origin of this cycle in brown seaweeds to a horizontal gene transfer from bacteria, and furthermore suggested a subsequent transfer to the green microalga Micromonas. Interestingly, genes of the mannitol cycle were not found in any of the currently sequenced diatoms, but were recently discovered in pelagophytes and dictyochophytes. In this study, we quantified the mannitol content in a number of ochrophytes (autotrophic stramenopiles) from different classes, as well as in Micromonas. Our results show that, in accordance with recent observations from EST libraries and genome analyses, this polyol is produced by most ochrophytes, as well as the green alga tested, although it was found at a wide range of concentrations. Thus, the mannitol cycle was probably acquired by a common ancestor of most ochrophytes, possibly after the separation from diatoms, and may play different physiological roles in different classes. PMID:21720212

  17. Biogas desulfurization using autotrophic denitrification process.

    Science.gov (United States)

    Bayrakdar, Alper; Tilahun, Ebrahim; Calli, Baris

    2016-01-01

    The aim of this study was to evaluate the performance of an autotrophic denitrification process for desulfurization of biogas produced from a chicken manure digester. A laboratory scale upflow fixed bed reactor (UFBR) was operated for 105 days and fed with sodium sulfide or H2S scrubbed from the biogas and nitrate as electron donor and acceptor, respectively. The S/N ratio (2.5 mol/mol) of the feed solution was kept constant throughout the study. When the UFBR was fed with sodium sulfide solution with an influent pH of 7.7, about 95 % sulfide and 90 % nitrate removal efficiencies were achieved. However, the inlet of the UFBR was clogged several times due to the accumulation of biologically produced elemental sulfur particles and the clogging resulted in operational problems. When the UFBR was fed with the H2S absorbed from the biogas and operated with an influent pH of 8-9, around 98 % sulfide and 97 % nitrate removal efficiencies were obtained. In this way, above 95 % of the H2S in the biogas was removed as elemental sulfur and the reactor effluent was reused as scrubbing liquid without any clogging problem. PMID:26428238

  18. NASA Classroom Bioreactor

    Science.gov (United States)

    Scully, Robert

    2004-01-01

    Exploration of space provides a compelling need for cell-based research into the basic mechanisms that underlie the profound changes that occur in terrestrial life that is transitioned to low gravity environments. Toward that end, NASA developed a rotating bioreactor in which cells are cultured while continuously suspended in a cylinder in which the culture medium rotates with the cylinder. The randomization of the gravity vector accomplished by the continuous rotation, in a low shear environment, provides an analog of microgravity. Because cultures grown in bioreactors develop structures and functions that are much closer to those exhibited by native tissue than can be achieved with traditional culture methods, bioreactors have contributed substantially to advancing research in the fields of cancer, diabetes, infectious disease modeling for vaccine production, drug efficacy, and tissue engineering. NASA has developed a Classroom Bioreactor (CB) that is built from parts that are easily obtained and assembled, user-friendly and versatile. It can be easily used in simple school settings to examine the effect cultures of seeds or cells. An educational brief provides assembly instructions and lesson plans that describes activities in science, math and technology that explore free fall, microgravity, orbits, bioreactors, structure-function relationships and the scientific method.

  19. NASA Bioreactor Schematic

    Science.gov (United States)

    2001-01-01

    The schematic depicts the major elements and flow patterns inside the NASA Bioreactor system. Waste and fresh medium are contained in plastic bags placed side-by-side so the waste bag fills as the fresh medium bag is depleted. The compliance vessel contains a bladder to accommodate pressure transients that might damage the system. A peristolic pump moves fluid by squeezing the plastic tubing, thus avoiding potential contamination. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  20. In situ nitrogen removal from leachate by bioreactor landfill with limited aeration

    International Nuclear Information System (INIS)

    The feasibility of simultaneous nitrification and denitrification in a bioreactor landfill with limited aeration was assessed. Three column reactors, simulating bioreactor landfill operations under anaerobic condition (as reference), intermittent forced aeration and enhanced natural aeration were hence established, where aerated columns passed through two phases, i.e., fresh landfill and well-decomposed landfill. The experimental results show that limited aeration decreased nitrogen loadings of leachate distinctly in the fresh landfill. In the well-decomposed landfill, the NH4+-N of the input leachate could be nitrified completely in the aerated landfill columns. The nitrifying loadings of the column cross section reached 7.9 g N/m2 d and 16.9 g N/m2 d in the simulated landfill columns of intermittent forced aeration and enhanced natural aeration, respectively. The denitrification was influenced by oxygen distribution in the landfill column. Intermittent existence of oxygen in the landfill with the intermittent forced aeration was favorable to denitrify the NO2--N and NO3--N, indicated by the high denitrification efficiency (>99%) under the condition of BOD5/TN of more than 5.4 in leachate; locally persistent existence of oxygen in the landfill with enhanced natural aeration could limit the denitrification, indicated by relatively low denitrification efficiency of about 75% even when the BOD5/TN in leachate had an average of 7.1

  1. Carbon budgets for three autotrophic Australian estuaries: Implications for global estimates of the coastal air-water CO2 flux

    Science.gov (United States)

    Maher, D. T.; Eyre, B. D.

    2012-03-01

    Estuaries are `hot spots' in the global carbon cycle, yet data on carbon dynamics, in particular air-sea CO2 fluxes, from autotrophic systems are rare. Estuarine carbon budgets were constructed for three geomorphically distinct warm temperate Australian estuaries over an annual cycle. All three estuaries were net autotrophic, with annual net ecosystem metabolism (NEM) ranging from 8 ± 13.4 molC m-2 yr-1 to 10 ± 14 molC m-2 yr-1. There was a net flux of CO2 from the atmosphere to the estuaries of between 0.4 ± 0.6 molC m-2 yr-1 and 2 ± 0.9 molC m-2 yr-1. Loading of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) to the estuaries varied markedly within and between the estuaries, and was directly related to freshwater inflow. While NEM was similar in all three estuaries, the ratio of benthic versus pelagic contributions to NEM differed, with NEM dominated by pelagic production in the river dominated system, benthic production dominating in the intermediate estuary, and equal contributions of benthic and pelagic production in the marine dominated lagoon. All three estuaries exported more organic carbon than was imported, fueled by additional organic carbon supplied by NEM. The estuaries essentially acted as bioreactors, transforming DIC to organic carbon. Burial of organic carbon ranged from 1.2 ± 0.3 molC m-2 yr-1 to 4.4 ± 1.2 molC m-2 yr-1 and represented up to half of NEM. The annual net uptake of atmospheric CO2 in these systems, along with previous estimates of the global estuarine CO2flux being based predominantly on heterotrophic, large river dominated estuarine systems, indicates that the global estimate of the estuarine air-water CO2flux may be over-estimated due to the lack of studies from autotrophic marine dominated estuaries.

  2. NASA Bioreactor tissue culture

    Science.gov (United States)

    1998-01-01

    Dr. Lisa E. Freed of the Massachusetts Institute of Technology and her colleagues have reported that initially disc-like specimens tend to become spherical in space, demonstrating that tissues can grow and differentiate into distinct structures in microgravity. The Mir Increment 3 (Sept. 16, 1996 - Jan. 22, 1997) samples were smaller, more spherical, and mechanically weaker than Earth-grown control samples. These results demonstrate the feasibility of microgravity tissue engineering and may have implications for long human space voyages and for treating musculoskeletal disorders on earth. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  3. A novel titrimetric method for monitoring toxicity on nitrifying biofilms.

    Science.gov (United States)

    Artiga, P; Oyanedel, V; Garrido, J M; Mendez, R

    2003-01-01

    A titrimetric method for monitoring toxicity in suspended biomass was applied in order to measure the activity of nitrifying biofilms and to determine the effect of several toxic compounds on the biofilm. Three typical tannery compounds, quebracho extract, NaCl and Cr+3 were selected to study their toxicity on the biofilms. The results obtained showed an acceptable repeatability of the method for all the toxicants tested with an average standard deviation of less than 10%. Biofilm systems showed higher resistance to the toxicants, when the results obtained using suspended nitrifying biomass, were compared with those found in the literature. The IC50 obtained with quebracho was 8.8 g/L of quebracho extract, while around 65% of maximum activity was attained with 8.7 g/L of NaCl or 120 mg/L Cr+3. The quebracho extract, NaCl and Cr+3 were 26%, 38% and 18%, respectively, less toxic in the biofilm system than for a suspended biomass culture. PMID:12701930

  4. Membrane bioreactor for waste gas treatment.

    OpenAIRE

    Reij, M W

    1997-01-01

    SummaryThis thesis describes the design and testing of a membrane bioreactor (MBR) for removal of organic pollutants from air. In such a bioreactor for biological gas treatment pollutants are degraded by micro-organisms. The membrane bioreactor is an alternative to other types of bioreactors for waste gas treatment, such as compost biofilters and bioscrubbers. Propene was used as a model pollutant to study the membrane bioreactor.A membrane bioreactor for waste gas treatment consists of a gas...

  5. Estimating autotrophic respiration in streams using daily metabolism data

    Science.gov (United States)

    Knowing the fraction of gross primary production (GPP) that is immediately respired by autotrophs and their closely associated heterotrophs (ARf) is necessary to understand the trophic base and carbon spiraling in streams. We show a means to estimate ARf from daily metabolism da...

  6. Autotrophic acetyl coenzyme A biosynthesis in Methanococcus maripaludis

    International Nuclear Information System (INIS)

    To detect autotrophic CO2 assimilation in cell extracts of Methanococcus maripaludis, lactate dehydrogenase and NADH were added to convert pyruvate formed from autotropically synthesized acetyl coenzyme A to lactate. The lactate produced was determined spectrophotometrically. When CO2 fixation was pulled in the direction of lactate synthesis, CO2 reduction to methane was inhibited. Bromoethanesulfonate (BES), a potent inhibitor of methanogenesis, enhanced lactate synthesis, and methyl coenzyme M inhibited it in the absence of BES. Lactate synthesis was dependent on CO2 and H2, but H2 + CO2-independent synthesis was also observed. In cell extracts, the rate of lactate synthesis was about 1.2 nmol min-1 mg of protein-1. When BES was added, the rate of lactate synthesis increased to 2.1 nmol min-1 mg of protein-1. Because acetyl coenzyme A did not stimulate lactate synthesis, pyruvate synthase may have been the limiting activity in these assays. Radiolabel from 14CO2 was incorporated into lactate. The percentages of radiolabel in the C-1, C-2, and C-3 positions of lactate were 73, 33, and 11%, respectively. Both carbon monoxide and formaldehyde stimulated lactate synthesis. 14CH2O was specifically incorporated into the C-3 of lactate, and 14CO was incorporated into the C-1 and C-2 positions. Low concentrations of cyanide also inhibited autotrophic growth, CO dehydrogenase activity, and autotrophic lactate synthesis. These observations are in agreement with the acetogenic pathway of autotrophic CO2 assimilation

  7. Oscillating Cell Culture Bioreactor

    Science.gov (United States)

    Freed, Lisa E.; Cheng, Mingyu; Moretti, Matteo G.

    2010-01-01

    To better exploit the principles of gas transport and mass transport during the processes of cell seeding of 3D scaffolds and in vitro culture of 3D tissue engineered constructs, the oscillatory cell culture bioreactor provides a flow of cell suspensions and culture media directly through a porous 3D scaffold (during cell seeding) and a 3D construct (during subsequent cultivation) within a highly gas-permeable closed-loop tube. This design is simple, modular, and flexible, and its component parts are easy to assemble and operate, and are inexpensive. Chamber volume can be very low, but can be easily scaled up. This innovation is well suited to work with different biological specimens, particularly with cells having high oxygen requirements and/or shear sensitivity, and different scaffold structures and dimensions. The closed-loop changer is highly gas permeable to allow efficient gas exchange during the cell seeding/culturing process. A porous scaffold, which may be seeded with cells, is fixed by means of a scaffold holder to the chamber wall with scaffold/construct orientation with respect to the chamber determined by the geometry of the scaffold holder. A fluid, with/without biological specimens, is added to the chamber such that all, or most, of the air is displaced (i.e., with or without an enclosed air bubble). Motion is applied to the chamber within a controlled environment (e.g., oscillatory motion within a humidified 37 C incubator). Movement of the chamber induces relative motion of the scaffold/construct with respect to the fluid. In case the fluid is a cell suspension, cells will come into contact with the scaffold and eventually adhere to it. Alternatively, cells can be seeded on scaffolds by gel entrapment prior to bioreactor cultivation. Subsequently, the oscillatory cell culture bioreactor will provide efficient gas exchange (i.e., of oxygen and carbon dioxide, as required for viability of metabolically active cells) and controlled levels of fluid

  8. N2O emissions from full-scale nitrifying biofilters.

    Science.gov (United States)

    Bollon, Julien; Filali, Ahlem; Fayolle, Yannick; Guerin, Sabrina; Rocher, Vincent; Gillot, Sylvie

    2016-10-01

    A full-scale nitrifying biofilter was continuously monitored during two measurement periods (September 2014; February 2015) during which both gaseous and liquid N2O fluxes were monitored on-line. The results showed diurnal and seasonal variations of N2O emissions. A statistical model was run to determine the main operational parameters governing N2O emissions. Modification of the distribution between the gas phase and the liquid phase was observed related to the effects of temperature and aeration flow on the volumetric mass transfer coefficient (kLa). With similar nitrification performance values, the N2O emission factor was twice as high during the winter campaign. The increase in N2O emissions in winter was correlated to higher effluent nitrite concentrations and suspected increased biofilm thickness. PMID:27318446

  9. Characterization of a marine origin aerobic nitrifying-denitrifying bacterium.

    Science.gov (United States)

    Zheng, Hai-Yan; Liu, Ying; Gao, Xi-Yan; Ai, Guo-Min; Miao, Li-Li; Liu, Zhi-Pei

    2012-07-01

    The bacterial strain F6 was isolated from a biological aerated filter that is used for purifying recirculating water in a marine aquaculture system and was identified as Marinobacter sp. based on the analysis of its 16S rRNA gene sequence. Strain F6 showed efficient aerobic denitrifying ability. One hundred percent of nitrates and 73.10% of nitrites were removed, and the total nitrogen (TN) removal rates reached 50.08% and 33.03% under a high nitrate and nitrite concentration in the medium, respectively. N(2)O and (15)N(2), as revealed by GC-MS and GC-IRMS, were the products of aerobic denitrification. Factors affecting the growth and aerobic denitrifying performance of strain F6 were investigated. The results showed that the optimum aerobic denitrification conditions for strain F6 were the presence of sodium succinate as a carbon source, a C/N ratio of 15, salinity ranging from 32-35 g/L of NaCl, incubation temperature of 30°C, an initial pH of 7.5, and rotation speed of 150 rpm [dissolved oxygen (DO) 6.75 mg/L]. In addition, strain F6 was confirmed to be a heterotrophic nitrifier through its NO(2)(-) generation and 25.96% TN removal when NH(4)(+) was used as the sole N source. Therefore, strain F6, the first reported member of genus Marinobacter with aerobic heterotrophic nitrifying-denitrifying ability, is an excellent candidate for facilitating simultaneous nitrification and denitrification (SND) in industry and aquaculture wastewater. PMID:22578593

  10. Sulfur-based mixotrophic denitrification corresponding to different electron donors and microbial profiling in anoxic fluidized-bed membrane bioreactors.

    Science.gov (United States)

    Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Bai, Yaohui; Qu, Jiuhui

    2015-11-15

    Sulfur-based mixotrophic denitrifying anoxic fluidized bed membrane bioreactors (AnFB-MBR) were developed for the treatment of nitrate-contaminated groundwater with minimized sulfate production. The nitrate removal rates obtained in the methanol- and ethanol-fed mixotrophic denitrifying AnFB-MBRs reached 1.44-3.84 g NO3 -N/L reactor d at a hydraulic retention time of 0.5 h, which were significantly superior to those reported in packed bed reactors. Compared to methanol, ethanol was found to be a more effective external carbon source for sulfur-based mixotrophic denitrification due to lower sulfate and total organic carbon concentrations in the effluent. Using pyrosequencing, the phylotypes of primary microbial groups in the reactor, including sulfur-oxidizing autotrophic denitrifiers, methanol- or ethanol-supported heterotrophic denitrifiers, were investigated in response to changes in electron donors. Principal component and heatmap analyses indicated that selection of electron donating substrates largely determined the microbial community structure. The abundance of Thiobacillus decreased from 45.1% in the sulfur-oxidizing autotrophic denitrifying reactor to 12.0% and 14.2% in sulfur-based methanol- and ethanol-fed mixotrophic denitrifying bioreactors, respectively. Heterotrophic Methyloversatilis and Thauera bacteria became more dominant in the mixotrophic denitrifying bioreactors, which were possibly responsible for the observed methanol- and ethanol-associated denitrification. PMID:26364226

  11. Sensing in tissue bioreactors

    Science.gov (United States)

    Rolfe, P.

    2006-03-01

    Specialized sensing and measurement instruments are under development to aid the controlled culture of cells in bioreactors for the fabrication of biological tissues. Precisely defined physical and chemical conditions are needed for the correct culture of the many cell-tissue types now being studied, including chondrocytes (cartilage), vascular endothelial cells and smooth muscle cells (blood vessels), fibroblasts, hepatocytes (liver) and receptor neurones. Cell and tissue culture processes are dynamic and therefore, optimal control requires monitoring of the key process variables. Chemical and physical sensing is approached in this paper with the aim of enabling automatic optimal control, based on classical cell growth models, to be achieved. Non-invasive sensing is performed via the bioreactor wall, invasive sensing with probes placed inside the cell culture chamber and indirect monitoring using analysis within a shunt or a sampling chamber. Electroanalytical and photonics-based systems are described. Chemical sensing for gases, ions, metabolites, certain hormones and proteins, is under development. Spectroscopic analysis of the culture medium is used for measurement of glucose and for proteins that are markers of cell biosynthetic behaviour. Optical interrogation of cells and tissues is also investigated for structural analysis based on scatter.

  12. Microfluidic conductimetric bioreactor.

    Science.gov (United States)

    Limbut, Warakorn; Loyprasert, Suchera; Thammakhet, Chongdee; Thavarungkul, Panote; Tuantranont, Adisorn; Asawatreratanakul, Punnee; Limsakul, Chusak; Wongkittisuksa, Booncharoen; Kanatharana, Proespichaya

    2007-06-15

    A microfluidic conductimetric bioreactor has been developed. Enzyme was immobilized in the microfluidic channel on poly-dimethylsiloxane (PDMS) surface via covalent binding method. The detection unit consisted of two gold electrodes and a laboratory-built conductimetric transducer to monitor the increase in the conductivity of the solution due to the change of the charges generated by the enzyme-substrate catalytic reaction. Urea-urease was used as a representative analyte-enzyme system. Under optimum conditions urea could be determined with a detection limit of 0.09 mM and linearity in the range of 0.1-10 mM (r=0.9944). The immobilized urease on the microchannel chip provided good stability (>30 days of operation time) and good repeatability with an R.S.D. lower than 2.3%. Good agreement was obtained when urea concentrations of human serum samples determined by the microfluidic flow injection conductimetric bioreactor system were compared to those obtained using the Berthelot reaction (P<0.05). After prolong use the immobilized enzyme could be removed from the PDMS microchannel chip enabling new active enzyme to be immobilized and the chip to be reused. PMID:17289366

  13. Denitrification characteristics of a sulfur autotrophic denitrification reactor

    Directory of Open Access Journals (Sweden)

    Chenxiao ZHANG

    2016-02-01

    Full Text Available The denitrification characteristics of a sulfur autotrophic denitrification reactor are investigated. The results show that domestication of sulfur autotrophic bacteria is completed within 15 days after biofilm formation in the reactor, which is shorter than other similar researches. The nitrogen removal rate remains over than 90%, and the denitrification rate reaches 18.5 mg N/(L·h with influent NO-3-N of 70 mg/L , influent pH of 8 and HRT of 4.3 h . Thiobacillus denitrificans are observed in the whole reactor when domestication finishes, while it is more abundant in the middle and lower part. The optimal influent NO-3-N concentration for the reactor is 50 mg/L, the optimal temperature is 30~35 ℃, the optimal influent pH is 7~8, and the nitrogen removal rate is over than 90%.

  14. Cells growing in NASA Bioreactor

    Science.gov (United States)

    1998-01-01

    For 5 days on the STS-70 mission, a bioreactor cultivated human colon cancer cells, which grew to 30 times the volume of control specimens grown on Earth. This significant result was reproduced on STS-85 which grew mature structures that more closely match what are found in tumors in humans. Shown here, clusters of cells slowly spin inside a bioreactor. On Earth, the cells continually fall through the buffer medium and never hit bottom. In space, they are naturally suspended. Rotation ensures gentle stirring so waste is removed and fresh nutrient and oxygen are supplied. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  15. Photo-autotrophic Production of Poly(hydroxyalkanoates) in Cyanobacteria

    OpenAIRE

    Drosg, B.; Fritz, I; Gattermayr, F.; Silvestrini, L.

    2015-01-01

    In the last two decades, poly(hydroxyalkanoates) (PHA) were solely produced using heterotrophic bacteria in aerobic cultivation. With respect to the great potential (500 Mt yr–1) of raw industrial CO2 streams and even greater potential of flue gases, the focus on photo-autotrophic biotechnological processes is increasing steadily. Primarily, PHA-gene transfer from heterotrophic bacteria into algae and plant cells was attempted, with the intention to combine the known biosynthesis pathway with...

  16. Comparison of the Modeling Approach between Membrane Bioreactor and Conventional Activated Sludge Processes

    DEFF Research Database (Denmark)

    Jiang, Tao; Sin, Gürkan; Spanjers, Henri;

    2009-01-01

    Activated sludge models (ASM) have been developed and largely applied in conventional activated sludge (CAS) systems. The applicability of ASM to model membrane bioreactors (MBR) and the differences in modeling approaches have not been studied in detail. A laboratory-scale MBR was modeled using ASM...... membrane can be modeled as a continuous flow-through point separator. This simplicity has only a minor effect on ASM simulation results; however, it significantly improved simulation speed. Water Environ. Res., 81, 432 (2009).......2d. It was found that the ASM2d model structure can still be used for MBR modeling. There are significant differences related to ASM modeling. First, a lower maximum specific growth rate for MBR nitrifiers was estimated. Independent experiments demonstrated that this might be attributed to the...

  17. Characterization of effluent water qualities from satellite membrane bioreactor facilities.

    Science.gov (United States)

    Hirani, Zakir M; Bukhari, Zia; Oppenheimer, Joan; Jjemba, Patrick; LeChevallier, Mark W; Jacangelo, Joseph G

    2013-09-15

    Membrane bioreactors (MBRs) are often a preferred treatment technology for satellite water recycling facilities since they produce consistent effluent water quality with a small footprint and require little or no supervision. While the water quality produced from centralized MBRs has been widely reported, there is no study in the literature addressing the effluent quality from a broad range of satellite facilities. Thus, a study was conducted to characterize effluent water qualities produced by satellite MBRs with respect to organic, inorganic, physical and microbial parameters. Results from sampling 38 satellite MBR facilities across the U.S. demonstrated that 90% of these facilities produced nitrified (NH4-N <0.4 mg/L-N) effluents that have low organic carbon (TOC <8.1 mg/L), turbidities of <0.7 NTU, total coliform bacterial concentrations <100 CFU/100 mL and indigenous MS-2 bacteriophage concentrations <21 PFU/100 mL. Multiple sampling events from selected satellite facilities demonstrated process capability to consistently produce effluent with low concentrations of ammonia, TOC and turbidity. UV-254 transmittance values varied substantially during multiple sampling events indicating a need for attention in designing downstream UV disinfection systems. Although enteroviruses, rotaviruses and hepatitis A viruses (HAV) were absent in all samples, adenoviruses were detected in effluents of all nine MBR facilities sampled. The presence of Giardia cysts in filtrate samples of two of nine MBR facilities sampled demonstrated the need for an appropriate disinfection process at these facilities. PMID:23871258

  18. Spiral vane bioreactor

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    1991-01-01

    A spiral vane bioreactor of a perfusion type is described in which a vertical chamber, intended for use in a microgravity condition, has a central rotating filter assembly and has flexible membranes disposed to rotate annularly about the filter assembly. The flexible members have end portions disposed angularly with respect to one another. A fluid replenishment medium is input from a closed loop liquid system to a completely liquid filled chamber containing microcarrier beads, cells and a fluid medium. Output of spent medium is to the closed loop. In the closed loop, the output and input parameters are sensed by sensors. A manifold permits recharging of the nutrients and pH adjustment. Oxygen is supplied and carbon dioxide and bubbles are removed and the system is monitored and controlled by a microprocessor.

  19. Biofilm development in membrane bioreactors

    OpenAIRE

    Savnik, Veronika

    2010-01-01

    Prevention of biofilm development and its removal has crucial meaning in membrane reactor. Biofilm causes pore blocking on membranes, which causes a drop in efficiency of mixed liquor filtration and consequently deteriorates the efficiency of whole membrane bioreactor. This thesis deals with factors that affect biofilm development in membrane bioreactors. Structure and growth of biofilm are presented from its initial attachment of individual particles, their parameters of adhesion, hydrodynam...

  20. Membrane Bioreactor With Pressure Cycle

    Science.gov (United States)

    Efthymiou, George S.; Shuler, Michael L.

    1991-01-01

    Improved class of multilayer membrane bioreactors uses convention forced by differences in pressure to overcome some of diffusional limitations of prior bioreactors. In reactor of new class, flow of nutrient solution reduces adverse gradients of concentration, keeps cells supplied with fresh nutrient, and sweeps away products faster than diffusion alone. As result, overall yield and rate of reaction increased. Pressures in sweeping gas and nutrient alternated to force nutrient liquid into and out of biocatalyst layer through hyrophilic membrane.

  1. Bioreactor Mass Transport Studies

    Science.gov (United States)

    Kleis, Stanley J.; Begley, Cynthia M.

    1997-01-01

    The objectives of the proposed research efforts were to develop both a simulation tool and a series of experiments to provide a quantitative assessment of mass transport in the NASA rotating wall perfused vessel (RWPV) bioreactor to be flown on EDU#2. This effort consisted of a literature review of bioreactor mass transport studies, the extension of an existing scalar transport computer simulation to include production and utilization of the scalar, and the evaluation of experimental techniques for determining mass transport in these vessels. Since mass transport at the cell surface is determined primarily by the relative motion of the cell assemblage and the surrounding fluid, a detailed assessment of the relative motion was conducted. Results of the simulations of the motion of spheres in the RWPV under microgravity conditions are compared with flight data from EDU#1 flown on STS-70. The mass transport across the cell membrane depends upon the environment, the cell type, and the biological state of the cell. Results from a literature review of cell requirements of several scalars are presented. As a first approximation, a model with a uniform spatial distribution of utilization or production was developed and results from these simulations are presented. There were two candidate processes considered for the experimental mass transport evaluations. The first was to measure the dissolution rate of solid or gel beads. The second was to measure the induced fluorescence of beads as a stimulant (for example hydrogen peroxide) is infused into the vessel. Either technique would use video taped images of the process for recording the quantitative results. Results of preliminary tests of these techniques are discussed.

  2. Nitrifying Community Analysis in a Single Submerged Attached-Growth Bioreactor for Treatment of High-Ammonia Waste Stream

    DEFF Research Database (Denmark)

    Gu, April Z.; Pedros, Philip B; Kristiansen, Anja;

    2007-01-01

    was used to quantify the identified AOB, and it was estimated that Nitrosomonas europaea/eutropha-like AOB accounted for 4.3% of the total volume of the biofilm, while Nitrosococcus mobilis-like AOB made up 1.2%; these numbers summed up to a total AOB fraction of 5.5% of the total volume on the...... biofilm. Nitrite-oxidizing bacteria (NOB) were not detectable in the biofilm samples with probes for either Nitrospira sp. or Nitrobacter sp., which indicated that NOB were either absent from the biofilters or present in numbers below the detection limit of FISH (<0.1% of the total biofilm). Nitrite...... in a SAGB reactor described in this study is applicable for high-ammonia-strength wastewater treatment, such as centrate or industrial wastes. Udgivelsesdato: December 2007...

  3. Occurrence of nitrifying bacteria and nitrification in Finnish drinking water distribution systems.

    Science.gov (United States)

    Lipponen, Mari T T; Suutari, Merja H; Martikainen, Pertti J

    2002-10-01

    Microbiological nitrification process may lead to chemical, microbiological and technical problems in drinking water distribution systems. Nitrification activity is regulated by several physical, and chemical, and operational factors. However, the factors affecting nitrification in the distribution systems in boreal region, having its specific environmental characteristics, are poorly known. We studied the occurrence and activity of nitrifying bacteria in 15 drinking water networks distributing water with very different origin and treatment practices. The waters included chloraminated surface water, chlorinated surface water, and non-disinfected groundwater. The networks were located in eight towns in different parts of Finland. Our results showed that nitrifying bacteria are common in boreal drinking water distribution systems despite their low temperature. Surprisingly high numbers and activities of nitrifiers were detected in pipeline sediment samples. The numbers of ammonia-oxidizing bacteria and their oxidation potentials were highest in chloraminated drinking water delivering networks, whereas the nitrite-oxidizing bacteria were present in the greatest numbers in those networks that used non-disinfected groundwater. The occurrence of nitrifying bacteria in drinking water samples correlated positively with the numbers of heterotrophic bacteria and turbidity, and negatively with the content of total chlorine. Although nitrifying bacteria grew well in drinking water distribution systems, the problems with nitrite accumulation are rare in Finland. PMID:12420937

  4. Intensified nitrogen removal in immobilized nitrifier enhanced constructed wetlands with external carbon addition.

    Science.gov (United States)

    Wang, Wei; Ding, Yi; Wang, Yuhui; Song, Xinshan; Ambrose, Richard F; Ullman, Jeffrey L

    2016-10-01

    Nitrogen removal performance response of twelve constructed wetlands (CWs) to immobilized nitrifier pellets and different influent COD/N ratios (chemical oxygen demand: total nitrogen in influent) were investigated via 7-month experiments. Nitrifier was immobilized on a carrier pellet containing 10% polyvinyl alcohol (PVA), 2.0% sodium alginate (SA) and 2.0% calcium chloride (CaCl2). A batch experiment demonstrated that 73% COD and 85% ammonia nitrogen (NH4-N) were degraded using the pellets with immobilized nitrifier cells. In addition, different carbon source supplement strategies were applied to remove the nitrate (NO3-N) transformed from NH4-N. An increase in COD/N ratio led to increasing reduction in NO3-N. Efficient nitrification and denitrification promoted total nitrogen (TN) removal in immobilized nitrifier biofortified constructed wetlands (INB-CWs). The results suggested that immobilized nitrifier pellets combined with high influent COD/N ratios could effectively improve the nitrogen removal performance in CWs. PMID:27396293

  5. Influence of water quality on nitrifier regrowth in two full-scale drinking water distribution systems.

    Science.gov (United States)

    Scott, Daniel B; Van Dyke, Michele I; Anderson, William B; Huck, Peter M

    2015-12-01

    The potential for regrowth of nitrifying microorganisms was monitored in 2 full-scale chloraminated drinking water distribution systems in Ontario, Canada, over a 9-month period. Quantitative PCR was used to measure amoA genes from ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), and these values were compared with water quality parameters that can influence nitrifier survival and growth, including total chlorine, ammonia, temperature, pH, and organic carbon. Although there were no severe nitrification episodes, AOB and AOA were frequently detected at low concentrations in samples collected from both distribution systems. A culture-based presence-absence test confirmed the presence of viable nitrifiers. AOB were usually present in similar or greater numbers than AOA in both systems. As well, AOB showed higher regrowth potential compared with AOA in both systems. Statistically significant correlations were measured between several water quality parameters of relevance to nitrification. Total chlorine was negatively correlated with both nitrifiers and heterotrophic plate count (HPC) bacteria, and ammonia levels were positively correlated with nitrifiers. Of particular importance was the strong correlation between HPC and AOB, which reinforced the usefulness of HPC as an operational parameter to measure general microbiological conditions in distribution systems. PMID:26518069

  6. Platelet bioreactor-on-a-chip

    OpenAIRE

    Thon, Jonathan N.; Mazutis, Linas; Wu, Stephen; Sylman, Joanna L.; Ehrlicher, Allen; Machlus, Kellie R.; Feng, Qiang; Lu, Shijiang; Lanza, Robert; Neeves, Keith B.; Weitz, David A; Italiano, Joseph E.

    2014-01-01

    We have developed a biomimetic microfluidic platelet bioreactor that recapitulates bone marrow and blood vessel microenvironments.Application of shear stress in this bioreactor triggers physiological proplatelet production, and platelet release.

  7. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    Science.gov (United States)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  8. Open Source Software to Control Bioflo Bioreactors

    OpenAIRE

    Burdge, David A.; Libourel, Igor G. L.

    2014-01-01

    Bioreactors are designed to support highly controlled environments for growth of tissues, cell cultures or microbial cultures. A variety of bioreactors are commercially available, often including sophisticated software to enhance the functionality of the bioreactor. However, experiments that the bioreactor hardware can support, but that were not envisioned during the software design cannot be performed without developing custom software. In addition, support for third party or custom designed...

  9. Progress in bioreactors of bioartiifcial livers

    Institute of Scientific and Technical Information of China (English)

    Cheng-Bo Yu; Xiao-Ping Pan; Lan-Juan Li

    2009-01-01

    BACKGROUND: Bioartiifcial liver support systems are becoming an effective therapy for hepatic failure. Bioreactors, as key devices in these systems, can provide a favorable growth and metabolic environment, mass exchange, and immunological isolation as a platform. Currently, stagnancy in bioreactor research is the main factor restricting the development of bioartiifcial liver support systems. DATA SOURCES: A PubMed database search of English-language literature was performed to identify relevant articles using the keywords "bioreactor", "bioartiifcial liver", "hepatocyte", and "liver failure". More than 40 articles related to the bioreactors of bioartiifcial livers were reviewed. RESULTS: Some progress has been made in the improvement of structures, functions, and modiifed macromolecular materials related to bioreactors in recent years. The current data on the improvement of bioreactor conifgurations for bioartiifcial livers or on the potential of the use of certain scaffold materials in bioreactors, combined with the clinical efifcacy and safety evaluation of cultured hepatocytesin vitro, indicate that the AMC (Academic Medical Center) BAL bioreactor and MELS (modular extracorporeal liver support) BAL bioreactor system can partly replace the synthetic and metabolic functions of the liver in phaseⅠ clinical studies. In addition, it has been indicated that the microlfuidic PDMS (polydimethylsiloxane) bioreactor, or SlideBioreactor, and the microfabricated grooved bioreactor are appropriate for hepatocyte culture, which is also promising for bioartiifcial livers. Similarly, modiifed scaffolds can promote the adhesion, growth, and function of hepatocytes, and provide reliable materials for bioreactors.CONCLUSIONS: Bioreactors, as key devices in bioartiifcial livers, play an important role in the therapy for liver failure both now and in the future. Bioreactor conifgurations are indispensable for the development of bioartiifcial livers used for liver

  10. Effects of aboveground grazing on coupling among nitrifier activity, abundance and community structure.

    Science.gov (United States)

    Le Roux, Xavier; Poly, Franck; Currey, Pauline; Commeaux, Claire; Hai, Brigitte; Nicol, Graeme W; Prosser, James I; Schloter, Michael; Attard, Eléonore; Klumpp, Katja

    2008-02-01

    The influence of switches in grassland management to or from grazing on the dynamics of nitrifier activity, as well as the abundance of ammonia-oxidizing bacteria, AOB and ammonia-oxidizing archeae, AOA, was analyzed for two years after changing management. Additionally community structure of AOB was surveyed. Four treatments were compared in mesocosms: grazing on previously grazed grassland (G-G); no grazing on ungrazed grassland (U-U); grazing on ungrazed grassland (U-G) and cessation of grazing on grazed grassland (G-U). Nitrifier activity and abundance were always higher for G-G than U-U treatments and AOB community structure differed between these treatments. AOA abundance was in the same range as AOB abundance and followed the same trend. Grazing led to a change in AOB community structure within <5 months and a subsequent (5-12 months) increase in nitrifier activity and abundance. In contrast, cessation of grazing led to a decrease in nitrifier activity and abundance within <5 months and to a later (5-12 months) change in AOB community structure. Activity in G-U and U-G was similar to that in U-U and G-G, respectively, after 12 months. Sequence analysis of 16S rRNA gene clones showed that AOB retrieved from soils fell within the Nitrosospira lineage and percentages of AOB related to known Nitrosospira groups were affected by grazing. These results demonstrate that AOB and AOA respond quickly to changes in management. The selection of nitrifiers adapted to novel environmental conditions was a prerequisite for nitrification enhancement in U-G, whereas nitrification decrease in G-U was likely due to a partial starvation and decrease in the abundance of nitrifiers initially present. The results also suggest that taxonomic affiliation does not fully infer functional traits of AOB. PMID:18049458

  11. Tissue grown in NASA Bioreactor

    Science.gov (United States)

    1998-01-01

    Cells from kidneys lose some of their special features in conventional culture but form spheres replete with specialized cell microvilli (hair) and synthesize hormones that may be clinically useful. Ground-based research studies have demonstrated that both normal and neoplastic cells and tissues recreate many of the characteristics in the NASA bioreactor that they display in vivo. Proximal kidney tubule cells that normally have rich apically oriented microvilli with intercellular clefts in the kidney do not form any of these structures in conventional two-dimensional monolayer culture. However, when normal proximal renal tubule cells are cultured in three-dimensions in the bioreactor, both the microvilli and the intercellular clefts form. This is important because, when the morphology is recreated, the function is more likely also to be rejuvenated. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC).

  12. Lipid-based liquid biofuels from autotrophic microalgae: energetic and environmental performance

    NARCIS (Netherlands)

    L. Reijnders

    2013-01-01

    Commercial cultivation of autotrophic microalgae for food production dates back to the 1950s. Autotrophic microalgae have also been proposed as a source for lipid-based liquid biofuels. As yet, there is no commercial production of such biofuels and estimated near-term prices are far in excess of fos

  13. Bioreactor technology for herbal plants

    International Nuclear Information System (INIS)

    Plants have been an important source of medicine for thousands of years and herbs are hot currency in the world today. During the last decade, popularity of alternative medicine increased significantly worldwide with noticeable trend. This in turn accelerated the global trade of herbal raw materials and herbal products and created greater scope for Asian countries that possess the major supply of herbal raw materials within their highly diversified tropical rain forest. As such, advanced bioreactor culture system possesses a great potential for large scale production than the traditional tissue culture system. Bioreactor cultures have many advantages over conventional cultures. Plant cells in bioreactors can grow fast and vigorously in shorter period as the culture conditions in bioreactor such as temperature, pH, concentrations of dissolved oxygen, carbon dioxide and nutrients can be optimised by on-line manipulation. Nutrient uptake can also be enhanced by continuous medium circulation, which ultimately increased cell proliferation rate. Consequently, production period and cost are substantially reduced, product quality is controlled and standardized as well as free of pesticide contamination and production of raw material can be conducted all year round. Taking all these into consideration, current research efforts were focused on varying several parameters such as inoculation density, air flow, medium formulation, PGRs etc. for increased production of cell and organ cultures of high market demand herbal and medicinal plants, particularly Eurycoma longifolia, Panax ginseng and Labisia pumila. At present, the production of cell and organ culture of these medicinal plants have also been applied in airlift bioreactor with different working volumes. It is hope that the investment of research efforts into this advanced bioreactor technology will open up a bright future for the modernization of agriculture and commercialisation of natural product. (author)

  14. Characteristics of the bioreactor landfill system using an anaerobic-aerobic process for nitrogen removal.

    Science.gov (United States)

    He, Ruo; Liu, Xin-Wen; Zhang, Zhi-Jian; Shen, Dong-Sheng

    2007-09-01

    A sequential upflow anaerobic sludge blanket (UASB) and air-lift loop sludge blanket (ALSB) treatment was introduced into leachate recirculation to remove organic matter and ammonia from leachate in a lab-scale bioreactor landfill. The results showed that the sequential anaerobic-aerobic process might remove above 90% of COD and near to 100% of NH4+ -N from leachate under the optimum organic loading rate (OLR). The total COD removal efficiency was over 98% as the OLR increased to 6.8-7.7 g/l d, but the effluent COD concentration increased to 2.9-4.8 g/l in the UASB reactor, which inhibited the activity of nitrifying bacteria in the subsequent ALSB reactor. The NO3- -N concentration in recycled leachate reached 270 mg/l after treatment by the sequential anaerobic-aerobic process, but the landfill reactor could efficiently denitrify the nitrate. After 56 days operation, the leachate TN and NH4+ -N concentrations decreased to less than 200 mg/l in the bioreactor landfill system. The COD concentration was about 200 mg/l with less than 8 mg/l BOD in recycled leachate at the late stage. In addition, it was found that nitrate in recycled leachate had a negative effect on waste decomposition. PMID:17071082

  15. Autotrophic and heterotrophic activity in Arctic first-year sea ice: seasonal study from Malene Bight, SW Greenland

    DEFF Research Database (Denmark)

    Søgaard, Dorte Haubjerg; Kristensen, Morten; Rysgaard, Søren; Glud, Ronnie Nøhr; Hansen, Per Juel; Hillingsøe, Karen Marie

    2010-01-01

    followed by an algal bloom in late March and April, leading to a net autotrophic community. During February and March, the oxygen level in the bag incubations remained constant, validating the low balanced heterotrophic and autotrophic activity. As the autotrophic activity exceeded the heterotrophic...

  16. Cattle activities affect abundance and activity of nitrifying and denitrifying microbial communities in upland soil

    Czech Academy of Sciences Publication Activity Database

    Chroňáková, Alica; Radl, V.; Čuhel, Jiří; Gattinger, A.; Šimek, Miloslav; Elhottová, Dana; Schloter, M.

    Uppsala : Swedish University of Agriculture Sciences, 2007. [Achievements of COST 856. Denitrification and related aspects. Final meeting of the ESF COST Action 856 /14./. 05.12.2007-08.12.2007, Uppsala] Institutional research plan: CEZ:AV0Z60660521 Keywords : cattle activities * nitrifying and denitrifying microbial communities * upland soil Subject RIV: EH - Ecology, Behaviour

  17. Distribution of baroduric, psychrotrophic and culturable nitrifying and denitrifying bacteria in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; PradeepRam, A.S.; Nair, S.; Nath, B.N.; Chandramohan, D.

    The abundance of baroduric, culturable nitrifying and denitrifying bacteria in the deep-sea cores of Central Indian Basin (CIB) at ca 5000 m depth was investigated. Analysis of 8 cores, sampled between 10 degrees 00 minutes S and 75 degrees 55...

  18. Nitrification performance of nitrifying bacteria immobilized in waterborne polyurethane at low ammonia nitrogen concentrations

    Institute of Scientific and Technical Information of China (English)

    Yamei Dong; Zhenjia Zhang; Yongwei Jin; Zhirong Li; Jian Lu

    2011-01-01

    Suspended and waterborne polyurethane immobilized nitrifying bacteria have been adopted for evaluating the effects of environmental changes, such as temperature, dissolved oxygen (DO) concentration and pH, on nitrification characteristics under conditions of low ammonia concentrations.The results showed that nitrification was prone to complete with increasing pH, DO and temperature.Sensitivity analysis demonstrated the effects of temperature and pH on nitrification feature of suspended bacteria were slightly greater than those of immobilized nitrifying bacteria.Immobilized cells could achieve complete nitrification at low ammonia concentrations when DO was sufficient.Continuous experiments were carried out to discuss the removal of ammonia nitrogen from synthetic micropollute source water with the ammonia concentration of about 1 mg/L using immobilized nitrifying bacteria pellets in an up-flow inner circulation reactor under different hydraulic retention times (HRT).The continuous removal rate remains above 80% even under HRT 30 min.The results verified that the waterborne polyurethane immobilized nitrifying bacteria pellets had great potential applications for micro-pollution source water treatment.

  19. The behavior of nitrifying sludge in presence of sulfur compounds using a floating biofilm reactor.

    Science.gov (United States)

    Beristain-Cardoso, Ricardo; Gómez, Jorge; Méndez-Pampín, Ramón

    2010-11-01

    The tolerance, kinetic and oxidizing capability of a nitrifying sludge exposed to different initial concentrations of sulfide (1.7 to 18mg/L) was evaluated in batch experiments. A nitrifying sludge fed with ammonium and thiosulfate and produced in steady state conditions was used as inoculum. Sulfide induced a significant effect either on ammonium consumption rates or nitrite accumulation. In spite of the nitrifying kinetic was affected, the ammonium consumption efficiencies were close to 100%, with nitrate production yields around 1.0. The IC(50) value for ammonium oxidizing-process was 13mg/L of sulfide. Sulfide was oxidized in two steps: first sulfide was oxidized to elemental sulfur and afterward into sulfate. FISH oligonucleotide probes for Thiobacillusdenitrificans, Nitrosomonas spp., and Nitrobacter spp. were used in order to know if these bacteria were part of the microbial ecology. The obtained results showed that under nitrifying conditions are possible to carry out simultaneously two biological processes, nitrification and sulfur oxidation. PMID:20620047

  20. Transcriptional and physiological responses of nitrifying bacteria to heavy metal inhibition

    Science.gov (United States)

    Heavy metals have been shown to inhibit nitrification, a key process in the removal of nitrogen in wastewater treatment plants. In the present study, the effects of nickel, zinc, lead and cadmium on nitrifying enrichment cultures were studied in batch reactors. The transcriptiona...

  1. Autotrophic and heterotrophic bacterial diversity from Yucca Mountain

    International Nuclear Information System (INIS)

    A basic understanding of the types and functions of microbiota present within the deep subsurface of Yucca Mountain will be important in terms of modeling the long term stability of a nuclear waste repository. Microorganisms can degrade building materials used in tunnel construction such as concrete and steel. For example, high concentrations of nitrifying bacteria, may cause corrosion of concrete due to the release of nitric acid. Likewise, sulfur-oxidizing and iron-oxidizing bacteria have been implicated in microbially influenced corrosion (MIC), and may contribute to the degradation of waste packages. In addition, the metabolic activities of microbiota may alter the geochemistry of surrounding environments, which may in turn influence the permeability of subsurface strata and the fate of radioactive compounds. Microorganisms that play roles in these processes have diverse methods of obtaining the energy required for growth and metabolism and have been recovered from a wide range of environments, including the deep subsurface. The purpose of this research was to determine if these bacterial groups, important to the long-term success of a high-level nuclear waste repository, were indigenous to Yucca Mountain

  2. Effects of alkalinity on membrane bioreactors for reject water treatment: Performance improvement, fouling mitigation and microbial structures.

    Science.gov (United States)

    Hu, Dalong; Zhou, Zhen; Shen, Xuelian; Wei, Haijuan; Jiang, Lu-Man; Lv, Yan

    2015-12-01

    Two submerged membrane bioreactors (MBRs) for reject water treatment were operated to investigate effects of sodium bicarbonate (SB) addition on enhancing process performance and mitigating membrane fouling. Results showed that SB addition enhanced average removal efficiencies of COD and NH4-N by 14.6% and 38.3%, respectively. With SB addition, the extracellular polymeric substances (EPS) content in activated sludge increased, but those in membrane foulants greatly decreased. Gel permeation chromatography analysis demonstrated that EPS in MBRs for reject water treatment had much larger molecular weight (MW) and broader MW distribution than those in MBRs for municipal wastewater treatment. The fouling mitigation by SB was attributed to a deprotonation mechanism reduced EPS adsorption on negatively charged membrane surfaces, and improvement of degradation efficiency of macromolecular organic matters. SB addition into MBRs for reject water treatment increased microbial abundance, enriched nitrifying bacteria, and converted predominant AOB genus from Nitrosomonas to Nitrosospira. PMID:26340030

  3. [Analysis on Diversity of Denitrifying Microorganisms in Sequential Batch Bioreactor Landfill].

    Science.gov (United States)

    Li, Wei-Hua; Sun, Ying-Jie; Liu, Zi-Liang; Ma, Qiang; Yang, Qiang

    2016-01-15

    A denitrification functional microorganism gene clone library (amoA, nosZ) and the PCR-RFLP technology was constructed to investigate the microbial diversity of denitrifying microorganisms in the late period of stabilization of sequential batch bioreactor landfill. The results indicated that: the bacterial diversity of ammonia oxidizing bacteria in the aged refuse reactor was very high, and most of them were unknown groups, also, all bacteria were unculturable or had not been isolated. The phylogenetic analysis suggested that the dominant ammonia oxidizing bacteria were presumably Nitrosomonas of 6-Proteobacteria. The diversity of denitrifying bacteria in fresh refuse reactor was abundant, which mainly included Thauera and Thiobacillus of 6-Proteobacteria. As Thauera sp. has the denitrification characteristics under the condition of aerobic while Thiobacillus denitrificans has the autotrophic denitrification characteristics, it was speculated that aerobic denitrification and autotrophic denitrification might be the main pathways for nitrogen removal in the fresh refuse reactor at the late period of stabilization. Additionally, another group in the gene clone library of denitrifying bacteria may be classified as Bradyrhizobiaceae of alpha-Proteobacteria. PMID:27078976

  4. Effect of different salt adaptation strategies on the microbial diversity, activity, and settling of nitrifying sludge in sequencing batch reactors

    NARCIS (Netherlands)

    Bassin, J.P.; Kleerebezem, R.; Muyzer, G.; Rosado, A.S.; Van Loosdrecht, M.C.M.; Dezotti, M.

    2011-01-01

    The effect of salinity on the activity of nitrifying bacteria, floc characteristics, and microbial community structure accessed by fluorescent in situ hybridization and polymerase chain reaction–denaturing gradient gel electrophoresis techniques was investigated. Two sequencing batch reactors (SRB1

  5. Anaerobic membrane bioreactor under extreme conditions (poster)

    OpenAIRE

    Munoz Sierra, J.D.; De Kreuk, M.K.; Spanjers, H.; van Lier, J B

    2013-01-01

    Membrane bioreactors ensure biomass retention by the application of micro or ultrafiltration processes. This allows operation at high sludge concentrations. Previous studies have shown that anaerobic membrane bioreactors is an efficient way to retain specialist microorganisms for treating wastewaters from different industries such as coke, textile, food, and chemical. However, few research has been found into the use of membrane bioreactors for anaerobic treatment of wastewater under extreme ...

  6. Inhibition of Nitrifiers and Methanotrophs from an Agricultural Humisol by Allylsulfide and Its Implications for Environmental Studies

    OpenAIRE

    Neufeld, Josh D.; Knowles, Roger

    1999-01-01

    Allylsulfide, an inhibitor of ammonia monooxygenase, was tested to determine its ability to inhibit nitrification and methane oxidation in pure cultures, in agricultural humisol enrichment cultures, and in humisol slurries. We confirmed that allylsulfide is a differential inhibitor of cultures of nitrifiers and methanotrophs at concentrations of 1 and 200 μM, respectively, which result in 50% inhibition. However, although a nitrifying enrichment culture added to sterilized humisol was inhibit...

  7. Diversity, Abundance, and Potential Activity of Nitrifying and Nitrate-Reducing Microbial Assemblages in a Subglacial Ecosystem ▿ †

    OpenAIRE

    Boyd, Eric S.; Lange, Rachel K.; Mitchell, Andrew C.; Havig, Jeff R.; Hamilton, Trinity L.; Lafrenière, Melissa J.; Shock, Everett L.; Peters, John W.; Skidmore, Mark

    2011-01-01

    Subglacial sediments sampled from beneath Robertson Glacier (RG), Alberta, Canada, were shown to harbor diverse assemblages of potential nitrifiers, nitrate reducers, and diazotrophs, as assessed by amoA, narG, and nifH gene biomarker diversity. Although archaeal amoA genes were detected, they were less abundant and less diverse than bacterial amoA, suggesting that bacteria are the predominant nitrifiers in RG sediments. Maximum nitrification and nitrate reduction rates in microcosms incubate...

  8. Review of nonconventional bioreactor technology

    Energy Technology Data Exchange (ETDEWEB)

    Turick, C.E.; Mcllwain, M.E.

    1993-09-01

    Biotechnology will significantly affect many industrial sectors in the future. Industrial sectors that will be affected include pharmaceutical, chemical, fuel, agricultural, and environmental remediation. Future research is needed to improve bioprocessing efficiency and cost-effectiveness in order to compete with traditional technologies. This report describes recent advances in bioprocess technologies and bioreactor designs and relates them to problems encountered in many industrial bioprocessing operations. The primary focus is directed towards increasing gas and vapor transfer for enhanced bioprocess kinetics as well as unproved by-product separation and removal. The advantages and disadvantages of various conceptual designs such as hollow-fiber, gas-phase, hyperbaric/hypobaric, and electrochemical bioreactors are also discussed. Specific applications that are intended for improved bioprocesses include coal desulfurization, coal liquefaction, soil bioremediation, biomass conversion to marketable chemicals, biomining, and biohydrometallurgy as well as bioprocessing of gases and vapors.

  9. Optimizing of Culture Conditionin Horizontal Rotating Bioreactor

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionBioreactor is the most important equipment in tissue engineering. It can mimic the micro-environment of cell growth in vitro. At present, horizontal rotating bioreactor is the most advanced equipment for cell culture in the world. 2 Rotating bioreactors2.1 Working principleThere are two kinds of horizontal rotating bioreactor: HARV(high aspect ratio vessel) and RCCS (rotary cell culture system). It is drived by step motor with horizontal rotation, the culture medium and cell is filled between ...

  10. Prostate tumor grown in NASA Bioreactor

    Science.gov (United States)

    2001-01-01

    This prostate cancer construct was grown during NASA-sponsored bioreactor studies on Earth. Cells are attached to a biodegradable plastic lattice that gives them a head start in growth. Prostate tumor cells are to be grown in a NASA-sponsored Bioreactor experiment aboard the STS-107 Research-1 mission in 2002. Dr. Leland Chung of the University of Virginia is the principal investigator. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Credit: NASA and the University of Virginia.

  11. Filtration characteristics in membrane bioreactors

    OpenAIRE

    Evenblij, H.

    2006-01-01

    Causes of and remedies for membrane fouling in Membrane Bioreactors for wastewater treatment are only poorly understood and described in scientific literature. A Filtration Characterisation Installation and a measurement protocol were developed with the aim of a) unequivocally determination and quantification of the filterability of an activated sludge and b) carrying out short term experiments at labscale to determine foulants and/or fouling propensity determining factors. The installation w...

  12. Image Analysis and Multiphase Bioreactors

    OpenAIRE

    Ferreira, E. C.; Mota, M.; Pons, M.N.

    2001-01-01

    The applications of visualisation and image analysis to bioreactors can be found in two main areas: the characterisation of biomass (fungi, bacteria, yeasts, animal and plant cells, etc), in terms of size, morphology and physiology, that is the far most developed, and the characterisation of the multiphase behaviour of the reactors (flow patterns, velocity fields, bubble size and shape distribution, foaming), that may require sophisticated visualisation techniques.

  13. Denitrification using immersed membrane bioreactors

    OpenAIRE

    McAdam, Ewan J.

    2008-01-01

    Nitrate is practically ubiquitous in waters abstracted for municipal potable water production in Europe due to decades of intensive agricultural practice. Ion exchange is principally selected to target abstracted waters with elevated nitrate concentrations. However, the cost associated with disposal of the waste stream has re-ignited interest in destructive rather concentrative technologies. This thesis explores the potential of membrane bioreactor (MBR) technology for the remo...

  14. Regulation of carbon dioxide fixation in facultatively autotrophic bacteria. A phisiological and genetical study.

    OpenAIRE

    Meijer, Wilhelmus Gerhardus

    1990-01-01

    Autotrophic bactcria are capable of CO2 fixation via the Calvin cycle, emplofng energy derived from the oxidation of anorganic substrates (e.g. Hz), simple organic substrates (one-carbon compounds, e.g. methanol, formate), or from light. Ribulose-1,5-bisphospbate carboxylase/oxygenase (RuBisC/O), pbosphoribulokinase (PRK) and fructosebisphosphatase (FBPase) are the unique enzymes of this autotrophic pathway (Chapter 1). ... Zie: Summary

  15. Current views on the regulation of autotrophic carbon dioxide fixation via the Calvin cycle in bacteria

    OpenAIRE

    Dijkhuizen, L; Harder, W

    1984-01-01

    The Calvin cycle of carbon dioxide fixation constitutes a biosynthetic pathway for the generation of (multi-carbon) intermediates of central metabolism from the one-carbon compound carbon dioxide. The product of this cycle can be used as a precursor for the synthesis of all components of cell material. Autotrophic carbon dioxide fixation is energetically expensive and it is therefore not surprising that in the various groups of autotrophic bacteria the operation of the cycle is under strict m...

  16. Investigation of mixotrophic, heterotrophic, and autotrophic growth of Chlorella vulgaris under agricultural waste medium.

    Science.gov (United States)

    Mohammad Mirzaie, M A; Kalbasi, M; Mousavi, S M; Ghobadian, B

    2016-01-01

    Growth of Chlorella vulgaris and its lipid production were investigated under autotrophic, heterotrophic, and mixotrophic conditions. Cheap agricultural waste molasses and corn steep liquor from industries were used as carbon and nitrogen sources, respectively. Chlorella vulgaris grew remarkably under this agricultural waste medium, which resulted in a reduction in the final cost of the biodiesel production. Maximum dry weight of 2.62 g L(-1) was obtained in mixotrophic growth with the highest lipid concentration of 0.86 g L(-1). These biomass and lipid concentrations were, respectively, 140% and 170% higher than autotrophic growth and 300% and 1200% higher than heterotrophic growth. In mixotrophic growth, independent or simultaneous occurrence of autotrophic and heterotrophic metabolisms was investigated. The growth of the microalgae was observed to take place first heterotrophically to a minimum substrate concentration with a little fraction in growth under autotrophic metabolism, and then the cells grew more autotrophically. It was found that mixotrophic growth was not a simple combination of heterotrophic and autotrophic growth. PMID:25807048

  17. Morphology and physiology of facultative autotrophic coryneformic bacteria with ability of carbon monoxide oxidation

    International Nuclear Information System (INIS)

    Two coryneform bacterial strains (IFAM 1131 and IFAM 1133) capable of living on CO as the sole energy and carbon source were selected from a number of co-tolerant bacteria and studied more closely. Both strains could provisionally be grouped in the genera Arthrobacter. Their ability for hetorotrophic growth with a variety of C-sources and also autotrophic growth under CO and H2 atmospheric conditions characterised the test strains as facultative autotrophs. They could clearly be distinguished from all other CO- and H2-autotrophic bacterial strains described in the literature. Studies on strain IFAM 1131 using 14CO shared that for CO-autotrophic growth, carbon monoxide is oxidised to CO2. Ribulose 1,5-bisphosphate carboxylase activity, only found in autotrophically - grown cells, provided evidence for CO2 as the C-source and its fixation via the calvin cycle. The CO-oxidising system was also active in the absence of CO2. Gas chromatographically determined conversion rates for CO-autotrophically-grown static cultures of the strain IFAM 1131 revealed that some 20% of the CO oxidised to CO2 was fixed during logarithmic growth. (orig./MG)

  18. HYDROGEN KINETICS LIMITATION OF AN AUTOTROPHIC SULPHATE REDUCTION REACTOR

    Directory of Open Access Journals (Sweden)

    CÉSAR SÁEZ-NAVARRETE

    2012-01-01

    Full Text Available El uso de sustratos inorgánicos podría reducir los costos y simplificar la operación de sistemas de tratamiento de aguas que utilizan bacterias reductoras de sulfato. Sin embargo, el uso de H2 como sustrato energético y la bioproducción de H2S podrían provocar limitaciones cinéticas. El objetivo de este estudio fue evaluar las condiciones en las que la capacidad de transferencia de masa de un bioreactor de reducción de sulfato, limita su cinética de reducción. La cinética del reactor fue obtenida monitoreando la presión del sistema en condiciones de no limitación por sulfato. Se concluyó que el diseño del bioreactor debería basarse en sus propiedades de transferencia. La tasa de consumo de H2 alcanzó un máximo de 10-4 M/min, para una tasa de reducción de sulfato de 3.4 g·L-1·d-1. Para evitar limitación por H2 se requirió un kLa de 1.48 min-1 a 1.2·109 cells/L (1.23·10-9 L·min-1·cell-1, valor relevante para propósitos de escalamiento.

  19. Modelling the fate of nitrite in an urbanized river using experimentally obtained nitrifier growth parameters

    OpenAIRE

    Raimonet, Mélanie; Vilmin, Lauriane; Flipo, Nicolas; Rocher, Vincent; Laverman, Anniet M

    2015-01-01

    International audience Maintaining low nitrite concentrations in aquatic systems is a major issue for stakeholders due to nitrite's high toxicity for living species. This study reports on a cost-effective and realistic approach to study nitrite dynamics and improve its modelling in human-impacted river systems. The implementation of different nitrifying biomasses to model riverine communities and waste water treatment plant (WWTP)-related communities enabled us to assess the impact of a ma...

  20. Temporal Dynamics of Active Prokaryotic Nitrifiers and Archaeal Communities from River to Sea

    OpenAIRE

    Hugoni, Mylène; Agogué, Hélène; Taib, Najwa; Domaizon, Isabelle; Moné, Anne; Pierre E Galand; Bronner, Gisèle; Debroas, Didier; Mary, Isabelle

    2015-01-01

    International audience To test if different niches for potential nitrifiers exist in estuarine systems, we assessed by pyrosequencing the diversity of archaeal gene transcript markers for taxonomy (16S ribosomal RNA (rRNA)) during an entire year along a salinity gradient in surface waters of the Charente estuary (Atlantic coast, France). We further investigated the potential for estuarine prokaryotes to oxidize ammonia and hydrolyze urea by quantifying thaumarchaeal amoA and ureC and bacte...

  1. Community Structure and Activity Dynamics of Nitrifying Bacteria in a Phosphate-Removing Biofilm

    OpenAIRE

    Gieseke, Armin; Purkhold, Ulrike; Wagner, Michael; Amann, Rudolf; Schramm, Andreas

    2001-01-01

    The microbial community structure and activity dynamics of a phosphate-removing biofilm from a sequencing batch biofilm reactor were investigated with special focus on the nitrifying community. O2, NO2−, and NO3− profiles in the biofilm were measured with microsensors at various times during the nonaerated-aerated reactor cycle. In the aeration period, nitrification was oxygen limited and restricted to the first 200 μm at the biofilm surface. Additionally, a delayed onset of nitrification aft...

  2. Study of nitrifying sequencing batch reactor in presence of m-Cresol

    International Nuclear Information System (INIS)

    The process of the nitrification has been studied scantly in presence of phenolic compounds such as m-cresol. the aim of this study was evaluate the tolerance of a nitrifying SBR (Sequencing Batch Reactor) to m-cresol and the ability of the sludge to consume this phenolic compound. Nitrification is the process of oxidation of ammonia to nitrite and nitrate by lithoautotrophic ammonia-and nitrite-oxidizing bacteria. (Author)

  3. Application of Molecular Techniques to the Characterization of a Nitrifying Bioaugmentation Culture

    OpenAIRE

    Fouratt, Melissa Amanda

    2001-01-01

    Nitrification is the biological process whereby ammonia is converted first to nitrite by ammonia-oxidizing bacteria, and then the nitrite is subsequently converted to nitrate by nitrite-oxidizing bacteria. Ammonia and nitrite levels are closely monitored during treatment of wastewater due to their toxicity to other biological processes. Sybron Chemicals, Inc., is a company that manufactures a nitrifying bioaugmentation culture (1010N) that is used to enhance the naturally occurring levels o...

  4. Bioreactor microbial ecosystems for thiocyanate and cyanide degradation unravelled with genome-resolved metagenomics.

    Science.gov (United States)

    Kantor, Rose S; van Zyl, A Wynand; van Hille, Robert P; Thomas, Brian C; Harrison, Susan T L; Banfield, Jillian F

    2015-12-01

    Gold ore processing uses cyanide (CN(-) ), which often results in large volumes of thiocyanate- (SCN(-) ) contaminated wastewater requiring treatment. Microbial communities can degrade SCN(-) and CN(-) , but little is known about their membership and metabolic potential. Microbial-based remediation strategies will benefit from an ecological understanding of organisms involved in the breakdown of SCN(-) and CN(-) into sulfur, carbon and nitrogen compounds. We performed metagenomic analysis of samples from two laboratory-scale bioreactors used to study SCN(-) and CN(-) degradation. Community analysis revealed the dominance of Thiobacillus spp., whose genomes harbour a previously unreported operon for SCN(-) degradation. Genome-based metabolic predictions suggest that a large portion of each bioreactor community is autotrophic, relying not on molasses in reactor feed but using energy gained from oxidation of sulfur compounds produced during SCN(-) degradation. Heterotrophs, including a bacterium from a previously uncharacterized phylum, compose a smaller portion of the reactor community. Predation by phage and eukaryotes is predicted to affect community dynamics. Genes for ammonium oxidation and denitrification were detected, indicating the potential for nitrogen removal, as required for complete remediation of wastewater. These findings suggest optimization strategies for reactor design, such as improved aerobic/anaerobic partitioning and elimination of organic carbon from reactor feed. PMID:26031303

  5. Effect of organic carbon on nitrification efficiency and community composition of nitrifying biofilms

    Institute of Scientific and Technical Information of China (English)

    HU Jie; LI Daping; LIU Qiang; TAO Yong; HE Xiaohong; WANG Xiaomei; LI Xudong; GAO Ping

    2009-01-01

    The effects of organic carbon/inorganic nitrogen (C/N) ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (DGGE) analysis. The results showed that the nitrification rate decreased with an increasing organic concentration. However, the effect became weak when the carbon concentration reached sufficiently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8 and 16 compare to control (C/N = 0). The loss of nitrogen at C/N = 0.5, 1, 2, 4, (8 and 16 was 31%, 18%, 24%, 65%, 59% and 62% respectively, after 24 h. Sequence analysis of 16S rRNA gene fragments revealed that the dominant populations changed from nitrifying bacteria (Nitrosomonas europaea and Nitrobacter sp.) to denitrifying bacteria (Pseudomonas sp., Acidovorax sp. and Comamonas sp.) with C/N ratio increase. Although at high C/N ratio the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Conrrespondingly, nitrification process coexisted with denitrification.

  6. Effect of wastewater COD/N ratio on aerobic nitrifying sludge granulation and microbial population shift

    Institute of Scientific and Technical Information of China (English)

    Lei Wu; Chengyao Peng; Yongzhen Peng; Lingyun Li; Shuying Wang; Yong Ma

    2012-01-01

    The effect of COD/N ratio on the granulation process and microbial population succession was investigated.Four identical sequencing batch reactors,R1,R2,R3 and R4,were operated with various initial COD/N ratios ranging from 0/200 to 800/200 (m/n).Ethanol was fed as the source of COD.Aerobic granules were successfully cultivated in R2 and R3,operating with the COD/N ratio of 200/200 and 400/200,respectively.Scanning electron microscope observations indicated that short rod-shaped and spherical bacteria were dominant in R2,while granules produced in R3 were surrounded with a large amount of filamentous bacteria.The average specific nitritation rate in R2 and R3 were 0.019 and 0.008 mg N/(mg MLVSS.hr),respectively.Fluorescence in situ hybridization results demonstrated that nitrifying bacteria population was enriched remarkably in R2.It indicated that nitrification ability and nitrifying bacteria population were enriched remarkably at low COD/N ratio.However,no granules were formed in R1and R4 which might attribute to either limited or excessive extracellular polymeric substances production.This study contributed to a better understanding of the role of COD/N ratio in nitrifying sludge granulation.

  7. Influence of nitrifying conditions on the biodegradation and sorption of emerging micropollutants.

    Science.gov (United States)

    Fernandez-Fontaina, E; Omil, F; Lema, J M; Carballa, M

    2012-10-15

    High biodegradation efficiencies of different emerging micropollutants were obtained with nitrifying activated sludge (NAS) working at high nitrogen loading rates (NLR), that boosted the development of biomass with high nitrifying activities (>1 g N-NH(4)(+)/g VSS d). Come-tabolic biodegradation seemed to be responsible for the removal of most compounds due to the action of the ammonium monooxygenase enzyme. NAS showed a different affinity for each compound, probably due to steric hindrance, activation energy limitations or the presence of specific functional groups. Increasing loading rates of micropollutants were removed at shorter hydraulic retention times, although the biodegradation efficiencies of compounds with slow/intermediate kinetics, such as fluoxetine, erythromycin, roxithromycin and trimethoprim, diminished due to kinetic and/or stoichiometric limitations. Solids retention time, always above the minimum to avoid the washout of nitrifiers, did not enhance the biodegradation of any of the selected compounds, with the exception of diclofenac. Regarding sorption, the solid-liquid distribution coefficients (K(d)) obtained in NAS were very similar to those found in conventional activated sludge by other authors. No correlation between K(d) values and any of the operational parameters was found for the selected substances. PMID:22877882

  8. Following an Optimal Batch Bioreactor Operations Model

    DEFF Research Database (Denmark)

    Ibarra-Junquera, V.; Jørgensen, Sten Bay; Virgen-Ortíz, J.J.;

    2012-01-01

    The problem of following an optimal batch operation model for a bioreactor in the presence of uncertainties is studied. The optimal batch bioreactor operation model (OBBOM) refers to the bioreactor trajectory for nominal cultivation to be optimal. A multiple-variable dynamic optimization of fed-batch...... reactor for biomass production is studied using a differential geometry approach. The maximization problem is solved by handling both the optimal filling policy and substrate concentration in the inlet stream. In order to follow the OBBOM, a master–slave synchronization is used. The OBBOM is considered as...... the master system which includes the optimal cultivation trajectory for the feed flow rate and the substrate concentration. The “real” bioreactor, the one with unknown dynamics and perturbations, is considered as the slave system. Finally, the controller is designed such that the real bioreactor is...

  9. Development of Denitrifying and Nitrifying Bacteria and Their Co-occurrence in Newly Created Biofilms in Urban Streams

    Science.gov (United States)

    Vaessen, T. N.; Martí Roca, E.; Pinay, G.; Merbt, S. N.

    2015-12-01

    Biofilms play a pivotal role on nutrient cycling in streams, which ultimately dictates the export of nutrients to downstream ecosystems. The extent to which biofilms influence the concentration of dissolved nutrients, oxygen and pH in the water column may be determined by the composition of the microbial assemblages and their activity. Evidence of biological interactions among bacteria and algae are well documented. However, the development, succession and co-occurence of nitrifying and denitrifying bacteria remain poorly understood. These bacteria play a relevant role on the biogeochemical process associated to N cycling, and their relative abundance can dictate the fate of dissolved inorganic nitrogen in streams. In particular, previous studies indicated that nitrifiers are enhanced in streams receiving inputs from wastewater treatment plant (WWTP) effluents due to both increases in ammonium concentration and inputs of nitrifiers. However, less is known about the development of denitrifiers in receiving streams, although environmental conditions seem to favor it. We conducted an in situ colonization experiment in a stream receiving effluent from a WWTP to examine how this input influences the development and co-occurrence of nitrifying and denitrifying bacteria. We placed artificial substrata at different locations relative to the effluent and sampled them over time to characterize the developed biofilm in terms of bulk measurements (organic matter content and algae) as well as in terms of abundance of nitrifiers and denitrifiers (using qPCR). The results of this study contribute to a better understanding of the temporal dynamics of denitrifiers and nitrifiers in relation to the developed organic matter, dissolved oxygen and pH and the biomass accrual in stream biofilms under the influence of nutrients inputs from WWTP effluent. Ultimately, the results provide insights on the potential role of nitrifiers and denitrifiers on N cycling in WWTP effluent receiving

  10. Expanding leaves of mature deciduous forest trees rapidly become autotrophic.

    Science.gov (United States)

    Keel, Sonja G; Schädel, Christina

    2010-10-01

    Emerging leaves in evergreen tree species are supplied with carbon (C) from the previous year's foliage. In deciduous trees, no older leaves are present, and the early phase of leaf development must rely on C reserves from other tissues. How soon developing leaves become autotrophic and switch from being C sinks to sources has rarely been studied in mature forest trees, and simultaneous comparisons of species are scarce. Using a canopy crane and a simple (13)CO(2)-pulse-labelling technique, we demonstrate that young leaves of mature trees in three European deciduous species (Fagus sylvatica L., Quercus petraea (Matt.) Liebl., Tilia platyphyllos Scop.) start assimilating CO(2) at a very early stage of development (10-50% expanded). One month after labelling, all leaves were still strongly (13)C enriched, suggesting that recent photosynthates had been incorporated into slow turnover pools such as cellulose or lignin and thus had contributed to leaf growth. In line with previous studies performed at the same site, we found stronger incorporation of recent photosynthates into growing tissues of T. platyphyllos compared with F. sylvatica and Q. petraea. Non-structural carbohydrate (NSC) concentrations analysed for one of the three study species (F. sylvatica) showed that sugar and starch pools rapidly increased during leaf development, suggesting that newly developed leaves soon produce more NSC than can be used for growth. In conclusion, our findings indicate that expanding leaves of mature deciduous trees become C autonomous at an early stage of development despite the presence of vast amounts of mobile carbohydrate reserves. PMID:20688879

  11. Measuring Water in Bioreactor Landfills

    Science.gov (United States)

    Han, B.; Gallagher, V. N.; Imhoff, P. T.; Yazdani, R.; Chiu, P.

    2004-12-01

    Methane is an important greenhouse gas, and landfills are the largest anthropogenic source in many developed countries. Bioreactor landfills have been proposed as one means of abating greenhouse gas emissions from landfills. Here, the decomposition of organic wastes is enhanced by the controlled addition of water or leachate to maintain optimal conditions for waste decomposition. Greenhouse gas abatement is accomplished by sequestration of photosynthetically derived carbon in wastes, CO2 offsets from energy use of waste derived gas, and mitigation of methane emission from the wastes. Maintaining optimal moisture conditions for waste degradation is perhaps the most important operational parameter in bioreactor landfills. To determine how much water is needed and where to add it, methods are required to measure water within solid waste. However, there is no reliable method that can measure moisture content simply and accurately in the heterogeneous environment typical of landfills. While well drilling and analysis of solid waste samples is sometimes used to determine moisture content, this is an expensive, time-consuming, and destructive procedure. To overcome these problems, a new technology recently developed by hydrologists for measuring water in the vadose zone --- the partitioning tracer test (PTT) --- was evaluated for measuring water in solid waste in a full-scale bioreactor landfill in Yolo County, CA. Two field tests were conducted in different regions of an aerobic bioreactor landfill, with each test measuring water in ≈ 250 ft3 of solid waste. Tracers were injected through existing tubes inserted in the landfill, and tracer breakthrough curves were measured through time from the landfill's gas collection system. Gas samples were analyzed on site using a field-portable gas chromatograph and shipped offsite for more accurate laboratory analysis. In the center of the landfill, PTT measurements indicated that the fraction of the pore space filled with water

  12. Alkalinity and pH effects on nitrification in a membrane aerated bioreactor: an experimental and model analysis.

    Science.gov (United States)

    Shanahan, John W; Semmens, Michael J

    2015-05-01

    A nitrifying biofilm was grown in a laboratory-scale membrane aerated bioreactor (MABR) to calibrate and test a one-dimensional biofilm model incorporating chemical equilibria to calculate local pH values. A previously developed model (Shanahan and Semmens, 2004) based upon AQUASIM was modified to incorporate the impact of local pH changes within the biofilm on the kinetics of nitrification. Shielded microelectrodes were used to measure the concentration profiles of dissolved oxygen, ammonium, nitrate, and pH within the biofilm and the overlying boundary layer under actual operating conditions. Operating conditions were varied to assess the impact of bicarbonate loading (alkalinity), ammonium loading, and intra-membrane oxygen partial pressure on biofilm performance. Nitrification performance improved with increased ammonium and bicarbonate loadings over the range of operating conditions tested, but declined when the intra-membrane oxygen partial pressure was increased. Minor discrepancies between the measured and predicted concentration profiles within the biofilm were attributed to changes in biofilm density and vertical heterogeneities in biofilm structure not accounted for by the model. Nevertheless, predicted concentration profiles within the biofilm agreed well with experimental results over the range of conditions studied and highlight the fact that pH changes in the biofilm are significant especially in low alkalinity waters. The influent pH and buffer capacity of a wastewater may therefore have a significant impact on the performance of a membrane-aerated bioreactor with respect to nitrification, and nitrogen removal. PMID:25703659

  13. Sulfide-driven autotrophic denitrification significantly reduces N2O emissions.

    Science.gov (United States)

    Yang, Weiming; Zhao, Qing; Lu, Hui; Ding, Zhi; Meng, Liao; Chen, Guang-Hao

    2016-03-01

    The Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI) process build on anaerobic carbon conversion through biological sulfate reduction and autotrophic denitrification by using the sulfide byproduct from the previous reaction. This study confirmed extra decreases in N2O emissions from the sulfide-driven autotrophic denitrification by investigating N2O reduction, accumulation, and emission in the presence of different sulfide/nitrate (S/N) mass ratios at pH 7 in a long-term laboratory-scale granular sludge autotrophic denitrification reactor. The N2O reduction rate was linearly proportional to the sulfide concentration, which confirmed that no sulfide inhibition of N2O reductase occurred. At S/N = 5.0 g-S/g-N, this rate resulted by sulfide-driven autotrophic denitrifying granular sludge (average granule size = 701 μm) was 27.7 mg-N/g-VSS/h (i.e., 2 and 4 times greater than those at 2.5 and 0.8 g-S/g-N, respectively). Sulfide actually stimulates rather than inhibits N2O reduction no matter what granule size of sulfide-driven autotrophic denitrifying sludge engaged. The accumulations of N2O, nitrite and free nitrous acid (FNA) with average granule size 701 μm of sulfide-driven autotrophic denitrifying granular sludge engaged at S/N = 5.0 g-S/g-N were 4.7%, 11.4% and 4.2% relative to those at 3.0 g-S/g-N, respectively. The accumulation of FNA can inhibit N2O reduction and increase N2O accumulation during sulfide-driven autotrophic denitrification. In addition, the N2O gas emission level from the reactor significantly increased from 14.1 ± 0.5 ppmv (0.002% of the N load) to 3707.4 ± 36.7 ppmv (0.405% of the N load) as the S/N mass ratio in the influent decreased from 2.1 to 1.4 g-S/g-N over the course of the 120-day continuous monitoring period. Sulfide-driven autotrophic denitrification may significantly reduce greenhouse gas emissions from biological nutrient removal when sulfur conversion processes are applied. PMID

  14. Woodchip-sulfur based heterotrophic and autotrophic denitrification (WSHAD) process for nitrate contaminated water remediation.

    Science.gov (United States)

    Li, Rui; Feng, Chuanping; Hu, Weiwu; Xi, Beidou; Chen, Nan; Zhao, Baowei; Liu, Ying; Hao, Chunbo; Pu, Jiaoyang

    2016-02-01

    Nitrate contaminated water can be effectively treated by simultaneous heterotrophic and autotrophic denitrification (HAD). In the present study, woodchips and elemental sulfur were used as co-electron donors for HAD. It was found that ammonium salts could enhance the denitrifying activity of the Thiobacillus bacteria, which utilize the ammonium that is produced by the dissimilatory nitrate reduction to ammonium (DNRA) in the woodchip-sulfur based heterotrophic and autotrophic denitrification (WSHAD) process. The denitrification performance of the WSHAD process (reaction constants range from 0.05485 h(-1) to 0.06637 h(-1)) is better than that of sulfur-based autotrophic denitrification (reaction constants range from 0.01029 h(-1) to 0.01379 h(-1)), and the optimized ratio of woodchips to sulfur is 1:1 (w/w). No sulfate accumulation is observed in the WSHAD process and the alkalinity generated in the heterotrophic denitrification can compensate for alkalinity consumption by the sulfur-based autotrophic denitrification. The symbiotic relationship between the autotrophic and the heterotrophic denitrification processes play a vital role in the mixotrophic environment. PMID:26650451

  15. Diversity and succession of autotrophic microbial community in high-elevation soils along deglaciation chronosequence.

    Science.gov (United States)

    Liu, Jinbo; Kong, Weidong; Zhang, Guoshuai; Khan, Ajmal; Guo, Guangxia; Zhu, Chunmao; Wei, Xiaojie; Kang, Shichang; Morgan-Kiss, Rachael M

    2016-10-01

    Global warming has resulted in substantial glacier retreats in high-elevation areas, exposing deglaciated soils to harsh environmental conditions. Autotrophic microbes are pioneering colonizers in the deglaciated soils and provide nutrients to the extreme ecosystem devoid of vegetation. However, autotrophic communities remain less studied in deglaciated soils. We explored the diversity and succession of the cbbL gene encoding the large subunit of form I RubisCO, a key CO2-fixing enzyme, using molecular methods in deglaciated soils along a 10-year deglaciation chronosequence on the Tibetan Plateau. Our results demonstrated that the abundance of all types of form I cbbL (IA/B, IC and ID) rapidly increased in young soils (0-2.5 years old) and kept stable in old soils. Soil total organic carbon (TOC) and total nitrogen (TN) gradually increased along the chronosequence and both demonstrated positive correlations with the abundance of bacteria and autotrophs, indicating that soil TOC and TN originated from autotrophs. Form IA/B autotrophs, affiliated with cyanobacteria, exhibited a substantially higher abundance than IC and ID. Cyanobacterial diversity and evenness increased in young soils (<6 years old) and then remained stable. Our findings suggest that cyabobacteria play an important role in accumulating TOC and TN in the deglaciated soils. PMID:27465079

  16. Pyruvic Oxime Nitrification and Copper and Nickel Resistance by a Cupriavidus pauculus, an Active Heterotrophic Nitrifier-Denitrifier

    Directory of Open Access Journals (Sweden)

    Miguel Ramirez

    2014-01-01

    Full Text Available Heterotrophic nitrifiers synthesize nitrogenous gasses when nitrifying ammonium ion. A Cupriavidus pauculus, previously thought an Alcaligenes sp. and noted as an active heterotrophic nitrifier-denitrifier, was examined for its ability to produce nitrogen gas (N2 and nitrous oxide (N2O while heterotrophically nitrifying the organic substrate pyruvic oxime [CH3–C(NOH–COOH]. Neither N2 nor N2O were produced. Nucleotide and phylogenetic analyses indicated that the organism is a member of a genus (Cupriavidus known for its resistance to metals and its metabolism of xenobiotics. The microbe (a Cupriavidus pauculus designated as C. pauculus strain UM1 was examined for its ability to perform heterotrophic nitrification in the presence of Cu2+ and Ni2+ and to metabolize the xenobiotic phenol. The bacterium heterotrophically nitrified well when either 1 mM Cu2+ or 0.5 mM Ni2+ was present in either enriched or minimal medium. The organism also used phenol as a sole carbon source in either the presence or absence of 1 mM Cu2+ or 0.5 mM Ni2+. The ability of this isolate to perform a number of different metabolisms, its noteworthy resistance to copper and nickel, and its potential use as a bioremediation agent are discussed.

  17. Tissue grown in space in NASA Bioreactor

    Science.gov (United States)

    1998-01-01

    For 5 days on the STS-70 mission, a bioreactor cultivated human colon cancer cells, such as the culture section shown here, which grew to 30 times the volume of control specimens grown on Earth. This significant result was reproduced on STS-85 which grew mature structures that more closely match what are found in tumors in humans. The two white circles within the tumor are part of a plastic lattice that helped the cells associate. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators.

  18. Development of Fundamental Technologies for Micro Bioreactors

    Science.gov (United States)

    Sato, Kiichi; Kitamori, Takehiko

    This chapter reviews the development of fundamental technologies required for microchip-based bioreactors utilizing living mammalian cells and pressure driven flow. The most important factor in the bioreactor is the cell culture. For proper cell culturing, continuous medium supply from a microfluidic channel and appropriate modification of the channel surface to accommodate cell attachment is required. Moreover, the medium flow rate should be chosen carefully, because shear stress affects cell activity. The techniques presented here could be applied to the development of micro bioreactors such as microlivers, pigment production by plant cells, and artificial insemination.

  19. Spatial Experiment Technologies Suitable for Unreturnable Bioreactor

    Science.gov (United States)

    Zhang, Tao; Zheng, Weibo; Tong, Guanghui

    2016-07-01

    The system composition and main function of the bioreactor piggybacked on TZ cargo transport spacecraft are introduced briefly in the paper.The spatial experiment technologies which are suitable for unreturnable bioreactor are described in detail,including multi-channel liquid transportion and management,multi-type animal cells circuit testing,dynamic targets microscopic observation in situ etc..The feasibility and effectiveness of these technologies which will be used in space experiment in bioreactor are verified in tests and experiments on the ground.

  20. Diversity and distribution of amoA-type nitrifying and nirS-type denitrifying microbial communities in the Yangtze River estuary

    OpenAIRE

    Y. Zhang; Xie, X.; Jiao, N.; Hsiao, S. S.-Y.; Kao, S.-J.

    2014-01-01

    Coupled nitrification–denitrification plays a critical role in the removal of excess nitrogen, which is chiefly caused by humans, to mitigate estuary and coastal eutrophication. Despite its obvious importance, limited information about the relationships between nitrifying and denitrifying microbial communities in estuaries, and their controlling factors have been documented. We investigated the nitrifying and denitrifying microbial communities in the estuary of turbid subtro...

  1. Development of Novel Random Network Theory-Based Approaches to Identify Network Interactions among Nitrifying Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Cindy

    2015-07-17

    The interactions among different microbial populations in a community could play more important roles in determining ecosystem functioning than species numbers and their abundances, but very little is known about such network interactions at a community level. The goal of this project is to develop novel framework approaches and associated software tools to characterize the network interactions in microbial communities based on high throughput, large scale high-throughput metagenomics data and apply these approaches to understand the impacts of environmental changes (e.g., climate change, contamination) on network interactions among different nitrifying populations and associated microbial communities.

  2. Nitrifying and denitrifying bacteria in aerobic granules formed in sequencing batch airlift reactors

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; YANG Fenglin; QI Aijiu

    2007-01-01

    The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH3 -N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.

  3. Performance of Anammox granular sludge bed reactor started up with nitrifying granular sludge

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ping; LIN Feng-mei; HU Bao-lan; CHEN Jian-song

    2004-01-01

    The anaerobic ammonia oxidation(Anammox) granular sludge bed reactor was started up successfully withnitrifying granular sludge. During the operation, the nitrifying granular sludge was gradually converted into Anammoxgranular sludge with good settling property and high conversion activity. The Anammox reactor worked well with theshortest HRT of 2.43 h. Under the condition that HRT was 6.39 h and influent concentration of ammonia and nitritewas 10 mmol/L, the removal of ammonia and nitrite was 97.17% and 100.00%, respectively. Corresponding

  4. Elemental sulfur formation and nitrogen removal from wastewaters by autotrophic denitrifiers and anammox bacteria.

    Science.gov (United States)

    Liu, Chunshuang; Zhao, Dongfeng; Yan, Laihong; Wang, Aijie; Gu, Yingying; Lee, Duu-Jong

    2015-09-01

    Elemental sulfur (S(0)) formation from and nitrogen removal on sulfide, nitrate and ammonium-laden wastewaters were achieved by denitrifying ammonium oxidation (DEAMOX) reactor with autotrophic denitrifiers and anaerobic ammonium oxidation (anammox) bacteria. The sulfide to nitrate ratio is a key process parameter for excess accumulation of S(0) and a ratio of 1.31:1 is a proposed optimum. The Alishewanella, Thauera and Candidatus Anammoximicrobium present respectively the autotrophic denitrifiers and anammox bacteria for the reactor. DEAMOX is demonstrated promising biological process for treating organics-deficient (S+N) wastewaters with excess S(0) production. PMID:26022701

  5. Nitrogen removal in a single-chamber microbial fuel cell with nitrifying biofilm enriched at the air cathode

    KAUST Repository

    Yan, Hengjing

    2012-05-01

    Nitrogen removal is needed in microbial fuel cells (MFCs) for the treatment of most waste streams. Current designs couple biological denitrification with side-stream or combined nitrification sustained by upstream or direct aeration, which negates some of the energy-saving benefits of MFC technology. To achieve simultaneous nitrification and denitrification, without extra energy input for aeration, the air cathode of a single-chamber MFC was pre-enriched with a nitrifying biofilm. Diethylamine-functionalized polymer (DEA) was used as the Pt catalyst binder on the cathode to improve the differential nitrifying biofilm establishment. With pre-enriched nitrifying biofilm, MFCs with the DEA binder had an ammonia removal efficiency of up to 96.8% and a maximum power density of 900 ± 25 mW/m 2, compared to 90.7% and 945 ± 42 mW/m 2 with a Nafion binder. A control with Nafion that lacked nitrifier pre-enrichment removed less ammonia and had lower power production (54.5% initially, 750 mW/m 2). The nitrifying biofilm MFCs had lower Coulombic efficiencies (up to 27%) than the control reactor (up to 36%). The maximum total nitrogen removal efficiency reached 93.9% for MFCs with the DEA binder. The DEA binder accelerated nitrifier biofilm enrichment on the cathode, and enhanced system stability. These results demonstrated that with proper cathode pre-enrichment it is possible to simultaneously remove organics and ammonia in a single-chamber MFC without supplemental aeration. © 2012 Elsevier Ltd.

  6. Removal of carbonaceous and nitrogenous pollutants from a synthetic wastewater using a membrane-coupled bioreactor.

    Science.gov (United States)

    Ghosh, Sudeshna; LaPara, Timothy M

    2004-09-01

    Two modified Ludzack-Ettinger (MLE)-type membrane-coupled bioreactors (MBRs) were investigated in this study for the purpose of removing both nitrogenous and carbonaceous pollutants from a synthetic wastewater. During the first MBR experiment, removal efficiencies were high (>90%) for chemical oxygen demand (COD) and ammonia, but total nitrogenous pollutant removal efficiency was poor (approximately 25%). Bacterial community analysis of ammonia oxidizing bacteria (AOB) by a nested PCR-DGGE approach detected two Nitrosomonas-like populations and one Nitrosospira-like population. During the initial portion of the second MBR experiment, COD and ammonia removal efficiencies were similar to the first MBR experiment until the COD of the influent wastewater was increased to provide additional electron donors to support denitrification. Total nitrogen removal efficiencies eventually exceeded 90%, with a hydraulic residence time (HRT) of 24 h and a recirculation ratio of 8. When the HRT of the MBR experiment was decreased to 12 h, however, ammonia removal efficiency was adversely affected. A subsequent increase in the HRT to 18 h helped improve removal efficiencies for both ammonia (>85%) and total nitrogenous compounds (approximately 70%). Our research demonstrates that MBRs can be effectively designed to remove both carbonaceous and nitrogenous pollutants. The ability of the microbial community to switch between anoxic (denitrifying) and oxic (nitrifying) conditions, however, represents a critical process constraint for the application of MLE-type MBR systems, such that little benefit is gained compared to conventional designs. PMID:15338423

  7. Sequential batch membrane bio-reactor for wastewater treatment: The effect of increased salinity.

    Science.gov (United States)

    Mannina, Giorgio; Capodici, Marco; Cosenza, Alida; Di Trapani, Daniele; Viviani, Gaspare

    2016-06-01

    In this work, a sequential batch membrane bioreactor pilot plant is investigated to analyze the effect of a gradual increase in salinity on carbon and nutrient removal, membrane fouling and biomass kinetic parameters. The salinity was increased by 2gNaClL(-1) per week up to 10gNaClL(-1). The total COD removal efficiency was quite high (93%) throughout the experiment. A gradual biomass acclimation to the salinity level was observed during the experiment, highlighting the good recovery capabilities of the system. Nitrification was also influenced by the increase in salinity, with a slight decrease in nitrification efficiency (the lowest value was obtained at 10gNaClL(-1) due to lower nitrifier activity). Irreversible cake deposition was the predominant fouling mechanism observed during the experiment. Respirometric tests exhibited a stress effect due to salinity, with a reduction in the respiration rates observed (from 8.85mgO2L(-1)h(-1) to 4mgO2L(-1)h(-1)). PMID:26970923

  8. A new photo-activated sludge system for nitrification by an algal-bacterial consortium in a photo-bioreactor with biomass recycle.

    Science.gov (United States)

    van der Steen, Peter; Rahsilawati, Kuntarini; Rada-Ariza, Angélica M; Lopez-Vazquez, Carlos M; Lens, Piet N L

    2015-01-01

    Wastewater treatment technologies requiring large areas may be less feasible in urbanizing regions of developing countries. Therefore, a new technology, named photo-activated sludge (PAS), was investigated to combine the advantages of regular activated sludge systems with those of algae ponds for the removal of ammonium. The PAS consisted of a mixed photo-bioreactor, continuously fed with BG-11 medium, adjusted to 66 mgN-NH4⁺/l. The reactor volume was 2 l, hydraulic retention time was 24 hours, with a depth of 8 cm, and continuous illumination at the water surface was 66 μmol PAR/m²/s (photosynthetically active radiation). Reactor effluent passed through a settler and settled biomass was returned to the reactor. A well settling biomass developed, that contained both algae and nitrifiers. Effluent contained 10 mgN-NH4⁺/L and 51 mgN-NOx⁻/L. Using a simplified model, the specific algae growth rate was estimated at about 0.62 day⁻¹, which was within the expected range. For nitrifiers (ammonia oxidizers), the specific growth rate was 0.11 day⁻¹, which was lower than reported for regular activated sludge. The in-situ photo-oxygenation process by algae contributed 82% of the oxygen input, whereas oxygen diffusion through the mixed surface provided the remaining 18%. The foreseen energy savings that a PAS system could achieve warrant further investigations with real wastewater. PMID:26204077

  9. Influence of wastewater composition on nutrient removal behaviors in the new anaerobic–anoxic/nitrifying/induced crystallization process

    OpenAIRE

    Shi, Jing; Xiwu LU; Yu, Ran; Gu, Qian; Zhou, Yi

    2013-01-01

    In this study, the new anaerobic–anoxic/nitrifying/induced crystallization (A2N–IC) system was compared with anaerobic-anoxic/nitrifying (A2N) process to investigate nutrient removal performance under different influent COD and ammonia concentrations. Ammonia and COD removal rates were very stable in both processes, which were maintained at 84.9% and 86.6% when the influent ammonia varied from 30 mg L−1 to 45 mg L−1 and COD ranged from 250 mg L−1 to 300 mg L−1. The effluent phosphorus always ...

  10. Immobilized yeast in bioreactor for alcohol fermentation

    International Nuclear Information System (INIS)

    Mutant of Saccharomyces cerevisiae was developed using a Co-60 source. Cells were immobilized onto sterile, channeled alumina beads and packed into bioreactor column under controlled temperature. Feedstocks containing substrate and nutrients were fed into the bioreactor at specific rates. Beads with greatest porosity and surface area produced the most ethanol. Factors affecting ethanol productivity included: temperature, pH, flow rate, nutrients and substrate in the feedstock

  11. Aeration and hydrodynamics in submerged membrane bioreactors

    OpenAIRE

    Braak, Etienne; Alliet-Gaubert, Marion; Schetrite, Sylvie; Albasi, Claire

    2011-01-01

    Membrane bioreactor (MBR) is already a well-developed wastewater treatment process for both municipal and industrial applications. Nonetheless, membrane fouling remains a significant problem for its wider development. In the case of submerged membrane bioreactors (SMBRs), one of the most efficient strategies to limit fouling is the use of a gas/liquid two-phase flow to enhance the mass transfer. However, the effect of aeration still remains incompletely understood. The complexity ...

  12. New bioreactors systems for pharmacological screening

    OpenAIRE

    Vozzi, Federico

    2007-01-01

    Bioreactors, biotechnological devices for in vitro cell cultures with dynamic conditions, have the potential to provide information on local cell behavior and function. The development of bioreactors could lead to a multitude of applications from drug testing and development, tissue engineering and basic research to the identification of new and alternative therapies for many disorders. High quality, reliable, in vitro data also provide a shift in focus from large scale animal testing to the ...

  13. Heart tissue grown in NASA Bioreactor

    Science.gov (United States)

    2001-01-01

    Lisa Freed and Gordana Vunjak-Novakovic, both of the Massachusetts Institute of Technology (MIT), have taken the first steps toward engineering heart muscle tissue that could one day be used to patch damaged human hearts. Cells isolated from very young animals are attached to a three-dimensional polymer scaffold, then placed in a NASA bioreactor. The cells do not divide, but after about a week start to cornect to form a functional piece of tissue. Here, a transmission electron micrograph of engineered tissue shows a number of important landmarks present in functional heart tissue: (A) well-organized myofilaments (Mfl), z-lines (Z), and abundant glycogen granules (Gly); and (D) intercalcated disc (ID) and desmosomes (DES). The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). Credit: MIT

  14. Simplified Bioreactor For Growing Mammalian Cells

    Science.gov (United States)

    Spaulding, Glenn F.

    1995-01-01

    Improved bioreactor for growing mammalian cell cultures developed. Designed to support growth of dense volumes of mammalian cells by providing ample, well-distributed flows of nutrient solution with minimal turbulence. Cells relatively delicate and, unlike bacteria, cannot withstand shear forces present in turbulent flows. Bioreactor vessel readily made in larger sizes to accommodate greater cell production quantities. Molding equipment presently used makes cylinders up to 30 centimeters long. Alternative sintered plastic techniques used to vary pore size and quantity, as necessary.

  15. Colon tumor cells grown in NASA Bioreactor

    Science.gov (United States)

    2001-01-01

    These photos compare the results of colon carcinoma cells grown in a NASA Bioreactor flown on the STS-70 Space Shuttle in 1995 flight and ground control experiments. The cells grown in microgravity (left) have aggregated to form masses that are larger and more similar to tissue found in the body than the cells cultured on the ground (right). The principal investigator is Milburn Jessup of the University of Texas M. D. Anderson Cancer Center. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). Credit: NASA and University of Texas M. D. Anderson Cancer Center.

  16. Effect of heterotrophic versus autotrophic food on feeding and reproduction of the calanoid copepod Acartia tonsa : relationship with prey fatty acid composition

    DEFF Research Database (Denmark)

    Broglio, E.; Jonasdottir, Sigrun; Calbet, A.; Jakobsen, Hans Henrik; Saiz, E.

    2003-01-01

    ) and ingestion rates, or as the quotient: EPR/ingestion rate. The diets, offered in monoculture, were the heterotrophic ciliates Strombidium sulcatum or Mesodinium pulex, the heterotrophic dinoflagellate Gymnodinium dominans, the autotrophic cryptophyte Rhodomonas salina and the autotrophic...

  17. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions.

    Science.gov (United States)

    Maestre, Juan P; Wahman, David G; Speitel, Gerald E

    2016-06-21

    Chloramines are the second most used secondary disinfectant by United States water utilities. However, chloramination may promote nitrifying bacteria. Recently, monochloramine cometabolism by the pure culture ammonia-oxidizing bacteria, Nitrosomonas europaea, was shown to increase monochloramine demand. The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under more relevant drinking water conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Four types of batch kinetic experiments were conducted: (1) positive controls to estimate ammonia kinetic parameters, (2) negative controls to account for biomass reactivity, (3) utilization associated product (UAP) controls to account for UAP reactivity, and (4) cometabolism experiments to estimate cometabolism kinetic parameters. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to the experimental data. Cometabolism kinetics were best described by a first-order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism accounted for 30% of the observed monochloramine loss. These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; therefore, monochloramine cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems. PMID:27196729

  18. Monitoring of population shifts in an enriched nitrifying system under gradually increased cadmium loading

    Energy Technology Data Exchange (ETDEWEB)

    Mertoglu, Bulent [Department of Bioengineering, Marmara University, 34722 Goztepe, Istanbul (Turkey)], E-mail: bmertoglu@eng.marmara.edu.tr; Semerci, Neslihan [Department of Environmental Engineering, Marmara University, 34722 Goztepe, Istanbul (Turkey); Guler, Nuray [TUBITAK-Marmara Research Center, Chemistry and Environmental Institute, 41470 Gebze, Kocaeli (Turkey); Calli, Baris [Department of Environmental Engineering, Marmara University, 34722 Goztepe, Istanbul (Turkey); Cecen, Ferhan [Institute of Environmental Sciences, Bogazici University, Bebek, Istanbul (Turkey); Saatci, Ahmet Mete [Department of Environmental Engineering, Marmara University, 34722 Goztepe, Istanbul (Turkey)

    2008-12-30

    The changes in nitrifying bacterial population under cadmium loading were monitored and evaluated in a laboratory scale continuous-flow enriched nitrification system. For this purpose, the following molecular microbiological methods were used: slot-blot hybridization, denaturing gradient gel electrophoresis (DGGE), real-time PCR followed by melting curve analysis, cloning and sequence analysis. The initial cadmium concentration was incrementally increased from 1 to 10 mg/l which led to a drop in ammonia removal efficiency from 99 to 10%. Inhibition was recovered when cadmium loading was stopped. During the second application of cadmium, nitrifying population became more tolerant. Even at 15 mg/l Cd, only a minor inhibition was observed. To investigate the variations in ammonia and nitrite oxidizing bacteria populations in a period of 483 days, ammonia monooxygenase (amoA) and 16S rRNA genes-based molecular techniques were used. An obvious shift was experienced in the diversity of ammonia oxidizers after the first application of 10 mg/l Cd. Metal-tolerant ammonia oxidizing species became dominant and the microbial diversity sharply shifted from Nitrosomonas and Nitrosococcus sp. to Nitrosospira sp. which were observed to tolerate higher cadmium loadings. This result indicated that the extent of nitrification inhibition was not only related to the metal concentration and quantity of microorganisms but also depended on the type of species.

  19. Production of NO2/-/ and N2O by nitrifying bacteria at reduced concentrations of oxygen

    Science.gov (United States)

    Goreau, T. J.; Kaplan, W. A.; Wofsy, S. C.; Mcelroy, M. B.; Valois, F. W.; Watson, S. W.

    1980-01-01

    The influence of oxygen concentration on the production of NO2(-) and N2O by nitrifying marine bacteria of the genus Nitrosomonas is investigated. Pure cultures of the ammonium-oxiding bacteria isolated from the Western Tropical Atlantic Ocean were grown at oxygen partial pressures from 0.005 to 0.2 atm, and concentrations of N2O in the air above the growth medium and dissolved NO2(-) were determined. Decreasing oxygen concentrations are observed to induce a marked decrease in NO2(-) production rates and increase in N2O evolution, leading to an increase of the relative yield of N2O with respect to NO2(-) from 0.3% to nearly 10%. Similar yields of N2O at atmospheric oxygen levels are found for nitrifying bacteria of the genera Nitrosomonas, Nitrosolobus, Nitrosospira and Nitrosococcus, while nitrite-oxydizing bacteria and a dinoflagellate did not produce detectable quantities of N2O. Results support the view that nitrification is a major source of N2O in the environment.

  20. Temporal Dynamics of Active Prokaryotic Nitrifiers and Archaeal Communities from River to Sea.

    Science.gov (United States)

    Hugoni, Mylène; Agogué, Hélène; Taib, Najwa; Domaizon, Isabelle; Moné, Anne; Galand, Pierre E; Bronner, Gisèle; Debroas, Didier; Mary, Isabelle

    2015-08-01

    To test if different niches for potential nitrifiers exist in estuarine systems, we assessed by pyrosequencing the diversity of archaeal gene transcript markers for taxonomy (16S ribosomal RNA (rRNA)) during an entire year along a salinity gradient in surface waters of the Charente estuary (Atlantic coast, France). We further investigated the potential for estuarine prokaryotes to oxidize ammonia and hydrolyze urea by quantifying thaumarchaeal amoA and ureC and bacterial amoA transcripts. Our results showed a succession of different nitrifiers from river to sea with bacterial amoA transcripts dominating in the freshwater station while archaeal transcripts were predominant in the marine station. The 16S rRNA sequence analysis revealed that Thaumarchaeota marine group I (MGI) were the most abundant overall but other archaeal groups like Methanosaeta were also potentially active in winter (December-March) and Euryarchaeota marine group II (MGII) were dominant in seawater in summer (April-August). Each station also contained different Thaumarchaeota MGI phylogenetic clusters, and the clusters' microdiversity was associated to specific environmental conditions suggesting the presence of ecotypes adapted to distinct ecological niches. The amoA and ureC transcript dynamics further indicated that some of the Thaumarchaeota MGI subclusters were involved in ammonia oxidation through the hydrolysis of urea. Our findings show that ammonia-oxidizing Archaea and Bacteria were adapted to contrasted conditions and that the Thaumarchaeota MGI diversity probably corresponds to distinct metabolisms or life strategies. PMID:25851445

  1. Rapid Nitrogen Cycling Following Wet-Up Results from Heterotroph, then Nitrifier Response

    Science.gov (United States)

    Placella, S.; Herman, D.; Firestone, M.

    2009-12-01

    The first rainfall following the hot, dry summer in arid and semi-arid ecosystems, known as wet-up, results in large pulses of carbon dioxide and nitrous oxide, two radiatively important gases. Nitrous oxide in general, is produced by nitrifiers and denitrifiers. Using laboratory simulations of wet-up, we monitored soil pools of ammonium and nitrate, gross rates of nitrogen mineralization and nitrification, effluxes of carbon dioxide and nitrous oxide, and gene expression of archaeal and bacterial amoA, a functional gene for nitrification and nirK, a functional gene for denitrification. Results from a California annual grassland soil show significant increases in the ammonium pool within one hour of water addition followed by a significant increase in the nitrate pool within three hours of water addition. Gross nitrogen mineralization and gross nitrification were very high with nitrogen mineralization being highest within three hours of wet-up. Ammonia-oxidizers were most active at nine hours after water addition. Nitrous oxide emissions followed the same pattern as nitrifiers, suggesting nitrification may play an important role in nitrous oxide emissions during wet-up.

  2. Assessment of bacterial community structure in nitrifying biofilm under inorganic carbon-sufficient and -limited conditions.

    Science.gov (United States)

    Bae, Hyokwan; Chung, Yun-Chul; Yang, Heejeong; Lee, Changsoo; Aryapratama, Rio; Yoo, Young J; Lee, Seockheon

    2015-01-01

    In this work, nitrification and changes in the composition of the total bacterial community under inorganic carbon (IC)-limited conditions, in a nitrifying moving bed biofilm reactor, was investigated. A culture-independent analysis of cloning and sequencing based on the 16S rRNA gene was applied to quantify the bacterial diversity and to determine bacterial taxonomic assignment. IC concentrations had significant effects on the stability of ammonia-oxidation as indicated by the reduction of the nitrogen conversion rate with high NH4(+)-N loadings. The predominance of Nitrosomonas europaea was maintained in spite of changes in the IC concentration. In contrast, heterotrophic bacterial species contributed to a high bacterial diversity, and to a dynamic shift in the bacterial community structure, under IC-limited conditions. In this study, individual functions of heterotrophic bacteria were estimated based on taxonomic information. Possible key roles of coexisting heterotrophic bacteria are the assimilation of organic compounds of extracellular polymeric substances produced by nitrifiers, and biofilm formation by providing a filamentous structure and aggregation properties. PMID:25560266

  3. Culture-independent detection of 'TM7' bacteria in a streptomycin-resistant acidophilic nitrifying process

    International Nuclear Information System (INIS)

    Nitrification in biological wastewater treatment processes has been believed for long time to take place under neutral conditions and is inhibited under acidic conditions. However, we previously constructed acidophilic nitrifying sequencing-batch reactors (ANSBRs) being capable of nitrification at −1 was added. In all reactors, the pH varied between 2.7 and 4.0, and ammonium was completely converted to nitrate in every batch cycle. PCR-aided denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes revealed that some major clones assigned to TM7 bacteria and Gammaproteobacteria were constantly present during the overall period of operation. Fluorescence in situ hybridization (FISH) with specific oligonucleotide probes also showed that TM7 bacteria predominated in all SRAN reactors, accounting for 58% of the total bacterial population on average. Although the biological significance of the TM7 bacteria in the SRAN reactors are unknown, our results suggest that these bacteria are possibly streptomycin-resistant and play some important roles in the acidophilic nitrifying process

  4. Regulation of carbon dioxide fixation in facultatively autotrophic bacteria. A phisiological and genetical study.

    NARCIS (Netherlands)

    Meijer, Wilhelmus Gerhardus

    1990-01-01

    Autotrophic bactcria are capable of CO2 fixation via the Calvin cycle, emplofng energy derived from the oxidation of anorganic substrates (e.g. Hz), simple organic substrates (one-carbon compounds, e.g. methanol, formate), or from light. Ribulose-1,5-bisphospbate carboxylase/oxygenase (RuBisC/O), pb

  5. Estimation of autotrophic soil respiration in a boreal forest using three different approaches

    Science.gov (United States)

    Kulmala, Liisa; Pumpanen, Jukka; Heinonsalo, Jussi

    2016-04-01

    It is generally challenging to separate autotrophic and heterotrophic soil respiration. The reason for these difficulties is connected with the intimate interaction of the key processes in soil. Root-associated microbes practically colonize the whole soil volume while decomposition processes occur in the same matrix. Therefore, autotrophic and heterotrophic processes cannot be separated in natural systems. However, there are several methods that can be used to better understand the dynamics of these two. A classical method is called 'trenching' where a trench is dug around a known volume of soil and the roots entering the soil are cut from the living trees thus blocking the C flow from them. The second way to separate autotrophic and heterotrophic respiration relies on the difference in the isotopic signature (13C) of plant-derived or decomposition-derived CO2. The third way to separate the sources is to study the differences in the short- and long-term temperature dependencies in CO2 soil emissions. This is possible especially in boreal forests where the biological activity has a strong seasonal cycle. We compared these three methods in an experiment conducted in a southern boreal middle-aged Scots pine stand in Finland. Our data provides a unique possibility to critically evaluate current methods for estimating autotrophic and heterotrophic soil respiration. The knowledge is needed to study further plant physiology and plant-microbe interactions in soil.

  6. Fluidization velocity assessment of commercially available sulfur particles for use in autotrophic denitrification biofilters

    Science.gov (United States)

    There has been no evaluation of sulfur-based autotrophic denitrification using fluidized biofilters in a recirculating aquaculture system to mitigate nitrate-nitrogen loads. The objectives of this work were to quantify the particle size distribution, specific surface area, and fluidization velocitie...

  7. Expression of Heterogenous Arsenic Resistance Genes in the Obligately Autotrophic Biomining Bacterium Thiobacillus ferrooxidans

    OpenAIRE

    Peng, Ji-Bin; Yan, Wang-Ming; Bao, Xue-Zhen

    1994-01-01

    Two arsenic-resistant plasmids were constructed and introduced into Thiobacillus ferrooxidans strains by conjugation. The plasmids with the replicon of wide-host-range plasmid RSF1010 were stable in T. ferrooxidans. The arsenic resistance genes originating from the heterotroph were expressed in this obligately autotrophic bacterium, but the promoter derived from T. ferrooxidans showed no special function in its original host.

  8. Autotrophic nitrogen removal from low strength waste water at low temperature

    NARCIS (Netherlands)

    Hendrickx, T.L.G.; Wang, Y.; Kampman, C.; Zeeman, G.; Temmink, B.G.; Buisman, C.J.N.

    2012-01-01

    Direct anaerobic treatment of municipal waste waters allows for energy recovery in the form of biogas. A further decrease in the energy requirement for waste water treatment can be achieved by removing the ammonium in the anaerobic effluent with an autotrophic process, such as anammox. Until now, an

  9. Detection of autotrophic verrucomicrobial methanotrophs in a geothermal environment using stable isotope probing

    Directory of Open Access Journals (Sweden)

    Christine eSharp

    2012-08-01

    Full Text Available Genomic analysis of the methanotrophic verrucomicrobium Methylacidiphilum infernorum strain V4 has shown that most pathways conferring its methanotrophic lifestyle are similar to those found in proteobacterial methanotrophs. However, due to the large sequence divergence of its methane monooxygenase-encoding genes (pmo, ‘universal’ pmoA polymerase chain reaction (PCR primers do not target these bacteria. Unlike proteobacterial methanotrophs, Methylacidiphilum fixes carbon autotrophically, and uses methane only for energy generation. As a result, techniques used to detect methanotrophs in the environment such as 13CH4-stable isotope probing (SIP and pmoA-targeted PCR do not detect verrucomicrobial methanotrophs, and they may have been overlooked in previous environmental studies. We developed a modified SIP technique to identify active methanotrophic verrucomicrobia in the environment by labelling with 13CO2 and 13CH4, individually and in combination. Testing the protocol in M. infernorum strain V4 resulted in assimilation of 13CO2 but not 13CH4, verifying its autotrophic lifestyle. To specifically detect methanotrophs (as opposed to other autotrophs via 13CO2-SIP, a quantitative PCR (qPCR assay specific for verrucomicrobial-pmoA genes was developed and used in combination with SIP. Incubation of an acidic, high-temperature geothermal soil with 13CH4 + 12CO2 caused little shift in the density distribution of verrucomicrobial-pmoA genes relative to controls. However, labelling with 13CO2 in combination with 12CH4 or 13CH4 induced a strong shift in the distribution of verrucomicrobial-pmoA genes towards the heavy DNA fractions. The modified SIP technique demonstrated that the primary methanotrophs active in the soil were autotrophs and belonged to the Verrucomicrobia. This is the first demonstration of autotrophic, non-proteobacterial methanotrophy in situ, and provides a tool to detect verrucomicrobial methanotrophs in other ecosystems.

  10. Stimulation of autotrophic denitrification by intrusions of the Bosporus Plume into the anoxic Black Sea

    Directory of Open Access Journals (Sweden)

    Clara A. Fuchsman

    2012-07-01

    Full Text Available Autotrophic denitrification was measured in the southwestern coastal Black Sea, where the Bosporus Plume injects oxidized chemical species (especially O2 and NO3- into the oxic, suboxic and anoxic layers. Prominent oxygen intrusions caused an overlap of NOx- and sulfide at the same station where autotrophic denitrification activity was detected with incubation experiments. Several bacteria that have been proposed to oxidize sulfide in other low oxygen environments were found in the Black Sea including SUP05, Sulfurimonas, Arcobacter, and BS-GSO2. Comparison of TRFLP profiles from this mixing zone station and the Western Gyre (a station not affected by the Bosporus Plume indicate the greatest relative abundance of Sulfurimonas and Arcobacter at the appropriate depths at the mixing zone station. The autotrophic gammaproteobacterium BS-GSO2 correlated with ammonium fluxes rather than with sulfide fluxes and the maximum in SUP05 peak height was shallower than the depths where autotrophic denitrification was detected. Notably, anammox activity was not detected at the mixing zone station, though low levels of DNA from the anammox bacteria Candidatus Scalindua were present. These results provide evidence for a modified ecosystem with different N2 production pathways in the southwest coastal region compared to that found in the rest of the Black Sea. Moreover, the same Sulfurimonas phylotype (BS139 was previously detected on >30 μm particles in the suboxic zone of the Western Gyre along with DNA of potential sulfate reducers, so it is possible that particle-attached autotrophic denitrification may be an overlooked N2 production pathway in the central Black Sea as well.

  11. Optimizing of Culture Condition in Horizontal Rotating Bioreactor

    Institute of Scientific and Technical Information of China (English)

    Yan-Fang ZHANG; Huai-Qing CHEN; Hua HUANG

    2005-01-01

    @@ 1 Introduction Bioreactor is the most important equipment in tissue engineering. It can mimic the micro-environment of cell growth in vitro. At present, horizontal rotating bioreactor is the most advanced equipment for cell culture in the world.

  12. Preservation of Nitrifying Capacity and Nitrate Availability in Waterlogged Soils by Radial Oxygen Loss from Roots of Wetland Plants

    NARCIS (Netherlands)

    Engelaar, W.M.H.G.; Symens, J.C.; Laanbroek, H.J.; Blom, C.W.P.M.

    1995-01-01

    The effects of radial O-2 loss from roots on nitrification and NO3- availability were studied. Plants of the flooding- resistant species Rumex palustris and the flooding-sensitive species Rumex thyrsiflorus were grown on drained and waterlogged soils with an initially high nitrifying capacity. Nitra

  13. Preservation of Nitrifying Capacity and Nitrate Availability in Waterlogged Soils by Radial Oxygen Loss from Roots of Wetland Plants

    NARCIS (Netherlands)

    Engelaar, W.M.H.G; Symens, J.C.; Laanbroek, H.J.; Blom, C.W.P.M.

    1995-01-01

    The effects of radial 02 loss from roots on nitrification and NO3- availability were studied. Plants of the flooding-resistant species Rumex palustris and the flooding-sensitive species Rumex thyrsiflorus were grown on drained and waterlogged soils with an initially high nitrifying capacity. Nitrate

  14. Contamination of a high-cell-density continuous bioreactor

    OpenAIRE

    Domingues, Lucília; Lima, Nelson; Teixeira, J. A.

    2000-01-01

    Continuous fermentations were carried out with a recombinant flocculent Saccharomyces cerevisiae strain in an airlift bioreactor. Once operating under steady state at a dilution rate of 0.45 h−1, the bioreactor was contaminated with Escherichia coli cells. The faster growing E. coli strain was washed out of the bioreactor and the recombinant, slower growing flocculating S. cerevisiae strain remained as the only species detected in the bioreactor. Flocculation, besides ...

  15. Evaluation of upflow hybrid bioreactor system for treating low-strength nitrogenous wastewater under low-shear environment

    Directory of Open Access Journals (Sweden)

    Maliwan Kutako

    2015-02-01

    Full Text Available Lab-scale upflow bioreactor system without biomass-liquid separation unit was built to treat low-strength nitrogenous wastewater based on intermittent aeration under low-shear environment. Biomass zone formed in the absence of gas bubbles provided simultaneous biomass retention, biodegradation of nitrogenous and carbonaceous compounds, and biomass-liquid separation. Biomass zone was stable as indicated by insignificant biomass washout rates (14–29 mg VSS/day and relatively constant biomass zone height (26–30 cm up to the shear gradient of 1.8 s-1. Nitrogen treatment efficiency of wastewater containing 15 mg NH4 + -N/L was 15.3±1.96% under continuous oxygen influx of 95 mg O2 /L/day and autotrophic environment, whereas it increased significantly, 88.2±7.05%, after intermittent aeration (3 hrs air-on and 3 hrs air-off and organic carbon source were supplied to the bioreactor system. Carbon removal efficiencies for both continuous and intermittent aeration were comparable reported at 85±1.76% and 91±2.1%, respectively.

  16. Bioreactor design and optimization – a future perspective

    OpenAIRE

    Gernaey, Krist

    2011-01-01

    Bioreactor design and optimisation are essential in translating the experience gained from lab or pilot scale experiments to efficient production processes in industrial scale bioreactors. This article gives a future perspective on bioreactor design and optimisation, where it is foreseen that technologies including mechanistic models, process simulation and advanced model analysis will play an increasingly important role.

  17. Bioreactor design and optimization – a future perspective

    DEFF Research Database (Denmark)

    Gernaey, Krist

    Bioreactor design and optimisation are essential in translating the experience gained from lab or pilot scale experiments to efficient production processes in industrial scale bioreactors. This article gives a future perspective on bioreactor design and optimisation, where it is foreseen that...

  18. Contribution of Methanotrophic and Nitrifying Bacteria to CH4 and NH4+ Oxidation in the Rhizosphere of Rice Plants as Determined by New Methods of Discrimination

    OpenAIRE

    Bodelier, Paul L. E.; Frenzel, Peter

    1999-01-01

    Methanotrophic and nitrifying bacteria are both able to oxidize CH4 as well as NH4+. To date it is not possible to estimate the relative contribution of methanotrophs to nitrification and that of nitrifiers to CH4 oxidation and thus to assess their roles in N and C cycling in soils and sediments. This study presents new options for discrimination between the activities of methanotrophs and nitrifiers, based on the competitive inhibitor CH3F and on recovery after inhibition with C2H2. By using...

  19. Evolution of Bioreactors for Extracorporeal Liver Support

    Directory of Open Access Journals (Sweden)

    Vilkova Е.V.

    2014-03-01

    Full Text Available The development of effective extracorporeal liver support systems in acute and chronic hepatic failure for transplantology purposes and in toxic injuries is a promising direction in modern biomedical studies. Widely used techniques are based on physicochemical interactions of biological molecules, and able to perform a detoxification function only (hemodialysis, hemofiltration, hemodiafiltration, sorption, albumin dialysis, plasmapheresis. However, support systems combining both blood/plasma perfusion and cellular technologies to maintain metabolic, synthetic and regulatory hepatic functions — “artificial liver” systems — are being extensively developed in recent decades. The review describes the main types of cell lines cultured to occupy bioreactors, various technological concepts for bioreactor design (dynamic, static, scaffold-carriers as part of bioreactors (structure, biochemical composition. The study gives metabolic characteristics of a cellular component of “bioartificial liver”: nourishment, oxygen saturation. Various types of existing extracorporeal support systems, their evolution, and preclinical and clinical test results are presented.

  20. Stimulatory effect of xenobiotics on oxidative electron transport of chemolithotrophic nitrifying bacteria used as biosensing element.

    Directory of Open Access Journals (Sweden)

    Andrzej Woznica

    Full Text Available Electron transport chain (ETCh of ammonium (AOB and nitrite oxidizing bacteria (NOB participates in oxidation of ammonium to nitrate (nitrification. Operation of ETCh may be perturbed by a range of water-soluble xenobiotics. Therefore, consortia of nitrifying bacteria may be used as a biosensor to detect water contamination. A surprising feature of this system is an increase of oxygen consumption, detected in the presence of certain inhibitors of ETCh. Thus, to shed light on the mechanism of this effect (and other differences between inhibitors we monitored separately respiration of the bacteria of the first (AOB - Nitrosomonas and second (NOB -Nitrobacter stages of nitrification. Furthermore, we measured plasma membrane potential and the level of reduction of NAD(PH. We propose a novel model of ETCh in NOB to explain the role of reverse electron transport in the stimulation of oxygen consumption (previously attributed to hormesis.

  1. Fate of water borne therapeutic agents and associated effects on nitrifying biofilters in recirculating aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Lars-Flemming

    of these agents on biofilter nitrification performance. All experiments were conducted through addition of chemical additives to closed pilot scale recirculating aquaculture systems (RAS) with fixed media submerged biofilters under controlled operating conditions with rainbow trout (Oncorhynchus mykiss......) in a factorial design with true replicates. Biofilter nitrification performances were evaluated by changes in chemical processes, and nitrifying populations were identified by fluorescence in situ hybridisation (FISH) analysis. FA was degraded at a constant rate immediately after addition, and found......Recent discharge restrictions on antibiotics and chemotherapeutant residuals used in aquaculture have several implications to the aquaculture industry. Better management practices have to be adopted, and documentation and further knowledge of the chemical fate is required for proper administration...

  2. Attempts to improve nitrogen utilization efficiency of aquaponics through nitrifies addition and filler gradation.

    Science.gov (United States)

    Zou, Yina; Hu, Zhen; Zhang, Jian; Xie, Huijun; Liang, Shuang; Wang, Jinhe; Yan, Runxin

    2016-04-01

    Aquaponics has attracted worldwide attention in recent years and is considered as an alternative technology for conventional aquaculture. In this study, common carp (Cyprinus carpio) and pakchoi (Brassica chinensis) were cultured in lab-scale aquaponics, and attempts were conducted to enhance its nitrogen utilization efficiency (NUE) through two optimization methods, i.e., nitrifies addition (NA) and filler gradation (FG). Results showed that NA and FG could improve the NUE of aquaponics by 8.8 and 16.0%, respectively, compared with control. The total ammonia (TAN) and nitrite (NO2(-)) concentrations in NA and FG systems were maintained at relatively low level (TAN aquaponics also contributed to global warming. Although the two proposed attempts in this study caused more N2O emission, they made new breakthrough in improving the NUE of aquaponics. PMID:26645232

  3. Start-up of a completely autotrophic nitrogen removal process in a three- dimensional electrode-biofilm reactor%三维电极生物膜反应器全程自养脱氮的启动研究

    Institute of Scientific and Technical Information of China (English)

    郭劲松; 杨琳; 陈猷鹏; 方芳; 唐金晶

    2012-01-01

    A completely autotrophic nitrogen removal process was started up in a three-dimensional electrode-biofilm reactor for artificial ammonia wastewater treatment. The titanium rod coated with a thin layer of ruthenium was used as anode to generate oxygen. In the aerobic area, NH4^+-N was oxidized to NO3^- -N or NO2^- -N by nitrifying bacteria. The active carbon fiber-felt was used as cathode to generate hydrogen. And in this anaerobic area, the denitrification was completed while hydrogen was acted as the electron donor. A lot of carbon particles were filled in tbe cathode area used as three- dimensional electrode. Nitrification and denitrification process were controlled by adjusting dissolved oxygen and pH values under the condition that the initial concentration of ammonia-nitrogen was 30 mg·L^-1 , the hydraulic retention time was 24h and the temperature was 30℃. After biofilm was formed and stabilized, the removal rate of NH4^+-N and TN achieved 97.8% and 92.4% respectively. It was indicated that the completely autotrophic nitrogen removal was started up successfully. The scanning electron microscopy showed that the bacteria on surface of activated carbon fiber felt were mainly short rod-shaped Pseudomonas, while the bacteria on the surface of the activated carbon particles were Micrococcus denitrificans. They both belong to hydrogen autotrophic denitrifying bacteria. In the reactor, the stable autotrophic nitrogen system was gradually established.%采用人工配制氨氮废水,对三维电极生物膜反应器进行全程自养脱氮的启动研究.反应器中阳极采用钌涂层钛棒,在阳极区电解水产氧供硝化菌进行硝化反应;阴极采用活性炭纤维毡,并在阴极区填充活性炭颗粒构建三维电极,在阴极区电解水产氢供反硝化菌完成反硝化过程.在进水NH4^+-N浓度30mg·L^-1、温度30℃、HRT为24h的试验条件下,通过调节DO和pH实现对硝化和反硝化反应的控制.结果

  4. Bioreactor and methods for producing synchronous cells

    Science.gov (United States)

    Helmstetter, Charles E. (Inventor); Thornton, Maureen (Inventor); Gonda, Steve (Inventor)

    2005-01-01

    Apparatus and methods are directed to a perfusion culture system in which a rotating bioreactor is used to grow cells in a liquid culture medium, while these cells are attached to an adhesive-treated porous surface. As a result of this arrangement and its rotation, the attached cells divide, with one cell remaining attached to the substrate, while the other cell, a newborn cell is released. These newborn cells are of approximately the same age, that are collected upon leaving the bioreactor. The populations of newborn cells collected are of synchronous and are minimally, if at all, disturbed metabolically.

  5. Lactate dehydrogenase from autotrophic and heterotrophic cells of the marine diatom Cylindrotheca fusiformis Reimann & Lewin.

    Science.gov (United States)

    Darley, W M; Smiley, R H

    1976-10-01

    Cultures of Cylindrotheca furisormis grown either autotrohpically or heterotrophically on lactate contained significant amounts of NAD-dependent L(+)-lactate dehydrogenase (EC 1.1.1.27). Polyacylamide gel electrophoresis of crude enzyme extracts revealed a single band which was indistinguishable between autotrohpic and heterotrohpic cells. The Km for lactate of partially purified preparations was lower under heterotrophic conditions. The specific activity in crude extracts was higher under autotrophic than heterotrophic conditions; it dropped precipitously when autotrophic cells were transferred to the dark, increasing again only in the presence of lactate. These and related observations suggest that this enzyme has at most only a minor role in the assimilation of lactate during heterotrophic growth on lactate. PMID:184899

  6. Autotrophic microbe metagenomes and metabolic pathways differentiate adjacent red sea brine pools

    KAUST Repository

    Wang, Yong

    2013-04-29

    In the Red Sea, two neighboring deep-sea brine pools, Atlantis II and Discovery, have been studied extensively, and the results have shown that the temperature and concentrations of metal and methane in Atlantis II have increased over the past decades. Therefore, we investigated changes in the microbial community and metabolic pathways. Here, we compared the metagenomes of the two pools to each other and to those of deep-sea water samples. Archaea were generally absent in the Atlantis II metagenome; Bacteria in the metagenome were typically heterotrophic and depended on aromatic compounds and other extracellular organic carbon compounds as indicated by enrichment of the related metabolic pathways. In contrast, autotrophic Archaea capable of CO2 fixation and methane oxidation were identified in Discovery but not in Atlantis II. Our results suggest that hydrothermal conditions and metal precipitation in the Atlantis II pool have resulted in elimination of the autotrophic community and methanogens.

  7. Acclimation Behavior of Nitrifying Sludge Against Trichloroethylene by Membrane Bioreactor%膜生物反应器中污泥的TCE硝化反应特性

    Institute of Scientific and Technical Information of China (English)

    丁原红; 熊小京; 洪华生

    2003-01-01

    采用一体式浸没膜生物反应器,在曝气、连续的条件下,间歇投加硝化反应的抑制物TCE(三氯乙烯),考察在不同TCE投加浓度下,TCE及其共代谢中间产物对硝化菌和异养菌活性的抑制情况,以及在TCE停止投加后,污泥相对硝化活性的变化趋势.虽然TCE对异养菌酶活性有一定的抑制作用,使CODMn的去除率呈下降趋势,但仍然没有被大幅度地降低;硝化菌由于对环境比较敏感,在TCE投加的初期,受抑制作用比较明显,氨氮的去除率呈下降趋势,但当硝化菌慢慢适应TCE共存环境后,其硝化活性将慢慢恢复,氨氮去除率将逐渐提高;停止投加TCE后,硝化菌仍然具有一定的耐TCE抑制的能力,且较高浓度TCE驯化的污泥的耐TCE抑制的能力也较高,但随着停止投加时间的延长,这种耐TCE抑制的能力将逐渐下降,直至消失.

  8. Autotrophic and heterotrophic food sources of copepods in the Scheldt estuary as traced by stable C and N isotopes

    OpenAIRE

    L. De Brabandere

    2005-01-01

    Estuaries draining densely populated watersheds experience significant anthropogenic pressure and sustain large autotrophic and heterotrophic production owing to an increased input of nutrients and organic matter. Polluted estuaries are often net heterotrophic systems. Our objective was to study the relative contributionof autotrophic and heterotrophic food webs in sustaining the high productivity of pelagic estuarine ecosystems along the estuarine gradient of the Scheldt estuary. We concentr...

  9. Detection of autotrophic verrucomicrobial methanotrophs in a geothermal environment using stable isotope probing

    OpenAIRE

    ChristineSharp; MatthewStott

    2012-01-01

    Genomic analysis of the methanotrophic verrucomicrobium “Methylacidiphilum infernorum” strain V4 has shown that most pathways conferring its methanotrophic lifestyle are similar to those found in proteobacterial methanotrophs. However, due to the large sequence divergence of its methane monooxygenase-encoding genes (pmo), ‘universal’ pmoA polymerase chain reaction (PCR) primers do not target these bacteria. Unlike proteobacterial methanotrophs, “Methylacidiphilum” fixes carbon autotrophically...

  10. Detection of autotrophic verrucomicrobial methanotrophs in a geothermal environment using stable isotope probing

    OpenAIRE

    Sharp, Christine E; Stott, Matthew B.; Dunfield, Peter F.

    2012-01-01

    Genomic analysis of the methanotrophic verrucomicrobium “Methylacidiphilum infernorum” strain V4 has shown that most pathways conferring its methanotrophic lifestyle are similar to those found in proteobacterial methanotrophs. However, due to the large sequence divergence of its methane monooxygenase-encoding genes (pmo), “universal” pmoA polymerase chain reaction (PCR) primers do not target these bacteria. Unlike proteobacterial methanotrophs, “Methylacidiphilum” fixes carbon autotrophically...

  11. Expression of Heterogenous Arsenic Resistance Genes in the Obligately Autotrophic Biomining Bacterium Thiobacillus ferrooxidans.

    Science.gov (United States)

    Peng, J B; Yan, W M; Bao, X Z

    1994-07-01

    Two arsenic-resistant plasmids were constructed and introduced into Thiobacillus ferrooxidans strains by conjugation. The plasmids with the replicon of wide-host-range plasmid RSF1010 were stable in T. ferrooxidans. The arsenic resistance genes originating from the heterotroph were expressed in this obligately autotrophic bacterium, but the promoter derived from T. ferrooxidans showed no special function in its original host. PMID:16349341

  12. Autotrophic Ammonia-Oxidizing Bacteria Contribute Minimally to Nitrification in a Nitrogen-Impacted Forested Ecosystem

    OpenAIRE

    Jordan, F L; Cantera, JJL; Fenn, M E; Stein, L.Y.

    2005-01-01

    Deposition rates of atmospheric nitrogenous pollutants to forests in the San Bernardino Mountains range east of Los Angeles, California, are the highest reported in North America. Acidic soils from the west end of the range are N-saturated and have elevated rates of N-mineralization, nitrification, and nitrate leaching. We assessed the impact of this heavy nitrogen load on autotrophic ammonia-oxidizing communities by investigating their composition, abundance, and activity. Analysis of 177 cl...

  13. Nitrogen removal by autotrophic ammonium oxidizing bacteria enrichment under anaerobic conditions

    OpenAIRE

    Pongsak (Lek) Noophan; Chalermraj Wantawin; Siriporn Sripiboon; Sanya Sirivitayapakorn

    2008-01-01

    Sludge from an anoxic tank at the centralized wastewater treatment plant, Nong Khaem, Bangkok, Thailand, was inoculatedin an anaerobic sequencing batch reactor (ASBR). The optimal compositions and operating conditions of the stock of autotrophic ammonium oxidizing bacteria medium were determined. The process of oxidizing ammonium with bacteria under anaerobic conditions is often referred to as the Anammox process (NO2- to N2 gas, using NH4+ as the electron donor and NO2- as the electron accep...

  14. Modeling, Experimentation, and Control of Autotrophic Nitrogen Removal in Granular Sludge Systems

    DEFF Research Database (Denmark)

    Vangsgaard, Anna Katrine

    is convenient for treating anaerobic digester liquor, landfill leachate, or special industrial wastewaters, because costs related to the need for aeration and carbon addition are lowered by 60% and 100%, respectively, compared to conventional nitrification denitrification treatment. Energy and......Complete autotrophic nitrogen removal (CANR) is a novel process that can increase the treatment capacity for wastewaters containing high concentrations of nitrogen and low organic carbon to nitrogen ratios, through an increase of the volumetric removal rate by approximately five times. This process...

  15. Partitioning Longleaf Pine Soil Respiration into Its Heterotrophic and Autotrophic Components through Root Exclusion

    OpenAIRE

    Althea A. ArchMiller; Lisa J. Samuelson

    2016-01-01

    Rapid and accurate estimations of the heterotrophic and autotrophic components of total soil respiration (Rs) are important for calculating forest carbon budgets and for understanding carbon dynamics associated with natural and management-related disturbances. The objective of this study was to use deep (60 cm) root exclusion tubes and paired control (i.e., no root exclusion) collars to estimate heterotrophic respiration (Rh) and Rs, respectively, in three 26-year-old longleaf pine (Pinus pal...

  16. Modelling the biological performance of a side-stream membrane bioreactor using ASM1

    Institute of Scientific and Technical Information of China (English)

    TIAN Ke-jun; LIU Xin-ai; JIANG Tao; M.D. Kennedy; J.C. Schippers; P.A. Vanrolleghem

    2004-01-01

    Membrane bioreactors(MBRs) are attracting global interest but the mathematical modeling of the biological performance of MBRs remains very limited. This study focuses on the modelling of a side-stream MBR system using Activated Sludge Model No.1(ASM1), and comparing the results with the modelling of traditional activated sludge processes. ASM1 parameters relevant for the long-term biological behaviour in MBR systems were calibrated(i.e. YH=0.72gCOD/gCOD, YA=0.25gCOD/gN, bH=0.25 d-1, bA=0.080 d-1 and fP=0.06), and generally agreed with the parameters in traditional activated sludge processes, with the exception that a higher autotrophic biomass decay rate was observed in the MBR. A sensitivity analysis for steady state operation and DO dynamics suggested that the biological performance of the MBR system(the sludge concentration, effluent quality and the DO dynamics) are very sensitive to the parameters(i.e. YH, YA, bH, bA, (maxH and (maxA), and influent wastewater components(XI, Ss, Xs, SNH).

  17. The abundance and diversity of ammonia-oxidizing bacteria in activated sludge under autotrophic domestication.

    Science.gov (United States)

    Li, Qiang; Ma, Chao; Sun, Shifang; Xie, Hui; Zhang, Wei; Feng, Jun; Song, Cunjiang

    2013-04-01

    Ammonia-oxidizing bacteria (AOB) play a key role in nitrogen-removal wastewater treatment plants (WWTPs) as they can transform ammonia into nitrite. AOB can be enriched in activated sludge through autotrophic domestication although they are difficult to be isolated. In this study, autotrophic domestication was carried out in a lab-scale sequencing-batch-reactor (SBR) system with two activated sludge samples. The ammonia removal capacity of the sludge samples increased during the domestication, and pH exhibited a negative correlation with the ammonia removal amount, which indicated that it was one important factor of microbial ammonia oxidation. The count of AOB, measured by the most probable number (MPN) method, increased significantly during autotrophic domestication as ammonia oxidation efficiency was enhanced. We investigated the changes in the community structure of AOB before and after domestication by amoA clone library and T-RFLP profile. It showed that AOB had been successfully enriched and the community structure significantly shifted during the domestication. Two groups of AOB were found in sludge samples: Nitrosomonas-like group remained predominant all the time and Nitrosospira-like group changed obviously. Simultaneously, the total heterotrophic bacteria were investigated by MPN and Biolog assay. The metabolic diversity of heterotrophs had changed minutely, although the count of them decreased significantly and lost superiority of microbial communities in the sludge. PMID:24620598

  18. Anaerobic membrane bioreactors: Are membranes really necessary?

    NARCIS (Netherlands)

    Davila, M.; Kassab, G.; Klapwijk, A.; Lier, van J.B.

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A

  19. Human cell culture in a space bioreactor

    Science.gov (United States)

    Morrison, Dennis R.

    1988-01-01

    Microgravity offers new ways of handling fluids, gases, and growing mammalian cells in efficient suspension cultures. In 1976 bioreactor engineers designed a system using a cylindrical reactor vessel in which the cells and medium are slowly mixed. The reaction chamber is interchangeable and can be used for several types of cell cultures. NASA has methodically developed unique suspension type cell and recovery apparatus culture systems for bioprocess technology experiments and production of biological products in microgravity. The first Space Bioreactor was designed for microprocessor control, no gaseous headspace, circulation and resupply of culture medium, and slow mixing in very low shear regimes. Various ground based bioreactors are being used to test reactor vessel design, on-line sensors, effects of shear, nutrient supply, and waste removal from continuous culture of human cells attached to microcarriers. The small Bioreactor is being constructed for flight experiments in the Shuttle Middeck to verify systems operation under microgravity conditions and to measure the efficiencies of mass transport, gas transfer, oxygen consumption and control of low shear stress on cells.

  20. Establishing Liver Bioreactors for In Vitro Research.

    Science.gov (United States)

    Rebelo, Sofia P; Costa, Rita; Sousa, Marcos F Q; Brito, Catarina; Alves, Paula M

    2015-01-01

    In vitro systems that can effectively model liver function for long periods of time are fundamental tools for preclinical research. Nevertheless, the adoption of in vitro research tools at the earliest stages of drug development has been hampered by the lack of culture systems that offer the robustness, scalability, and flexibility necessary to meet industry's demands. Bioreactor-based technologies, such as stirred tank bioreactors, constitute a feasible approach to aggregate hepatic cells and maintain long-term three-dimensional cultures. These three-dimensional cultures sustain the polarity, differentiated phenotype, and metabolic performance of human hepatocytes. Culture in computer-controlled stirred tank bioreactors allows the maintenance of physiological conditions, such as pH, dissolved oxygen, and temperature, with minimal fluctuations. Moreover, by operating in perfusion mode, gradients of soluble factors and metabolic by-products can be established, aiming at resembling the in vivo microenvironment. This chapter provides a protocol for the aggregation and culture of hepatocyte spheroids in stirred tank bioreactors by applying perfusion mode for the long-term culture of human hepatocytes. This in vitro culture system is compatible with feeding high-throughput screening platforms for the assessment of drug elimination pathways, being a useful tool for toxicology research and drug development in the preclinical phase. PMID:26272143

  1. Sulfate-reducing bacteria in anaerobic bioreactors.

    NARCIS (Netherlands)

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrenc

  2. Computational fluid dynamics simulation of bioreactors

    Directory of Open Access Journals (Sweden)

    Bjørn H. Hjertager

    1995-10-01

    Full Text Available Multi-dimensional models of flow processes in bioreactors are presented. Particular emphasis is given to models that use the two-fluid technique. The models use a two-equation turbuluence model and a Monod type kinetic reaction model. Predictions are given for both bubble column and mechanically stirred reactors.

  3. Engineering skeletal muscle tissue in bioreactor systems

    Institute of Scientific and Technical Information of China (English)

    An Yang; Li Dong

    2014-01-01

    Objective To give a concise review of the current state of the art in tissue engineering (TE) related to skeletal muscle and kinds of bioreactor environment.Data sources The review was based on data obtained from the published articles and guidelines.Study selection A total of 106 articles were selected from several hundred original articles or reviews.The content of selected articles is in accordance with our purpose and the authors are authorized scientists in the study of engineered muscle tissue in bioreactor.Results Skeletal muscle TE is a promising interdisciplinary field which aims at the reconstruction of skeletal muscle loss.Although numerous studies have indicated that engineering skeletal muscle tissue may be of great importance in medicine in the near future,this technique still represents a limited degree of success.Since tissue-engineered muscle constructs require an adequate connection to the vascular system for efficient transport of oxygen,carbon dioxide,nutrients and waste products.Moreover,functional and clinically applicable muscle constructs depend on adequate neuromuscular junctions with neural calls.Third,in order to engineer muscle tissue successfully,it may be beneficial to mimic the in vivo environment of muscle through association with adequate stimuli from bioreactors.Conclusion Vascular system and bioreactors are necessary for development and maintenance of engineered muscle in order to provide circulation within the construct.

  4. Critical Review of Membrane Bioreactor Models

    DEFF Research Database (Denmark)

    Naessens, W.; Maere, T.; Ratkovich, Nicolas Rios;

    2012-01-01

    Membrane bioreactor technology exists for a couple of decades, but has not yet overwhelmed the market due to some serious drawbacks of which operational cost due to fouling is the major contributor. Knowledge buildup and optimisation for such complex systems can heavily benefit from mathematical...

  5. LANDFILL BIOREACTOR PERFORMANCE, SECOND INTERIM REPORT

    Science.gov (United States)

    A bioreactor landfill is a landfill that is operated in a manner that is expected to increase the rate and extent of waste decomposition, gas generation, and settlement compared to a traditional landfill. This Second Interim Report was prepared to provide an interpretation of fie...

  6. MONITORING APPROACHES FOR BIOREACTOR LANDFILLS - Report

    Science.gov (United States)

    Experimental bioreactor landfill operations at operating Municipal Solid Waste (MSW) landfills can be approved under the research development and demonstration (RD&D) provisions of 30CFR 258.4. To provide a basis for consistent data collection for future decision-making in suppor...

  7. Culture-independent detection of 'TM7' bacteria in a streptomycin-resistant acidophilic nitrifying process

    Energy Technology Data Exchange (ETDEWEB)

    Kurogi, T.; Linh, N. T. T.; Kuroki, T.; Yamada, T. [Department of Environmental and Life Science, Toyohashi University of Technology, Toyohashi 441-8580 (Japan); Hiraishi, A. [Department of Environmental and Life Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan and Electronics-inspired Interdisciplinary Institute (EIIRIS), Toyohashi University of Technology, Toyohashi 441-8580 (Japan)

    2014-02-20

    Nitrification in biological wastewater treatment processes has been believed for long time to take place under neutral conditions and is inhibited under acidic conditions. However, we previously constructed acidophilic nitrifying sequencing-batch reactors (ANSBRs) being capable of nitrification at < pH 4 and harboring bacteria of the candidate phylum 'TM7' as the major constituents of the microbial community. In light of the fact that the 16S rRNA of TM7 bacteria has a highly atypical base substitution possibly responsible for resistance to streptomycin at the ribosome level, this study was undertaken to construct streptomycin-resistant acidophilic nitrifying (SRAN) reactors and to demonstrate whether TM7 bacteria are abundant in these reactors. The SRAN reactors were constructed by seeding with nitrifying sludge from an ANSBR and cultivating with ammonium-containing mineral medium (pH 4.0), to which streptomycin at a concentration of 10, 30 and 50 mg L{sup −1} was added. In all reactors, the pH varied between 2.7 and 4.0, and ammonium was completely converted to nitrate in every batch cycle. PCR-aided denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes revealed that some major clones assigned to TM7 bacteria and Gammaproteobacteria were constantly present during the overall period of operation. Fluorescence in situ hybridization (FISH) with specific oligonucleotide probes also showed that TM7 bacteria predominated in all SRAN reactors, accounting for 58% of the total bacterial population on average. Although the biological significance of the TM7 bacteria in the SRAN reactors are unknown, our results suggest that these bacteria are possibly streptomycin-resistant and play some important roles in the acidophilic nitrifying process.

  8. Effect of land use on the density of nitrifying and denitrifying bacteria in the colombian coffee region

    OpenAIRE

    Vallejo Quintero, Victoria Eugenia; Gómez, María M.; Cubillos, Ana M.; Roldán, Fabio

    2012-01-01

    Soil microbial communities involved in the cycling of nitrogen (N) are essential to maintaining and improving soil fertility, productivity and functionality of natural and agricultural ecosystems. However, some compounds generated during the metabolic processes performed by nitrifying (NB) and denitrifying (DB) bacteria are associated with the production of greenhouse gases, groundwater pollution and acidification. Therefore, the study of these bacteria is essential for economic and environme...

  9. Preservation of nitrifying capacity and nitrate availability in waterlogged soils by radial oxygen loss from roots of wetland plants

    OpenAIRE

    Engelaar, W.M.H.G.; Symens, J.C.; Laanbroek, H. J.; Blom, C.W.P.M.

    1995-01-01

    The effects of radial 02 loss from roots on nitrification and NO3- availability were studied. Plants of the flooding-resistant species Rumex palustris and the flooding-sensitive species Rumex thyrsiflorus were grown on drained and waterlogged soils with an initially high nitrifying capacity. Nitrate reductase activity in the plant leaves was used as an indicator of NO3- availability to the plants. In a separate experiment these species were shown to have higher levels of nitrate reductase act...

  10. Combined photocatalysis and membrane bioreactor for the treatment of feedwater containing thin film transistor-liquid crystal display discharge.

    Science.gov (United States)

    You, Sheng-Jie; Semblante, Galilee Uy; Chen, Yu-Pu; Chang, Tien-Chin

    2015-01-01

    The nitrogen content of waste water generated by the thin film transistor-liquid crystal display (TFT-LCD) industry is not satisfactorily removed through the conventional aerobic-activated sludge process. In this study, the performance of three reactors – suspended type TiO2 membrane photoreactor (MPR), anoxic/oxic membrane bioreactor (AOMBR), and their combination (MPR-AOMBR) – was evaluated using feedwater containing TFT-LCD discharge. The parameters that maximized monoethanolamine (MEA) removal in the MPR were continuous ultraviolet (UV) irradiation and pH 11. Among the tested loadings, 0.1 g/l of TiO2 promoted MEA removal but degradation rate may further increase with photocatalyst concentration. The nitrified sludge recycle ratio R of the AOMBR was adjusted to 1.5 to minimize the amount of nitrate in the effluent. The AOMBR greatly decreased chemical oxygen demand and MEA, but removed only 32.7% of tetramethyl ammonium hydroxide (TMAH). The MPR was configured as the pre-treatment unit for AOMBR, and the combined MPR-AOMBR has improved TMAH removal by 80.1%. The MPR bolstered performance by decomposing slowly biodegradable compounds, and had no negative effects on denitrification and carbon removal. PMID:25952015

  11. A fuzzy-logic based diagnosis and control of a reactor performing complete autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine; Gernaey, Krist; Sin, Gürkan

    Diagnosis and control modules based on fuzzy set theory were tested for novel bioreactor monitoring and control. Two independent modules were used jointly to carry out first the diagnosis of the state of the system and then use transfer this information to control the reactor. The separation in...

  12. A fuzzy-logic based diagnosis and control of a reactor performing complete autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine; Gernaey, Krist; Sin, Gürkan

    This contribution explores the use of diagnosis and control modules based on fuzzy set theory and logic for bioreactor monitoring and control. With this aim, two independent modules were used jointly to carry out first the diagnosis of the state of the system and then use transfer this information...

  13. Autotrophic Biological Denitrification for Complete Removal of Nitrogen from Septic System Wastewater

    International Nuclear Information System (INIS)

    The overall objective of this research was to develop a reliable, robust, and maintenance-free passive system for biological denitrification in on-site wastewater treatment systems. The process relies on sulfur oxidizing denitrifying bacteria in upflow packed bioreactors. Since this process consumes alkalinity, it is necessary to add a solid-phase buffer that can scavenge the H+ as it is generated by the biologically-mediated reaction and arrest the drop in the pH value. This study investigated the use of limestone, marble chips and crushed oyster shell as solid-phase buffers that provide alkalinity.Two bench-scale upflow column reactors and two field-scale bioreactors were constructed and packed with sulfur pellets and an alkalinity source. The pilot scale bioreactors (∼200 L each) were installed at the Massachusetts Alternative Septic System Test Center (MASSTC) in Sandwich, MA. The pilot-scale bioreactors performed better when oyster shell was used as the solid-phase buffer vis-a-vis marble chips. In both (pilot-scale and laboratory-scale) systems, denitrification rates were high with the effluent NO3- -N concentration consistently below 8 mg/L

  14. Bioreactors as a low cost option for tissue culture

    International Nuclear Information System (INIS)

    Bioreactors are vessels designed for large-scale cell, tissue or organ culture in liquid media. Functionally, plant culture bioreactors can be divided into two broad types: those in which the cultures are immersed partially or temporarily in the medium, and those in which the cultures are continuously submerged. Bioreactors provide more precise control of the plant growth gaseous exchange, illumination, medium agitation, temperature and pH than the conventional culture vessels. Bioreactor-based propagation of plants can increase rate of multiplication and growth of cultures and reduce space, energy and labour requirements in commercial micropropagation. They can therefore be attractive to developing countries as regards new or expanding plant culture facilities, in combination with a conventional laboratory. However, to be cost- effective, use of bioreactors requires indexed plant cultures, and attention to aseptic procedures during handling of plant material. Hence, the integration of bioreactors into production systems should only be attempted by facilities with skilled and experienced propagators. (author)

  15. Modeling of a membrane bioreactor for production of biodiesel

    International Nuclear Information System (INIS)

    Through the use of an enzymatic catalyst lipase, produced by Candida Antarctica a membrane bioreactor was modeled and simulated to obtain biodiesel from palm oil and ethanol. A conversion of 0.97 was reached for a residence time of 10.64 min. The membrane bioreactor was compared to a CSTR reactor, where a conversion of 0.76 was obtained. It was concluded that the membrane bioreactor is a better way of producing biodiesel than the CSTR

  16. Investigations concerning the use of membrane bioreactor systems

    International Nuclear Information System (INIS)

    Membrane bioreactor systems are increasingly being used to clean leachates from landfills. Besides being compact they can, especially, be easily combined with further cleaning techniques. The paper first of all gives an overview on landfill leachate cleaning standards in Austria. A combination of processes is applied where the membrane bioreactor forms a preferred element. Finally, results are presented which should help with the dimensioning of membrane bioreactors. (orig.)

  17. Simulation of Temperature Control in Fermentation Bioreactor for Ethanol Production

    OpenAIRE

    MARGINEAN Calin; MARGINEAN Ana-Maria; TRIFA Viorel

    2012-01-01

    Present paper deals with aspects regardingthe simulation of fermentation bioreactor process andfermentation bioreactor control for ethanolproduction. The bioreactor model was implemented inMatlab Simulink and the results of simulation usingdifferent control strategies are presentedcomparatively. Three types of control strategy are usedrespectively, PID, Neural Network Model PredictiveController (NN-MPC) and Nonlinear Auto RegressiveMoving Average(NARMA-L2) control strategy.

  18. Proton translocation during denitrification by a nitrifying--denitrifying Alcaligenes sp.

    Science.gov (United States)

    Castignetti, D; Hollocher, T C

    1983-04-01

    A heterotrophic nitrifying Alcaligenes sp. from soil was grown as a denitrifier on nitrate and subjected to oxidant pulse experiments to ascertain the apparent efficiencies of proton translocations during O2 and nitrogen-oxide respirations. With endogenous substrate as the reducing agent the leads to H+/2e- ratios, extrapolated to zero amount of oxidant per pulse, were 9.4, 3.7, 4.3 and 3.5 for O2, nitrate, nitrite and N2O, respectively. The value for O2 and those for the N-oxides are, respectively, somewhat larger and smaller than corresponding values for Paracoccus denitrificans. None of the three permeant ions employed with the Alcaligenes sp. (valinomycin-K+, thiocyanate and triphenylmethylphosphonium) was ideal for all purposes. Thiocyanate provided highest ratios for O2 but abolished the oxidant pulse response for nitrate and N2O. Valinomycin was slow to penetrate to the cytoplasmic membrane and relatively high concentrations were required for optimal performance. Triphenylmethylphosphonium enhanced passive proton permeability and diminished proton translocation at concentrations required to realize the maximal oxidant pulse response. PMID:6311094

  19. Investigation of Temperature and Influent Load on Nitrifying Wastewater Treatments Using CFD

    Directory of Open Access Journals (Sweden)

    Baharak Sajjadi

    2011-02-01

    Full Text Available The paper describes the effect of temperature, ammonia concentration and feed flow rate on nitrifying treatment of wastewater usage Computational Fluid Dynamics (CFD for two phase bubbly flow in a split cylindrical airlift reactor with a 0.085 m initiator diameter and 0.505 m height. Superficial gas velocity was used as the operational parameter, air was used as the dispersed phase, and wastewater containing ammonia was used as continuous phase. Temperature enhancement in a constant O2 and NH4+ concentrations, resulted the increase of reactions rate also NO2- had an increase of about 3 times as much. By the feed flow rate increase, O2 consumption increase and the rate of NO2- production increase more than NO3- but decrease the reactions efficiency decrease in a constant time. NH4+ concentration enhancement leads to the increase of O2 consumption and better reactions efficiency at higher NH4+ concentration, NO2- concentration increases more. Modeling results are compared with the experimental data. The CFD modeling results show suitable agreement with the experimental data.

  20. Chronic impact of sulfamethoxazole on the metabolic activity and composition of enriched nitrifying microbial culture.

    Science.gov (United States)

    Katipoglu-Yazan, Tugce; Merlin, Christophe; Pons, Marie-Noëlle; Ubay-Cokgor, Emine; Orhon, Derin

    2016-09-01

    This study investigated the chronic impact of sulfamethoxazole (SMX) on activated sludge sustaining an enriched nitrifying biomass. For this purpose, a laboratory scale fill and draw reactor was operated with 100 mg COD/L of peptone mixture and 50 mg N/L of ammonia at a sludge age of 15 days. Additionally, the biomass was exposed to a daily SMX dose of 50 mg/L once the reactor reached steady-state conditions. The reactor performance and microbial composition were monitored for 37 days with conventional parameters and molecular techniques based on the gene for ammonia monooxygenase subunit A (amoA) and the prokaryotic 16S rRNA gene. Denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene cloning analyses suggested a microbial community change concurrent with the addition of SMX. Specifically, quantitative polymerase chain reaction analyses (qPCR/RT-qPCR) revealed a significant reduction in the levels and activity of ammonia oxidizing bacteria (AOB). However, the acclimation period ended with high amoA mRNA levels and improved nitrification efficiency. Partial degradation of SMX by heterotrophic bacteria was also observed. PMID:27235775

  1. Physiological and transcriptional responses of nitrifying bacteria exposed to copper in activated sludge.

    Science.gov (United States)

    Ouyang, Fan; Zhai, Hongyan; Ji, Min; Zhang, Hongyang; Dong, Zhao

    2016-01-15

    Cu inhibition of gene transcription in ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were rarely studied simultaneously in activated sludge. In this study, the transcription of amoA (for AOB) and nxrB (for NOB), nitrification efficiencies, AOB and NOB respiratory rates, and Cu distribution were simultaneously investigated. Modeling the relationships among the aforementioned parameters revealed that in complex activated sludge systems, nitrification efficiency was an insensitive parameter for showing Cu inhibition. Respiration activities and gene transcription were sensitive to Cu and positively correlated with each other. The transcription of amoA and nxrB genes indicated that the Cu had different inhibitory effects on AOB and NOB. AOB were more susceptible to Cu toxicity than NOB. Moreover, the degree of Cu inhibition on ammonia oxidation was greater than on nitrite oxidation. The analysis and related modeling results indicate that the inhibitory actions of Cu on nitrifying bacteria could mainly be attributed to intracellular Cu. The findings from this study provide insight into the mechanism of Cu inhibition on nitrification in complex activated sludge systems. PMID:26348150

  2. Impact of Heavy Metals on Transcriptional and Physiological Activity of Nitrifying Bacteria.

    Science.gov (United States)

    Kapoor, Vikram; Li, Xuan; Elk, Michael; Chandran, Kartik; Impellitteri, Christopher A; Santo Domingo, Jorge W

    2015-11-17

    Heavy metals can inhibit nitrification, a key process for nitrogen removal in wastewater treatment. The transcriptional responses of amoA, hao, nirK, and norB were measured in conjunction with specific oxygen uptake rate (sOUR) for nitrifying enrichment cultures exposed to different metals (Ni(II), Zn(II), Cd(II), and Pb(II)). There was significant decrease in sOUR with increasing concentrations for Ni(II) (0.03-3 mg/L), Zn(II) (0.1-10 mg/L), and Cd(II) (0.03-1 mg/L) (p amoA and hao decreased when exposed to Ni(II) dosages. Slight up-regulation of amoA, hao, and nirK (0.5-1.5-fold) occurred after exposure to 0.3-3 mg/L Zn(II), although their expression decreased for 10 mg/L Zn(II). With the exception of 1000 mg/L Pb(II), stimulation of all genes occurred on Cd(II) and Pb(II) exposure. While overall the results show that RNA-based function-specific assays can be used as potential surrogates for measuring nitrification activity, the degree of inhibition inferred from sOUR and gene transcription is different. We suggest that variations in transcription of functional genes may supplement sOUR based assays as early warning indicators of upsets in nitrification. PMID:26501957

  3. Nutrient removal and phosphorus recovery performances of a novel anaerobic-anoxic/nitrifying/induced crystallization process.

    Science.gov (United States)

    Shi, Jing; Lu, Xiwu; Yu, Ran; Zhu, Wentao

    2012-10-01

    An anaerobic-anoxic/nitrifying (A(2)N) two sludge process coupled with induced crystallization (IC) called A(2)N-IC process was developed for wastewater nutrient removal and phosphorus recovery. The performances of A(2)N-IC process in comparison with A(2)N process at different COD to phosphorus (COD/P) feeding ratios were investigated. The results indicated that A(2)N-IC achieved not only high and stable nutrient removal but also phosphorus recovery. Calcium phosphorus crystals were formed in the crystallization reactor in A(2)N-IC. Moreover, the incorporation of chemical induced crystallization improved biological phosphorus removal. In A(2)N-IC process, phosphorus removal efficiency was consistently maintained at 99.2%, whereas in A(2)N it decreased from 93.0% to 65.7% with the decrease of feeding COD/P ratio. The COD and ammonia removal efficiencies were regardless of feeding COD/P ratio in the two processes. PMID:22858484

  4. Autotrophic and heterotrophic denitrification for simultaneous removal of nitrogen, sulfur and organic matter.

    Science.gov (United States)

    Guerrero, Lorna; Aguirre, Juan P; Muñoz, Maria A; Barahona, Andrea; Huiliñir, Cesar; Montalvo, Silvio; Borja, Rafael

    2016-07-01

    The aim of this investigation was to assess the startup and operation of a laboratory-scale hybrid UASB-Anaerobic Filter Reactor (UASFB) of 1 L volume, kept at 30°C, in order to carry out a simultaneous autotrophic and heterotrophic denitrification process. First, the heterotrophic and autotrophic populations were separately enriched, with specific cultures and subsequently the UASFB was inoculated with 2 g L(-1) of volatile suspended solids (VSS), with a ratio of 1.5:1 (autotrophs: heterotrophs). The influent or synthetic wastewater used was composed of: Na2S2O3·5H2O, CH3COOK, NaNO3, NaHCO3, K2HPO4, NH4Cl and saline solution. The concentrations varied depending on the organic loading rate (OLR), nitrogen loading rate (NLR) and sulfur loading rate (SLR) applied. In the UASFB reactor, two experimental conditions were tested and assessed: (i) COD/N ratio of 3.6 and SLR of 0.75 kg S m(-3) d(-1); and (ii) COD/N ratio of 5.8 and SLR of 0.25 kg S m(-3) d(-1). The results obtained demonstrated that an inoculum coming from an anaerobic reactor was able to carry out the process, obtaining a maximum nitrate removal of 85.3% in the first stage of operation and 99.5% in the second stage. The recovery of sulfur in form of sulfate in the effluent did not present a tendency to stabilize during the measured time, with a maximum thiosulfate removal of 32.5%, when the SLR was lowered to 0.25 kg S m(-3) d(-1). The maximum organic matter elimination, measured as COD, was 75.8%, which indicates the relatively good performance and behavior of the heterotrophic microorganisms. PMID:27093220

  5. Enhanced start-up of anaerobic facultatively autotrophic biocathodes in bioelectrochemical systems

    KAUST Repository

    Zaybak, Zehra

    2013-12-01

    Biocathodes in bioelectrochemical systems (BESs) can be used to convert CO2 into diverse organic compounds through a process called microbial electrosynthesis. Unfortunately, start-up of anaerobic biocathodes in BESs is a difficult and time consuming process. Here, a pre-enrichment method was developed to improve start-up of anaerobic facultatively autotrophic biocathodes capable of using cathodes as the electron donor (electrotrophs) and CO2 as the electron acceptor. Anaerobic enrichment of bacteria from freshwater bog sediment samples was first performed in batch cultures fed with glucose and then used to inoculate BES cathode chambers set at -0.4V (versus a standard hydrogen electrode; SHE). After two weeks of heterotrophic operation of BESs, CO2 was provided as the sole electron acceptor and carbon source. Consumption of electrons from cathodes increased gradually and was sustained for about two months in concert with a significant decrease in cathode chamber headspace CO2. The maximum current density consumed was -34±4mA/m2. Biosynthesis resulted in organic compounds that included butanol, ethanol, acetate, propionate, butyrate, and hydrogen gas. Bacterial community analyses based on 16S rRNA gene clone libraries revealed Trichococcus palustris DSM 9172 (99% sequence identity) as the prevailing species in biocathode communities, followed by Oscillibacter sp. and Clostridium sp. Isolates from autotrophic cultivation were most closely related to Clostridium propionicum (99% sequence identity; ZZ16), Clostridium celerecrescens (98-99%; ZZ22, ZZ23), Desulfotomaculum sp. (97%; ZZ21), and Tissierella sp. (98%; ZZ25). This pre-enrichment procedure enables simplified start-up of anaerobic biocathodes for applications such as electrofuel production by facultatively autotrophic electrotrophs. © 2013 Elsevier B.V.

  6. Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor

    International Nuclear Information System (INIS)

    Highlights: → Intensified biofilm-electrode reactor using cooperative denitrification is developed. → IBER combines heterotrophic and autotrophic denitrification. → CO2 formed by heterotrophic denitrification is used by autotrophic bacteria. → Optimum running conditions are C/N = 0.75, HRT = 8 h, and I = 40 mA. → A novel degradation mechanism for cooperating denitrification process is proposed. - Abstract: An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO3-N50 mg L-1) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO3-N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO2 produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.

  7. Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yingxin [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan); Feng, Chuanping, E-mail: fengchuangping@gmail.com [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Wang, Qinghong; Yang, Yingnan; Zhang, Zhenya; Sugiura, Norio [Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan)

    2011-09-15

    Highlights: {yields} Intensified biofilm-electrode reactor using cooperative denitrification is developed. {yields} IBER combines heterotrophic and autotrophic denitrification. {yields} CO{sub 2} formed by heterotrophic denitrification is used by autotrophic bacteria. {yields} Optimum running conditions are C/N = 0.75, HRT = 8 h, and I = 40 mA. {yields} A novel degradation mechanism for cooperating denitrification process is proposed. - Abstract: An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO{sub 3}{sup -}N50 mg L{sup -1}) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO{sub 3}{sup -}N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO{sub 2} produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.

  8. Sulfate-reducing bacteria in anaerobic bioreactors.

    OpenAIRE

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrence of sulfate reduction was considered to be undesired. However, there are some recent developments in which sulfate reduction is optimized for the removal of sulfur compounds from waste streams. In...

  9. Control of Dissolved Oxygen in Stirred Bioreactors

    OpenAIRE

    Åkesson, Mats; Hagander, Per

    1998-01-01

    This report discusses control of dissolved oxygen in a bioreactor where the oxygen supply is manipulated using the stirrer speed. In batch and fed-batch cultivations the operating conditions change significantly which may cause tuning problems. Analysis using a linearized process model shows that the process dynamics is mainly affected by changes in the volumetric oxygen transfer coefficient $K_La$. % To account for the process variations, a control strategy based on PID control and gain sche...

  10. Membrane Bioreactors: Past, Present and Future?

    OpenAIRE

    Hermanowicz, Slav W

    2011-01-01

    A brief description of membrane bioreactor (MBR) historical evolution has been presented with emphasis on continual decline of treatment costs and energy requirements. Although MBR can operate at biomass (MLSS) concentrations 5 to 10 times higher than activated sludge these concentrations are limited in practice by increasing biomass suspension viscosity that in turn increases “reversible” membrane fouling and decreases oxygen transfer rates. “Irreversible” fouling is a major operational chal...

  11. Anaerobic membrane bioreactors for municipal wastewater treatment

    OpenAIRE

    Fawehinmi, Folasade

    2006-01-01

    Anaerobic treatment has historically been considered unsuitable for the treatment of domestic wastewaters. The work presented in this thesis focuses on the incorporation of membranes into the anaerobic bioreactor to uncouple solid retention time and hydraulic retention time. This in turn prevents biomass washout and allows sufficient acclimatisation periods for anaerobes. However, the exposure of membranes to anaerobic biomass comes with its own inherent problems namely fouling. Fouling w...

  12. Oxygen transfer in a pressurized airlift bioreactor.

    Science.gov (United States)

    Campani, Gilson; Ribeiro, Marcelo Perencin Arruda; Horta, Antônio Carlos Luperni; Giordano, Roberto Campos; Badino, Alberto Colli; Zangirolami, Teresa Cristina

    2015-08-01

    Airlift bioreactors (ALBs) offer advantages over conventional systems, such as simplicity of construction, reduced risk of contamination, and efficient gas-liquid dispersion with low power consumption. ALBs are usually operated under atmospheric pressure. However, in bioprocesses with high oxygen demand, such as high cell density cultures, oxygen limitation may occur even when operating with high superficial gas velocity and air enriched with oxygen. One way of overcoming this drawback is to pressurize the reactor. In this configuration, it is important to assess the influence of bioreactor internal pressure on the gas hold-up, volumetric oxygen transfer coefficient (k(L)a), and volumetric oxygen transfer rate (OTR). Experiments were carried out in a concentric-tube airlift bioreactor with a 5 dm(3) working volume, equipped with a system for automatic monitoring and control of the pressure, temperature, and inlet gas flow rate. The results showed that, in disagreement with previous published results for bubble column and external loop airlift reactors, overpressure did not significantly affect k(L)a within the studied ranges of pressure (0.1-0.4 MPa) and superficial gas velocity in the riser (0.032-0.065 m s(-1)). Nevertheless, a positive effect on OTR was observed: it increased up to 5.4 times, surpassing by 2.3 times the oxygen transfer in a 4 dm(3) stirred tank reactor operated under standard cultivation conditions. These results contribute to the development of non-conventional reactors, especially pneumatic bioreactors operated using novel strategies for oxygen control. PMID:25903476

  13. Immersed Membrane Bioreactors for Produced Water Treatment

    OpenAIRE

    Brookes, Adam

    2005-01-01

    The performance of a submerged membrane bioreactor for the duty of gas field produced water treatment was appraised. The system was operated under steady state conditions at a range of mixed liquor suspended solids (MLSS) concentrations and treatment and membrane performance examined. Organics removal (COD and TOC) display removal rates between 90 and 97%. Removal of specific target compounds Benzene, Toulene, Ethylbenzene and Xylene were removed to above 99% in liquid phase...

  14. Engineering stem cell niches in bioreactors

    OpenAIRE

    2013-01-01

    Stem cells, including embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells and amniotic fluid stem cells have the potential to be expanded and differentiated into various cell types in the body. Efficient differentiation of stem cells with the desired tissue-specific function is critical for stem cell-based cell therapy, tissue engineering, drug discovery and disease modeling. Bioreactors provide a great platform to regulate the stem cell microenvironment, known as “ni...

  15. Bioreactor Yields Extracts for Skin Cream

    Science.gov (United States)

    2015-01-01

    Johnson Space Flight Center researchers created a unique rotating-wall bioreactor that simulates microgravity conditions, spurring innovations in drug development and medical research. Renuèll Int'l Inc., based in Aventure, Florida, licensed the technology and used it to produce a healing skin care product, RE`JUVEL. In a Food and Drug Administration test, RE`JUVEL substantially increased skin moisture and elasticity while reducing dark blotches and wrinkles.

  16. Filterability and Sludge Concentration in Membrane Bioreactors

    OpenAIRE

    Lousada-Ferreira, M

    2011-01-01

    The Thesis entitled “Filterability and Sludge Concentration in Membrane Bioreactors” aims at explaining the relation between Mixed Liquid Suspended Solids (MLSS) concentration, the amount of solids in the wastewater being treated, also designated as sludge, and filterability, being the ability of the sludge to be filtrated through a membrane, in a wastewater treatment system designated as Membrane Bioreactor (MBR). An MBR is a wastewater treatment system that combines an activated sludge proc...

  17. Anaerobic membrane bioreactors: Are membranes really necessary?

    OpenAIRE

    Davila, M.; Kassab, G.; Klapwijk, A.; Van, Lier, G

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A self-forming dynamic membrane only requires a support material over which a cake layer is formed, which determines the rejection properties of the system. The present research studies the applicat...

  18. Replaceable Sensor System for Bioreactor Monitoring

    Science.gov (United States)

    Mayo, Mike; Savoy, Steve; Bruno, John

    2006-01-01

    A sensor system was proposed that would monitor spaceflight bioreactor parameters. Not only will this technology be invaluable in the space program for which it was developed, it will find applications in medical science and industrial laboratories as well. Using frequency-domain-based fluorescence lifetime technology, the sensor system will be able to detect changes in fluorescence lifetime quenching that results from displacement of fluorophorelabeled receptors bound to target ligands. This device will be used to monitor and regulate bioreactor parameters including glucose, pH, oxygen pressure (pO2), and carbon dioxide pressure (pCO2). Moreover, these biosensor fluorophore receptor-quenching complexes can be designed to further detect and monitor for potential biohazards, bioproducts, or bioimpurities. Biosensors used to detect biological fluid constituents have already been developed that employ a number of strategies, including invasive microelectrodes (e.g., dark electrodes), optical techniques including fluorescence, and membrane permeable systems based on osmotic pressure. Yet the longevity of any of these sensors does not meet the demands of extended use in spacecraft habitat or bioreactor monitoring. It was therefore necessary to develop a sensor platform that could determine not only fluid variables such as glucose concentration, pO2, pCO2, and pH but can also regulate these fluid variables with controlled feedback loop.

  19. Aujeszky's disease virus production in disposable bioreactor

    Indian Academy of Sciences (India)

    I Slivac; V Gaurina Srček; K Radošević; I Kmetič; Z Kniewald

    2006-09-01

    A novel, disposable-bag bioreactor system that uses wave action for mixing and transferring oxygen was evaluated for BHK 21 C13 cell line growth and Aujeszky’s disease virus (ADV) production. Growth kinetics of BHK 21 C13 cells in the wave bioreactor during 3-day period were determined. At the end of the 3-day culture period and cell density of 1.82 × 106 cells ml–1, the reactor was inoculated with 9 ml of gE- Bartha K-61 strain ADV suspension (105.9 TCID50) with multiplicity of infection (MOI) of 0.01. After a 144 h incubation period, 400 ml of ADV harvest was obtained with titre of 107.0 TCID50 ml–1, which corresponds to 40,000 doses of vaccine against AD. In conclusion, the results obtained with the wave bioreactor using BHK 21 C13 cells showed that this system can be considered as suitable for ADV or BHK 21 C13 cell biomass production.

  20. Degradation of Refuse in Hybrid Bioreactor Landfill

    Institute of Scientific and Technical Information of China (English)

    YAN LONG; Yu-YANG LONG; HAI-CHUN LIU; DONG-SHENG SHEN

    2009-01-01

    Objectivess To explore the process of refuse decomposition in hybrid bioreactor landfill. Methods The bioreactor landfill was operated in sequencing of facultative-anaerobic and aerobic conditions with leachate recireulation, pH, COD, and ammonia in the leachate and pH, biodegradable organic matter (BDM), and cation exchange capacity (CEC) in refuse were detected. Results CEC increased gradually with the degradation of refuse, which was negatively correlad, With BDM. COD and ammonia in the leachate was declined to 399.2 mg L-1 and 20.6 mg N L-1, respectively, during the 357-day operation. The respective concentrations of ammonia and COD were below the second and the third levels of current discharge standards in China. Conclusion The refuse is relatively stable at the end of hybrid bioreactor landfill operation. Most of the readily biodegradable organic matter is mineralized in the initial phase of refuse degradation, whereas the hard-biodegradable organic matter is mainly humidified in the maturity phase of refuse degradation.

  1. Heterotrophic denitrification vs. autotrophic anammox – quantifying collateral effects on the oceanic carbon cycle

    Directory of Open Access Journals (Sweden)

    W. Koeve

    2010-08-01

    Full Text Available The conversion of fixed nitrogen to N2 in suboxic waters is estimated to contribute roughly a third to total oceanic losses of fixed nitrogen and is hence understood to be of major importance to global oceanic production and, therefore, to the role of the ocean as a sink of atmospheric CO2. At present heterotrophic denitrification and autotrophic anammox are considered the dominant sinks of fixed nitrogen. Recently, it has been suggested that the trophic nature of pelagic N2-production may have additional, "collateral" effects on the carbon cycle, where heterotrophic denitrification provides a shallow source of CO2 and autotrophic anammox a shallow sink. Here, we analyse the stoichiometries of nitrogen and associated carbon conversions in marine oxygen minimum zones (OMZ focusing on heterotrophic denitrification, autotrophic anammox, and dissimilatory nitrate reduction to nitrite and ammonium in order to test this hypothesis quantitatively. For open ocean OMZs the combined effects of these processes turn out to be clearly heterotrophic, even with high shares of the autotrophic anammox reaction in total N2-production and including various combinations of dissimilatory processes which provide the substrates to anammox. In such systems, the degree of heterotrophy (ΔCO2:ΔN2, varying between 1.7 and 6.5, is a function of the efficiency of nitrogen conversion. On the contrary, in systems like the Black Sea, where suboxic N-conversions are supported by diffusive fluxes of NH4+ originating from neighbouring waters with sulphate reduction, much lower values of ΔCO2:ΔN2 can be found. However, accounting for concomitant diffusive fluxes of CO2, the ratio approaches higher values similar to those computed for open ocean OMZs. Based on this analysis, we question the significance of collateral effects concerning the trophic

  2. Redox stratified biofilms to support completely autotrophic nitrogen removal: Principles and results

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Smets, Barth F.

    biofilm structure with aerobic ammonium oxidizing bacteria dominating the areas of the biofilm closer to the membrane surface while anaerobic oxidizing bacteria populated mainly the outer biofilm region. The biofilm was approximately 500 m thick and featured both aerobic and anaerobic ammonium oxidizing...... the outgrowth of nitrite oxidizing bacteria communities. Autotrophic nitrogen removal is already revealing itself as a cheap alternative to treat concentrated nitrogen streams. However, we believe that this concept can be taken a step further in MABRs and become an even more cost-effective, compact...

  3. Performance of an autotrophic nitrogen removing reactor: Diagnosis through fuzzy logic

    DEFF Research Database (Denmark)

    Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Mutlu, Ayten Gizem; Gernaey, Krist; Smets, Barth F.; Sin, Gürkan

    Autotrophic nitrogen removal through nitritation-anammox in one stage SBRs is an energy and cost efficient alternative to conventional treatment methods. Intensification of an already complex biological system challenges our ability to observe, understand, diagnose, and control the system. A fuzzy...... logic diagnosis tool was developed, utilizing stoichiometric and concentration ratio measurements and removal efficiencies, along with rules derived from process knowledge. The tool could accurately determine the overall performance of the system and can therefore serve as a powerful tool to provide...

  4. Distribution and microbial community structure analysis of a single-stage partial nitritation/anammox granular sludge bioreactor operating at low temperature.

    Science.gov (United States)

    Rodriguez-Sanchez, Alejandro; Purswani, Jessica; Lotti, Tommaso; Maza-Marquez, Paula; van Loosdrecht, M C M; Vahala, Riku; Gonzalez-Martinez, Alejandro

    2016-09-01

    In the last decade, autotrophic nitrogen removal technologies based on anammox metabolism have become state of the art in urban and industrial wastewater treatment systems, due to their advantages over traditional nitrogen removal processes. However, their application is currently limited to the treatment of warm wastewater (25-40°C) mainly due to the low growth rate of the anammox bacteria. The extension of the application field to wastewater characterized by lower temperatures (8-20°C), such as those typical for municipal sewage, allows the design of treatment systems with a net energy production. In this study, the distribution and bacterial community structure of a lab-scale single-stage partial nitritation/anammox (PN/A) granular sludge bioreactor operating at low temperatures was analysed using next-generation sequencing techniques. The presence of ammonium-oxidizing bacteria and anammox bacteria was found, but the appearance of other bacterial species shows a complex microbial ecosystem. Evaluation of ecological roles of representative species inside the single-stage PN/A bioreactor was accomplished. Results obtained will be helpful for the future design and operation of PN/A systems performing at low temperatures. PMID:26829222

  5. The sulfocyanic theory on the origin of life: towards a critical reappraisal of an autotrophic theory

    Science.gov (United States)

    Perezgasga, L.; Silva, E.; Lazcano, A.; Negrin-Mendoza, A.

    2003-10-01

    In the early 1930s, Alfonso L. Herrera proposed his so-called sulfocyanic theory on the origin of life, an autotrophic proposal on the first living beings according to which NH4SCN and H2CO acted as raw materials for the synthesis of bio-organic compounds inside primordial photosynthetic protoplasmic structures. Although the work of Herrera is frequently cited in historical analysis of the development of the origin of life studies, very little attention has been given to the chemical significance of the reactions he published. In this paper we report the results of our search for amino acids obtained from a reactive mixture used by Herrera from 1933 onwards. Chromatograms using the high-pressure liquid chromatography (HPLC) technique suggest the presence of several amino acids, the total yield being 2% of the initial thiocyanate used. Preliminary identification based on HPLC retention times suggests the presence of glycine, alanine, cysteine and methionine. Alanine was the most abundant amino acid in all samples of fractionated material analysed. Although the starting materials used by Herrera were determined by his autotrophic hypothesis on the origin of cells, our results show that his experiments may provide insights into the abiotic synthesis of sulfur-containing amino acids within the framework of a heterotrophic emergence of life.

  6. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions.

    Science.gov (United States)

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ(15)NNO3), carbon in dissolved inorganic carbon (δ(13)CDIC), and sulfur in sulfate (δ(34)SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ(13)CDIC (from -7.7‰ to -12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was -4.7‰), suggesting the contribution of C of trisodium citrate (δ(13)C=-12.4‰). No SO4(2-) and δ(34)SSO4 changes were observed. In the AD experiment, clear fractionation of δ(13)CDIC during DIC consumption (εC=-7.8‰) and δ(34)SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN=-12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field. PMID:26529303

  7. High CO2 subsurface environment enriches for novel microbial lineages capable of autotrophic carbon fixation

    Science.gov (United States)

    Probst, A. J.; Jerett, J.; Castelle, C. J.; Thomas, B. C.; Sharon, I.; Brown, C. T.; Anantharaman, K.; Emerson, J. B.; Hernsdorf, A. W.; Amano, Y.; Suzuki, Y.; Tringe, S. G.; Woyke, T.; Banfield, J. F.

    2015-12-01

    Subsurface environments span the planet but remain little understood from the perspective of the capacity of the resident organisms to fix CO2. Here we investigated the autotrophic capacity of microbial communities in range of a high-CO2 subsurface environments via analysis of 250 near-complete microbial genomes (151 of them from distinct species) that represent the most abundant organisms over a subsurface depth transect. More than one third of the genomes belonged to the so-called candidate phyla radiation (CPR), which have limited metabolic capabilities. Approximately 30% of the community members are autotrophs that comprise 70% of the microbiome with metabolism likely supported by sulfur and nitrogen respiration. Of the carbon fixation pathways, the Calvin Benson Basham Cycle was most common, but the Wood-Ljungdhal pathway was present in the greatest phylogenetic diversity of organisms. Unexpectedly, one organism from a novel phylum sibling to the CPR is predicted to fix carbon by the reverse TCA cycle. The genome of the most abundant organism, an archaeon designated "Candidatus Altiarchaeum hamiconexum", was also found in subsurface samples from other continents including Europe and Asia. The archaeon was proven to be a carbon fixer using a novel reductive acetyl-CoA pathway. These results provide evidence that carbon dioxide is the major carbon source in these environments and suggest that autotrophy in the subsurface represents a substantial carbon dioxide sink affecting the global carbon cycle.

  8. Nitrogen removal by autotrophic ammonium oxidizing bacteria enrichment under anaerobic conditions

    Directory of Open Access Journals (Sweden)

    Pongsak (Lek Noophan

    2008-07-01

    Full Text Available Sludge from an anoxic tank at the centralized wastewater treatment plant, Nong Khaem, Bangkok, Thailand, was inoculatedin an anaerobic sequencing batch reactor (ASBR. The optimal compositions and operating conditions of the stock of autotrophic ammonium oxidizing bacteria medium were determined. The process of oxidizing ammonium with bacteria under anaerobic conditions is often referred to as the Anammox process (NO2- to N2 gas, using NH4+ as the electron donor and NO2- as the electron acceptor. The startup period for the anammox culture took more than three months. With ammoniumand nitrite concentration ratios of 1:1.38 and 1:1.6, the nitrogen conversion rate zero order. Fluorescent in situ hybridization(FISH was used to identify specific autotrophic ammonium oxidizing bacteria (Nitrosomonas spp., Candidatus Brocadia anammoxidans, and Candidatus Kuenenia stuttgartiensis. Results from this work demonstrated a shift in the species of ammonium oxidizing bacteria from Nitrosomonas spp. to Candidati Brocadia anammoxidans and Kuenenia stuttgartiensis, with increased ammonium concentrations from 3 mM to 15 mM. Under NH4+:NO2- ratios of 1:1.38 and 1:1.6 the ammoniumoxidizing bacteria were able to remove both ammonium and nitrite simultaneously. The specific nitrogen removal rate of theanammox bacteria (Candidati Brocadia anammoxidans and Kuenenia stuttgartiensis was significantly higher than that of anaerobic ammonium oxidizing bacteria (Nitrosomonas spp.. Anaerobic ammonium oxidizing bacteria (Candidati Brocadia anammoxidans and Kuenenia stuttgartiensis are strict anaerobes.

  9. The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage.

    Science.gov (United States)

    Ma, Bin; Zhang, Shujun; Zhang, Liang; Yi, Peng; Wang, Junmin; Wang, Shuying; Peng, Yongzhen

    2011-09-01

    The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage was examined in this study. The obtained results showed that total nitrogen (TN) could be efficiently removed by 88.38% when influent TN and chemical oxygen demand (COD) were 45.87 and 44.40 mg/L, respectively. In the first stage, nitritation was instantly achieved by the bioaugmentation strategy, and can be maintained under limited oxygen condition (below 0.2mg/L). The ratio of nitrite to ammonium in the effluent of the nitritation reactor can be controlled at approximate 1.0 by adjusting aeration rate. In the second stage, anammox was realized in the upflow anaerobic sludge blanket (UASB) reactor, where the total nitrogen removal rate was 0.40 kg Nm(-3)d(-1) under limited-substrate condition. Therefore, the organic matter in sewage can be firstly concentrated in biomass which could generate biogas (energy). Then, nitrogen in sewage could be removed in a two-stage autotrophic nitrogen removal process. PMID:21719278

  10. Particulate Pyrite Autotrophic Denitrification (PPAD) for Remediation of Nitrate-contaminated Groundwater

    Science.gov (United States)

    Tong, S.; Rodriguez-Gonzalez, L. C.; Henderson, M.; Feng, C.; Ergas, S. J.

    2015-12-01

    The rapid movement of human civilization towards urbanization, industrialization, and increased agricultural activities has introduced a large amount of nitrate into groundwater. Nitrate is a toxic substance discharged from groundwater to rivers and leads to decreased dissolved oxygen and eutrophication. For this experiment, an electron donor is needed to convert nitrate into non-toxic nitrogen gas. Pyrite is one of the most abundant minerals in the earth's crust making it an ideal candidate as an electron donor. The overall goal of this research was to investigate the potential for pyrite to be utilized as an electron donor for autotrophic denitrification of nitrate-contaminated groundwater. Batch studies of particulate pyrite autotrophic denitrification (PPAD) of synthetic groundwater (100 mg NO3--N L-1) were set up with varying biomass concentration, pyrite dose, and pyrite particle size. Reactors were seeded with mixed liquor volatile suspended solids (VSS) from a biological nitrogen removal wastewater treatment facility. PPAD using small pyrite particles (treatment and promoted the utilization of pyrite in the field of environmental remediation.

  11. Bio-electrochemical synthesis of commodity chemicals by autotrophic acetogens utilizing CO_{2} for environmental remediation

    Indian Academy of Sciences (India)

    GUGAN JABEEN; ROBINA FAROOQ

    2016-09-01

    Bio-electrochemical synthesis (BES) is a technique in which electro-autotrophic bacteria such as Clostridiumljungdahlii utilize electric currents as an electron source from the cathode to reduce CO_{2} to extracellular, multicarbon,exquisite products through autotrophic conversion. The BES of volatile fatty acids and alcohols directly fromCO_{2} is a sustainable alternative for non-renewable, petroleum-based polymer production. This conversion ofCO_{2} implies reduction of greenhouse gas emissions. The synthesis of heptanoic acid, heptanol, hexanoic acidand hexanol, for the first time, by Clostridium ljungdahlii was a remarkable achievement of BES. In ourstudy, these microorganisms were cultivated on the cathode of a bio-electrochemical cell at −400 mV by aDC power supply at 37°C, pH 6.8, and was studied for both batch and continuous systems. Pre-enrichment ofbio-cathode enhanced the electroactivity of cells and resulted in maximizing extracellular products in lesstime. The main aim of the research was to investigate the impact of low-cost substrate CO_{2}, and the longercathode recovery range was due to bacterial reduction of CO_{2} to multicarbon chemical commodities withelectrons driven from the cathode. Reactor design was simplified for cost-effectiveness and to enhance energyefficiencies. The Columbic recovery of ethanoic acid, ethanol, ethyl butyrate, hexanoic acid, heptanoic acidand hexanol being in excess of 80% proved that BES was a remarkable technology.

  12. Bio-electrochemical synthesis of commodity chemicals by autotrophic acetogens utilizing CO2 for environmental remediation.

    Science.gov (United States)

    Jabeen, Gugan; Farooq, Robina

    2016-09-01

    Bio-electrochemical synthesis (BES) is a technique in which electro-autotrophic bacteria such as Clostridium ljungdahlii utilize electric currents as an electron source from the cathode to reduce CO2 to extracellular, multicarbon, exquisite products through autotrophic conversion. The BES of volatile fatty acids and alcohols directly from CO2 is a sustainable alternative for non-renewable, petroleum-based polymer production. This conversion of CO2 implies reduction of greenhouse gas emissions. The synthesis of heptanoic acid, heptanol, hexanoic acid and hexanol, for the first time, by Clostridium ljungdahlii was a remarkable achievement of BES. In our study, these microorganisms were cultivated on the cathode of a bio-electrochemical cell at -400 mV by a DC power supply at 37 degree Centrigrade, pH 6.8, and was studied for both batch and continuous systems. Pre-enrichment of bio-cathode enhanced the electroactivity of cells and resulted in maximizing extracellular products in less time. The main aim of the research was to investigate the impact of low-cost substrate CO2, and the longer cathode recovery range was due to bacterial reduction of CO2 to multicarbon chemical commodities with electrons driven from the cathode. Reactor design was simplified for cost-effectiveness and to enhance energy efficiencies. The Columbic recovery of ethanoic acid, ethanol, ethyl butyrate, hexanoic acid, heptanoic acid and hexanol being in excess of 80 percent proved that BES was a remarkable technology. PMID:27581929

  13. Heterotrophic and Autotrophic Microbial Populations in Cold Perennial Springs of the High Arctic ▿ †

    Science.gov (United States)

    Perreault, Nancy N.; Greer, Charles W.; Andersen, Dale T.; Tille, Stefanie; Lacrampe-Couloume, Georges; Lollar, Barbara Sherwood; Whyte, Lyle G.

    2008-01-01

    The saline springs of Gypsum Hill in the Canadian high Arctic are a rare example of cold springs originating from deep groundwater and rising to the surface through thick permafrost. The heterotrophic bacteria and autotrophic sulfur-oxidizing bacteria (up to 40% of the total microbial community) isolated from the spring waters and sediments were classified into four phyla (Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria) based on 16S rRNA gene analysis; heterotrophic isolates were primarily psychrotolerant, salt-tolerant, facultative anaerobes. Some of the isolates contained genes for thiosulfate oxidation (soxB) and anoxygenic photosynthesis (pufM), possibly enabling the strains to better compete in these sulfur-rich environments subject to long periods of illumination in the Arctic summer. Although leucine uptake by the spring water microbial community was low, CO2 uptake was relatively high under dark incubation, reinforcing the idea that primary production by chemoautotrophs is an important process in the springs. The small amounts of hydrocarbons in gases exsolving from the springs (0.38 to 0.51% CH4) were compositionally and isotopically consistent with microbial methanogenesis and possible methanotrophy. Anaerobic heterotrophic sulfur oxidation and aerobic autotrophic sulfur oxidation activities were demonstrated in sediment slurries. Overall, our results describe an active microbial community capable of sustainability in an extreme environment that experiences prolonged periods of continuous light or darkness, low temperatures, and moderate salinity, where life seems to rely on chemolithoautotrophy. PMID:18805995

  14. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions

    Science.gov (United States)

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ15NNO3), carbon in dissolved inorganic carbon (δ13CDIC), and sulfur in sulfate (δ34SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ13CDIC (from - 7.7‰ to - 12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was - 4.7‰), suggesting the contribution of C of trisodium citrate (δ13C = - 12.4‰). No SO42 - and δ34SSO4 changes were observed. In the AD experiment, clear fractionation of δ13CDIC during DIC consumption (εC = - 7.8‰) and δ34SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN = - 12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  15. [Distribution Characteristics of Nitrifiers and Denitrifiers in the River Sediments of Tongling City].

    Science.gov (United States)

    Cheng, Jian-hua; Dou, Zhi-yong; Sun, Qing-ye

    2016-04-15

    Rivers in mining areas were influenced by contaminants such as nitrogen, phosphorus and organic matter due to domestic and agricultural wastewater discharge in addition to pollutants caused by mining activities. In this study, surface sediment samples of rivers in Tongling city were collected to address the effect of season and pollution type on the abundance of nitrifiers and denitrifiers using quantitative polymerase chain reaction (QPCR) technique targeting at the ammonia monooxygenase (amoA) and nitrite reductase (nir) genes. The results showed that the average ahundance of ammonia oxidizing archaea (AGA) (ranging from 1.74 x 10⁵ to 1.45 x 10⁸ copies · g⁻¹) was 4.39 times that of ammonia oxidizing hacteria (AGH) (ranging from 1.39 x 10⁵ to 3.39 x 10⁷ copies · g⁻¹); and the average abundance of nirK gene (ranging from 4.45 x 10⁶ to 1.51 x 10⁸ copies · g) was almost a thirtieth part of nirS gene (ranging from 1.69 x 10⁷ to 8.55 x 10⁹ copies · g⁻¹). The abundance of AOA was higher in spring and autumn, and lower in summer and winter. And sediment AOB abundance was higher in spring and winter than in summer and autumn. Meanwhile, the abundance of nir genes was in the order of spring (nirS )/autumn (nirK) > summer > winter > autumn (nirS )/spring (nirK). Moreover, the abundance of bacterial and archaeal arnoA and nirS genes in sediments influenced by mine pollution was generally higher than that in sediments influenced by agricultural non-point pollution, whereas the abundance of nirK gene showed an opposite trend. PMID:27548957

  16. Ecology of Nitrogen Fixing, Nitrifying, and Denitrifying Microorganisms in Tropical Forest Soils

    Science.gov (United States)

    Pajares, Silvia; Bohannan, Brendan J. M.

    2016-01-01

    Soil microorganisms play important roles in nitrogen cycling within forest ecosystems. Current research has revealed that a wider variety of microorganisms, with unexpected diversity in their functions and phylogenies, are involved in the nitrogen cycle than previously thought, including nitrogen-fixing bacteria, ammonia-oxidizing bacteria and archaea, heterotrophic nitrifying microorganisms, and anammox bacteria, as well as denitrifying bacteria, archaea, and fungi. However, the vast majority of this research has been focused in temperate regions, and relatively little is known regarding the ecology of nitrogen-cycling microorganisms within tropical and subtropical ecosystems. Tropical forests are characterized by relatively high precipitation, low annual temperature fluctuation, high heterogeneity in plant diversity, large amounts of plant litter, and unique soil chemistry. For these reasons, regulation of the nitrogen cycle in tropical forests may be very different from that of temperate ecosystems. This is of great importance because of growing concerns regarding the effect of land use change and chronic-elevated nitrogen deposition on nitrogen-cycling processes in tropical forests. In the context of global change, it is crucial to understand how environmental factors and land use changes in tropical ecosystems influence the composition, abundance and activity of key players in the nitrogen cycle. In this review, we synthesize the limited currently available information regarding the microbial communities involved in nitrogen fixation, nitrification and denitrification, to provide deeper insight into the mechanisms regulating nitrogen cycling in tropical forest ecosystems. We also highlight the large gaps in our understanding of microbially mediated nitrogen processes in tropical forest soils and identify important areas for future research. PMID:27468277

  17. Efficient red-emission InGaN/GaN multilayered structure on Si with surface-nitrified HfO2 film as buffer layer

    International Nuclear Information System (INIS)

    A four-period InGaN/GaN (8 nm/48 nm) layered structure was deposited on a Si substrate with a surface-nitrified HfO2 film as a buffer layer (5 nm). A high In concentration of In0.36Ga0.64N was obtained in the InGaN layers. Red photoluminescence of 648 nm was observed from the layered structure. The internal quantum efficiency of the red emission from the InGaN layers on the surface-nitrified HfO2/Si was 52 %, which was more than 18 times larger than that on the Si substrate without HfO2. The surface-nitrified HfO2 provides another effective buffer layer to grow the InGaN/GaN layered structure on the Si substrate. (orig.)

  18. STATE OF THE PRACTICE FOR BIOREACTOR LANDFILLS - SUMMARY OF USEPA WORKSHOP ON BIOREACTOR LANDFILLS: SUMMARY

    Science.gov (United States)

    This is a summary of the Workshop on Landfill Bioreactors, held 9/6-7/2000 in Arlington, VA. The purpose of the workshop was to provide a forum to EPA, state and local governments, solid waste industry, and academic research representatives to exchange information and ideas on b...

  19. The response of nitrifying microbial assemblages to ammonium (NH4+) enrichment from salmon farm activities in a northern Chilean Fjord

    Science.gov (United States)

    Elizondo-Patrone, Claudia; Hernández, Klaudia; Yannicelli, Beatriz; Olsen, Lasse Mork; Molina, Verónica

    2015-12-01

    The consequences of aquaculture include alterations in nitrogen cycling in aquatic environments that may lead to ecosystem degradation. Herein salmon aquaculture release of ammonium (NH4+) to the water column and its effects on natural archaea and bacteria ammonia-oxidizers (AOA and AOB) and nitrite-oxidizing bacteria (NOB) community structure were studied in the Comau fjord using molecular approaches, such as: cloning (AOA and AOB richness), qPCR for C. Nitrosopumilus maritimus (AOA) and Nitrospina sp. (NOB) abundance (DNA) and RT-qPCR only for Nitrospina sp activity (RNA). Sampling was carried out in brackish (0.7-25 salinity, 30 salinity, 25 m depth) waters during contrasting salmon production periods: rest (winter 2012), growth and harvest (summer and winter 2013). During the rest period, the highest NH4+ concentration was observed at Vodudahue River, whereas during productive periods NH4+ accumulated in the brackish layer inside salmon cages and in the vicinty (up to 700 m distance from the cages). The nitrifier community from the fjord reference station (Stn-C) was characterized by C. N. maritimus (AOA) and Nitrosomonas sp. (AOB) sequences affiliated with cosmopolitan ecotypes (e.g., marine, freshwater, hydrothermal), maxima abundances of C. N. maritimus (AOA) and Nitrospina sp. and extreme ranges of Nitrospina sp. activity occurred in the brackish layer. During productive periods, abundances of C. N. maritimus were co-varied with NH4+ concentrations inside salmon cages (summer) and the adjacent areas (winter). Productive periods were characterized by lower abundances but more homogeneity between brackish and marine areas than for the Stn-C nitrifiers. The physiological state of Nitrospina sp. estimated from cDNA:DNA ratios indicated higher growth during winter 2013 associated with NH4+ enrichment derived from production and river input. Our results suggest that in Comau Fjord, NH4+ enrichment events occur during salmon production and also naturally by river

  20. Tissue grown in space in NASA Bioreactor

    Science.gov (United States)

    2001-01-01

    Dr. Lisa E. Freed of the Massachusetts Institute of Technology and her colleagues have reported that initially disc-like specimens tend to become spherical in space, demonstrating that tissues can grow and differentiate into distinct structures in microgravity. The Mir Increment 3 (Sept. 16, 1996 - Jan. 22, 1997) samples were smaller, more spherical, and mechanically weaker than Earth-grown control samples. These results demonstrate the feasibility of microgravity tissue engineering and may have implications for long human space voyages and for treating musculoskeletal disorders on earth. Final samples from Mir and Earth appeared histologically cartilaginous throughout their entire cross sections (5-8 mm thick), with the exception of fibrous outer capsules. Constructs grown on Earth (A) appeared to have a more organized extracellular matrix with more uniform collagen orientation as compared with constructs grown on Mir (B), but the average collagen fiber diameter was similar in the two groups (22 +- 2 nm) and comparable to that previously reported for developing articular cartilage. Randomly oriented collagen in Mir samples would be consistent with previous reports that microgravity disrupts fibrillogenesis. These are transmission electron micrographs of constructs from Mir (A) and Earth (B) groups at magnifications of x3,500 and x120,000 (Inset). The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Credit: Proceedings of the National Academy of Sciences.

  1. An operation protocol for facilitating start-up of single-stage autotrophic nitrogen removing reactors based on process stoichiometry

    DEFF Research Database (Denmark)

    Mutlu, A. Gizem; Vangsgaard, Anna Katrine; Sin, Gürkan; Smets, Barth F.

    2012-01-01

    Start-up and operation of single-stage nitritation/anammox reactor employing complete autotrophic nitrogen can be difficult. Keeping the performance criteria and monitoring the microbial community composition may not be easy or fast enough to take action on time. In this study, a control strategy...

  2. Coniochaeta ligniaria: antifungal activity of the cryptic endophytic fungus associated with autotrophic cultures of the medicinal plant Smallanthus sonchifolius (Asteraceae)

    Science.gov (United States)

    Few studies have addressed the presence and bioactivity of endophytic fungi living in plantlets growing under in vitro conditions. We isolated a fungus UM 109 from autotrophic cultures of the medicinal plant Smallanthus sonchifolius (yacon). The species was identified as Coniochaeta ligniaria using ...

  3. Decadal warming causes a consistent and persistent shift from heterotrophic to autotrophic respiration in contrasting permafrost ecosystems.

    Science.gov (United States)

    Hicks Pries, Caitlin E; van Logtestijn, Richard S P; Schuur, Edward A G; Natali, Susan M; Cornelissen, Johannes H C; Aerts, Rien; Dorrepaal, Ellen

    2015-12-01

    Soil carbon in permafrost ecosystems has the potential to become a major positive feedback to climate change if permafrost thaw increases heterotrophic decomposition. However, warming can also stimulate autotrophic production leading to increased ecosystem carbon storage-a negative climate change feedback. Few studies partitioning ecosystem respiration examine decadal warming effects or compare responses among ecosystems. Here, we first examined how 11 years of warming during different seasons affected autotrophic and heterotrophic respiration in a bryophyte-dominated peatland in Abisko, Sweden. We used natural abundance radiocarbon to partition ecosystem respiration into autotrophic respiration, associated with production, and heterotrophic decomposition. Summertime warming decreased the age of carbon respired by the ecosystem due to increased proportional contributions from autotrophic and young soil respiration and decreased proportional contributions from old soil. Summertime warming's large effect was due to not only warmer air temperatures during the growing season, but also to warmer deep soils year-round. Second, we compared ecosystem respiration responses between two contrasting ecosystems, the Abisko peatland and a tussock-dominated tundra in Healy, Alaska. Each ecosystem had two different timescales of warming (permafrost ecosystems. PMID:26150277

  4. Cross effect of temperature, pH and free ammonia on autotrophic denitrification process with sulphide as electron donor.

    Science.gov (United States)

    Fajardo, Carmen; Mora, Mabel; Fernández, Isaac; Mosquera-Corral, Anuska; Campos, José Luis; Méndez, Ramón

    2014-02-01

    Autotrophic denitrification is a suitable technology to simultaneously remove oxidised nitrogen compounds and reduced sulphur compounds yielding nitrogen gas, sulphur and sulphate as the main products. In this work, several batch tests were conducted to investigate the cross effect of temperature, pH and free ammonia on the autotrophic denitrification. Denitrification efficiencies above 95% were achieved at 35°C and pH 7.5-8.0 with maximum specific autotrophic denitrifying activities up to 188mgN2g(-1)VSSd(-1). Free ammonia did not show any effect on denitrification at concentrations up to 53mg NH3-NL(-1). Different sulphide concentrations were also tested with stoichiometric nitrite and nitrate concentrations. Sulphide inhibited denitrification at concentrations higher than 200mgS(2-)L(-1). A 50% inhibition was also found at nitrite concentrations above 48mg NO2(-)-NL(-1). The maximum specific activity decreased until a value of 25mgN2g(-1) VSSd(-1) at 232mg NO2(-)-NL(-1). The Haldane model was used to describe denitrification inhibition caused by nitrite. Kinetic parameters determined from the fitting of experimental data were rmax=176mgN2g(-1)VSSd(-1), Ks=10.7mg NO2(-)-NL(-1) and Ki=34.7mg NO2(-)-NL(-1). The obtained model allowed optimising an autotrophic denitrification process by avoiding situations of inhibition and thus obtaining higher denitrification efficiencies. PMID:24216266

  5. Autotrophic and heterotrophic activity in Arctic first-year sea-ice: Seasonal study from Marlene Bight, SW Greenland

    DEFF Research Database (Denmark)

    Søgaard, Dorte Haubjerg; Kristensen, Morten; Rysgaard, Søren;

    2010-01-01

    We present a study of autotrophic and heterotrophic activities of Arctic sea ice (Malene Bight, SW Greenland) as measured by 2 different approaches: (1) standard incubation techniques ((HCO3-)-C-14 and [H-3] thymidine incubation) on sea ice cores brought to the laboratory and (2) cores incubated ...

  6. Selection of controlled variables in bioprocesses. Application to a SHARON-Anammox process for autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Valverde Perez, Borja; Sin, Gürkan

    Selecting the right controlled variables in a bioprocess is challenging since the objectives of the process (yields, product or substrate concentration) are difficult to relate with a given actuator. We apply here process control tools that can be used to assist in the selection of controlled...... variables to the case of the SHARON-Anammox process for autotrophic nitrogen removal....

  7. High Oxygen Concentration Increases the Abundance and Activity of Bacterial Rather than Archaeal Nitrifiers in Rice Field Soil.

    Science.gov (United States)

    Ke, Xiubin; Lu, Wei; Conrad, Ralf

    2015-11-01

    Oxygen is considered as a limiting factor for nitrification in rice paddy soil. However, little is known about how the nitrifying microbial community responds to different oxygen concentrations at community and transcript level. In this study, soil and roots were harvested from 50-day-old rice microcosms and were incubated for up to 45 days under two oxygen concentrations: 2 % O(2) and 20 % O(2) (ambient air). Nitrification rates were measured from the accumulation of nitrite plus nitrate. The population dynamics of bacterial (AOB) and archaeal (AOA) ammonia oxidizers was determined from the abundance (using quantitative PCR (qPCR)) and composition (using terminal restriction fragment length polymorphism and cloning/sequencing) of their amoA genes, that of nitrite oxidizers (NOB) by quantifying the nxrA gene of Nitrobacter spp. and the 16S rRNA gene of Nitrospira spp. The activity of the nitrifiers was determined by quantifying the copy numbers of amoA and nxrA transcripts (using RT-qPCR). Different oxygen concentrations did not affect the community compositions of AOB, AOA, and NOB, which however were different between surface soil, bottom soil, and rice roots. However, nitrification rates were higher under ambient air than 2 % O(2), and abundance and transcript activities of AOB, but not of AOA, were also higher. Abundance and transcript copy numbers of Nitrobacter were also higher at ambient air. These results indicate that AOB and NOB, but not AOA, were sensitive to oxygen availability. PMID:26054702

  8. The effects of salinity on nitrification using halophilic nitrifiers in a Sequencing Batch Reactor treating hypersaline wastewater.

    Science.gov (United States)

    Cui, You-Wei; Zhang, Hong-Yu; Ding, Jie-Ran; Peng, Yong-Zhen

    2016-01-01

    With annual increases in the generation and use of saline wastewater, the need to avoid environmental problems such as eutrophication is critical. A previous study identified ways to start up a halophilic sludge domesticated from estuarine sediments to remove nitrogen from wastewater with a salinity of 30 g/L. This investigation expands that work to explore the impact of salinity on nitrogen removal. This study demonstrated that the mixed halophilic consortia removed nitrogen from wastewater with a salinity of 30-85 g/L. A kinetic analysis showed that halophilic nitrifiers selected based on hypersalinity were characterized by low Ks, μmax and specific ammonium oxidization rates. This explains the decrease in ammonium removal efficiency in the high salinity operational phases. Salinity inhibited ammonia oxidizing bacteria (AOB) activity, as well as the number of dominant AOB, but did not significantly affect the AOB dominant species. Three most dominant AOB lineages in the halophilic sludge were Nitrosomonas marina, Nitrosomonas europaea, and Nitrosococcus mobilis. Nitrosomonas europaea and Nitrosococcus mobilis were mainly affected by salinity, while nitrite accumulation and ammonia loading played the key role in determining the abundance of Nitrosococcus mobilis and Nitrosococcus europaea. The study contributes insights about shifts in halophilic nitrifying bacterial populations. PMID:27109617

  9. Removal of steroid estrogens from municipal wastewater in a pilot scale expanded granular sludge blanket reactor and anaerobic membrane bioreactor.

    Science.gov (United States)

    Ito, Ayumi; Mensah, Lawson; Cartmell, Elise; Lester, John N

    2016-01-01

    Anaerobic treatment of municipal wastewater offers the prospect of a new paradigm by reducing aeration costs and minimizing sludge production. It has been successfully applied in warm climates, but does not always achieve the desired outcomes in temperate climates at the biochemical oxygen demand (BOD) values of municipal crude wastewater. Recently the concept of 'fortification' has been proposed to increase organic strength and has been demonstrated at the laboratory and pilot scale treating municipal wastewater at temperatures of 10-17°C. The process treats a proportion of the flow anaerobically by combining it with primary sludge from the residual flow and then polishing it to a high effluent standard aerobically. Energy consumption is reduced as is sludge production. However, no new treatment process is viable if it only addresses the problems of traditional pollutants (suspended solids - SS, BOD, nitrogen - N and phosphorus - P); it must also treat hazardous substances. This study compared three potential municipal anaerobic treatment regimes, crude wastewater in an expanded granular sludge blanket (EGSB) reactor, fortified crude wastewater in an EGSB and crude wastewater in an anaerobic membrane bioreactor. The benefits of fortification were demonstrated for the removal of SS, BOD, N and P. These three systems were further challenged with the removal of steroid estrogens at environmental concentrations from natural indigenous sources. All three systems removed these compounds to a significant degree, confirming that estrogen removal is not restricted to highly aerobic autotrophs, or aerobic heterotrophs, but is also a faculty of anaerobic bacteria. PMID:26212345

  10. Development of novel control strategies for single-stage autotrophic nitrogen removal: A process oriented approach

    DEFF Research Database (Denmark)

    Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Gernaey, Krist;

    2014-01-01

    The autotrophic nitrogen removing granular sludge process is a novel and intensified process. However, its stable operation and control remain a challenging issue. In this contribution, a process oriented approach was used to develop, evaluate and benchmark novel control strategies to ensure stable...... operation and rejection of disturbances. Three novel control strategies were developed, evaluated, and benchmarked against each other: a feedforward control (control structure 1 – CS#1), a rule-based feedback control (CS#2), and a feedforward–feedback controller, in which the feedback loop updates the set...... satisfactorily. Thus, the appropriate design will depend on the specific disturbances in the influent generated in the upstream units of the wastewater treatment plant....

  11. Autotrophic Nitrogen Removal in a Membrane-Aerated Biofilm Reactor Under Continuous Aeration: A Demonstration

    DEFF Research Database (Denmark)

    Gilmore, Kevin R.; Terada, Akihiko; Smets, Barth F.;

    2013-01-01

    allowed anaerobic ammonium-oxidizing bacteria (AnaerAOB) to develop and be retained for > 250 days. Daily autotrophic nitrogen removal of 1.7 g N/m(2) (75% of influent N load) was achieved at an oxygen/nitrogen surface loading ratio of 2.2, with up to 85% of the influent N proceeding through Anaer......AOB. During early nitritation, nitrogen oxide (NO(g), NO2(g), and N2O(g)) emissions comprised up to 10% of the removed influent nitrogen, but emissions disappeared after proliferation of AnaerAOB. Microbial communities were radially stratified, with aerobic ammonium-oxidizing bacteria (AerAOB) colonizing...... elimination of gaseous nitrogen oxide emissions....

  12. A novel control strategy for single-stage autotrophic nitrogen removal in SBR

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine; Gernaey, Krist; Smets, Barth F.; Sin, Gürkan

    2015-01-01

    A novel feedforward–feedback control strategy was developed for complete autotrophic nitrogen removal in a sequencing batch reactor. The aim of the control system was to carry out the regulation of the process while keeping the system close to the optimal operation. The controller was designed...... based on a process model and then tested experimentally. The resulting batch-to-batch control strategy had the total nitrogen removal efficiency as controlled variable and the setting of the aeration mass flow controller as manipulated variable. Compared to manual operation mode (constant air supply...... lab-scale reactor is a promising result, which brings this control strategy one step closer to full-scale implementation....

  13. MEMBRANE BIOREACTOR FOR TREATMENT OF RECALCITRANT WASTEWATERS

    Directory of Open Access Journals (Sweden)

    Suprihatin Suprihatin

    2012-02-01

    Full Text Available The low biodegradable wastewaters remain a challenge in wastewater treatment technology. The performance of membrane bioreactor systems with submerged hollow fiber micro- and ultrafiltration membrane modules were examined for purifying recalcitrant wastewaters of leachate of a municipal solid waste open dumping site and effluent of pulp and paper mill. The use of MF and UF membrane bioreactor systems showed an efficient treatment for both types wastewaters with COD reduction of 80-90%. The membrane process achieved the desirable effects of maintaining reasonably high biomass concentration and long sludge retention time, while producing a colloid or particle free effluent. For pulp and paper mill effluent a specific sludge production of 0.11 kg MLSS/kg COD removed was achieved. A permeate flux of about 5 L/m²h could be achieved with the submerged microfiltration membrane. Experiments using ultrafiltration membrane produced relatively low permeate fluxes of 2 L/m²h. By applying periodical backwash, the flux could be improved significantly. It was indicated that the particle or colloid deposition on membrane surface was suppressed by backwash, but reformation of deposit was not effectively be prevented by shear-rate effect of aeration. Particle and colloid started to accumulate soon after backwash. Construction of membrane module and operation mode played a critical role in achieving the effectiveness of aeration in minimizing deposit formation on the membrane surface.

  14. Membrane bioreactor for drinking water denitrification

    Energy Technology Data Exchange (ETDEWEB)

    Barreiros, A.M. [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa (Portugal)]|[Escola Superior de Tecnologia, Instituto Politecnico de Setubal, Rua do Vale de Chaves, Estefanilha, 2900 Setubal (Portugal); Rodrigues, C.M.; Crespo, J.P.S.G.; Reis, M.A.M. [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa (Portugal)

    1998-04-01

    The aim of this study is to evaluate the performance of a membrane bioreactor with cell recycle to be used for drinking water denitrification, when operated with a high nitrate load (up to 7.68 kgNO{sub 3}{sup -}/m{sup 3} day) and low hydraulic retention time (down to 0.625 h). Nitrate and nitrite were always completely removed for all the operational conditions used. The effluent`s nitrite concentration kept below 0.1 mg NO{sub 2}{sup -}/l with exception of a short period, during the reactor start-up, when it accumulates. The performance of the membrane bioreactor was also evaluated using a groundwater containing 148 mg NO{sub 3}{sup -}/l. Nitrate and nitrite concentration in the effluent were below the recommended values for drinking water when the reactor was controlled at pH 7.0. The membrane flux decreases during operation as a consequence of membrane fouling. The flux decrease was more severe during operation with synthetic medium than with contaminated groundwater due to the existence of molecular complexes in the synthetic broth. A backshock technique was used to reduce the surface fouling of the membrane. Combining this technique with the use of a reserve asymmetric structured membrane it was found that the membrane flux remains nearly unchanged. (orig.) With 7 figs., 14 refs.

  15. LTCC based bioreactors for cell cultivation

    Science.gov (United States)

    Bartsch, H.; Welker, T.; Welker, K.; Witte, H.; Müller, J.

    2016-01-01

    LTCC multilayers offer a wide range of structural options and flexibility of connections not available in standard thin film technology. Therefore they are considered as material base for cell culture reactors. The integration of microfluidic handling systems and features for optical and electrical capturing of indicators for cell culture growth offers the platform for an open system concept. The present paper assesses different approaches for the creation of microfluidic channels in LTCC multilayers. Basic functions required for the fluid management in bioreactors include temperature and flow control. Both features can be realized with integrated heaters and temperature sensors in LTCC multilayers. Technological conditions for the integration of such elements into bioreactors are analysed. The temperature regulation for the system makes use of NTC thermistor sensors which serve as real value input for the control of the heater. It allows the adjustment of the fluid temperature with an accuracy of 0.2 K. The tempered fluid flows through the cell culture chamber. Inside of this chamber a thick film electrode array monitors the impedance as an indicator for the growth process of 3-dimensional cell cultures. At the system output a flow sensor is arranged to monitor the continual flow. For this purpose a calorimetric sensor is implemented, and its crucial design parameters are discussed. Thus, the work presented gives an overview on the current status of LTCC based fluid management for cell culture reactors, which provides a promising base for the automation of cell culture processes.

  16. Novel Hydrogen Bioreactor and Detection Apparatus.

    Science.gov (United States)

    Rollin, Joseph A; Ye, Xinhao; Del Campo, Julia Martin; Adams, Michael W W; Zhang, Y-H Percival

    2016-01-01

    In vitro hydrogen generation represents a clear opportunity for novel bioreactor and system design. Hydrogen, already a globally important commodity chemical, has the potential to become the dominant transportation fuel of the future. Technologies such as in vitro synthetic pathway biotransformation (SyPaB)-the use of more than 10 purified enzymes to catalyze unnatural catabolic pathways-enable the storage of hydrogen in the form of carbohydrates. Biohydrogen production from local carbohydrate resources offers a solution to the most pressing challenges to vehicular and bioenergy uses: small-size distributed production, minimization of CO2 emissions, and potential low cost, driven by high yield and volumetric productivity. In this study, we introduce a novel bioreactor that provides the oxygen-free gas phase necessary for enzymatic hydrogen generation while regulating temperature and reactor volume. A variety of techniques are currently used for laboratory detection of biohydrogen, but the most information is provided by a continuous low-cost hydrogen sensor. Most such systems currently use electrolysis for calibration; here an alternative method, flow calibration, is introduced. This system is further demonstrated here with the conversion of glucose to hydrogen at a high rate, and the production of hydrogen from glucose 6-phosphate at a greatly increased reaction rate, 157 mmol/L/h at 60 °C. PMID:25022362

  17. Landfill leachate treatment in assisted landfill bioreactor

    Institute of Scientific and Technical Information of China (English)

    HE Pin-jing; QU Xian; SHAO Li-ming; LEE Duu-jong

    2006-01-01

    Landfill is the major disposal route of municipal solid waste(MSW) in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was proposed as an effective alternative for leachate treatment by taking the landfill as a bioreactor. This process was proved not only considerably reducing the pollution potential of leachate, but also enhancing organic degradation in the landfill. However, as this paper shows, although direct leachate recycling was effective in landfilled MSW with low food waste fraction (3.5%, w/w), it failed in MSW containing 54% food waste, as normally noted in Asian countries. The initial acid stuck would inhibit methanogenesis to build up, hence strong leachate was yielded from landfill to threaten the quality of receiving water body. We demonstrated the feasibility to use an assisted bioreactor landfill, with a well-decomposed refuse layer as ex-situ anaerobic digester to reducing COD loading in leachate. By doing so, the refuse in simulated landfill column (2.3 m high) could be stabilized in 30 weeks while the COD in leachate reduced by 95%(61000 mg/L to 3000 mg/L). Meanwhile, the biogas production was considerably enhanced, signaling by the much greater amount and much higher methane content in the biogas.

  18. Landfill leachate treatment in assisted landfill bioreactor.

    Science.gov (United States)

    He, Pin-Jing; Qu, Xian; Shao, Li-Ming; Lee, Duu-Jong

    2006-01-01

    Landfill is the major disposal route of municipal solid waste (MSW) in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was proposed as an effective alternative for leachate treatment by taking the landfill as a bioreactor. This process was proved not only considerably reducing the pollution potential of leachate, but also enhancing organic degradation in the landfill. However, as this paper shows, although direct leachate recycling was effective in landfilled MSW with low food waste fraction (3.5%, w/w), it failed in MSW containing 54% food waste, as normally noted in Asian countries. The initial acid stuck would inhibit methanogenesis to build up, hence strong leachate was yielded from landfill to threaten the quality of receiving water body. We demonstrated the feasibility to use an assisted bioreactor landfill, with a well-decomposed refuse layer as ex-situ anaerobic digester to reducing COD loading in leachate. By doing so, the refuse in simulated landfill column (2.3 m high) could be stabilized in 30 weeks while the COD in leachate reduced by 95% (61000 mg/L to 3000 mg/L). Meanwhile, the biogas production was considerably enhanced, signaling by the much greater amount and much higher methane content in the biogas. PMID:20050569

  19. High retention membrane bioreactors: challenges and opportunities.

    Science.gov (United States)

    Luo, Wenhai; Hai, Faisal I; Price, William E; Guo, Wenshan; Ngo, Hao H; Yamamoto, Kazuo; Nghiem, Long D

    2014-09-01

    Extensive research has focussed on the development of novel high retention membrane bioreactor (HR-MBR) systems for wastewater reclamation in recent years. HR-MBR integrates high rejection membrane separation with conventional biological treatment in a single step. High rejection membrane separation processes currently used in HR-MBR applications include nanofiltration, forward osmosis, and membrane distillation. In these HR-MBR systems, organic contaminants can be effectively retained, prolonging their retention time in the bioreactor and thus enhancing their biodegradation. Therefore, HR-MBR can offer a reliable and elegant solution to produce high quality effluent. However, there are several technological challenges associated with the development of HR-MBR, including salinity build-up, low permeate flux, and membrane degradation. This paper provides a critical review on these challenges and potential opportunities of HR-MBR for wastewater treatment and water reclamation, and aims to guide and inform future research on HR-MBR for fast commercialisation of this innovative technology. PMID:24996563

  20. Performance of pulsed plate bioreactor for biodegradation of phenol

    International Nuclear Information System (INIS)

    Biodegradation of phenol was carried out using Nocardia hydrocarbonoxydans immobilised on glass beads, in a pulsed plate bioreactor. The effect of operating parameters like frequency of pulsation and amplitude of pulsation on the performance of pulsed plate bioreactor for biodegradation of phenol in a synthetic wastewater containing 500 ppm phenol was studied. Axial concentration profile measurements revealed that the pulsed plate bioreactor shows continuous stirred tank behaviour. As the amplitude was increased, percentage degradation increased, reaching 100% at amplitude of 4.7 cm and higher. Introduction of pulsation is found to increase the percentage degradation. Percentage degradation has increased with increase in frequency and 100% degradation was achieved at 0.5 s-1 and above. Biofilms developed in a non-pulsed bioreactor were thicker than those in the pulsed plate bioreactor. But biofilm thickness remained almost constant with increasing frequency. Biofilm density was found to be influenced by pulsation. The time required to reach steady state was more for pulsed reactor than the non-pulsed reactor and this start-up time had increased with increase in frequency of pulsation. The performance studies reveal that the pulsed plate bioreactor with immobilized cells has the potential to be an efficient bioreactor for wastewater treatment

  1. The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars

    Directory of Open Access Journals (Sweden)

    Viktoria Shcherbakova

    2015-09-01

    Full Text Available The terrestrial permafrost represents a range of possible cryogenic extraterrestrial ecosystems on Earth-like planets without obvious surface ice, such as Mars. The autotrophic and chemolithotrophic psychrotolerant methanogens are more likely than aerobes to function as a model for life forms that may exist in frozen subsurface environments on Mars, which has no free oxygen, inaccessible organic matter, and extremely low amounts of unfrozen water. Our research on the genesis of methane, its content and distribution in permafrost horizons of different ages and origin demonstrated the presence of methane in permanently frozen fine-grained sediments. Earlier, we isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. In this paper we study the effect of sodium and magnesium perchlorates on growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper we study the effect of sodium and magnesium perchlorates on the growth of permafrost and nonpermafrost methanogens, and present evidence that permafrost hydogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2T M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth’s subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbor methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars.

  2. Emergent macrophytes select for nitrifying and denitrifying microorganisms in constructed wetlands

    Science.gov (United States)

    Trias, Rosalia; Ramió Pujol, Sara; Bañeras, Lluis

    2014-05-01

    The use of constructed wetlands for wastewater treatment is a reliable low-cost alternative that has been widely developed during the last years. Several processes involving plants, sediments, and microbial communities contribute to nitrogen removal in wetlands. Vegetation plays an important role in this process, not only by nutrient assimilation but also by the stimulation of the plant associated microbiota. Plants supply oxygen at the close proximity of the root surface that may favour ammonia oxidizers. At the same time, exudation of organic compounds potentially speeds-up denitrification in the anoxic environment. The aim of this work was to understand the plant-microbe interactions at the root level in the Empuriabrava free water surface constructed wetland (Spain). The roots of the macrophytes Typha latifolia, Typha angustifolia, Phragmites australis and Bolboschoenus maritimus were sampled at four dates from January to September 2012, covering all the stages of plant growth. Additionally, sediment surrounding vegetation and non-vegetated sediments were sampled. Microbial community structure was analysed by pyrosequencing of bacterial and archaeal 16S rDNA and functional genes (nirK, nirS, nosZ and amoA). Bacterial communities were significantly different in sediments of the vegetated areas compared to the root surface. Plant roots exhibited a higher proportion of proteobacteria whereas Actinobacteria were dominant in sediments. The nitrifiers Nitrosomonas sp. and Nitrosococcus sp. accounted for less than 1% of all sequences. Archaeal communities were dominated by the Miscellaneous Crenarchaeotic Groups C2 and C3 and Methanomicrobia. Higher relative abundances of MCG were found in roots of P. australis, B. maritimus and T. angustifolia. Ammonia oxidizing archaea accounted for less than 0.1% of all sequences but were consistently more abundant in sediment samples compared to roots. NirK and NirS-type bacterial communities showed clearly distinct distribution

  3. Residence time of carbon substrate for autotrophic respiration of a grassland ecosystem correlates with the carbohydrate status of its vegetation

    Science.gov (United States)

    Ostler, Ulrike; Lehmeier, Christoph A.; Schleip, Inga; Schnyder, Hans

    2016-04-01

    Ecosystem respiration is composed of two component fluxes: (1) autotrophic respiration, which comprises respiratory activity of plants and plant-associated microbes that feed on products of recent photosynthetic activity and (2) heterotrophic respiration of microbes that decompose organic matter. The mechanistic link between the availability of carbon (C) substrate for ecosystem respiration and its respiratory activity is not well understood, particularly in grasslands. Here, we explore, how the kinetic features of the supply system feeding autotrophic ecosystem respiration in a temperate humid pasture are related to the content of water-soluble carbohydrates and remobilizable protein (as potential respiratory substrates) in vegetation biomass. During each September 2006, May 2007 and September 2007, we continuously labeled 0.8 m2 pasture plots with 13CO2/12CO2 and observed ecosystem respiration and its tracer content every night during the 14-16 day long labeling periods. We analyzed the tracer kinetics with a pool model, which allowed us to precisely partition ecosystem respiration into its autotrophic and heterotrophic flux components. At the end of a labeling campaign, we harvested aboveground and belowground plant biomass and analyzed its non-structural C contents. Approximately half of ecosystem respiration did not release any significant amount of tracer during the labeling period and was hence characterized as heterotrophic. The other half of ecosystem respiration was autotrophic, with a mean residence time of C in the respiratory substrate pool between 2 and 6 d. Both the rate of autotrophic respiration and the turnover of its substrate supply pool were correlated with plant carbohydrate content, but not with plant protein content. These findings are in agreement with studies in controlled environments that revealed water-soluble carbohydrates as the main substrate and proteins as a marginal substrate for plant respiration under favorable growth conditions

  4. Can we distinguish autotrophic respiration from heterotrophic respiration in a field site using high temporal resolution CO2 flux measurements?

    Science.gov (United States)

    Biro, Beatrice; Berger, Sina; Praetzel, Leandra; Blodau, Christian

    2016-04-01

    The processes behind C-cycling in peatlands are important to understand for assessing the vulnerability of peatlands as carbon sinks under changing climate conditions. Especially boreal peatlands are likely to underlie strong alterations in the future. It is expected that C-pools that are directly influenced by vegetation and water table fluctuations can be easily destabilized. The CO2 efflux through respiration underlies autotrophic and heterotrophic processes that show different feedbacks on changing environmental conditions. In order to understand the respiration fluxes better for more accurate modelling and prognoses, the determination of the relative importance of different respiration sources is necessary. Earlier studies used e.g. exfoliation experiments, incubation experiments or modelling approaches to estimate the different respiration sources for the total ecosystem respiration (Reco). To further the understanding in this topic, I want to distinguish autotrophic and heterotrophic respiration using high temporal resolution measurements. The study site was selected along a hydrological gradient in a peatland in southern Ontario (Canada) and measurements were conducted from May to September 2015 once per month. Environmental controls (water table, soil temperature and soil moisture) that effect the respiration sources were recorded. In my study I used a Li-COR 6400XT and a Los Gatos greenhouse gas analyzer (GGA). Reco was determined by chamber flux measurements with the GGA, while simultaneously CO2 respiration measurements on different vegetation compartments like roots, leaves and mosses were conducted using the Li-COR 6400XT. The difference between Reco and autotrophic respiration equals heterotrophic respiration. After the measurements, the vegetation plots were harvested and separated for all compartments (leaves, roots, mosses, soil organic matter), dried and weighed. The weighted respiration rates from all vegetation compartments sum up to

  5. Cattle grazing and trampling activities affect abundance and activity of nitrifying and denitrifying microbial communities and N.sub.2./sub.O production in upland soil

    Czech Academy of Sciences Publication Activity Database

    Chroňáková, Alica; Radl, V.; Čuhel, Jiří; Gattinger, A.; Šimek, Miloslav; Elhottová, Dana; Schloter, M.

    Braunschweig : Bba - Federal Biological Research Centre for Agriculture and Forestry, 2007. s. 159-160. [Symposium on Bacterial Genetics and Ecology. BAGECO 9. Microbial Community Networks /9./. 23.06.2007-27.06.2007, Wernigerode] Institutional research plan: CEZ:AV0Z60660521 Keywords : cattle grazing and trampling activities * nitrifying and denitrifying microbial communities * upland soil Subject RIV: EH - Ecology, Behaviour

  6. Mechanobiologic Research in a Microgravity Environment Bioreactor

    Science.gov (United States)

    Guidi, A.; Dubini, G.; Tominetti, F.; Raimondi, M.

    A current problem in tissue culturing technology is the unavailability of an effective Bioreactor for the in vitro cultivation of cells and explants. It has, in fact, proved extremely difficult to promote the high-density three-dimensional in vitro growth of human tissues that have been removed from the body and deprived of their normal in vivo vascular sources of nutrients and gas exchange. A variety of tissue explants can be maintained for a short period of time on a supportive collagen matrix surrounded by culture medium. But this system provides only limited mass transfer of nutrients and wastes through the tissue, and gravity-induced sedimentation prevents complete three- dimensional cell-cell and cell-matrix interactions. Several devices presently on the market have been used with only limited success since each has limitations, which restrict usefulness and versatility. Further, no Bioreactor or culture vessel is known that will allow for unimpeded growth of three dimensional cellular aggregates or tissue. Extensive research on the effect of mechanical stimuli on cell metabolism suggests that tissues may respond to mechanical stimulation via loading-induced flow of the interstitial fluids. During the culture, cells are subject to a flow of culture medium. Flow properties such as flow field, flow regime (e.g. turbulent or laminar), flow pattern (e.g. circular), entity and distribution of the shear stress acting on the cells greatly influence fundamental aspects of cell function, such as regulation and gene expression. This has been demonstrated for endothelial cells and significant research efforts are underway to elucidate these mechanisms in various other biological systems. Local fluid dynamics is also responsible of the mass transfer of nutrients and catabolites as well as oxygenation through the tissue. Most of the attempts to culture tissue-engineered constructs in vitro have utilized either stationary cultures or systems generating relatively small

  7. Comparative study of emerging micropollutants removal by aerobic activated sludge of large laboratory-scale membrane bioreactors and sequencing batch reactors under low-temperature conditions.

    Science.gov (United States)

    Kruglova, Antonina; Kråkström, Matilda; Riska, Mats; Mikola, Anna; Rantanen, Pirjo; Vahala, Riku; Kronberg, Leif

    2016-08-01

    Four emerging micropollutants ibuprofen, diclofenac, estrone (E1) and 17α-ethinylestradiol (EE2) were studied in large laboratory-scale wastewater treatment plants (WWTPs) with high nitrifying activity. Activated sludge (AS) with sludge retention times (SRTs) of 12days and 14days in sequencing batch reactors (SBRs) and 30days, 60days and 90days in membrane bioreactors (MBRs) were examined at 8°C and 12°C. Concentrations of pharmaceuticals and their main metabolites were analysed in liquid phase and solid phase of AS by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A remarkable amount of contaminants were detected in solids of AS, meaning the accumulation of micropollutants in bacterial cells. The biodegradation rate constants (Kbiol) were affected by SRT and temperature. MBR with a 90-day SRT showed the best results of removal. Conventional SBR process was inefficient at 8°C showing Kbiol values lower than 0.5lgSS(-1)d(-1) for studied micropollutants. PMID:27128192

  8. Production of monoclonal antibody with Celline-350 bioreactor

    International Nuclear Information System (INIS)

    Monoclonal antibodies are protein that are highly specific and sensitive in their reaction with specific sites on target molecules that they have become reagents of central importance in the diagnostic and treatment of human diseases. This paper reports the use of CELLine-350 bioreactor to produce continuous supply of serum-free breast cancer monoclonal antibody. Initial volume of 5ml (1.5 x 106 viable cells/ml) is inoculated into the bioreactor and harvesting is done every 5 days to obtain high yield monoclonal antibody. The serum-free supernatant is precipitated with 50% saturated ammonia sulfate and the antibody is purified by protein-G affinity chromatography. The concentration of monoclonal antibody successfully produced by the bioreactor is 0.91mg/ml respectively and it is measured by the Lowry method. This result shows that bioreactor Celline-350 is easy to handle and cost effective for the continuous production of serum free monoclonal antibody. (Author)

  9. EMERGING TECHNOLOGY BULLETIN - METHANOTROPHIC BIOREACTOR SYSTEM - BIOTROL, INC.

    Science.gov (United States)

    BioTrol's Methanotrophic Bioreactor is an above-ground remedial system for water contaminated with halogenated volatile organic compounds, including trichloroethylene (ICE) and related chemicals. Its design features circumvent problems peculiar to treatment of this unique class o...

  10. The Potential for Microalgae as Bioreactors to Produce Pharmaceuticals.

    Science.gov (United States)

    Yan, Na; Fan, Chengming; Chen, Yuhong; Hu, Zanmin

    2016-01-01

    As photosynthetic organisms, microalgae can efficiently convert solar energy into biomass. Microalgae are currently used as an important source of valuable natural biologically active molecules, such as carotenoids, chlorophyll, long-chain polyunsaturated fatty acids, phycobiliproteins, carotenoids and enzymes. Significant advances have been achieved in microalgae biotechnology over the last decade, and the use of microalgae as bioreactors for expressing recombinant proteins is receiving increased interest. Compared with the bioreactor systems that are currently in use, microalgae may be an attractive alternative for the production of pharmaceuticals, recombinant proteins and other valuable products. Products synthesized via the genetic engineering of microalgae include vaccines, antibodies, enzymes, blood-clotting factors, immune regulators, growth factors, hormones, and other valuable products, such as the anticancer agent Taxol. In this paper, we briefly compare the currently used bioreactor systems, summarize the progress in genetic engineering of microalgae, and discuss the potential for microalgae as bioreactors to produce pharmaceuticals. PMID:27322258

  11. Hydrofocusing Bioreactor for Three-Dimensional Cell Culture

    Science.gov (United States)

    Gonda, Steve R.; Spaulding, Glenn F.; Tsao, Yow-Min D.; Flechsig, Scott; Jones, Leslie; Soehnge, Holly

    2003-01-01

    The hydrodynamic focusing bioreactor (HFB) is a bioreactor system designed for three-dimensional cell culture and tissue-engineering investigations on orbiting spacecraft and in laboratories on Earth. The HFB offers a unique hydrofocusing capability that enables the creation of a low-shear culture environment simultaneously with the "herding" of suspended cells, tissue assemblies, and air bubbles. Under development for use in the Biotechnology Facility on the International Space Station, the HFB has successfully grown large three-dimensional, tissuelike assemblies from anchorage-dependent cells and grown suspension hybridoma cells to high densities. The HFB, based on the principle of hydrodynamic focusing, provides the capability to control the movement of air bubbles and removes them from the bioreactor without degrading the low-shear culture environment or the suspended three-dimensional tissue assemblies. The HFB also provides unparalleled control over the locations of cells and tissues within its bioreactor vessel during operation and sampling.

  12. Salmonella Typhimurium grown in a rotating wall bioreactor

    Science.gov (United States)

    2003-01-01

    Salmonella typhimurium appears green in on human intestinal tissue (stained red) cultured in a NASA rotating wall bioreactor. Dr. Cheryl Nickerson of Tulane University is studying the effects of simulated low-g on a well-known pathogen, Salmonella typhimurium, a bacterium that causes two to four million cases of gastrointestinal illness in the United States each year. While most healthy people recover readily, S. typhimurium can kill people with weakened immune systems. Thus, a simple case of food poisoning could disrupt a space mission. Using the NASA rotating-wall bioreactor, Nickerson cultured S. typhimurium in modeled microgravity. Mice infected with the bacterium died an average of three days faster than the control mice, indicating that S. typhimurium's virulence was enhanced by the bioreactor. Earlier research showed that 3 percent of the genes were altered by exposure to the bioreactor. Nickerson's work earned her a 2001 Presidential Early Career Award for Scientists and Engineers.

  13. Hairy root culture: bioreactor design and process intensification.

    Science.gov (United States)

    Stiles, Amanda R; Liu, Chun-Zhao

    2013-01-01

    The cultivation of hairy roots for the production of secondary metabolites offers numerous advantages; hairy roots have a fast growth rate, are genetically stable, and are relatively simple to maintain in phytohormone free media. Hairy roots provide a continuous source of secondary metabolites, and are useful for the production of chemicals for pharmaceuticals, cosmetics, and food additives. In order for hairy roots to be utilized on a commercial scale, it is necessary to scale-up their production. Over the last several decades, significant research has been conducted on the cultivation of hairy roots in various types of bioreactor systems. In this review, we discuss the advantages and disadvantages of various bioreactor systems, the major factors related to large-scale bioreactor cultures, process intensification technologies and overview the mathematical models and computer-aided methods that have been utilized for bioreactor design and development. PMID:23604206

  14. Modelling across bioreactor scales: methods, challenges and limitations

    DEFF Research Database (Denmark)

    Gernaey, Krist

    Scale-up and scale-down of bioreactors are very important in industrial biotechnology, especially with the currently available knowledge on the occurrence of gradients in industrial-scale bioreactors. Moreover, it becomes increasingly appealing to model such industrial scale systems, considering...... that it is challenging and expensive to acquire experimental data of good quality that can be used for characterizing gradients occurring inside a large industrial scale bioreactor. But which model building methods are available? And how can one ensure that the parameters in such a model are properly...... estimated? And what are the limitations of different types of mod - els? This paper will provide examples of models that have been published in the literature for use across bioreactor scales, including computational fluid dynamics (CFD) and population balance models. Furthermore, the importance of good...

  15. Upflow bioreactor with septum and pressure release mechanism

    Science.gov (United States)

    Hansen, Conly L.; Hansen, Carl S.; Pack, Kevin; Milligan, John; Benefiel, Bradley C.; Tolman, C. Wayne; Tolman, Kenneth W.

    2010-04-20

    An upflow bioreactor includes a vessel having an inlet and an outlet configured for upflow operation. A septum is positioned within the vessel and defines a lower chamber and an upper chamber. The septum includes an aperture that provides fluid communication between the upper chamber and lower chamber. The bioreactor also includes means for releasing pressure buildup in the lower chamber. In one configuration, the septum includes a releasable portion having an open position and a closed position. The releasable portion is configured to move to the open position in response to pressure buildup in the lower chamber. In the open position fluid communication between the lower chamber and the upper chamber is increased. Alternatively the lower chamber can include a pressure release line that is selectively actuated by pressure buildup. The pressure release mechanism can prevent the bioreactor from plugging and/or prevent catastrophic damage to the bioreactor caused by high pressures.

  16. The Potential for Microalgae as Bioreactors to Produce Pharmaceuticals

    Science.gov (United States)

    Yan, Na; Fan, Chengming; Chen, Yuhong; Hu, Zanmin

    2016-01-01

    As photosynthetic organisms, microalgae can efficiently convert solar energy into biomass. Microalgae are currently used as an important source of valuable natural biologically active molecules, such as carotenoids, chlorophyll, long-chain polyunsaturated fatty acids, phycobiliproteins, carotenoids and enzymes. Significant advances have been achieved in microalgae biotechnology over the last decade, and the use of microalgae as bioreactors for expressing recombinant proteins is receiving increased interest. Compared with the bioreactor systems that are currently in use, microalgae may be an attractive alternative for the production of pharmaceuticals, recombinant proteins and other valuable products. Products synthesized via the genetic engineering of microalgae include vaccines, antibodies, enzymes, blood-clotting factors, immune regulators, growth factors, hormones, and other valuable products, such as the anticancer agent Taxol. In this paper, we briefly compare the currently used bioreactor systems, summarize the progress in genetic engineering of microalgae, and discuss the potential for microalgae as bioreactors to produce pharmaceuticals. PMID:27322258

  17. Process optimization by decoupled control of key microbial populations: distribution of activity and abundance of polyphosphate-accumulating organisms and nitrifying populations in a full-scale IFAS-EBPR plant

    DEFF Research Database (Denmark)

    Onnis-Hayden, Annalisa; Majed, Nehreen; Schramm, Andreas;

    2011-01-01

    ammonia concentration becomes limiting. Our results showthat IFAS-EBPR systems enable decoupling of solid residence time (SRT) control for nitrifiers and PAOs that require or prefer conflicting SRT values (e.g. >15 days required for nitrifiers and <5 days preferred for PAOs). Allowing the slow......-growing nitrifiers to attach to the carrier media and the faster-growing phosphorus (P)-removing organisms (and other heterotrophs, e.g. denitrifiers) to be in the suspended mixed liquor (ML), the EBPR-IFAS system facilitates separate SRT controls and overall optimization for both N and P removal processes....

  18. Water reuse by membrane bioreactors (MBR)

    International Nuclear Information System (INIS)

    This paper shows an up-to date overview of the use of membrane bioreactor (MBR) to obtain water treated for reusing it. Considering the existing rules. it has been presented a summary of published studies in which the quality of the effluent is analyzed in terms on physico-chemical and biological parameters. Furthermore, MBR results are compared with the conventional treatment ones. Due to the suitability of MBR technology for removing pathogens, particular attention has been paid to disinfection process and the mechanism that govern it. Results from reviewed studies of MBR have showed equal or better quality of water treated than conventional treatments (activated sludge plus disinfection tertiary treatment by the addition of antibacterial agents). (Author) 32 refs.

  19. Rotating bio-reactor cell culture apparatus

    Science.gov (United States)

    Schwarz, Ray P. (Inventor); Wolf, David A. (Inventor)

    1991-01-01

    A bioreactor system is described in which a tubular housing contains an internal circularly disposed set of blade members and a central tubular filter all mounted for rotation about a common horizontal axis and each having independent rotational support and rotational drive mechanisms. The housing, blade members and filter preferably are driven at a constant slow speed for placing a fluid culture medium with discrete microbeads and cell cultures in a discrete spatial suspension in the housing. Replacement fluid medium is symmetrically input and fluid medium is symmetrically output from the housing where the input and the output are part of a loop providing a constant or intermittent flow of fluid medium in a closed loop.

  20. Robust Control Methods for a Recycle Bioreactor

    Directory of Open Access Journals (Sweden)

    Cosmin IONETE

    2001-12-01

    Full Text Available The paper presents a robust control design strategy for bioprocesses, which are characterized by strongly nonlinear dynamics. More precisely, we present the H2 methodology in order to compute the controller for a recycle Continuous Stirred Tank Bioreactor (CSTB. We consider a general method of formulating control problem, which makes use of linear fractional transformation as introduced by Doyle (1978. The formulation makes use of the general two-port configuration of the generalized plant with a generalized controller. The H2 norm is the quadratic criterion used in optimal control as LQG. The overall control objective is to minimize the H2 norm of the transfer matrix function from the weighted exogenous inputs to the weighted controlled outputs. The advantage of H2 control technique, which uses the linearized model of the CSTB, is that it is completely automated and very flexible. Finally, we prove that the closed loop control structure has very good inner robustness.

  1. Microbial Bioreactor Development in the ALS NSCORT

    Science.gov (United States)

    Mitchell, Cary; Whitaker, Dawn; Banks, M. Katherine; Heber, Albert J.; Turco, Ronald F.; Nies, Loring F.; Alleman, James E.; Sharvelle, Sybil E.; Li, Congna; Heller, Megan

    The NASA Specialized Center of Research and Training in Advanced Life Support (the ALS NSCORT), a partnership of Alabama A & M, Howard, and Purdue Universities, was established by NASA in 2002 to develop technologies that will reduce the Equivalent System Mass (ESM) of regenerative processes within future space life-support systems. A key focus area of NSCORT research has been the development of efficient microbial bioreactors for treatment of human, crop, and food-process wastes while enabling resource recovery. The approach emphasizes optimizing the energy-saving advantages of hydrolytic enzymes for biomass degradation, with focus on treatment of solid wastes including crop residue, paper, food, and human metabolic wastes, treatment of greywater, cabin air, off-gases from other treatment systems, and habitat condensate. This summary includes important findings from those projects, status of technology development, and recommendations for next steps. The Plant-based Anaerobic-Aerobic Bioreactor-Linked Operation (PAABLO) system was developed to reduce crop residue while generating energy and/or food. Plant residues initially were added directly to the bioreactor, and recalcitrant residue was used as a substrate for growing plants or mushrooms. Subsequently, crop residue was first pretreated with fungi to hydrolyze polymers recalcitrant to bacteria, and leachate from the fungal beds was directed to the anaerobic digester. Exoenzymes from the fungi pre-soften fibrous plant materials, improving recovery of materials that are more easily biodegraded to methane that can be used for energy reclamation. An Autothermal Thermophilic Aerobic Digestion (ATAD) system was developed for biodegradable solid wastes. Objectives were to increase water and nutrient recovery, reduce waste volume, and inactivate pathogens. Operational parameters of the reactor were optimized for degradation and resource recovery while minimizing system requirements and footprint. The start-up behavior

  2. Start-up Strategy for Continuous Bioreactors

    Directory of Open Access Journals (Sweden)

    A.C. da Costa

    1997-06-01

    Full Text Available Abstract - The start-up of continuous bioreactors is solved as an optimal control problem. The choice of the dilution rate as the control variable reduces the dimension of the system by making the use of the global balance equation unnecessary for the solution of the optimization problem. Therefore, for systems described by four or less mass balance equations, it is always possible to obtain an analytical expression for the singular arc as a function of only the state variables. The steady state conditions are shown to satisfy the singular arc expression and, based on this knowledge, a feeding strategy is proposed which leads the reactor from an initial state to the steady state of maximum productivity

  3. Vortex breakdown in a truncated conical bioreactor

    Science.gov (United States)

    Balci, Adnan; Brøns, Morten; Herrada, Miguel A.; Shtern, Vladimir N.

    2015-12-01

    This numerical study explains the eddy formation and disappearance in a slow steady axisymmetric air-water flow in a vertical truncated conical container, driven by the rotating top disk. Numerous topological metamorphoses occur as the water height, Hw, and the bottom-sidewall angle, α, vary. It is found that the sidewall convergence (divergence) from the top to the bottom stimulates (suppresses) the development of vortex breakdown (VB) in both water and air. At α = 60°, the flow topology changes eighteen times as Hw varies. The changes are due to (a) competing effects of AMF (the air meridional flow) and swirl, which drive meridional motions of opposite directions in water, and (b) feedback of water flow on AMF. For small Hw, the AMF effect dominates. As Hw increases, the swirl effect dominates and causes VB. The water flow feedback produces and modifies air eddies. The results are of fundamental interest and can be relevant for aerial bioreactors.

  4. Radiotracer investigation in a rotary fluidized bioreactor

    International Nuclear Information System (INIS)

    A rotary fluidized bioreactor (RFBR) designed for treatment of wastewater was required to be investigated for its hydrodynamic behaviour and validation of design. A radiotracer investigation was carried out to measure residence time distribution (RTD) of wastewater in the RFBR using 82Br as a radiotracer. The radiotracer was instantaneously injected into the inlet feed line and monitored at the inlet and outlet of the reactor using collimated scintillation detectors connected to a data acquisition system. The measured RTD data was treated and simulated using a tanks-in-series model and model parameters i.e. number of tanks describing the degree of mixing was obtained. The results of the investigation showed no flow abnormalities and the reactor behaved as an ideal continuously stirred-tank reactor at all the operating conditions. Based on the results, the design of the reactor was validated. (author)

  5. The Role of Bioreactors in Tissue Engineering for Musculoskeletal Applications

    OpenAIRE

    Oragui, Emeka; Nannaparaju, Madhusudhan; Khan, Wasim S.

    2011-01-01

    Tissue engineering involves using the principles of biology, chemistry and engineering to design a ‘neotissue’ that augments a malfunctioning in vivo tissue. The main requirements for functional engineered tissue include reparative cellular components that proliferate on a biocompatible scaffold grown within a bioreactor that provides specific biochemical and physical signals to regulate cell differentiation and tissue assembly. We discuss the role of bioreactors in tissue engineering and eva...

  6. Biodegradation of petroleum hydrocarbons in an immobilized cell airlift bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Kermanshahi Pour, A.; Karamanev, D.; Margaritis, A. [Universityn of Western Ontario, London (Canada). Dept. of Chemical and Biochemical Engineering

    2005-09-01

    An ''immobilized cell airlift bioreactor'', was used for the aerobic bioremediation of simulated diesel fuel contaminated groundwater and tested with p-xylene and naphthalene in batch and continuous regimes. The innovative design of the experiments consists of two stages. At the first stage ''immobilized soil bioreactor'' (ISBR) was used to develop an efficient microbial consortium from the indigenous microorganisms, which exist in diesel fuel contaminated soil. The concept of ISBR relies on the entrapment of the soil particles into the pores of a semi-permeable membrane, which divides the bioreactor into two aerated and non-aerated portions. The second stage involves inoculating the ''immobilized cell air lift bioreactor'' with the cultivated microbial consortia of the first stage. Immobilized cell airlift bioreactor has the same configuration as ISBR except that in this bioreactor instead of soil, microorganisms were immobilized on the fibers of the membrane. The performance of a 0.83 L immobilized cell airlift bioreactor was investigated at various retention time (0.5-6 h) and concentrations of p-xylene (15, 40 and 77 mg/L) and naphthalene (8, 15 and 22 mg/L) in the continuous operation. In the batch regime, 0.9 L bioreactor was operated at various biodegradation times (15-135 min) and concentrations of p-xylene (13.6, 44.9 and 67.5 mg/L) and naphthalene (1.5 and 3.8 mg/L). Under the conditions of the complete biodegradation of p-xylene and naphthalene, the obtained volumetric biodegradation rates at biomass density of 720 mg/L were 15 and 16 mg/L h, respectively. (author)

  7. Optimisation of a hollow fibre membrane bioreactor for water refuse

    OpenAIRE

    Verrecht, Bart

    2010-01-01

    Over the last two decades, implementation of membrane bioreactors (MBRs) has increased due to their superior effluent quality and low plant footprint. However, they are still viewed as a high-cost option, both with regards to capital and operating expenditure (capex and opex). The present thesis extends the understanding of the impact of design and operational parameters of membrane bioreactors on energy demand, and ultimately whole life cost. A simple heuristic aeration model ...

  8. Integrated operation of membrane bioreactors: simulation and experimental studies

    OpenAIRE

    Dalmau Figueras, Montserrat

    2014-01-01

    Membrane bioreactors (MBR) are a combination of common bioreactors and membrane filtration units for biomass retention, presenting unique advantages like high effluent quality and a smaller footprint than the one by conventional wastewater treatment plants. However, fouling and its associated costs are the main drawbacks related to this technology. This thesis presents a step towards the integrated operation of MBRs through experimental and model-based studies. Interactions between the biolog...

  9. Studies on a Novel Bioreactor Design for Chondrocyte Culture

    OpenAIRE

    Patil, Harshad; Chandel, Ishan Saurav; Rastogi, Amit K.; Srivastava, Pradeep

    2013-01-01

    A bioreactor system plays an important role in tissue engineering and enables reproduction and controlled changes in the environmental factor. The bioreactor provides technical means to perform controlled processes in safe and reduced reproducible generation of time. Cartilage cells were grown in vitro by mimicking the in vivo condition. The basic unit of cartilage, that is, chondrocyte, requires sufficient shear, strain, and hydrodynamic pressure for regular growth as it is nonvascular tissu...

  10. Targeting Autotrophic and Lithotrophic Microorganisms from Fumarolic Ice Caves of Mt. Erebus, Antarctica

    Science.gov (United States)

    Anitori, R.; Davis, R.; Connell, L.; Kelley, M.; Staudigel, H.; Tebo, B. M.

    2011-12-01

    Terrestrial and aquatic volcanic oligotrophic environments can host microorganisms that obtain their energy from reduced inorganic chemicals present in volcanic rocks and soils. We sampled basaltic rock from terrestrial Dark Oligotrophic Volcanic Ecosystems (DOVEs) located in two fumarole ice caves, Warren and Warren West, located near the summit of Mt. Erebus, Antarctica. For reference, we sampled a similar cave, Harry's Dream, which receives continuous light during the Austral summer. We report here culturing data for bacterial and eukaryotic microbes from rocky soils in these caves when targeting lithotrophic organisms using media containing reduced inorganic compounds (Mn2+, Fe2+, NH4+). In addition, to test for the possible presence of inorganic carbon fixation, we screened samples for the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gene. Culturing of soil samples on media targeting both autotrophs and heterotrophs yielded a diverse collection of generally slow-growing colonies of bacteria (majority), fungi and non-fungal eukaryotes. Manganese(II)-oxidizing colonies were identified in Warren and Harry's Dream, and these exhibited two colony morphotypes upon subculturing. Sequencing of the PCR amplified 16S rRNA gene identified a bacterium distantly related to Pseudonocardia sp., a genus with known manganese oxidizers. Other bacteria enriched included members of the Actinobacteria, Alphaproteobacteria and Betaproteobacteria. There was a low diversity in cultured eukaryotes representing several potential undescribed species (Geomyces sp., Penicillium sp.) and isolates that may represent alternate, previously undescribed habitats and forms (Psilolechia leprosa, Alternaria alternata). One Warren isolate was a 99% 16S rRNA match to the N2 fixer Bradyrhizobium sp.; when inoculated into liquid medium specific for N2 fixers, growth was maintained upon subculture. Putative iron oxidizers were also enriched from the two DOVE caves, using slush agar iron

  11. N2O production dynamics in nitrifying/denitrifying activated sludge under defined environmental conditions

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Jensen, Marlene Mark; Petersen, Morten S.;

    Nitrous oxide (N2O) is a gaseous pollutant emitted as an unwanted product in wastewater treatment plants during the nitrification-denitrification process. Even though the emission capacity of the process with respect to this compound is still under debate, N2O has been identified as an important ...... that a minor portion of the N2O produced was actually released to the gas phase. This work represents a step further in the use and calibration of process models to control and understand better N2O production and emissions during conventional wastewater treatment....... contributor to global warming and the destruction of the ozone layer. The present study makes use of unique datasets collected during controlled batch tests with activated sludge biomass to test and calibrate a pseudo-mechanistic model that predicts N2O production by nitrifying and heterotrophic bacteria...

  12. A shift in the archaeal nitrifier community in response to natural and anthropogenic disturbances in the northern Gulf of Mexico.

    Science.gov (United States)

    Newell, Silvia E; Eveillard, Damien; McCarthy, Mark J; Gardner, Wayne S; Liu, Zhanfei; Ward, Bess B

    2014-02-01

    The Gulf of Mexico is affected by hurricanes and suffers seasonal hypoxia. The Deepwater Horizon oil spill impacted every trophic level in the coastal region. Despite their importance in bioremediation and biogeochemical cycles, it is difficult to predict the responses of microbial communities to physical and anthropogenic disturbances. Here, we quantify sediment ammonia-oxidizing archaeal (AOA) community diversity, resistance and resilience, and important geochemical factors after major hurricanes and the oil spill. Dominant AOA archetypes correlated with different geochemical factors, suggesting that different AOA are constrained by distinct parameters. Diversity was lowest after the hurricanes, showing weak resistance to physical disturbances. However, diversity was highest during the oil spill and coincided with a community shift, suggesting a new alternative stable state sustained for at least 1 year. The new AOA community was not significantly different from that at the spill site 1 year after the spill. This sustained shift in nitrifier community structure may be a result of oil exposure. PMID:24596268

  13. Biodegradation of ibuprofen, diclofenac and carbamazepine in nitrifying activated sludge under 12 °C temperature conditions

    International Nuclear Information System (INIS)

    Pharmaceuticals constitute a well-known group of emerging contaminants with an increasing significance in water pollution. This study focuses on three pharmaceuticals extensively used in Finland and which can be found in environmental waters: ibuprofen, diclofenac and carbamazepine. Biodegradation experiments were conducted in a full-scale Wastewater Treatment Plant (WWTP) and in laboratory-scale Sequencing Batch Reactors (SBRs). The SBRs were operated at 12 °C, with a sludge retention time (SRT) 10–12 d and organic loading rates (OLRs) of 0.17, 0.27 and 0.33 kg BOD7 m-3d-1. Ibuprofen was found to biodegrade up to 99%. The biodegradation rate constants (kbiol) for ibuprofen were calculated for full-scale and laboratory processes as well as under different laboratory conditions and found to differ from 0.9 up to 5.0 l gSS−1 d−1. Diclofenac demonstrated an unexpected immediate drop of concentration in three SBRs and partial recovery of the initial concentration in one of the reactors. High fluctuating in diclofenac concentration was presumably caused by removal of this compound under different concentrations of nitrites during development of nitrifying activated sludge. Carbamazepine showed no biodegradation in all the experiments. - Highlights: • The biodegradation of three pharmaceuticals examined under 12 °C conditions. • kbiol constants for ibuprofen proposed for full-scale and laboratory-scale processes. • Influence of OLR on ibuprofen biodegradation was studied. • Removal followed by recovery of diclofenac detected in nitrifying activated sludge

  14. Biodegradation of ibuprofen, diclofenac and carbamazepine in nitrifying activated sludge under 12 °C temperature conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kruglova, Antonina; Ahlgren, Pia; Korhonen, Nasti; Rantanen, Pirjo; Mikola, Anna; Vahala, Riku

    2014-11-15

    Pharmaceuticals constitute a well-known group of emerging contaminants with an increasing significance in water pollution. This study focuses on three pharmaceuticals extensively used in Finland and which can be found in environmental waters: ibuprofen, diclofenac and carbamazepine. Biodegradation experiments were conducted in a full-scale Wastewater Treatment Plant (WWTP) and in laboratory-scale Sequencing Batch Reactors (SBRs). The SBRs were operated at 12 °C, with a sludge retention time (SRT) 10–12 d and organic loading rates (OLRs) of 0.17, 0.27 and 0.33 kg BOD{sub 7} m{sup -3}d{sup -1}. Ibuprofen was found to biodegrade up to 99%. The biodegradation rate constants (k{sub biol}) for ibuprofen were calculated for full-scale and laboratory processes as well as under different laboratory conditions and found to differ from 0.9 up to 5.0 l g{sub SS}{sup −1} d{sup −1}. Diclofenac demonstrated an unexpected immediate drop of concentration in three SBRs and partial recovery of the initial concentration in one of the reactors. High fluctuating in diclofenac concentration was presumably caused by removal of this compound under different concentrations of nitrites during development of nitrifying activated sludge. Carbamazepine showed no biodegradation in all the experiments. - Highlights: • The biodegradation of three pharmaceuticals examined under 12 °C conditions. • k{sub biol} constants for ibuprofen proposed for full-scale and laboratory-scale processes. • Influence of OLR on ibuprofen biodegradation was studied. • Removal followed by recovery of diclofenac detected in nitrifying activated sludge.

  15. Reducing N2O Emission from a Domestic-Strength Nitrifying Culture by Free Nitrous Acid-Based Sludge Treatment.

    Science.gov (United States)

    Wang, Dongbo; Wang, Qilin; Laloo, Andrew Elohim; Yuan, Zhiguo

    2016-07-19

    An increase of nitrite in the domestic-strength range is generally recognized to stimulate nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB). It was found in this study, however, that N2O emission from a mainstream nitritation system (cyclic nitrite = 25-45 mg of N/L) that was established by free nitrous acid (FNA)-based sludge treatment was not higher but much lower than that from the initial nitrifying system with full conversion of NH4(+)-N to NO3(-)-N. Under dissolved oxygen (DO) levels of 2.5-3.0 mg/L, N2O emission from the nitritation stage was 76% lower than that from the initial stage. Even when the DO level was reduced to 0.3-0.8 mg/L, N2O emission from the nitritation stage was still 40% lower. An investigation of the mechanism showed that FNA treatment caused a shift of the stimulation threshold of nitrite on N2O emission. At the nitritation stage, the maximal N2O emission factor occurred at ∼16 mg of N/(L of nitrite). However, it increased with increasing nitrite in the range of 0-56 mg of N/L at the initial stage. FNA treatment decreased the biomass-specific N2O production rate, suggesting that the enzymes relevant to nitrifier denitrification were inhibited. Microbial analysis revealed that FNA treatment decreased the microbial community diversity but increased the abundances of AOB and denitrifiers. PMID:27294698

  16. Sequential Aeration of Membrane-Aerated Biofilm Reactors for High-Rate Autotrophic Nitrogen Removal: Experimental Demonstration

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Sun, Sheng-Peng; Lackner, Susanne;

    2010-01-01

    One-stage autotrophic nitrogen (N) removal, requiring the simultaneous activity of aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB), can be obtained in spatially redox-stratified biofilms. However, previous experience with Membrane-Aerated Biofilm Reactors (MABRs) has revealed a...... difficulty in reducing the abundance and activity of nitrite oxidizing bacteria (NOB), which drastically lowers process efficiency. Here we show how sequential aeration is an effective strategy to attain autotrophic N removal in MABRs: Two separate MABRs, which displayed limited or no N removal under......S rRNA gene confirmed that sequential aeration, even at elevated average O2 loads, stimulated the abundance of AnAOB and AOB and prevented the increase in NOB. Nitrous oxide (N2O) emissions were 100-fold lower compared to other anaerobic ammonium oxidation (Anammox)-nitritation systems. Hence, by...

  17. Autotrophic, hydrogen-oxidizing, denitrifying bacteria in groundwater, potential agents for bioremediation of nitrate contamination

    Science.gov (United States)

    Smith, R.L.; Ceazan, M.L.; Brooks, M.H.

    1994-01-01

    Addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (Cape Cod, Mass.). Hydrogen uptake by the core material was immediate and rapid, with an apparent K(m) of 0.45 to 0.60 ??M and a V(max) of 18.7 nmol cm-3 h-1 at 30??C. Nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. Eight of the strains grew autotrophically on hydrogen with either oxygen or nitrate as the electron acceptor. One strain grew mixotrophically. All of the isolates were capable of heterotrophic growth, but none were similar to Paracoccus denitrificans, a well-characterized hydrogen-oxidizing denitrifier. The kinetics for hydrogen uptake during denitrification were determined for each isolate with substrate depletion progress curves; the K(m)s ranged from 0.30 to 3.32 ??M, with V(max)s of 1.85 to 13.29 fmol cell-1 h-1. Because these organisms appear to be common constituents of the in situ population of the aquifer, produce innocuous end products, and could be manipulated to sequentially consume oxygen and then nitrate when both were present, these results suggest that these organisms may have significant potential for in situ bioremediation of nitrate contamination in groundwater.

  18. Nitrate removal and microbial analysis by combined micro-electrolysis and autotrophic denitrification.

    Science.gov (United States)

    Xing, Wei; Li, Desheng; Li, Jinlong; Hu, Qianyi; Deng, Shihai

    2016-07-01

    A process combining micro-electrolysis and autotrophic denitrification (CEAD) with iron-carbon micro-electrolysis carriers was developed for nitrate removal. The process was performed using organic-free influent with a NO3(-)-N concentration of 40.0±3.0mg/L and provided an average nitrate removal efficiency of 95% in stable stages. The total nitrogen removal efficiency reached 75%, with 21% of NO3(-)-N converted into NH4(+)-N. The corresponding hydraulic retention time was 8-10h, and the optimal pH ranged from 8.5 to 9.5. Microbial analysis with high-throughput sequencing revealed that dominant microorganisms in the reactor belonged to the classes of β-, γ-, and α-Proteobacteria. The abundance of the genera Thermomonas significantly increased during the operation, comprising 21.4% and 24.1% in sludge attached to the carriers in the middle and at the bottom of the reactor, respectively. The developed CEAD achieved efficient nitrate removal from water without organics, which is suitable for practical application. PMID:27019127

  19. Investigating the association between photosynthetic efficiency and generation of biophotoelectricity in autotrophic microbial fuel cells

    Science.gov (United States)

    Ciniciato, Gustavo P. M. K.; Ng, Fong-Lee; Phang, Siew-Moi; Jaafar, Muhammad Musoddiq; Fisher, Adrian C.; Yunus, Kamran; Periasamy, Vengadesh

    2016-01-01

    Microbial fuel cells operating with autotrophic microorganisms are known as biophotovoltaic devices. It represents a great opportunity for environmentally-friendly power generation using the energy of the sunlight. The efficiency of electricity generation in this novel system is however low. This is partially reflected by the poor understanding of the bioelectrochemical mechanisms behind the electron transfer from these microorganisms to the electrode surface. In this work, we propose a combination of electrochemical and fluorescence techniques, giving emphasis to the pulse amplitude modulation fluorescence. The combination of these two techniques allow us to obtain information that can assist in understanding the electrical response obtained from the generation of electricity through the intrinsic properties related to the photosynthetic efficiency that can be obtained from the fluorescence emitted. These were achieved quantitatively by means of observed changes in four photosynthetic parameters with the bioanode generating electricity. These are the maximum quantum yield (Fv/Fm), alpha (α), light saturation coefficient (Ek) and maximum rate of electron transfer (rETRm). The relationship between the increases in the current density collected by the bioanode to the decrease of the rETRm values in the photosynthetic pathway for the two microorganisms was also discussed. PMID:27502051

  20. Startup and oxygen concentration effects in a continuous granular mixed flow autotrophic nitrogen removal reactor.

    Science.gov (United States)

    Varas, Rodrigo; Guzmán-Fierro, Víctor; Giustinianovich, Elisa; Behar, Jack; Fernández, Katherina; Roeckel, Marlene

    2015-08-01

    The startup and performance of the completely autotrophic nitrogen removal over nitrite (CANON) process was tested in a continuously fed granular bubble column reactor (BCR) with two different aeration strategies: controlling the oxygen volumetric flow and oxygen concentration. During the startup with the control of oxygen volumetric flow, the air volume was adjusted to 60mL/h and the CANON reactor had volumetric N loadings ranging from 7.35 to 100.90mgN/Ld with 36-71% total nitrogen removal and high instability. In the second stage, the reactor was operated at oxygen concentrations of 0.6, 0.4 and 0.2mg/L. The best condition was 0.2 mgO2/L with a total nitrogen removal of 75.36% with a CANON reactor activity of 0.1149gN/gVVSd and high stability. The feasibility and effectiveness of CANON processes with oxygen control was demonstrated, showing an alternative design tool for efficiently removing nitrogen species. PMID:25965951

  1. Effects of HRT and water temperature on nitrogen removal in autotrophic gravel filter.

    Science.gov (United States)

    Xu, Jing-Hang; He, Sheng-Bing; Wu, Su-Qing; Huang, Jung-Chen; Zhou, Wei-Li; Chen, Xue-Chu

    2016-03-01

    Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively. When HRT increased to 24 h, the average TN removal increased accordingly to 41% at 3-6 °C, suggesting denitrification performance was improved by extended HRT at low water temperatures. Due to denitrification, 96% of added nitrate nitrogen (NO3(-)-N) was converted to nitrogen gas, with a mean flux of nitrous oxide (N2O) was 0.0268-0.1500 ug m(-2) h(-1), while 98.86% of thiosulfate was gradually converted to sulfate throughout the system. Thus, our results show that the sulfur driven autotrophic denitrification constructed wetland demonstrated an excellent removal efficiency of nitrate for wastewater treatment. The HRT and water temperature proved to be two influencing factors in this constructed wetland treatment system. PMID:26766357

  2. Performance of completely autotrophic nitrogen removal over nitrite process under different aeration modes and dissolved oxygen

    Institute of Scientific and Technical Information of China (English)

    Jinsong GUO; Guohong YANG; Fang FANG; Yu QIN

    2008-01-01

    In this study, three sequential batch biofilm reactors (SBBRs) were operated for 155 days to evaluate the performance of completely autotrophic nitrogen removal over nitrite (CANON) process under different aeration modes and dissolved oxygen (DO). Synthetic wastewater with 160-mg NH4+-N/L was fed into the reac-tors. In the continuously-aerated reactor, the efficiency of the ammonium nitrogen conversion and total nitrogen (TN) removal reached 80% and 70%, respectively, with DO between 0.8-1.0 mg/L. Whereas in the intermit-tently-aerated reactor, at the aeration/non-aeration ratio of 1.0, ammonium was always under the detection limit and 86% of TN was removed with DO between 2.0 2.5 mg/L during the aeration time. Results show that CANON could be achieved in both continuous and inter-mittent aeration pattern. However, to achieve the same nitrogen removal efficiency, the DO needed in the inter-mittently-aerated sequential batch biofilm reactor (SBBR) during the aeration period was higher than that in the continuously-aerated SBBR. In addition, the DO in the CANON system should be adjusted to the aeration mode, and low DO was not a prerequisite to CANON process.

  3. Study of a combined heterotrophic and sulfur autotrophic denitrification technology for removal of nitrate in water

    International Nuclear Information System (INIS)

    A combined two-step process of heterotrophic denitrification in a fluidized reactor and sulfur autotrophic denitrification processes (CHSAD) was developed for the removal of nitrate in drinking water. In this process, the advantage of high efficiency of heterotrophic denitrification with non-excessive methanol and the advantage of non-pollution of sulfur autotriphic denitrification were integrated in this CHSAD process. And, this CHSAD process had the capacity of pH balance and could control the concentration of SO42- in effluent by adjusting the operation condition. When the influent nitrate was 30 mg NO3--N/L, the reactor could be operated efficiently at the hydraulic retention time (HRT) ranging from 20 to 40 min with C:N ratio (mg CH3OH:mg NO3--N) of 2.0 (methanol as carbon source). The nitrate removal was nearly 100% and there was no accumulated nitrite or residual methanol in the effluent. The effluent pH was about 7.5 and the sulfate concentration was lower than 130 mg/L. The maximum volume-loading rate of the reactor was 2.16 kg NO3--N/(m3 d). The biomass and scanning electron microscopy graphs of biofilm were also analyzed.

  4. Metabolic engineering of Cupriavidus necator for heterotrophic and autotrophic alka(e)ne production.

    Science.gov (United States)

    Crépin, Lucie; Lombard, Eric; Guillouet, Stéphane E

    2016-09-01

    Alkanes of defined carbon chain lengths can serve as alternatives to petroleum-based fuels. Recently, microbial pathways of alkane biosynthesis have been identified and enabled the production of alkanes in non-native producing microorganisms using metabolic engineering strategies. The chemoautotrophic bacterium Cupriavidus necator has great potential for producing chemicals from CO2: it is known to have one of the highest growth rate among natural autotrophic bacteria and under nutrient imbalance it directs most of its carbon flux to the synthesis of the acetyl-CoA derived polymer, polyhydroxybutyrate (PHB), (up to 80% of intracellular content). Alkane synthesis pathway from Synechococcus elongatus (2 genes coding an acyl-ACP reductase and an aldehyde deformylating oxygenase) was heterologously expressed in a C. necator mutant strain deficient in the PHB synthesis pathway. Under heterotrophic condition on fructose we showed that under nitrogen limitation, in presence of an organic phase (decane), the strain produced up to 670mg/L total hydrocarbons containing 435mg/l of alkanes consisting of 286mg/l of pentadecane, 131mg/l of heptadecene, 18mg/l of heptadecane, and 236mg/l of hexadecanal. We report here the highest level of alka(e)nes production by an engineered C. necator to date. We also demonstrated the first reported alka(e)nes production by a non-native alkane producer from CO2 as the sole carbon source. PMID:27212691

  5. Bioconversion of High Concentrations of Hydrogen Sulfide to Elemental Sulfur in Airlift Bioreactor

    OpenAIRE

    Mohamed Abdel-Monaem Zytoon; Abdulraheem Ahmad AlZahrani; Madbuli Hamed Noweir; Fadia Ahmed El-Marakby

    2014-01-01

    Several bioreactor systems are used for biological treatment of hydrogen sulfide. Among these, airlift bioreactors are promising for the bioconversion of hydrogen sulfide into elemental sulfur. The performance of airlift bioreactors is not adequately understood, particularly when directly fed with hydrogen sulfide gas. The objective of this paper is to investigate the performance of an airlift bioreactor fed with high concentrations of H2S with special emphasis on the effect of pH in combinat...

  6. Operation of a fluidized-bed bioreactor for denitrification

    International Nuclear Information System (INIS)

    Two denitrification fluidized-bed bioreactors of the same length (i.e., 5 m) but with different inside diameters (i.e., 5 and 10 cm) have been operated on feed ranging in nitrate concentration from 200 to 2000 g/m3; thus far, good agreement has been obtained. Two 10-cm-ID bioreactors operating in series have also been tested; the results are in accordance with predicted results based on the performance of a 5-cm-ID bioreactor. The overall denitrification rate in the dual 10-cm-ID bioreactor system was found to be 23 kg N(NO3-)/day-m3 using feed with a nitrate concentration of 1800 g/m3. Data obtained in operating-temperature tests indicate that the maximum denitrification rate is achieved between 22 and 300C. These data will form the basis of the design of our mobile pilot plant which consists of dual 20-cm-ID by 7.3-m-long bioreactors

  7. Bioreactor technology for production of valuable algal products

    Science.gov (United States)

    Liu, Guo-Cai; Cao, Ying

    1998-03-01

    Bioreactor technology has long been employed for the production of various (mostly cheap) food and pharmaceutical products. More recently, research has been mainly focused on the development of novel bioreactor technology for the production of high—value products. This paper reports the employment of novel bioreactor technology for the production of high-value biomass and metabolites by microalgae. These high-value products include microalgal biomass as health foods, pigments including phycocyanin and carotenoids, and polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid. The processes involved include heterotrophic and mixotrophic cultures using organic substrates as the carbon source. We have demonstrated that these bioreactor cultivation systems are particularly suitable for the production of high-value products from various microalgae. These cultivation systems can be further modified to improve cell densities and productivities by using high cell density techniques such as fed-batch and membrane cell recycle systems. For most of the microalgae investigated, the maximum cell concentrations obtained using these bioreactor systems in our laboratories are much higher than any so far reported in the literature.

  8. Osteocytes Mechanosensing in NASA Rotating Wall Bioreactor

    Science.gov (United States)

    Spatz, Jordan; Sibonga, Jean; Wu, Honglu; Barry, Kevin; Bouxsein, Mary; Pajevic, Paola Divieti

    2010-01-01

    Osteocyte cells are the most abundant (90%) yet least understood bone cell type in the human body. Osteocytes are theorized to be the mechanosensors and transducers of mechanical load for bones, yet the biological mechanism of this action remains elusive. However, recent discoveries in osteocyte cell biology have shed light on their importance as key mechanosensing cells regulating bone remodeling and phosphate homeostasis. The aim of this project was to characterize gene expression patterns and protein levels following exposure of MLO-Y4, a very well characterized murine osteocyte-like cell line, to simulated microgravity using the NASA Rotating Wall Vessel (RWV) Bioreactor. To determine mechanistic pathways of the osteocyte's gravity sensing ability, we evaluated in vitro gene and protein expression of osteocytes exposed to simulated microgravity. Improved understanding of the fundamental mechanisms of mechano transduction at the osteocyte cellular level may lead to revolutionary treatment otions to mitigate the effects of bone loss encountered by astronauts on long duration space missions and provide tailored treatment options for maintaining bone strength of immobilized/partially paralyzed patients here on Earth.

  9. Hydrodynamics of an Electrochemical Membrane Bioreactor

    Science.gov (United States)

    Wang, Ya-Zhou; Wang, Yun-Kun; He, Chuan-Shu; Yang, Hou-Yun; Sheng, Guo-Ping; Shen, Jin-You; Mu, Yang; Yu, Han-Qing

    2015-05-01

    An electrochemical membrane bioreactor (EMBR) has recently been developed for energy recovery and wastewater treatment. The hydrodynamics of the EMBR would significantly affect the mass transfers and reaction kinetics, exerting a pronounced effect on reactor performance. However, only scarce information is available to date. In this study, the hydrodynamic characteristics of the EMBR were investigated through various approaches. Tracer tests were adopted to generate residence time distribution curves at various hydraulic residence times, and three hydraulic models were developed to simulate the results of tracer studies. In addition, the detailed flow patterns of the EMBR were acquired from a computational fluid dynamics (CFD) simulation. Compared to the tank-in-series and axial dispersion ones, the Martin model could describe hydraulic performance of the EBMR better. CFD simulation results clearly indicated the existence of a preferential or circuitous flow in the EMBR. Moreover, the possible locations of dead zones in the EMBR were visualized through the CFD simulation. Based on these results, the relationship between the reactor performance and the hydrodynamics of EMBR was further elucidated relative to the current generation. The results of this study would benefit the design, operation and optimization of the EMBR for simultaneous energy recovery and wastewater treatment.

  10. Bioreactor for acid mine drainage control

    Science.gov (United States)

    Zaluski, Marek H.; Manchester, Kenneth R.

    2001-01-01

    A bioreactor for reacting an aqueous heavy metal and sulfate containing mine drainage solution with sulfate reducing bacteria to produce heavy metal sulfides and reduce the sulfuric acid content of the solution. The reactor is an elongated, horizontal trough defining an inlet section and a reaction section. An inlet manifold adjacent the inlet section distributes aqueous mine drainage solution into the inlet section for flow through the inlet section and reaction section. A sulfate reducing bacteria and bacteria nutrient composition in the inlet section provides sulfate reducing bacteria that with the sulfuric acid and heavy metals in the solution to form solid metal sulfides. The sulfate reducing bacteria and bacteria nutrient composition is retained in the cells of a honeycomb structure formed of cellular honeycomb panels mounted in the reactor inlet section. The honeycomb panels extend upwardly in the inlet section at an acute angle with respect to the horizontal. The cells defined in each panel are thereby offset with respect to the honeycomb cells in each adjacent panel in order to define a tortuous path for the flow of the aqueous solution.

  11. Performance of anaerobic membrane bioreactor during digestion and thickening of aerobic membrane bioreactor excess sludge.

    Science.gov (United States)

    Hafuka, Akira; Mimura, Kazuhisa; Ding, Qing; Yamamura, Hiroshi; Satoh, Hisashi; Watanabe, Yoshimasa

    2016-10-01

    In this study, we evaluated the performance of an anaerobic membrane bioreactor in terms of digestion and thickening of excess sludge from an aerobic membrane bioreactor. A digestion reactor equipped with an external polytetrafluoroethylene tubular microfiltration membrane module was operated in semi-batch mode. Solids were concentrated by repeated membrane filtration and sludge feeding, and their concentration reached 25,400mg/L after 92d. A high chemical oxygen demand (COD) removal efficiency, i.e., 98%, was achieved during operation. A hydraulic retention time of 34d and a pulse organic loading rate of 2200mg-COD/(L-reactor) gave a biogas production rate and biogas yield of 1.33L/(reactor d) and 0.08L/g-CODinput, respectively. The external membrane unit worked well without membrane cleaning for 90d. The transmembrane pressure reached 25kPa and the filtration flux decreased by 80% because of membrane fouling after operation for 90d. PMID:27394993

  12. A sensitive crude oil bioassay indicates that oil spills potentially induce a change of major nitrifying prokaryotes from the Archaea to the Bacteria

    International Nuclear Information System (INIS)

    The sensitivity of nitrifiers to crude oil released by the BP Deepwater Horizon oil spill in Gulf of Mexico was examined using characterized ammonia-oxidizing bacteria and archaea to develop a bioassay and to gain further insight into the ecological response of these two groups of microorganisms to marine oil spills. Inhibition of nitrite production was observed among all the tested ammonia-oxidizing organisms at 100 ppb crude oil. Nitrosopumilus maritimus, a cultured representative of the abundant Marine Group I Archaea, showed 20% inhibition at 1 ppb, a much greater degree of sensitivity to petroleum than the tested ammonia-oxidizing and heterotrophic bacteria. The differing susceptibility may have ecological significance since a shift to bacterial dominance in response to an oil spill could potentially persist and alter trophic interactions influenced by availability of different nitrogen species. - Oil spills potentially induce a change of major nitrifying prokaryotes from the archaea to the bacteria.

  13. Nitrifying bacterial biomass and nitrification activity evaluated by FISH and an automatic on-line instrument at full-scale Fusina (Venice, Italy) WWTP.

    Science.gov (United States)

    Badoer, S; Miana, P; Della Sala, S; Marchiori, G; Tandoi, V; Di Pippo, F

    2015-12-01

    In this study, monthly variations in biomass of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were analysed over a 1-year period by fluorescence in situ hybridization (FISH) at the full-scale Fusina WWTP. The nitrification capacity of the plant was also monitored using periodic respirometric batch tests and by an automated on-line titrimetric instrument (TITrimetric Automated ANalyser). The percentage of nitrifying bacteria in the plant was the highest in summer and was in the range of 10-15 % of the active biomass. The maximum nitrosation rate varied in the range 2.0-4.0 mg NH4 g(-1) VSS h(-1) (0.048-0.096 kg TKN kg(-1) VSS day(-1)): values obtained by laboratory measurements and the on-line instrument were similar and significantly correlated. The activity measurements provided a valuable tool for estimating the maximum total Kjeldahl nitrogen (TKN) loading possible at the plant and provided an early warning of whether the TKN was approaching its limiting value. The FISH analysis permitted determination of the nitrifying biomass present. The main operational parameter affecting both the population dynamics and the maximum nitrosation activity was mixed liquor volatile suspended solids (MLVSS) concentration and was negatively correlated with ammonia-oxidizing bacteria (AOB) (p = 0.029) and (NOB) (p = 0.01) abundances and positively correlated with maximum nitrosation rates (p = 0.035). Increases in concentrations led to decreases in nitrifying bacteria abundance, but their nitrosation activity was higher. These results demonstrate the importance of MLVSS concentration as key factor in the development and activity of nitrifying communities in wastewater treatment plants (WWTPs). Operational data on VSS and sludge volume index (SVI) values are also presented on 11-year basis observations. PMID:26282437

  14. Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.

    Directory of Open Access Journals (Sweden)

    Xavier Le Roux

    Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification

  15. Combined Molecular and Conventional Analyses of Nitrifying Bacterium Diversity in Activated Sludge: Nitrosococcus mobilis and Nitrospira-Like Bacteria as Dominant Populations

    OpenAIRE

    Juretschko, Stefan; Timmermann, Gabriele; Schmid, Markus; Schleifer, Karl-Heinz; Pommerening-Röser, Andreas; Koops, Hans-Peter; WAGNER, Michael

    1998-01-01

    The ammonia-oxidizing and nitrite-oxidizing bacterial populations occurring in the nitrifying activated sludge of an industrial wastewater treatment plant receiving sewage with high ammonia concentrations were studied by use of a polyphasic approach. In situ hybridization with a set of hierarchical 16S rRNA-targeted probes for ammonia-oxidizing bacteria revealed the dominance of Nitrosococcus mobilis-like bacteria. The phylogenetic affiliation suggested by fluorescent in situ hybridization (F...

  16. Exploratory Research - Using Volatile Organic Compounds to Separate Heterotrophic and Autotrophic Forest Soil Respiration

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Scott D [Mississippi State University; Hatten, Jeffrey A [Oregon State University

    2015-02-09

    The initial focus of this project was to develop a method to partition soil respiration into its components (autotrophic, heterotrophic etc.) using the fingerprint of volatile organic compounds (VOCs) from soils. We were able to identify 63 different VOCs in our study; however, due to technical difficulties we were unable to take reliable measurements in order to test our hypotheses and develop this method. In the end, we changed the objectives of the project. Our new objectives were to characterize the effects of species and soil moisture regime on the composition of soil organic matter. We utilized the soils from the greenhouse experiment we had established for the soil VOC study and determined the lignin biomarker profiles of each of the treatments. We found that moisture had a significant effect on the carbon content of the soils with the low moisture treatments having higher carbon content than the high moisture treatments. We found that the relative yield of syringyl phenols (SP), ligin (Lig), and substituted fatty acids (SFA) were elevated in deciduous planted pots and reduced in conifer planted pots relative to plant-free treatments. Our results suggest nuttall oak preserved lignin and SFA, while loblolly pine lost lignin and SFA similarly to the plant free treatments. Since we did not find that the carbon concentrations of the soils were different between the species, nuttall oak probably replaced more native soil carbon than loblolly pine. This suggests that relative to loblolly pine, nuttall oak is a priming species. Since priming may impact soil carbon pools more than temperature or moisture, determining which species are priming species may facilitate an understanding of the interaction that land use and climate change may have on soil carbon pools.

  17. Autotrophic carbon budget in coral tissue: a new 13C-based model of photosynthate translocation.

    Science.gov (United States)

    Tremblay, Pascale; Grover, Renaud; Maguer, Jean François; Legendre, Louis; Ferrier-Pagès, Christine

    2012-04-15

    Corals live in symbiosis with dinoflagellates of the genus Symbiodinum. These dinoflagellates translocate a large part of the photosynthetically fixed carbon to the host, which in turn uses it for its own needs. Assessing the carbon budget in coral tissue is a central question in reef studies that still vexes ecophysiologists. The amount of carbon fixed by the symbiotic association can be determined by measuring the rate of photosynthesis, but the amount of carbon translocated by the symbionts to the host and the fate of this carbon are more difficult to assess. In the present study, we propose a novel approach to calculate the budget of autotrophic carbon in the tissue of scleractinian corals, based on a new model and measurements made with the stable isotope (13)C. Colonies of the scleractinian coral Stylophora pistillata were incubated in H(13)CO (-)(3)-enriched seawater, after which the fate of (13)C was followed in the symbionts, the coral tissue and the released particulate organic carbon (i.e. mucus). Results obtained showed that after 15 min, ca. 60% of the carbon fixed was already translocated to the host, and after 48 h, this value reached 78%. However, ca. 48% of the photosynthetically fixed carbon was respired by the symbiotic association, and 28% was released as dissolved organic carbon. This is different from other coral species, where coral tissue after 48 h. Results show that our (13)C-based model could successfully trace the carbon flow from the symbionts to the host, and the photosynthetically acquired carbon lost from the symbiotic association. PMID:22442377

  18. Mutualism between autotrophic and heterophic bacteria in leaching of low grade ores

    International Nuclear Information System (INIS)

    During solubilization processes of low grade sulphidic ores, the auto trophic bacteria oxidize reduced sulphur compounds and ferrous iron to sulphates and ferric iron respectively. The ore leaching bio topes are not only colonized by auto trophic bacteria (Thiobacillus spp., Leptospirillum ferro oxidans and sulfolobus sp.) but the heterotrophic microorganisms, including bacteria and fungi of various species are also found in these habitats. The autotrophs, in addition to energy metabolism, also produce organic compounds which in excess amount inhibit their growth. Through the utilization of such compounds and also through the production of carbon dioxide and ammonia, these heterotorphs can help bio leaching processes. Effect of one of the heterotrophs; methylobacterium sp., a nitrogen scavenger, found in as association with the thio bacilli in one of the leaching bio tope in Germany was studied in leaching of a carbonate bearing complex (containing copper, iron, zinc and lead) sulphidic ore, in shake flask studies. T. ferro oxidans (Strain F-40) reported to be non nitrogen fixer and strain F-41, a nitrogen fixing thiobacillus were studied for leachability behaviour alone and in combination with T. thio oxidans (lacking nitrogen fixing ability) using media with and without added ammonium nitrogen. In addition the effect of methylobacterium sp. (alt-25) was also tested with the afore mentioned combinations. Nitrogen fixation by T. ferro oxidans did not suffice the nitrogen requirement and the leaching system in laboratory needed addition of nitrogen. The heterotrophic nitrogen scavenger also did not have a positive influence in nitrogen limited system. In case where ammonium nitrogen was also provided in the media, this heterotroph had a negative in own growth and leaving lesser amount available for thio bacilli. This high amount of acid is a limiting factor in bio leaching of high carbonate uranium ores. Uranium ore ecosystems have also been found to contain

  19. Autotrophic growth: methylated carbon monoxide dehydrogenase as an intermediate of acetyl-CoA synthesis

    International Nuclear Information System (INIS)

    A new pathway of autotrophic growth has been discovered in certain anaerobic bacteria in which acetyl-CoA is the product formed from CO2 for initiation of anabolism rather than 3-phosphoglycerate as in the Calvin Cycle. CO2 is reduced in combination with tetrahydrofolate to methyltetrahydrofolate (CH3THF) and is the source of the CH3 group. CO2 or CO is the source of the carbonyl group. CO dehydrogenase (CODH), corrinoid enzyme, methyltransferase, ferredoxin and CODH disulfide reductase have been isolated from Clostridium thermoaceticum and shown to catalyze the synthesis of acetyl-CoA from CH3THF, CO and CoA. The methyltransferase catalyzes transfer of the CH3 group from CH3THF to the corrinoid enzyme from which the methyl is transferred to CODH. CO is bound to the Ni of CODH forming a Ni-Fe-C center. When CO2 is the source of carbon, H2 and hydrogenase are required for reduction of the CO2 by CODH. CODH disulfide reductase is required for the addition of CoA to the CODH (Pezacka, E. and Wood, H.G. J. Biol. Chem., in press). Then, CODH catalyzes the combination of the three groups forming acetyl-CoA. The authors have now succeeded in methylating CODH using 14CH3I or 14CH3-B12. With the resulting 14CH3-CODH, only CODH disulfide reductase is required for synthesis of [14C]acetyl-CoA from CO and CoA. The amino acid sequence at the CH3-site is being investigated

  20. Partitioning Longleaf Pine Soil Respiration into Its Heterotrophic and Autotrophic Components through Root Exclusion

    Directory of Open Access Journals (Sweden)

    Althea A. ArchMiller

    2016-02-01

    Full Text Available Rapid and accurate estimations of the heterotrophic and autotrophic components of total soil respiration (Rs are important for calculating forest carbon budgets and for understanding carbon dynamics associated with natural and management-related disturbances. The objective of this study was to use deep (60 cm root exclusion tubes and paired control (i.e., no root exclusion collars to estimate heterotrophic respiration (Rh and Rs, respectively, in three 26-year-old longleaf pine (Pinus palustris Mill. stands in western Georgia. Root biomass was measured in root exclusion tubes and control collars after 102–104 days of incubation and fine root biomass loss from root exclusion was used to quantify root decay. Mean Rs from control collars was 3.3 micromol•CO2•m−2•s−1. Root exclusion tubes decreased Rs, providing an estimate of Rh. Mean Rh was 2.7 micromol•CO2•m−2•s−1 when uncorrected by pretreatment variation, root decay, or soil moisture compared to 2.1 micromol•CO2•m−2•s−1 when Rh was corrected for root decay. The corresponding ratio of Rh to Rs ranged from 66% to 82%, depending on the estimation method. This study provides an estimate of Rh in longleaf pine forests, and demonstrates the potential for deep root exclusion tubes to provide relatively rapid assessments (i.e., ~40 days post-treatment of Rh in similar forests. The range in Rh to Rs is comparable to other reports for similar temperate coniferous ecosystems.

  1. Autotrophic antimonate bio-reduction using hydrogen as the electron donor.

    Science.gov (United States)

    Lai, Chun-Yu; Wen, Li-Lian; Zhang, Yin; Luo, Shan-Shan; Wang, Qing-Ying; Luo, Yi-Hao; Chen, Ran; Yang, Xiaoe; Rittmann, Bruce E; Zhao, He-Ping

    2016-01-01

    Antimony (Sb), a toxic metalloid, is soluble as antimonate (Sb(V)). While bio-reduction of Sb(V) is an effective Sb-removal approach, its bio-reduction has been coupled to oxidation of only organic electron donors. In this study, we demonstrate, for the first time, the feasibility of autotrophic microbial Sb(V) reduction using hydrogen gas (H2) as the electron donor without extra organic carbon source. SEM and EDS analysis confirmed the production of the mineral precipitate Sb2O3. When H2 was utilized as the electron donor, the consortium was able to fully reduce 650 μM of Sb(V) to Sb(III) in 10 days, a rate comparable to the culture using lactate as the electron donor. The H2-fed culture directed a much larger fraction of it donor electrons to Sb(V) reduction than did the lactate-fed culture. While 98% of the electrons from H2 were used to reduce Sb(V) by the H2-fed culture, only 12% of the electrons from lactate was used to reduce Sb(V) by the lactate-fed culture. The rest of the electrons from lactate went to acetate and propionate through fermentation, to methane through methanogenesis, and to biomass synthesis. High-throughput sequencing confirmed that the microbial community for the lactate-fed culture was much more diverse than that for the H2-fed culture, which was dominated by a short rod-shaped phylotype of Rhizobium (α-Protobacteria) that may have been active in Sb(V) reduction. PMID:26519630

  2. Miniature Bioreactor System for Long-Term Cell Culture

    Science.gov (United States)

    Gonda, Steve R.; Kleis, Stanley J.; Geffert, Sandara K.

    2010-01-01

    A prototype miniature bioreactor system is designed to serve as a laboratory benchtop cell-culturing system that minimizes the need for relatively expensive equipment and reagents and can be operated under computer control, thereby reducing the time and effort required of human investigators and reducing uncertainty in results. The system includes a bioreactor, a fluid-handling subsystem, a chamber wherein the bioreactor is maintained in a controlled atmosphere at a controlled temperature, and associated control subsystems. The system can be used to culture both anchorage-dependent and suspension cells, which can be either prokaryotic or eukaryotic. Cells can be cultured for extended periods of time in this system, and samples of cells can be extracted and analyzed at specified intervals. By integrating this system with one or more microanalytical instrument(s), one can construct a complete automated analytical system that can be tailored to perform one or more of a large variety of assays.

  3. Bioreactor droplets from liposome-stabilized all-aqueous emulsions

    Science.gov (United States)

    Dewey, Daniel C.; Strulson, Christopher A.; Cacace, David N.; Bevilacqua, Philip C.; Keating, Christine D.

    2014-08-01

    Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed ~130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.

  4. Streamlined bioreactor-based production of human cartilage tissues.

    Science.gov (United States)

    Tonnarelli, B; Santoro, R; Adelaide Asnaghi, M; Wendt, D

    2016-01-01

    Engineered tissue grafts have been manufactured using methods based predominantly on traditional labour-intensive manual benchtop techniques. These methods impart significant regulatory and economic challenges, hindering the successful translation of engineered tissue products to the clinic. Alternatively, bioreactor-based production systems have the potential to overcome such limitations. In this work, we present an innovative manufacturing approach to engineer cartilage tissue within a single bioreactor system, starting from freshly isolated human primary chondrocytes, through the generation of cartilaginous tissue grafts. The limited number of primary chondrocytes that can be isolated from a small clinically-sized cartilage biopsy could be seeded and extensively expanded directly within a 3D scaffold in our perfusion bioreactor (5.4 ± 0.9 doublings in 2 weeks), bypassing conventional 2D expansion in flasks. Chondrocytes expanded in 3D scaffolds better maintained a chondrogenic phenotype than chondrocytes expanded on plastic flasks (collagen type II mRNA, 18-fold; Sox-9, 11-fold). After this "3D expansion" phase, bioreactor culture conditions were changed to subsequently support chondrogenic differentiation for two weeks. Engineered tissues based on 3D-expanded chondrocytes were more cartilaginous than tissues generated from chondrocytes previously expanded in flasks. We then demonstrated that this streamlined bioreactor-based process could be adapted to effectively generate up-scaled cartilage grafts in a size with clinical relevance (50 mm diameter). Streamlined and robust tissue engineering processes, as the one described here, may be key for the future manufacturing of grafts for clinical applications, as they facilitate the establishment of compact and closed bioreactor-based production systems, with minimal automation requirements, lower operating costs, and increased compliance to regulatory guidelines. PMID:27232665

  5. Biological reduction of nitrate wastewater using fluidized-bed bioreactors

    International Nuclear Information System (INIS)

    There are a number of nitrate-containing wastewater sources, as concentrated as 30 wt % NO3- and as large as 2000 m3/d, in the nuclear fuel cycle as well as in many commercial processes such as fertilizer production, paper manufacturing, and metal finishing. These nitrate-containing wastewater sources can be successfully biologically denitrified to meet discharge standards in the range of 10 to 20 gN(NO3-)/m3 by the use of a fluidized-bed bioreactor. The major strain of denitrification bacteria is Pseudomonas which was derived from garden soil. In the fluidized-bed bioreactor the bacteria are allowed to attach to 0.25 to 0.50-mm-diam coal particles, which are fluidized by the upward flow of influent wastewater. Maintaining the bacteria-to-coal weight ratio at approximately 1:10 results in a bioreactor bacteria loading of greater than 20,000 g/m3. A description is given of the results of two biodenitrification R and D pilot plant programs based on the use of fluidized bioreactors capable of operating at nitrate levels up to 7000 g/m3 and achieving denitrification rates as high as 80 gN(NO3-)/d per liter of empty bioreactor volume. The first of these pilot plant programs consisted of two 0.2-m-diam bioreactors, each with a height of 6.3 m and a volume of 208 liters, operating in series. The second pilot plant was used to determine the diameter dependence of the reactors by using a 0.5-m-diam reactor with a height of 6.3 m and a volume of 1200 liters. These pilot plants operated for a period of six months and two months respectively, while using both a synthetic waste and the actual waste from a gaseous diffusion plant operated by Goodyear Atomic Corporation

  6. Influence of wastewater composition on nutrient removal behaviors in the new anaerobic-anoxic/nitrifying/induced crystallization process.

    Science.gov (United States)

    Shi, Jing; Lu, Xiwu; Yu, Ran; Gu, Qian; Zhou, Yi

    2014-01-01

    In this study, the new anaerobic-anoxic/nitrifying/induced crystallization (A2N-IC) system was compared with anaerobic-anoxic/nitrifying (A2N) process to investigate nutrient removal performance under different influent COD and ammonia concentrations. Ammonia and COD removal rates were very stable in both processes, which were maintained at 84.9% and 86.6% when the influent ammonia varied from 30 mg L(-1) to 45 mg L(-1) and COD ranged from 250 mg L(-1) to 300 mg L(-1). The effluent phosphorus always maintained below 0.2 mg L(-1) in A2N-IC, whereas in A2N the effluent phosphorus concentration was 0.4-1.7 mg L(-1), demonstrating that A2N-IC is suitable to apply in a broader influent COD and ammonia concentration range. Under higher influent COD (300 mg L(-1)) or lower ammonia conditions (30 mg L(-1)), the main function of chemical induced crystallization was to coordinate better nutrient ratio for anoxic phosphorus uptake, whereas under high phosphorus concentration, it was to reduce phosphorus loading for biological system. Under the similar influent wastewater compositions, phosphorus release amounts were always lower in A2N-IC. To clarify the decrease procedure of phosphorus release in the A2N-IC, the equilibrium between chemical phosphorus removal and biological phosphorus removal in A2N-IC was analyzed by mass balance equations. During the long-term experiment, some undesirable phenomena were observed: the declining nitrification in post-aerobic tank and calcium phosphorus precipitation in the anaerobic tank. The reasons were analyzed; furthermore, the corresponding improvements were proposed. Nitrification effect could be enhanced in the post-aerobic tank, therefore ammonia removal rate could be increased; and biologically induced phosphorus precipitation could be inhibited by controlling pH at the anaerobic stage, so the phosphorus release and recovery could be improved. PMID:24596502

  7. ANAEROBIC MEMBRANE BIOREACTORS FOR DOMESTIC WASTEWATER TREATMENT. PRELIMINARY STUDY

    Directory of Open Access Journals (Sweden)

    Luisa Vera

    2014-12-01

    Full Text Available The operation of submerged anaerobic membrane bioreactors (SAnMBRs for domestic wastewaters treatment was studied in laboratory scale, with the objective to define sustainable filtration conditions of the suspensions along the process. During continuous experiments, the organic matter degradation by anaerobic way showed an average DQOT removal of 85% and 93%. Indeed, the degradation generated biogas after 12 days of operation and its relative methane composition was of 60% after 25 days of operation. Additionally, the comparison between membrane bioreactors (MBRs performance in aerobic and anaerobic conditions in filterability terms, reported that both systems behave similarly once reached the stationary state.

  8. BIOREACTOR WITH LID FOR EASY ACCESS TO INCUBATION CAVITY

    DEFF Research Database (Denmark)

    2012-01-01

    There is provided a bioreactor which is provided with a lid (13) that facilitates access to the incubation cavity. Specifically the end wall of the incubation cavity is constituted by the lid (13) so that removal of the cap renders the incubation cavity fully accessible.......There is provided a bioreactor which is provided with a lid (13) that facilitates access to the incubation cavity. Specifically the end wall of the incubation cavity is constituted by the lid (13) so that removal of the cap renders the incubation cavity fully accessible....

  9. Production of galanthamine by Leucojum aestivum shoots grown in different bioreactor systems.

    Science.gov (United States)

    Schumann, Anika; Berkov, Strahil; Claus, Diana; Gerth, André; Bastida, Jaume; Codina, Carles

    2012-08-01

    The production of galanthamine by shoots of Leucojum aestivum grown in different bioreactor systems (shaking and nonshaking batch culture, temporary immersion system, bubble bioreactor, continuous and discontinuous gassing bioreactor) under different culture conditions was studied. The influence of the nutrient medium, weight of inoculum, and size of bioreactor on both growth and galanthamine production was studied. The maximal yield of galanthamine (19.416 mg) was achieved by cultivating the L. aestivum shoots (10 g of fresh inoculum) in a temporary immersion system in a 1-L bioreactor vessel which was used as an airlift culture vessel, gassing 12 times per day (5 min). PMID:22639366

  10. Hydrofocusing Bioreactor Produces Anti-Cancer Alkaloids

    Science.gov (United States)

    Gonda, Steve R.; Valluri, Jagan V.

    2011-01-01

    A methodology for growing three-dimensional plant tissue models in a hydrodynamic focusing bioreactor (HFB) has been developed. The methodology is expected to be widely applicable, both on Earth and in outer space, as a means of growing plant cells and aggregates thereof under controlled conditions for diverse purposes, including research on effects of gravitation and other environmental factors upon plant growth and utilization of plant tissue cultures to produce drugs in quantities greater and at costs lower than those of conventional methodologies. The HFB was described in Hydro focus - ing Bioreactor for Three-Dimensional Cell Culture (MSC-22358), NASA Tech Briefs, Vol. 27, No. 3 (March 2003), page 66. To recapitulate: The HFB offers a unique hydrofocusing capability that enables the creation of a low-shear liquid culture environment simultaneously with the herding of suspended cells and tissue assemblies and removal of unwanted air bubbles. The HFB includes a rotating cell-culture vessel with a centrally located sampling port and an internal rotating viscous spinner attached to a rotating base. The vessel and viscous spinner can be made to rotate at the same speed and direction or different speeds and directions to tailor the flow field and the associated hydrodynamic forces in the vessel in order to obtain low-shear suspension of cells and control of the locations of cells and air bubbles. For research and pharmaceutical-production applications, the HFB offers two major benefits: low shear stress, which promotes the assembly of cells into tissue-like three-dimensional constructs; and randomization of gravitational vectors relative to cells, which affects production of medicinal compounds. Presumably, apposition of plant cells in the absence of shear forces promotes cell-cell contacts, cell aggregation, and cell differentiation. Only gentle mixing is necessary for distributing nutrients and oxygen. It has been postulated that inasmuch as cells in the simulated

  11. Study of metabolic pathways for hydrogen production in chlamydomonas reinhardtii and transposition on a torus photo bioreactor

    International Nuclear Information System (INIS)

    Considering the recent increase in energy consumption. aide associated environmental risks, new trails are followed today to develop the use of clean and renewable alternative energies. In this context hydrogen seems to be a serious solution and this study, based on micro-algae photosynthetic capacities exploitation, will allow to devise a process for hydrogen production from only water and solar energy without greenhouse gas release. The sulphur deprivation protocol on TAP medium, known to lead to hydrogen production in Chlamydomonas reinhardtii species was particularly studied. At the metabolic level, two important phenomena are induced under these conditions: an over-accumulation of the intracellular starch reserves and a simultaneous alteration of the PsII activity which leads to anoxia and Fe-hydrogenase induction, an enzyme with a strong specific activity responsible for the hydrogen production. The contribution of the two electron transfer pathways implied in the hydrogen production process (PsII-dependent and PSII-independent) as well as the importance of the previously accumulated starch were highlighted here. We also investigated the potential for designing autotrophic protocols for hydrogen photoproduction. Various protocols, considered to be relevant, were then transposed on a torus photo-bioreactor, specifically developed in this study and which allows the control of culture parameters as well as the precise measurement of gas release kinetics, in order to obtain first estimates of productivity of the system. Integration of the physical; aspects of the pilot and biological aspects of the process in a model, finally opens new prospects for subject development, in particular for a reasoned optimization of hydrogen production via this double physiology/process approach. (author)

  12. Lake acidification and oxygen depletion may synergistically enhance nitrous oxide (N2O) production by nitrifier denitrification in a subalpine lake

    Science.gov (United States)

    Frame, C. H.; Goepfert, T. J.; Rollog, M.; Lehmann, M. F.

    2013-12-01

    Ammonia-oxidizing microorganisms are an important source of the greenhouse gas nitrous oxide (N2O). They produce N2O through two mechanisms: by the decomposition of an intermediate in the ammonia (NH3) oxidation reaction, and by nitrifier denitrification, which is the enzymatic reduction of nitrite (NO2-). We investigated the impact of water pH and oxygen (O2) concentrations on rates of N2O production by these two mechanisms in the water column of Lake Lugano, a subalpine lake between Switzerland and Italy. Acidification of natural waters is known to reduce the rate of ammonia oxidation by forcing the equilibrium NH4+ ←→ NH3 + H+ away from NH3, the form that is preferentially taken up by ammonia oxidizers. In turn, this reduces the rate of N2O production by decomposition of the reaction intermediate during ammonia oxidation. However, using 15NH4+ and 15NO2- tracer additions during lake water incubations, we showed that reducing the pH from in situ values of 7.5 to 8 down to 6 to 7 actually increased the rate of N2O production by nitrifier denitrification. Hypoxia is thought to enhance N2O production by nitrifier denitrification. We did not observe nitrifier denitrification in incubations that were fully oxic (partial pressure of O2 = 20.9%) or had reduced O2 (partial pressure = 12%). However, when the incubation pH was lowered and the O2 reduced to 12%, N2O production by nitrifier denitrification was much greater than it was in incubations where only the pH was reduced or only the O2 concentration was reduced. Water for these experiments was drawn from depths just below the epilimnion of the monomictic south basin of Lugano, an environment whose pH, O2, and nutrient concentrations fluctuate throughout the water column on a seasonal basis and change in the shallower depths on a daily basis. We discuss the implications of these changes for the flux of shallow N2O into the atmosphere and a possible mechanism that explains the synergistic influence of O2 and pH on

  13. Soil moisture sensitivity of autotrophic and heterotrophic forest floor respiration in boreal xeric pine and mesic spruce forests

    Science.gov (United States)

    Ťupek, Boris; Launiainen, Samuli; Peltoniemi, Mikko; Heikkinen, Jukka; Lehtonen, Aleksi

    2016-04-01

    Litter decomposition rates of the most process based soil carbon models affected by environmental conditions are linked with soil heterotrophic CO2 emissions and serve for estimating soil carbon sequestration; thus due to the mass balance equation the variation in measured litter inputs and measured heterotrophic soil CO2 effluxes should indicate soil carbon stock changes, needed by soil carbon management for mitigation of anthropogenic CO2 emissions, if sensitivity functions of the applied model suit to the environmental conditions e.g. soil temperature and moisture. We evaluated the response forms of autotrophic and heterotrophic forest floor respiration to soil temperature and moisture in four boreal forest sites of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) by a soil trenching experiment during year 2015 in southern Finland. As expected both autotrophic and heterotrophic forest floor respiration components were primarily controlled by soil temperature and exponential regression models generally explained more than 90% of the variance. Soil moisture regression models on average explained less than 10% of the variance and the response forms varied between Gaussian for the autotrophic forest floor respiration component and linear for the heterotrophic forest floor respiration component. Although the percentage of explained variance of soil heterotrophic respiration by the soil moisture was small, the observed reduction of CO2 emissions with higher moisture levels suggested that soil moisture response of soil carbon models not accounting for the reduction due to excessive moisture should be re-evaluated in order to estimate right levels of soil carbon stock changes. Our further study will include evaluation of process based soil carbon models by the annual heterotrophic respiration and soil carbon stocks.

  14. Phototrophic biofilm assembly in microbial-mat-derived unicyanobacterial consortia: model systems for the study of autotroph-heterotroph interactions

    Directory of Open Access Journals (Sweden)

    StephenRLindemann

    2014-04-01

    Full Text Available Microbial autotroph-heterotroph interactions influence biogeochemical cycles on a global scale, but the diversity and complexity of natural systems and their intractability to in situ manipulation make it challenging to elucidate the principles governing these interactions. The study of assembling phototrophic biofilm communities provides a robust means to identify such interactions and evaluate their contributions to the recruitment and maintenance of phylogenetic and functional diversity over time. To examine primary succession in phototrophic communities, we isolated two unicyanobacterial consortia from the microbial mat in Hot Lake, Washington, characterizing the membership and metabolic function of each consortium. We then analyzed the spatial structures and quantified the community compositions of their assembling biofilms. The consortia retained the same suite of heterotrophic species, identified as abundant members of the mat and assigned to Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes. Autotroph growth rates dominated early in assembly, yielding to increasing heterotroph growth rates late in succession. The two consortia exhibited similar assembly patterns, with increasing relative abundances of members from Bacteroidetes and Alphaproteobacteria concurrent with decreasing relative abundances of those from Gammaproteobacteria. Despite these similarities at higher taxonomic levels, the relative abundances of individual heterotrophic species were substantially different in the developing consortial biofilms. This suggests that, although similar niches are created by the cyanobacterial metabolisms, the resulting webs of autotroph-heterotroph and heterotroph-heterotroph interactions are specific to each primary producer. The relative simplicity and tractability of the Hot Lake unicyanobacterial consortia make them useful model systems for deciphering interspecies interactions and assembly principles relevant to natural

  15. Optimizing of Bioreactor Heat Supply and Material Feeding by Numerical Calculation

    Science.gov (United States)

    Zhou, Zhiwei; Song, Boyan; Zhu, Likuan; Li, Zuntao; Wang, Yang

    Cell culture at large scale normally uses stirred structure. And the situation of temperature field distribution is very important to the cell culture at large scale. Some cells are very sensitive to the circumstances. The local temperature is too high or too low all influences the cell survival and low the cell quantity at unit volume. This paper simulates the temperature field under three different heating conditions. Then analysis and contrast the simulation results. The mixed situation in bioreactor is extremely significant for nutrition transmit. Usually, use ways to measure the average mixture time in bioreactor, and improve the mixture circumstance in the bioreactor through stirred impeller and bioreactor structure change. This paper adopts numerical calculation method to investigate the flow field in bioreactor. It gets the mixture time of bioreactor through virtual tracer in simulate flow field and detects the tracer density time variation curve in the bioreactor.

  16. Productivity Studies Utilizing Recombinant CHO Cells In Stirred-Tank Bioreactors: A Comparative Study Between The Pitch-Blade And The Packed-Bed Bioreactor Systems

    OpenAIRE

    Hatton, Taylor Stephen

    2012-01-01

    A recombinat Chinese Hamster Ovary (rCHO) cell line designated as CHO SEAP was utilized in this investigation to optimize protein production. Two bench top stirred-tank bioreactors, namely a pitched-blade and a packed-bed basket bioreactor, were utilized for a comparative study to determine which bioreactor would produce the best results in terms of protein production. The objective of this research project was to provide basic data that shows cells cultured in a packed-bed basket bioreactor ...

  17. An operation protocol for facilitating start-up of single-stage autotrophic nitrogen removing reactors based on process stoichiometry

    DEFF Research Database (Denmark)

    Mutlu, A. Gizem; Vangsgaard, Anna Katrine; Sin, Gürkan;

    2012-01-01

    Start-up and operation of single-stage nitritation/anammox reactor employing complete autotrophic nitrogen can be difficult. Keeping the performance criteria and monitoring the microbial community composition may not be easy or fast enough to take action on time. In this study, a control strategy...... is developed based on stoichiometric analysis of monitored nitrogen species. This analysis can serve as a strong decision-making tool to take appropriate actions with respect to the operational conditions to accelerate start up or attainment of near complete nitritation-anammox performance....

  18. Layer-by-layer carbon nanotube bio-templates for in situ monitoring of the metabolic activity of nitrifying bacteria

    Science.gov (United States)

    Loh, Kenneth J.; Guest, Jeremy S.; Ho, Genevieve; Lynch, Jerome P.; Love, Nancy G.

    2009-03-01

    Despite the wide variety of effective disinfection and wastewater treatment techniques for removing organic and inorganic wastes, pollutants such as nitrogen remain in wastewater effluents. If left untreated, these nitrogenous wastes can adversely impact the environment by promoting the overgrowth of aquatic plants, depleting dissolved oxygen, and causing eutrophication. Although nitrification/denitrification processes are employed during advanced wastewater treatment, effective and efficient operation of these facilities require information of the pH, dissolved oxygen content, among many other parameters, of the wastewater effluent. In this preliminary study, a biocompatible CNT-based nanocomposite is proposed and validated for monitoring the biological metabolic activity of nitrifying bacteria in wastewater effluent environments (i.e., to monitor the nitrification process). Using carbon nanotubes and a pH-sensitive conductive polymer (i.e., poly(aniline) emeraldine base), a layer-by-layer fabrication technique is employed to fabricate a novel thin film pH sensor that changes its electrical properties in response to variations in ambient pH environments. Laboratory studies are conducted to evaluate the proposed nanocomposite's biocompatibility with wastewater effluent environments and its pH sensing performance.

  19. The Short-term Effects of Temperature and Free Ammonia on Ammonium Oxidization in Granular and Floccular Nitrifying System

    Institute of Scientific and Technical Information of China (English)

    吴蕾; 彭永臻; 马勇; 刘旭; 李凌云; 王淑莹

    2012-01-01

    The short-term effects of temperature and free ammonia (FA) on ammonium oxidization were investigated in this study by operating several batch tests with two different partial nitrification aggregates, formed as either granules or flocs. The results showed that the rate of ammonium oxidation in both cultures increased significantly as temperature increased from 10 to 30 °C. The specific ammonium oxidation rate with the granules was 2-3 times higher than that with flocs at the same temperature. Nitrification at various FA concentrations and temperatures combination exhibited obvious inhibition in ammonium oxidation rate when FA was 90 mg·L 1 and tempera- ture dropped to 10 °C in the two systems. However, the increase in substrate oxidation rate of ammonia at 30 °C was observed. The results suggested that higher reaction temperature was helpful to reduce the toxicity of FA. Granules appeared to be more tolerant to FA attributed to the much fraction of ammonia oxidizing bacteria (AOB) and higher resistance to the transfer of ammonia into the bacterial aggregates, whereas in the floc system, the bacteria distributed throughout the entire aggregate. These results may contribute to the applicability of the nitrifying granules in wastewater treatment operated at high ammonium concentration.

  20. Application of a novel functional gene microarray to probe the functional ecology of ammonia oxidation in nitrifying activated sludge.

    Directory of Open Access Journals (Sweden)

    Michael D Short

    Full Text Available We report on the first study trialling a newly-developed, functional gene microarray (FGA for characterising bacterial and archaeal ammonia oxidisers in activated sludge. Mixed liquor (ML and media biofilm samples from a full-scale integrated fixed-film activated sludge (IFAS plant were analysed with the FGA to profile the diversity and relative abundance of ammonia-oxidising archaea and bacteria (AOA and AOB respectively. FGA analyses of AOA and AOB communities revealed ubiquitous distribution of AOA across all samples - an important finding for these newly-discovered and poorly characterised organisms. Results also revealed striking differences in the functional ecology of attached versus suspended communities within the IFAS reactor. Quantitative assessment of AOB and AOA functional gene abundance revealed a dominance of AOB in the ML and approximately equal distribution of AOA and AOB in the media-attached biofilm. Subsequent correlations of functional gene abundance data with key water quality parameters suggested an important functional role for media-attached AOB in particular for IFAS reactor nitrification performance and indicate possible functional redundancy in some IFAS ammonia oxidiser communities. Results from this investigation demonstrate the capacity of the FGA to resolve subtle ecological shifts in key microbial communities in nitrifying activated sludge and indicate its value as a tool for better understanding the linkages between the ecology and performance of these engineered systems.

  1. Novel nitrifiers and comammox in a full-scale hybrid biofilm and activated sludge reactor revealed by metagenomic approach.

    Science.gov (United States)

    Chao, Yuanqing; Mao, Yanping; Yu, Ke; Zhang, Tong

    2016-09-01

    Biofilms are widely used in wastewater treatment for their particular enhancement of nitrogen removal and other significant advantages. In this study, the diversity and potential functions of nitrogen removal bacteria in suspended activated sludge (AS) and biofilm of a full-scale hybrid reactor were uncovered by metagenomes (∼34 Gb), coupled with PCR-based 454 reads (>33 K reads). The results indicated that the diversity and abundance of nitrifiers and denitrifiers in biofilm did not surpass that in AS, while more nitrification and denitrification genes were indeed found in biofilm than AS, suggesting that the increased nitrogen removal ability by applying biofilm might be attributed to the enhancement of removal efficiency, rather than the biomass accumulation of nitrogen removal bacteria. The gene annotation and phylogenetic analysis results revealed that AS and biofilm samples consisted of 6.0 % and 9.4 % of novel functional genes for nitrogen removal and 18 % and 30 % of new Nitrospira species for nitrite-oxidizing bacteria, respectively. Moreover, the identification of Nitrospira-like amoA genes provided metagenomic evidence for the presence of complete ammonia oxidizer (comammox) with the functional potential to perform the complete oxidation of ammonia to nitrate. These findings have significant implications in expanding our knowledge of the biological nitrogen transformations in wastewater treatment. PMID:27287850

  2. Oxygen Sensors Monitor Bioreactors and Ensure Health and Safety

    Science.gov (United States)

    2014-01-01

    In order to cultivate healthy bacteria in bioreactors, Kennedy Space Center awarded SBIR funding to Needham Heights, Massachusetts-based Polestar Technologies Inc. to develop sensors that could monitor oxygen levels. The result is a sensor now widely used by pharmaceutical companies and medical research universities. Other sensors have also been developed, and in 2013 alone the company increased its workforce by 50 percent.

  3. NASA's Bioreactor: Growing Cells in a Microgravity Environment. Educational Brief.

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    This brief discusses growing cells in a microgravity environment for grades 9-12. Students are provided with plans for building a classroom bioreactor that can then be used with the included activity on seed growth in a microgravity environment. Additional experimental ideas are also suggested along with a history and background on microgravity…

  4. Modelling and characterization of an airlift-loop bioreactor.

    NARCIS (Netherlands)

    Verlaan, P.

    1987-01-01

    An airlift-loop reactor is a bioreactor for aerobic biotechnological processes. The special feature of the ALR is the recirculation of the liquid through a downcomer connecting the top and the bottom of the main bubbling section. Due to the high circulation-flow rate, efficient mixing and oxygen tra

  5. Cell culture experiments planned for the space bioreactor

    Science.gov (United States)

    Morrison, Dennis R.; Cross, John H.

    1987-01-01

    Culturing of cells in a pilot-scale bioreactor remains to be done in microgravity. An approach is presented based on several studies of cell culture systems. Previous and current cell culture research in microgravity which is specifically directed towards development of a space bioprocess is described. Cell culture experiments planned for a microgravity sciences mission are described in abstract form.

  6. Scale-up of bioreactors: physiological approach contra geometrical similarity

    Czech Academy of Sciences Publication Activity Database

    Prell, Aleš; Sobotka, Miroslav; Kujan, Petr; Votruba, Jaroslav; Flieger, Miroslav

    Brooklyn, NY : Verlag, 2006, s. 15-15. [Natural Products Discovery and Production: New Challenges; New Opportunities. Santa Fe (US), 04.06.2006-08.06.2006] Grant ostatní: XE(XE) COOP-CT-2003-508169 BIOFERM Institutional research plan: CEZ:AV0Z50200510 Keywords : scale-up * bioreactors Subject RIV: EE - Microbiology, Virology

  7. Introducing Textiles as Material of Construction of Ethanol Bioreactors

    Directory of Open Access Journals (Sweden)

    Osagie A. Osadolor

    2014-11-01

    Full Text Available The conventional materials for constructing bioreactors for ethanol production are stainless and cladded carbon steel because of the corrosive behaviour of the fermenting media. As an alternative and cheaper material of construction, a novel textile bioreactor was developed and examined. The textile, coated with several layers to withstand the pressure, resist the chemicals inside the reactor and to be gas-proof was welded to form a 30 L lab reactor. The reactor had excellent performance for fermentative production of bioethanol from sugar using baker’s yeast. Experiments with temperature and mixing as process parameters were performed. No bacterial contamination was observed. Bioethanol was produced for all conditions considered with the optimum fermentation time of 15 h and ethanol yield of 0.48 g/g sucrose. The need for mixing and temperature control can be eliminated. Using a textile bioreactor at room temperature of 22 °C without mixing required 2.5 times longer retention time to produce bioethanol than at 30 °C with mixing. This will reduce the fermentation investment cost by 26% for an ethanol plant with capacity of 100,000 m3 ethanol/y. Also, replacing one 1300 m3 stainless steel reactor with 1300 m3 of the textile bioreactor in this plant will reduce the fermentation investment cost by 19%.

  8. Internal hydraulics of an agricultural drainage denitrification bioreactor

    Science.gov (United States)

    Denitrification bioreactors to reduce the amount of nitrate-nitrogen in agricultural drainage are now being deployed across the U.S. Midwest. However, there are still many unknowns regarding internal hydraulic-driven processes in these "black box" engineered treatment systems. To improve this unders...

  9. Optimising Microbial Growth with a Bench-Top Bioreactor

    Science.gov (United States)

    Baker, A. M. R.; Borin, S. L.; Chooi, K. P.; Huang, S. S.; Newgas, A. J. S.; Sodagar, D.; Ziegler, C. A.; Chan, G. H. T.; Walsh, K. A. P.

    2006-01-01

    The effects of impeller size, agitation and aeration on the rate of yeast growth were investigated using bench-top bioreactors. This exercise, carried out over a six-month period, served as an effective demonstration of the importance of different operating parameters on cell growth and provided a means of determining the optimisation conditions…

  10. Performance of Submerged Membrane Bioreactor for Domestic Wastewater Treatment

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the present research, a submerged membrane bioreactor was tested to treat domestic wastewater. Three experimental runs were conducted all with a hydraulic retention time of 5h and sludge retention times (SRTs) of 5, 10, and 20 d. The pollutant removal performance of the membrane bioreactor, the membrane effluent quality, and a kinetic model for sludge growth in the bioreactor were investigated. The combined process was capable of removing over 90% of both COD (chemical oxygen demand) and NH3-N on the average. The total removal for COD was almost independent of SRT, but that for NH3-N improved with increasing SRT. Membrane effluent quality meets the water quality standard for reuse issued by the Ministry of Construction of China. Increasing SRT causes the concentrations of suspended solids (SS) and volatile suspended solids (VSS) in the bioreactor to increase. However, the ratio of VSS/SS did not change much. Kinetic analysis showed that the sludge yield coefficient (kg-VSS·kg-COD-1) and the endogenous coefficient of microorganisms were 0.25 and 0.04d-1, which are similar to those of the conventional activated sludge process.

  11. Bioreactor landfill technology in municipal solid waste treatment: an overview.

    Science.gov (United States)

    Kumar, Sunil; Chiemchaisri, Chart; Mudhoo, Ackmez

    2011-03-01

    In recent years, due to an advance in knowledge of landfill behaviour and decomposition processes of municipal solid waste, there has been a strong thrust to upgrade existing landfill technologies for optimizing these degradation processes and thereafter harness a maximum of the useful bioavailable matter in the form of higher landfill gas generation rates. Operating landfills as bioreactors for enhancing the stabilization of wastes is one such technology option that has been recently investigated and has already been in use in many countries. A few full-scale implementations of this novel technology are gaining momentum in landfill research and development activities. The publication of bioreactor landfill research has resulted in a wide pool of knowledge and useful engineering data. This review covers leachate recirculation and stabilization, nitrogen transformation and corresponding extensive laboratory- and pilot-scale research, the bioreactor landfill concept, the benefits to be derived from this bioreactor landfill technology, and the design and operational issues and research trends that form the basis of applied landfill research. PMID:20578971

  12. Numerical study of fluid motion in bioreactor with two mixers

    International Nuclear Information System (INIS)

    Numerical study of hydrodynamic laminar behavior of a viscous fluid in bioreactor with multiple mixers is provided in the present paper. The reactor is equipped with two disk impellers. The fluid motion is studied in stream function-vorticity formulation. The calculations are made by a computer program, written in MATLAB. The fluid structure is described and numerical results are graphically presented and commented

  13. Hydraulic flow characteristics of agricultural residues for denitrifying bioreactor media

    Science.gov (United States)

    Denitrifying bioreactors are a promising technology to mitigate agricultural subsurface drainage nitrate-nitrogen losses, a critical water quality goal for the Upper Mississippi River Basin. This study was conducted to evaluate the hydraulic properties of agricultural residues that are potential bio...

  14. Numerical study of fluid motion in bioreactor with two mixers

    Science.gov (United States)

    Zheleva, I.; Lecheva, A.

    2015-10-01

    Numerical study of hydrodynamic laminar behavior of a viscous fluid in bioreactor with multiple mixers is provided in the present paper. The reactor is equipped with two disk impellers. The fluid motion is studied in stream function-vorticity formulation. The calculations are made by a computer program, written in MATLAB. The fluid structure is described and numerical results are graphically presented and commented.

  15. Numerical study of fluid motion in bioreactor with two mixers

    Energy Technology Data Exchange (ETDEWEB)

    Zheleva, I., E-mail: izheleva@uni-ruse.bg [Department of Heat Technology, Hydraulics and Ecology, Angel Kanchev University of Rousse, 8 Studentska str., 7017 Rousse (Bulgaria); Lecheva, A., E-mail: alecheva@uni-ruse.bg [Department of Mathematics, Angel Kanchev University of Rousse, 8 Studentska str., 7017 Rousse (Bulgaria)

    2015-10-28

    Numerical study of hydrodynamic laminar behavior of a viscous fluid in bioreactor with multiple mixers is provided in the present paper. The reactor is equipped with two disk impellers. The fluid motion is studied in stream function-vorticity formulation. The calculations are made by a computer program, written in MATLAB. The fluid structure is described and numerical results are graphically presented and commented.

  16. BIOREACTOR WITH LID FOR EASY ACCESS TO INCUBATION CAVITY

    OpenAIRE

    Fey, S J; Wrzesinski, Krzysztof

    2012-01-01

    There is provided a bioreactor which is provided with a lid (13) that facilitates access to the incubation cavity. Specifically the end wall of the incubation cavity is constituted by the lid (13) so that removal of the cap renders the incubation cavity fully accessible.

  17. MEASUREMENT OF FUGITIVE EMISSIONS AT A BIOREACTOR LANDFILL

    Science.gov (United States)

    This report focuses on three field campaigns performed in 2002 and 2003 to measure fugitive emissions at a bioreactor landfill in Louisville, KY, using an open-path Fourier transform infrared spectrometer. The study uses optical remote sensing-radial plume mapping. The horizontal...

  18. Reduced Order Dead-Beat Observers for a Bioreactor

    CERN Document Server

    Karafyllis, Iasson

    2010-01-01

    This paper studies the strong observability property and the reduced-order dead-beat observer design problem for a continuous bioreactor. New relationships between coexistence and strong observability, and checkable sufficient conditions for strong observability, are established for a chemostat with two competing microbial species. Furthermore, the dynamic output feedback stabilization problem is solved for the case of one species.

  19. Simulating woodchip bioreactor performance using a dual-porosity model

    Science.gov (United States)

    Nitrate in the Nation's surface waters has been a persistent health and ecological problem. The major source of nitrate is tile drainage from agricultural row crops. Denitrification bioreactors have been shown to be effective in removing much of the nitrate from tile drains. While we understand i...

  20. Anaerobic Membrane Bioreactors For Cost-Effective Municipal Water Reuse

    NARCIS (Netherlands)

    Özgün, H.

    2015-01-01

    In recent years, anaerobic membrane bioreactor (AnMBR) technology has been increasingly researched for municipal wastewater treatment as a means to produce nutrient-rich, solids free effluents with low levels of pathogens, while occupying a small footprint. An AnMBR can be used not only for on-site

  1. Adaptation of the autotrophic acetogen Sporomusa ovata to methanol accelerates the conversion of CO2 to organic products

    DEFF Research Database (Denmark)

    Tremblay, Pier-Luc; Höglund, Daniel; Koza, Anna;

    2015-01-01

    Acetogens are efficient microbial catalysts for bioprocesses converting C1 compounds into organic products. Here, an adaptive laboratory evolution approach was implemented to adapt Sporomusa ovata for faster autotrophic metabolism and CO2 conversion to organic chemicals. S. ovata was first adapted...... increased 5-fold. Furthermore, acetate production rate from CO2 with an electrode serving as the electron donor was increased 6.5-fold confirming that the acceleration of the autotrophic metabolism of the adapted strain is independent of the electron donor provided. Whole-genome sequencing, transcriptomic....... The results demonstrate that an efficient strategy to increase rates of CO2 conversion in bioprocesses like microbial electrosynthesis is to evolve the microbial catalyst by adaptive laboratory evolution to optimize its autotrophic metabolism....

  2. Metabolic potential of microbial mats and microbialites: Autotrophic capabilities described by an in silico stoichiometric approach from shared genomic resources.

    Science.gov (United States)

    Cerqueda-García, Daniel; Falcón, Luisa I

    2016-08-01

    Microbialites and microbial mats are complex communities with high phylogenetic diversity. These communities are mostly composed of bacteria and archaea, which are the earliest living forms on Earth and relevant to biogeochemical evolution. In this study, we identified the shared metabolic pathways for uptake of inorganic C and N in microbial mats and microbialites based on metagenomic data sets. An in silico analysis for autotrophic pathways was used to trace the paths of C and N to the system, following an elementary flux modes (EFM) approach, resulting in a stoichiometric model. The fragility was analyzed by the minimal cut sets method. We found four relevant pathways for the incorporation of CO2 (Calvin cycle, reverse tricarboxylic acid cycle, reductive acetyl-CoA pathway, and dicarboxylate/4-hydroxybutyrate cycle), some of them present only in archaea, while nitrogen fixation was the most important source of N to the system. The metabolic potential to incorporate nitrate to biomass was also relevant. The fragility of the network was low, suggesting a high redundancy of the autotrophic pathways due to their broad metabolic diversity, and highlighting the relevance of reducing power source. This analysis suggests that microbial mats and microbialites are "metabolic pumps" for the incorporation of inorganic gases and formation of organic matter. PMID:27324427

  3. Bioleaching mechanism of Zn, Pb, In, Ag, Cd and As from Pb/Zn smelting slag by autotrophic bacteria.

    Science.gov (United States)

    Wang, Jia; Huang, Qifei; Li, Ting; Xin, Baoping; Chen, Shi; Guo, Xingming; Liu, Changhao; Li, Yuping

    2015-08-15

    A few studies have focused on release of valuable/toxic metals from Pb/Zn smelting slag by heterotrophic bioleaching using expensive yeast extract as an energy source. The high leaching cost greatly limits the practical potential of the method. In this work, autotrophic bioleaching using cheap sulfur or/and pyrite as energy matter was firstly applied to tackle the smelting slag and the bioleaching mechanisms were explained. The results indicated autotrophic bioleaching can solubilize valuable/toxic metals from slag, yielding maximum extraction efficiencies of 90% for Zn, 86% for Cd and 71% for In, although the extraction efficiencies of Pb, As and Ag were poor. The bioleaching performance of Zn, Cd and Pb was independent of leaching system, and leaching mechanism was acid dissolution. A maximum efficiency of 25% for As was achieved by acid dissolution in sulfursulfur oxidizing bacteria (S-SOB), but the formation of FeAsO4 reduced extraction efficiency in mixed energy source - mixed culture (MS-MC). Combined works of acid dissolution and Fe(3+) oxidation in MS-MC was responsible for the highest extraction efficiency of 71% for In. Ag was present in the slag as refractory AgPb4(AsO4)3 and AgFe2S3, so extraction did not occur. PMID:25996622

  4. Interactions of the metal tolerant heterotrophic microorganisms and iron oxidizing autotrophic bacteria from sulphidic mine environment during bioleaching experiments.

    Science.gov (United States)

    Jeremic, Sanja; Beškoski, Vladimir P; Djokic, Lidija; Vasiljevic, Branka; Vrvić, Miroslav M; Avdalović, Jelena; Gojgić Cvijović, Gordana; Beškoski, Latinka Slavković; Nikodinovic-Runic, Jasmina

    2016-05-01

    Iron and sulfur oxidizing chemolithoautotrophic acidophilic bacteria, such as Acidithiobacillus species, hold the dominant role in mine environments characterized by low pH values and high concentrations of reduced sulfur and iron compounds, such as ores, rocks and acid drainage waters from mines. On the other hand, heterotrophic microorganisms, especially their biofilms, from these specific niches are receiving increased attention, but their potential eco-physiological roles have not been fully understood. Biofilms are considered a threat to human health, but biofilms also have beneficial properties as they are deployed in waste recycling and bioremediation systems. We have analyzed interactions of the metal tolerant heterotrophic microorganisms in biofilms with iron oxidizing autotrophic bacteria both from the sulphidic mine environment (copper mine Bor, Serbia). High tolerance to Cu(2+), Cd(2+) and Cr(6+) and the presence of genetic determinants for the respective metal tolerance and biofilm-forming ability was shown for indigenous heterotrophic bacteria that included strains of Staphylococcus and Rhodococcus. Two well characterized bacteria- Pseudomonas aeruginosa PAO1 (known biofilm former) and Cupriavidus metallidurans CH34 (known metal resistant representative) were also included in the study. The interaction and survivability of autotrophic iron oxidizing Acidithiobacillus bacteria and biofilms of heterotrophic bacteria during co-cultivation was revealed. Finally, the effect of heterotrophic biofilms on bioleaching process with indigenous iron oxidizing Acidithiobacillus species was shown not to be inhibitory under in vitro conditions. PMID:26942859

  5. Phototrophic Biofilm Assembly in Microbial-Mat-Derived Unicyanobacterial Consortia: Model Systems for the Study of Autotroph-Heterotroph Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Cole, Jessica K.; Hutchison, Janine R.; Renslow, Ryan S.; Kim, Young-Mo; Chrisler, William B.; Engelmann, Heather E.; Dohnalkova, Alice; Hu, Dehong; Metz, Thomas O.; Fredrickson, Jim K.; Lindemann, Stephen R.

    2014-04-07

    Though microbial autotroph-heterotroph interactions influence biogeochemical cycles on a global scale, the diversity and complexity of natural systems and their intractability to in situ environmental manipulation makes elucidation of the principles governing these interactions challenging. Examination of primary succession during phototrophic biofilm assembly provides a robust means by which to elucidate the dynamics of such interactions and determine their influence upon recruitment and maintenance of phylogenetic and functional diversity in microbial communities. We isolated and characterized two unicyanobacterial consortia from the Hot Lake phototrophic mat, quantifying the structural and community composition of their assembling biofilms. The same heterotrophs were retained in both consortia and included members of Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes, taxa frequently reported as consorts of microbial photoautotrophs. Cyanobacteria led biofilm assembly, eventually giving way to a late heterotrophic bloom. The consortial biofilms exhibited similar patterns of assembly, with the relative abundances of members of Bacteroidetes and Alphaproteobacteria increasing and members of Gammaproteobacteria decreasing as colonization progressed. Despite similar trends in assembly at higher taxa, the consortia exhibited substantial differences in community structure at the species level. These similar patterns of assembly with divergent community structures suggest that, while similar niches are created by the metabolism of the cyanobacteria, the resultant webs of autotroph-heterotroph and heterotroph-heterotroph interactions driving metabolic exchange are specific to each primary producer. Altogether, our data support these Hot Lake unicyanobacterial consortia as generalizable model systems whose simplicity and tractability permit the deciphering of community assembly principles relevant to natural microbial communities.

  6. Performance of a completely autotrophic nitrogen removal over nitrite process for treating wastewater with different substrates at ambient temperature

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Chang; Dong Li; Yuhai Liang; Zhuo Yang; Shaoming Cui; Tao Liu; Huiping Zeng

    2013-01-01

    The stability and parameters of a bio-ceramic filter for completely autotrophic nitrogen removal were investigated.The completely autotrophic nitrogen removal over nitrite (CANON) reactor was fed with different concentrations of ammonia (400,300,and 200 mg N/L) but constant influent ammonia load.The results showed that the CANON system can achieve good treatment performance at ambient temperature (15-23℃).The average removal rate and removal loading of NH4 +-N and TN was 83.90%,1.26 kg N/(m3.day),and 70.14%,1.09 kg N/(m3.day),respectively.Among the influencing factors like pH,dissolved oxygen and alkalinity,it was indicated that the pH was the key parameter of the performance of the CANON system.Observing the variation of pH would contribute to better control of the CANON system in an intuitive and fast way.Denaturing gradient gel electrophoresis analysis of microorganisms further revealed that there were some significant changes in the community structure of ammonium oxidizing bacteria,which had low diversity in different stages,while the species of anaerobic ammonium oxidizing (anammox) bacteria were fewer and the community composition was relatively stable.These observations showed that anaerobic ammonia oxidation was more stable than the aerobic ammonia oxidation,which could explain that why the CANON system maintained a good removal efficiency under the changing substrate conditions.

  7. Effect of inorganic carbon on the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor.

    Science.gov (United States)

    Chen, You-Peng; Li, Shan; Fang, Fang; Guo, Jin-Song; Zhang, Qiang; Gao, Xu

    2012-12-01

    Ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) are autotrophic microorganisms. Inorganic carbon (IC) is their main carbon source. The effects of IC limitation on AOB and AnAOB in the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor (SBBR) were examined. The optimal IC concentration in the influent was investigated. The start-up time of the CANON process from the activated sludge in the SBBR was 80 d under controlled free ammonia (FA) conditions and sufficient IC source. The AOB and AnAOB activities were limited by an IC concentration of 50 mg-C-L(-1) in the influent, whilst the nitrogen loading rate (NLR) was 200 mg-N x L(-1) x d(-1). The experiment on recovering the influent IC showed that AOB and AnAOB activities were affected by the IC limitation, and not by the pH or FA, at 200mg-N x L(-1) x d(-1) NLR and 50mg-C x L(-1) IC in the CANON process. The activities were recovered by increasing the IC concentration in the influent. From an economic point of view, the optimal IC concentration in the influent was 250mg-C x L(-1) at 200mg-N x L(-1) x d(-1) NLR in this CANON system. PMID:23437661

  8. Summer monsoon onset-induced changes of autotrophic pico- and nanoplankton in the largest monsoonal estuary along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Mohan, A.P.; Jyothibabu, R.; Jagadeesan, L.; Lallu, K.R.; Karnan, C.

        Environ. Monit. Assess., vol.188; 2016; no.93 doi: 10.1007/s10661-016-5096-7 Summer Monsoon Onset -induced Changes of Autotrophic Pico - and Nano - plankton in the Largest Monsoonal Estuary along the West Coast of India Arya P. Mohan, Jyothibabu, R...: Phytoplankton, Synechococcus, Prochlorococcus, Picoeukaryotes, Cochin Backwaters  2    1. Introduction Smaller autotrophic plankton consist of pico - (0.2 - 2 μm) and nano - (2 - 20 μm) size ranges inhabiting the euphotic ocean surface layer. Earlier studies...

  9. Potential autotrophic metabolisms in ultra-basic reducing springs associated with present-day continental serpentinization

    Science.gov (United States)

    Morrill, P. L.; Miles, S.; Kohl, L.; Kavanagh, H.; Ziegler, S. E.; Brazelton, W. J.; Schrenk, M. O.

    2013-12-01

    Ultra-basic reducing springs at continental sites of serpentinization act as windows into the biogeochemistry of this subsurface exothermic environment rich in H2 and CH4 gases. Biogeochemical carbon transformations in these systems are of interest because serpentinization creates conditions that are amenable to abiotic and biotic reduction of carbon. However, little is known about the metabolic capabilities of the microorganisms that live in this environment. To determine the potential for autotrophic metabolisms, bicarbonate and CO substrate addition microcosm experiments were performed using water and sediment from an ultra-basic reducing spring in the Tablelands, Newfoundland, Canada, a site of present-day continental serpentinization. CO was consistently observed to be utilized in the Live but not the Killed controlled replicates amended with 10% 13C labelled CO and non-labelled (natural C isotope abundance) CO. In the Live CO microcosms with natural C isotope abundance, the residual CO became enriched in 13C (~10 ‰) consistent with a decrease in the fraction of CO remaining. In the Killed CO controlled replicates with natural C isotope abundance the CO showed little 13C enrichment (~1.3 ‰). The data from the Live CO microcosms were well described by a Rayleigh isotopic distillation model, yielding an isotopic enrichment factor for microbial CO uptake of 15.7 ×0.5 ‰ n=2. These data suggest that there was microbial CO utilization in these experiments. The sediment and water from the 13C-labelled and non-labelled, Live and Killed microcosms were extracted for phospholipid fatty acids (PLFAs) to determine changes in community composition between treatments as well as to determine the microbial uptake of CO. The difference in community composition between the Live and Killed microcosms was not readily resolvable based on PLFA distributions. Additionally, the microbial uptake of 13CO had minimal to no affect on the δ13C of the cellular biomarkers, with the

  10. The effect of dissolved oxygen on N2O production by ammonia-oxidizing bacteria in an enriched nitrifying sludge.

    Science.gov (United States)

    Peng, Lai; Ni, Bing-Jie; Erler, Dirk; Ye, Liu; Yuan, Zhiguo

    2014-12-01

    Dissolved oxygen (DO) is commonly recognized as an important factor influencing nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB). However, it has been difficult to separate the true effect of DO from that of nitrite, as DO variation often affects nitrite accumulation. The effect of DO on N2O production by an enriched nitrifying sludge, consisting of both AOB and nitrite-oxidizing bacteria (NOB), was investigated in this study. Nitrite accumulation was minimised by augmenting nitrite oxidation through the addition of an enriched NOB sludge. It was demonstrated that the specific N2O production rate increased from 0 to 1.9 ± 0.09 (n = 3) mg N2O-N/hr/g VSS with an increase of DO concentration from 0 to 3.0 mg O2/L, whereas N2O emission factor (the ratio between N2O nitrogen emitted and the ammonium nitrogen converted) decreased from 10.6 ± 1.7% (n = 3) at DO = 0.2 mg O2/L to 2.4 ± 0.1% (n = 3) at DO = 3.0 mg O2/L. The site preference measurements indicated that both the AOB denitrification and hydroxylamine (NH2OH) oxidation pathways contributed to N2O production, and DO had an important effect on the relative contributions of the two pathways. This finding is supported by analysis of the process data using an N2O model describing both pathways. As DO increased from 0.2 to 3.0 mg O2/L, the contribution of AOB denitrification decreased from 92% - 95%-66% - 73%, accompanied by a corresponding increase in the contribution by the NH2OH oxidation pathway. PMID:25179869

  11. Optimization of operation conditions for the mitigation of nitrous oxide (N2O) emissions from aerobic nitrifying granular sludge system.

    Science.gov (United States)

    Liu, Rui-Ting; Wang, Xin-Hua; Zhang, Yan; Wang, Ming-Yu; Gao, Ming-Ming; Wang, Shu-Guang

    2016-05-01

    The optimization of operation parameters is a key consideration to minimize nitrous oxide (N2O) emissions in biological nitrogen removal processes. So far, different parameters have only been investigated individually, making it difficult to compare their specific effects and combined influences. In this study, we applied the Plackett-Burman (PB) multifactorial experimental design and response surface methodology (RSM) analysis to find the optimized condition for the mitigation of N2O release in a nitrifying granular sludge system. Seven parameters (temperature, pH, feeding strategy, C/N ratio, aeration rate, Cu(2+) concentration, and aeration mode) were tested in parallel. Five of them (other than chemical oxygen demand/nitrogen (C/N) ratio and Cu(2+) concentration) were selected as influential factors. Since the type of feeding strategies and aeration modes cannot be quantified, continuous feed strategy and anoxic/oxic aeration mode were applied for the following study. Influences of temperature, pH, and aeration rate on N2O emissions were tested with RSM analysis to further investigate the mutual interactions among the parameters and to identify the optimal values that would minimize N2O release. Results showed the minimum emission value could be obtained under the temperature of 22.3 °C, pH of 7.1 and aeration rate of 0.20 m(3)/h. Predicted results were then verified by subsequent validation experiments. The estimated N2O emission value of each design by RSM was also observed in good relationships with experimental result. PMID:26841778

  12. Different response of nitrifiers and denitrifiers to re-wetting shape the NO release from soils in laboratory incubation experiments

    Science.gov (United States)

    Behrendt, Thomas; Wu, Dianming; Song, Guozheng; Pommerenke, Bianca; Braker, Gesche

    2014-05-01

    Laboratory incubation studies incubating soils at a wide range of soil moistures, soil temperatures and mixing ratios of NO in the headspace and inorganic nutrient contents (NH4+,NO3-, NO2-) showed that release rates of NO follow an exponential function with increasing soil temperature and an optimum function for soil moisture. This approach assumes that environmental factors play the dominant role in shaping an ecosystem and thereby microbial communities and control the NO release from soil. We determined the NO release rate for a dryland farming soil under flooding irrigation in Xinjiang, China, a mid-latitude agricultural soil (Mainz, Germany), and a rice paddy (Ambai, India) upon wetting and subsequent drying out of soils. Only the release rate for the mid-latitude agricultural soil followed an optimum function for soil moisture. Release rates for the dryland farming soil and rice paddy, however, followed a two maxima function with distinct maxima at higher and lower soil moisture. Acknowledgement of two distinct maxima is critical for more accurately assessing regional biogenic NO emissions of soils under field conditions. To analyse the response of nitrifiers and denitrifiers involved in NO turnover in more detail we linked molecular analysis of functional gene expression (nirK and nirS, bacterial and archaeal amoA) and microbial community composition to NO release rates. We could show that the maximal transcriptional activity of denitrifiers and ammonia oxidizers differs with soil moisture and that higher transcriptional activity of nirS-type denitrifiers at higher soil moisture and of archaeal ammonia oxidizers at lower soil moisture may explain the two maxima for NO release.

  13. Diversity, Abundance, and Potential Activity of Nitrifying and Nitrate-Reducing Microbial Assemblages in a Subglacial Ecosystem

    Science.gov (United States)

    Skidmore, M. L.; Boyd, E. S.; Lange, R. K.; Mitchell, A. C.; Havig, J. R.; Hamilton, T. L.; Lafreniere, M. J.; Shock, E.; Peters, J.

    2011-12-01

    Ice currently covers 11% of the terrestrial landmass and has covered significantly greater portions of the planet during Earth's history. Significant microbial populations have been documented in all subglacial settings sampled to date. Recent research has demonstrated sizable volumes of subglacial sediment beneath the Antarctic Ice Sheet that are greater than 1km thick in places and where sampled active microbial populations have been documented. Collectively this suggests subglacial microbial populations may impact global biogeochemical cycles on glacial-interglacial timescales, however, nitrogen cycling in subglacial systems is poorly understood. Subglacial sediments sampled from beneath Robertson Glacier, Alberta, Canada harbor a diverse assemblage of potential nitrifiers, nitrate reducers, and diazotrophs, as assessed by amoA, narG, and nifH gene biomarker diversity. Archaeal amoA genes were less abundant and less diverse than bacterial amoA. Nitrification and nitrate reduction were measured in microcosms incubated at 4 degrees Celsius indicating the potential for these processes to occur in situ. Subglacial sediment porewaters and bulk meltwaters have low concentrations of dissolved inorganic and organic nitrogen compounds and a high C/N ratio of dissolved organic matter in sediment porewaters, indicating that the sediment communities are N limited. This may reflect the combined biological activities of organic N mineralization, nitrification, and nitrate reduction. Despite evidence for N limitation and detection of nifH, biological nitrogen fixation was not detected in subglacial sediment microcosm experiments at 4 degrees Celsius. Collectively, our results suggest a role for nitrification and nitrate reduction in sustaining microbial communities in subglacial environments.

  14. Anaerobic ammonium oxidation in a bioreactor treating slaughterhouse wastewater

    Directory of Open Access Journals (Sweden)

    V. Reginatto

    2005-12-01

    Full Text Available Ammonium oxidation was thought to be an exclusively aerobic process; however, as recently described in the literature, it is also possible under anaerobic conditions and this process was named ANAMMOX. This work describes the operation of a system consisting of a denitrifying reactor coupled to a nitrifying reactor used for removal of nitrogen from slaughterhouse wastewater. During operation of the denitrifying reactor an average nitrogen ammonium removal rate of 50 mg/Ld was observed. This biomass was used to seed a second reactor, operated in repeated fed batch mode, fed with synthetic medium specific to the growth of bacteria responsible for the ANAMMOX process. The nitrogen loading rate varied between 33 and 67 mgN/Ld and average nitrogen removal was 95% and 40%, respectively. Results of fluorescence in situ hybridization (FISH confirmed the presence of anammox-like microorganisms in the enriched biomass.

  15. The synergistic effects of dissolved oxygen and pH on N2O production in biological domestic wastewater treatment under nitrifying conditions.

    Science.gov (United States)

    Li, Pengzhang; Wang, Shuying; Peng, Yongzhen; Liu, Yue; He, Janzhong

    2015-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas, which is produced during nitrifying and denitrifying processes. Some factors and mechanisms affecting N2O emission have been reported in previous literature, but wastewater biological nitrification is accompanied by a dynamic process of dissolved oxygen (DO) consumption and pH reduction, it is more meaningful to study the synergistic effects between DO and pH on N2O production. In this study, the synergistic effects between DO and pH on N2O production were investigated with real domestic wastewater. The results showed that high DO levels and a high pH could improve the oxidation ratio of NH4+-N and the production ratio of NO2--N, while effectively reducing the accumulation ratio of N2O. The NH4+-N was a prerequisite for nitrifier denitrification; when NH4+-N was oxidized completely, there would be no N2O production and an even higher concentration of NO2- The pH factor is shown to directly affect N2O emission, although free ammonia and free nitrous acid which changed with pH had no correlation with N2O emission. There were two reasons: (1) pH can influence the flow direction of electrons afforded by NH2OH oxidation; at high pH, electrons were mainly used for combining H+ and O2 (O2+4H++4e-=2H2O), the accumulation of NO2- cannot be a result of denitrification, and a higher DO can get more electrons to prefer NO2- and (2) NH4+ was the prerequisite for NH2OH oxidation, since NH2OH oxidation process was the way to provide electrons for nitrifier denitrification. PMID:25619120

  16. Clinical scale rapid expansion of lymphocytes for adoptive cell transfer therapy in the WAVE® bioreactor

    Directory of Open Access Journals (Sweden)

    Somerville Robert PT

    2012-04-01

    Full Text Available Abstract Background To simplify clinical scale lymphocyte expansions, we investigated the use of the WAVE®, a closed system bioreactor that utilizes active perfusion to generate high cell numbers in minimal volumes. Methods We have developed an optimized rapid expansion protocol for the WAVE bioreactor that produces clinically relevant numbers of cells for our adoptive cell transfer clinical protocols. Results TIL and genetically modified PBL were rapidly expanded to clinically relevant scales in both static bags and the WAVE bioreactor. Both bioreactors produced comparable numbers of cells; however the cultures generated in the WAVE bioreactor had a higher percentage of CD4+ cells and had a less activated phenotype. Conclusions The WAVE bioreactor simplifies the process of rapidly expanding tumor reactive lymphocytes under GMP conditions, and provides an alternate approach to cell generation for ACT protocols.

  17. Production of bacterial cellulose membranes in a modified airlift bioreactor by Gluconacetobacter xylinus.

    Science.gov (United States)

    Wu, Sheng-Chi; Li, Meng-Hsun

    2015-10-01

    In this study, a novel bioreactor for producing bacterial cellulose (BC) is proposed. Traditional BC production uses static culture conditions and produces a gelatinous membrane. The potential for using various types of bioreactor, including a stirred tank, conventional airlift, and modified airlift with a rectangular wire-mesh draft tube, in large-scale production has been investigated. The BC obtained from these bioreactors is fibrous or in pellet form. Our proposed airlift bioreactor produces a membrane-type BC from Gluconacetobacter xylinus, the water-holding capacity of which is greater than that of cellulose types produced using static cultivation methods. The Young's modulus of the product can be manipulated by varying the number of net plates in the modified airlift bioreactor. The BC membrane produced using the proposed bioreactor exhibits potential for practical application. PMID:25823854

  18. Characterization of organic membrane foulants in a forward osmosis membrane bioreactor treating anaerobic membrane bioreactor effluent.

    Science.gov (United States)

    Ding, Yi; Tian, Yu; Li, Zhipeng; Liu, Feng; You, Hong

    2014-09-01

    In this study, two aerobic forward osmosis (FO) membrane bioreactors (MBR) were utilized to treat the effluent of mesophilic (35°C) and atmospheric (25°C) anaerobic MBRs, respectively. The results showed that the FO membrane process could significantly improve the removal efficiencies of N and P. Meanwhile, the flux decline of the FOMBR treating effluent of mesophilic AnMBR (M-FOMBR) was higher than that treating effluent of atmospheric AnMBR (P-FOMBR). The organic membrane foulants in the two FOMBRs were analyzed to understand the membrane fouling behavior in FO processes. It was found that the slightly increased accumulation of protein-like substances into external foulants did not cause faster flux decline in P-FOMBR than that in M-FOMBR. However, the quantity of organic matter tended to deposit or adsorb into FO membrane pores in P-FOMBR was less than that in M-FOMBR, which was accordance with the tendency of membrane fouling indicated by flux decline. PMID:24976492

  19. Sludge Bulking Property of Membrane Bio-reactor in Albumen Wqastewater Treatment

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Albumen wastewater was treated by Membrane Bio-reactor. Sludge bulking property of Membrane Bio-Reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in Membrane Bio-reactor increased slightly under the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures,the higher block rate of membrane pore and the great quantity of filamentous bacteria at the externalsurface pres...

  20. Rheological characterization of mixed liquor in a submerged membrane bioreactor: Interest for process management

    OpenAIRE

    Van Kaam, Romuald; Anne-Archard, Dominique; Alliet-Gaubert, Marion; Albasi, Claire

    2008-01-01

    Rheological analyses of a submerged membrane bioreactor mixed liquor were performed in the aim of characterizing the mixed liquor present in the bioreactor and thus proposing a process management. These analyses pointed out that the mixed liquor was characterized by its viscoplastic property, which leads to a possible restructuring ability when a shear stress lower than the yield stress is applied. As the shear stress in the bioreactor is essentially generated by coarse bubbles, specific expe...

  1. Biodegradation of Trichloroethylene in Continuous-Recycle Expanded-Bed Bioreactors

    OpenAIRE

    Phelps, T. J.; Niedzielski, J. J.; Schram, R M; Herbes, S. E.; White, D. C.

    1990-01-01

    Experimental bioreactors operated as recirculated closed systems were inoculated with bacterial cultures that utilized methane, propane, and tryptone-yeast extract as aerobic carbon and energy sources and degraded trichloroethylene (TCE). Up to 95% removal of TCE was observed after 5 days of incubation. Uninoculated bioreactors inhibited with 0.5% Formalin and 0.2% sodium azide retained greater than 95% of their TCE after 20 days. Each bioreactor consisted of an expanded-bed column through wh...

  2. An Update to Space Biomedical Research: Tissue Engineering in Microgravity Bioreactors

    OpenAIRE

    Abolfazl Barzegari; Amir Ata Saei

    2012-01-01

    Introduction: The severe need for constructing replacement tissues in organ transplantation has necessitated the development of tissue engineering approaches and bioreactors that can bring these approaches to reality. The inherent limitations of conventional bioreactors in generating realistic tissue constructs led to the devise of the microgravity tissue engineering that uses Rotating Wall Vessel (RWV) bioreactors initially developed by NASA. Methods: In this review article, we intend to hig...

  3. [Adaptation of coimmobilized Rhodococcus cells to oil hydrocarbons in a column bioreactor].

    Science.gov (United States)

    Serebrennikova, M K; Kuiukina, M S; Krivoruchko, A V; Ivshina, I B

    2014-01-01

    The possible adaptation of the association of Rhodococcus ruber and Rhodococcus opacus strains immobilized on modified sawdust to oil hydrocarbons in a column bioreactor was investigated. In the bioreactor, the bacterial population showed higher hydrocarbon and antibiotic resistance accompanied by the changes in cell surface properties (hydrophobicity, electrokinetic potential) and in the content of cellular lipids and biosurfactants. The possibility of using adapted Rhodococcus strains for the purification of oil-polluted water in the bioreactor was demonstrated. PMID:25757338

  4. Imaging Analysis of the In vivo Bioreactor: A Preliminary Study

    OpenAIRE

    Holt, Ginger E.; Halpern, Jennifer L.; Lynch, Conor C.; Devin, Clinton J; Schwartz, Herbert S.

    2008-01-01

    The in vivo bioreactor is a hermetically sealed, acellular hydroxyapatite scaffold coated with growth factors that has a pulsating vascular pedicle leash threaded through its center. Tissue-engineered bone is created in weeks while the bioreactor remains embedded under the skin of an animal. The bioreactor also provides a model to study osteogenesis and pathologic scenarios such as tumor progression and metastasis by creating a controlled microenvironment that makes skeletogenesis amenable to...

  5. Mathematical modeling and experimental testing of three bioreactor configurations based on windkessel models

    OpenAIRE

    Genevieve Lachance; Jean Ruel

    2010-01-01

    This paper presents an experimental study of three bioreactor configurations. The bioreactor is intended to be used for the development of tissue-engineered heart valve substitutes. Therefore it must be able to reproduce physiological flow and pressure waveforms accurately. A detailed analysis of three bioreactor arrangements is presented using mathematical models based on the windkessel (WK) approach. First, a review of the many applications of this approach in medical studies enhances its f...

  6. High cell density and productivity culture of Chinese hamster ovary cells in a fluidized bed bioreactor

    OpenAIRE

    Kong, D.; Cardak, S.; Chen, M.; Gentz, R; Zhang, J.

    1999-01-01

    A recombinant Chinese hamster ovary clone was cultivated in a 2L Cytopilot Mini fluidized bed bioreactor using Cytoline 1 microcarriers and a 10L B. Braun stirred tank bioreactor with Cytodex 1 microcarriers. Cytoline 1 is a macroporous polyethylene microcarrier and Cytodex 1 is a solid DEAE-dextran microcarrier. Cytoline 1 microcarriers in the fluidized bed bioreactor were gently mixed by an uplifting flow. Circulation and sparging in Cytopilot Mini were separated from the fluidized microcar...

  7. Regulation of Autotrophic and Heterotrophic Metabolism in Pseudomonas oxalaticus OX1. Growth on Fructose and on Mixtures of Fructose and Formate in Batch and Continuous Cultures

    NARCIS (Netherlands)

    Dijkhuizen, L.; Harder, W.

    1984-01-01

    In Pseudomonas oxalaticus the synthesis of enzymes involved in autotrophic CO2 fixation via the Calvin cycle is regulated by repression/derepression. During growth of the organism on fructose alone, the synthesis of ribulosebisphosphate carboxylase (RuBPCase) remained fully repressed, both in batch

  8. Formaldehyde as a carbon and electron shuttle between autotroph and heterotroph populations in acidic hydrothermal vents of Norris Geyser Basin, Yellowstone National Park.

    Science.gov (United States)

    Moran, James J; Whitmore, Laura M; Isern, Nancy G; Romine, Margaret F; Riha, Krystin M; Inskeep, William P; Kreuzer, Helen W

    2016-05-01

    The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonensis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with (13)C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community. PMID:26995682

  9. Aeration control by monitoring the microbiological activity using fuzzy logic diagnosis and control. Application to a complete autotrophic nitrogen removal reactor

    DEFF Research Database (Denmark)

    Boiocchi, Riccardo; Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine;

    2015-01-01

    microbial groups on the other hand, the diagnosis provides information on: nitritation, nitratation, anaerobic ammonium oxidation and overall autotrophic nitrogen removal. These four results give insight into the state of the process and are used as inputs for the controller that manipulates the aeration to...

  10. Formaldehyde as a carbon and electron shuttle between autotroph and heterotroph populations in acidic hydrothermal vents of Norris Geyser Basin, Yellowstone National Park

    Energy Technology Data Exchange (ETDEWEB)

    Moran, James J.; Whitmore, Laura M.; Isern, Nancy G.; Romine, Margaret F.; Riha, Krystin M.; Inskeep, William P.; Kreuzer, Helen W.

    2016-03-19

    The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonesis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with 13C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community.

  11. Bacterial study of the anaerobic bioreactor for distillery effluent

    International Nuclear Information System (INIS)

    This study relates with anaerobic bioreactors of Habib Sugar Mills, Nawabshah. Bacterial growth was studied through microscope along with its effect on the production of methane gas (Biogas) at all HRTs (Hydraulic Retention Times) between 15 and 28 days. The bacterium has the efficiency to convert 12% glucose within 24 hours to final product and cell mass. The acetogenic organisms also show their maximum growth on glucose in BGP-1 and BPG-2 at both the corks, where as Methanogenic organisms have shown their zero shown their zero growth on glucose. The efforts have been taken to determine the methanogenic, acetogenic and syntrophomonas sp. data of anaerobic bioreactors of BGP (Biogas Plant) I and II, when these samples were cultured on acetate, methanol, formate, butyrate, propionate and glucose. (author)

  12. Treatment of textile wastewater with membrane bioreactor: A critical review.

    Science.gov (United States)

    Jegatheesan, Veeriah; Pramanik, Biplob Kumar; Chen, Jingyu; Navaratna, Dimuth; Chang, Chia-Yuan; Shu, Li

    2016-03-01

    Membrane bioreactor (MBR) technology has been used widely for various industrial wastewater treatments due to its distinct advantages over conventional bioreactors. Treatment of textile wastewater using MBR has been investigated as a simple, reliable and cost-effective process with a significant removal of contaminants. However, a major drawback in the operation of MBR is membrane fouling, which leads to the decline in permeate flux and therefore requires membrane cleaning. This eventually decreases the lifespan of the membrane. In this paper, the application of aerobic and anaerobic MBR for textile wastewater treatment as well as fouling and control of fouling in MBR processes have been reviewed. It has been found that long sludge retention time increases the degradation of pollutants by allowing slow growing microorganisms to establish but also contributes to membrane fouling. Further research aspects of MBR for textile wastewater treatment are also considered for sustainable operations of the process. PMID:26776150

  13. Sensor equipment for quantification of spatial heterogeneity in large bioreactor

    DEFF Research Database (Denmark)

    Nørregaard, Anders; Formenti, Luca Riccardo; Stocks, Stuart M.;

    cannot be directly compared to laboratory scale experiments due to these reasons, and thus, in order to understand the large scale processes, experimental data has to be collected at large scale. The cost of acquiring data at large scale is high. The bioreactors are usually run with a limited array of...... sensors and in order to apply more sensor equipment the bioreactor has to be modified which is both costly and results in production downtime. The presence of three phases (gas, liquid, and solid), and the opaque nature of the fermentation broth together with the necessity of heat sterilization further...... increases the requirements to the sensor equipment. In order to address these issues this study aims to make an investigation into freely floating, battery driven sensor particles that can follow the liquid movement in the reactor and make measurements while being distributed in the whole volume of the...

  14. Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

    Directory of Open Access Journals (Sweden)

    Awad Abdelgadir

    2014-01-01

    Full Text Available The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB, namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT, Organic Loading Rate (OLR, and sludge retention time (SRT were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive.

  15. Hydrodynamic characterization of a column-type prototype bioreactor.

    Science.gov (United States)

    Espinosa-Solares, Teodoro; Morales-Contreras, Marcos; Robles-Martínez, Fabián; García-Nazariega, Melvin; Lobato-Calleros, Consuelo

    2008-03-01

    Agro-food industrial processes produce a large amount of residues, most of which are organic. One of the possible solutions for the treatment of these residues is anaerobic digestion in bioreactors. A novel 18-L bioreactor for treating waste water was designed based on pneumatic agitation and semispherical baffles. Flow patterns were visualized using the particle tracer technique. Circulation times were measured with the particle tracer and the thermal technique, while mixing times were measured using the thermal technique. Newtonian fluid and two non-Newtonian fluids were used to simulate the operational conditions. The results showed that the change from Newtonian to non-Newtonian properties reduces mixed zones and increases circulation and mixing times. Circulation time was similar when evaluated with the thermal and the tracer particle methods. It was possible to predict dimensionless mixing time (theta (m)) using an equivalent Froude number (Fr (eq)). PMID:18401759

  16. Enhancing inhibited fermentations through a dynamic electro-membrane bioreactor

    DEFF Research Database (Denmark)

    Prado Rubio, Oscar Andres; Garde, Arvid; Rype, Jens-Ulrik;

    challenging operation is associated with different dynamic behaviors of the individual units plus their interaction. The purpose of this contribution is to show the results of experimental and model based efforts done in order to investigate the operation of a membrane bioreactor. From modeling point of view...... technology ensures long operation time by reversing periodically the polarity of the imposed electrical field to significantly reduce the influence of membrane fouling. The periodic nature of the electrically driven membrane separation process makes the membrane bioreactor operation non trivial. This......, it is interesting to reveal to which extend the REED module can facilitate the pH control in the fermenter. In this case, the membrane and reactor unit interactions are exploited to substantially increase the lactate productivity and substrate utilization compared to a conventional fermentation with...

  17. Biological nitrogen removal using a submerged membrane bioreactor system

    International Nuclear Information System (INIS)

    A pilot-scale study was conducted using ZenoGem hollow-fiber microfiltration membrane bioreactor system to investigate the performance of membrane bioreactor process to remove nitrogen from primary effluent at a municipal wastewater treatment plant. Different operating conditions were examined by varying hydraulic retention time (HRT) and sludge retention time (SRT) between 5-8 h and 20-50 days, respectively. In addition, a series of laboratory batch tests were performed to measure the biodegradation kinetic and stoichiometric parameters under the conditions consistent with the pilot testing. The results showed that the process achieved removal efficiencies of 80-98% for COD, 93%-99% for BOD5, and 70-93% for nitrogen. The efficiency and kinetics of COD and nitrogen removal would change greatly from one operating condition to another. However, the measured kinetic parameters still fell within the typical range of those reported in the literature using Activated Sludge Models (ASM)

  18. The Potential for Microalgae as Bioreactors to Produce Pharmaceuticals

    OpenAIRE

    Na Yan; Chengming Fan; Yuhong Chen; Zanmin Hu

    2016-01-01

    As photosynthetic organisms, microalgae can efficiently convert solar energy into biomass. Microalgae are currently used as an important source of valuable natural biologically active molecules, such as carotenoids, chlorophyll, long-chain polyunsaturated fatty acids, phycobiliproteins, carotenoids and enzymes. Significant advances have been achieved in microalgae biotechnology over the last decade, and the use of microalgae as bioreactors for expressing recombinant proteins is receiving incr...

  19. Gel layer formation on membranes in Membrane Bioreactors

    OpenAIRE

    Van den Brink, P.F.H.

    2014-01-01

    The widespread application of membrane bioreactors (MBRs) for municipal wastewater treatment is hampered by membrane fouling. Fouling increases energy demand, reduces process performance and creates the need for more frequent (chemical) membrane cleaning or replacement. Membrane fouling in MBRs is known to be caused by several membrane fouling mechanisms. Extracellular polymeric substances (EPS) play a major role during fouling development. However, EPS concentration in the bulk solution can ...

  20. Mammalian cell retention devices for stirred perfusion bioreactors

    OpenAIRE

    Woodside, Steven M.; Bowen, Bruce D.; Piret, James M.

    1998-01-01

    Within the spectrum of current applications for cell culture technologies, efficient large-scale mammalian cell production processes are typically carried out in stirred fed-batch or perfusion bioreactors. The specific aspects of each individual process that can be considered when determining the method of choice are presented. A major challenge for perfusion reactor design and operation is the reliability of the cell retention device. Current retention systems include cross-flow membrane fil...

  1. ANAEROBIC MEMBRANE BIOREACTORS FOR DOMESTIC WASTEWATER TREATMENT. PRELIMINARY STUDY

    OpenAIRE

    Luisa Vera; Ignacio Ruigómez; Enrique González; Paula Bodelón; Juan Rodríguez-Sevilla

    2014-01-01

    The operation of submerged anaerobic membrane bioreactors (SAnMBRs) for domestic wastewaters treatment was studied in laboratory scale, with the objective to define sustainable filtration conditions of the suspensions along the process. During continuous experiments, the organic matter degradation by anaerobic way showed an average DQOT removal of 85% and 93%. Indeed, the degradation generated biogas after 12 days of operation and its relative methane composition was of 60% after 25 days of o...

  2. Bacteriorhodopsin as a Possible Element of Membrane Bioreactors

    Science.gov (United States)

    Maksimychev, A. V.; Chamorovskii, S. K.

    1988-06-01

    Certain approaches to the creation of membrane bioreactors, representing an example of integrated membrane systems, are examined. The characteristic features of the use of organised molecular assemblies in such systems as sensor and regulatory elements are discussed. The properties of the retinal-protein complex of bacteriorhodopsin as a promising component of integrated membrane systems, capable of carrying out regulatory functions, are examined. The bibliography includes 139 references.

  3. Membrane life estimation in full-scale immersed membrane bioreactors

    OpenAIRE

    Ayala, D. F.; Ferre, V; Judd, Simon J.

    2011-01-01

    Limited quantitative available information exists regarding the robustness of membranes used in immersed membrane bioreactor (iMBR) applications, and no information on the relative contribution of the two main membrane failure modes of permeability and integrity loss. Such information is crucial given the significance of membrane replacement costs to the viability and sustainability of iMBRs. Measurements of membrane permeability and integrity have been made on flat sheet (F...

  4. Automated HPLC monitoring of broth components on bioreactors

    OpenAIRE

    Favre, Eric; Pugeaud, Patrick; Raboud, Jean Philippe; Péringer, Paul

    1989-01-01

    Under proper operating conditions, a low dead volume continuous filtration module operated on biological broths (yeast and bacteria suspensions in stirred reactors) still fulfills the flow-rate requirements of an analytical apparatus (for example HPLC or FIA) without membrane regeneration. The filtrate stream has been successfully connected to a bioreactor in order to perform the automated HPLC analysis of broth components. The monitoring of the carbon source (lactose), and minor products (gl...

  5. Computational Model for Microbubble Enhanced Performance of Airlift Bioreactor (ALB)

    OpenAIRE

    Ng, W C; Brittle, S.; Howell, R; W. B. Zimmerman

    2014-01-01

    This paper presents a computational model for microbubble enhanced performance of an airlift bioreactor (ALB). Five different bubble diameters were defined in the model under the same conditions (440 µm to 1 mm bubble diameter). The computational model parameters and the size of the ALB were defined by referring to experimental work done previously. The main objective of the model is to study the effect of bubble size on the rising velocity and the liquid flow velocity in the airlift reactor...

  6. Mathematical interpretation of mass transfer process in anaerobic bioreactors

    OpenAIRE

    Ружинская, Людмила Ивановна; Фоменкова, Анастасия Алексеевна

    2013-01-01

    The article considers the methanogenesis in bioreactors with immobilized microflora on fixed media. The processes of decomposition of organic pollution of the wastewater and the formation of metabolic products are analyzed. At the same time, the decomposition of organic pollution is considered from the standpoint of a two-stage process. As the first stage, the hydrolysis and acid production is considered, as the second - methanogenesis. On the basis of this process the spatial distribution of...

  7. A Novel Seeding and Conditioning Bioreactor for Vascular Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Julia Schulte

    2014-07-01

    Full Text Available Multiple efforts have been made to develop small-diameter tissue engineered vascular grafts using a great variety of bioreactor systems at different steps of processing. Nevertheless, there is still an extensive need for a compact all-in-one system providing multiple and simultaneous processing. The aim of this project was to develop a new device to fulfill the major requirements of an ideal system that allows simultaneous seeding, conditioning, and perfusion. The newly developed system can be actuated in a common incubator and consists of six components: a rotating cylinder, a pump, a pulse generator, a control unit, a mixer, and a reservoir. Components that are in direct contact with cell media, cells, and/or tissue allow sterile processing. Proof-of-concept experiments were performed with polyurethane tubes and collagen tubes. The scaffolds were seeded with fibroblasts and endothelial cells that were isolated from human saphenous vein segments. Scanning electron microscopy and immunohistochemistry showed better seeding success of polyurethane scaffolds in comparison to collagen. Conditioning of polyurethane tubes with 100 dyn/cm2 resulted in cell detachments, whereas a moderate conditioning program with stepwise increase of shear stress from 10 to 40 dyn/cm2 induced a stable and confluent cell layer. The new bioreactor is a powerful tool for quick and easy testing of various scaffold materials for the development of tissue engineered vascular grafts. The combination of this bioreactor with native tissue allows testing of medical devices and medicinal substances under physiological conditions that is a good step towards reduction of animal testing. In the long run, the bioreactor could turn out to produce tissue engineered vascular grafts for human applications “at the bedside”.

  8. Transport Advances in Disposable Bioreactors for Liver Tissue Engineering

    Science.gov (United States)

    Catapano, Gerardo; Patzer, John F.; Gerlach, Jörg Christian

    Acute liver failure (ALF) is a devastating diagnosis with an overall survival of approximately 60%. Liver transplantation is the therapy of choice for ALF patients but is limited by the scarce availability of donor organs. The prognosis of ALF patients may improve if essential liver functions are restored during liver failure by means of auxiliary methods because liver tissue has the capability to regenerate and heal. Bioartificial liver (BAL) approaches use liver tissue or cells to provide ALF patients with liver-specific metabolism and synthesis products necessary to relieve some of the symptoms and to promote liver tissue regeneration. The most promising BAL treatments are based on the culture of tissue engineered (TE) liver constructs, with mature liver cells or cells that may differentiate into hepatocytes to perform liver-specific functions, in disposable continuous-flow bioreactors. In fact, adult hepatocytes perform all essential liver functions. Clinical evaluations of the proposed BALs show that they are safe but have not clearly proven the efficacy of treatment as compared to standard supportive treatments. Ambiguous clinical results, the time loss of cellular activity during treatment, and the presence of a necrotic core in the cell compartment of many bioreactors suggest that improvement of transport of nutrients, and metabolic wastes and products to or from the cells in the bioreactor is critical for the development of therapeutically effective BALs. In this chapter, advanced strategies that have been proposed over to improve mass transport in the bioreactors at the core of a BAL for the treatment of ALF patients are reviewed.

  9. Denitrification 'Woodchip' Bioreactors for Productive and Sustainable Agricultural Systems

    Science.gov (United States)

    Christianson, L. E.; Summerfelt, S.; Sharrer, K.; Lepine, C.; Helmers, M. J.

    2014-12-01

    Growing alarm about negative cascading effects of reactive nitrogen in the environment has led to multifaceted efforts to address elevated nitrate-nitrogen levels in water bodies worldwide. The best way to mitigate N-related impacts, such as hypoxic zones and human health concerns, is to convert nitrate to stable, non-reactive dinitrogen gas through the natural process of denitrification. This means denitrification technologies need to be one of our major strategies for tackling the grand challenge of managing human-induced changes to our global nitrogen cycle. While denitrification technologies have historically been focused on wastewater treatment, there is great interest in new lower-tech options for treating effluent and drainage water from one of our largest reactive nitrogen emitters -- agriculture. Denitrification 'woodchip' bioreactors are able to enhance this natural N-conversion via addition of a solid carbon source (e.g., woodchips) and through designs that facilitate development of anoxic conditions required for denitrification. Wood-based denitrification technologies such as woodchip bioreactors and 'sawdust' walls for groundwater have been shown to be effective at reducing nitrate loads in agricultural settings around the world. Designing these systems to be low-maintenance and to avoid removing land from agricultural production has been a primary focus of this "farmer-friendly" technology. This presentation provides a background on woodchip bioreactors including design considerations, N-removal performance, and current research worldwide. Woodchip bioreactors for the agricultural sector are an accessible new option to address society's interest in improving water quality while simultaneously allowing highly productive agricultural systems to continue to provide food in the face of increasing demand, changing global diets, and fluctuating weather.

  10. The determination and origin of fibre clogging in membrane bioreactors

    OpenAIRE

    Stefanski, M.; Kennedy, S.; Judd, Simon J.

    2011-01-01

    Membrane channel clogging in membrane bioreactors (MBRs) has been largely unexplored by the research community, despite it being widely recognised as the main impediment to sustainable MBR operation by practitioners, and reflects the difficulty of examining clogging with the same scientific rigour as membrane fouling. The incidence of clogging/“ragging” has been assessed across 10–12 full-scale flat sheet immersed MBRs, equipped with inlet screens of similar rating, and ...

  11. Biological treatment and thickening with a hollow fibre membrane bioreactor

    OpenAIRE

    Zsirai, T.; Wang, Z-Z.; Gabarrón, S.; Connery, K.; Fabiyi, M.; Larrea, A.; Judd, Simon J.

    2014-01-01

    Aerobic operation of an immersed hollow fibre membrane bioreactor, treating municipal wastewater supplemented with molasses solution, has been studied across mixed liquor suspended solids (MLSS) concentrations between 8 and 32 g L-1, the higher concentrations being normally associated with thickening operations. Only a marginal loss in membrane permeability was noted between 8 and 18 g L-1 when operation was conducted without clogging. The sustainable operational flux attainable above 18 g L-...

  12. Bubble Bed Bioreactor Malfunctions Revealed by Computational Flow Simulation Analysis

    Czech Academy of Sciences Publication Activity Database

    Fialová, Marie; Staykov, P.; Vlaev, S. D.

    Bratislava: Slovak University of Technology, 2009 - (Markoš, J.), s. 351 ISBN 978-80-227-3072-3. [International Conference of Slovak Society of Chemical Engineering /36./. Tatranské Matliare (SK), 25.05.2009-29.05.2009] R&D Projects: GA ČR GA104/07/1110 Institutional research plan: CEZ:AV0Z40720504 Keywords : bubble column bioreactor * gas holdup * CFD Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  13. Analysis and control of an anaerobic upflow Fixed bed bioreactor

    International Nuclear Information System (INIS)

    This paper presents the bifurcation analysis in an anaerobic upflow fixed bed bioreactor, which is an anaerobic digestion system useful for wastewater treatment. In the dynamic analysis part, the equilibrium points, linear stability and bifurcation curves are studied, focusing in the washout condition. For the self tuning regulator the parameter estimation and control law are designed, and an integral action is introduced in order to address the disturbances. The simulation studies show the improvement of the performance when a disturbance appears.

  14. Video of Tissue Grown in Space in NASA Bioreactor

    Science.gov (United States)

    2003-01-01

    Principal investigator Leland Chung grew prostate cancer and bone stromal cells aboard the Space Shuttle Columbia during the STS-107 mission. Although the experiment samples were lost along with the ill-fated spacecraft and crew, he did obtain downlinked video of the experiment that indicates the enormous potential of growing tissues in microgravity. Cells grown aboard Columbia had grown far larger tissue aggregates at day 5 than did the cells grown in a NASA bioreactor on the ground.

  15. Micropollutants removal and tecnological development of membrane bioreactors

    OpenAIRE

    Santos, Ana

    2010-01-01

    The increasing worldwide contamination of aquatic environment with pollutants introduced by anthropogenic sources has become of great concern. Although present at low concentration, many of these pollutants have considerable long-term impacts on the ecosystem, such that extremely challenging legislative limits on their concentration in effluents are being proposed. This has led to the examination of membrane bioreactor (MBR) technology for wastewater treatment, since it offers ...

  16. Startup and stabilization of anaerobic membrane bioreactors at ambient temperature

    OpenAIRE

    Benito Peña, Carlos

    2015-01-01

    There has been an increasing interest in wastewater treatment in last decades to reduce human footprint. Primarily, anaerobic technology focused on treatment and stabilization of sludge, but now the tendency is to give it a major role in low cost treatment of high/low strength wastewaters, since anaerobic digestion offers energy generation through gas production. Anaerobic membrane bioreactors (AnMBR) combine anaerobic digestion with membrane filtration. They are becoming a feasible opti...

  17. Cytotoxicity micropollutant removal in a crossflow membrane bioreactor

    OpenAIRE

    Delgado, Luis Fernando; Faucet-Marquis, Virginie; Pfohl-Leszkowicz, Annie; Dorandeu, Christophe; Marion, Bénédicte; Schetrite, Sylvie; Albasi, Claire

    2011-01-01

    The application of membrane bioreactor (MBR) technology was investigated with the aim of evaluating its potential for cytostatic drug and cytotoxicity bioremoval. The toxicity removal was assessed from biomarker test. CP removal of up to 80% was achieved under the operating conditions studied (HRT of 48 h and a SRT of 50 days). The increase of TMP was associated with an increase of supernatant toxicity as if fouling led to retention of the toxicity. Peaks of supernatant cytotoxicity were corr...

  18. Analysis of fouling mechanisms in anaerobic membrane bioreactors

    OpenAIRE

    Charfi, Amine; Ben Amar, Nihel; Harmand, Jérôme

    2012-01-01

    In this paper, we investigate the fouling mechanisms responsible for MF and UF membrane flux decline in Anaerobic Membrane Bioreactors (AnMBR). We have used the fouling mechanism models proposed by Hermia (1982), namely pore constriction, cake formation, complete blocking and intermediate blocking. Based on an optimization approach and using experimental data extracted from the literature, we propose a systematic procedure for identifying the most likely fouling mechanism in play. Short-term ...

  19. Anaerobic membrane bioreactors for wastewater treatment: feasibility and potential applications

    OpenAIRE

    Jeison, D.A.

    2007-01-01

    Biomass retention is a necessary feature for the successful application of anaerobic digestion for wastewater treatment. Biofilms and granule formation are the traditional way to achieve such retention, enabling reactor operation at high biomass concentrations, and therefore at high organic loading rates. Membrane filtration represents an alternative way to achieve biomass retention. In membrane bioreactors, complete biomass retention can be achieved, irrespective of cells capacity to form bi...

  20. Effects of dissolved oxygen on microbial community of single-stage autotrophic nitrogen removal system treating simulating mature landfill leachate.

    Science.gov (United States)

    Wen, Xin; Zhou, Jian; Wang, Jiale; Qing, Xiaoxia; He, Qiang

    2016-10-01

    The performance of four identical sequencing biofilm batch reactors (SBBR) for autotrophic nitrogen removal was investigated with 2000mg/L ammonia-containing mature landfill leachate at 30°C. The main objective of this study was to evaluate the effects of dissolved oxygen (DO) on the performance and microbial community of single-stage nitrogen removal using anammox and partial nitritation (SNAP) system. At an applied load of 0.5kgNm(-3)d(-1), average total nitrogen removal efficiency (TNRE) above 90% was long-term achieved with an optimal DO concentration of 2.7mg/L. The microelectrode-measured profiles showed the microenvironments inside the biofilms. 16S ribosomal Ribonucleic Acid (rRNA) amplicon pyrosequencing and denaturing gradient gel electrophoresis (DGGE) were used to analyze the microbial variations of different DO concentrations and different positions inside one reactor. PMID:27450126

  1. Autotrophic growth and lipid production of Chlorella sorokiniana in lab batch and BIOCOIL photobioreactors: Experiments and modeling.

    Science.gov (United States)

    Concas, Alessandro; Malavasi, Veronica; Costelli, Cristina; Fadda, Paolo; Pisu, Massimo; Cao, Giacomo

    2016-07-01

    A novel mathematical model for the quantitative assessment of the effect of dissolved nitrogen on the autotrophic batch-growth and lipid accumulation of Chlorella sorokiniana, is proposed in this work. Model results have been validated through comparison with suitable experimental data performed in lab photobioreactors. Further experiments have been then performed using the BIOCOIL photobioreactor operated in fed-batch mode. The experimental results, which show that a maximum growth rate of 0.52day(-1) and a lipid content equal to 25%wt can be achieved with the BIOICOIL, have been successfully predicted through the proposed model. Therefore, the model might represent a first step toward the development of a tool for the scale-up and optimization of the operating conditions of BIOCOIL photobioreactors. Finally, the fatty acid methyl esters obtained by trans-esterification of lipids extracted from C. sorokiniana, have been analyzed in view of the assessment of their usability for producing biodiesel. PMID:27030952

  2. Biogas Production from Citrus Waste by Membrane Bioreactor

    Directory of Open Access Journals (Sweden)

    Rachma Wikandari

    2014-08-01

    Full Text Available Rapid acidification and inhibition by d-limonene are major challenges of biogas production from citrus waste. As limonene is a hydrophobic chemical, this challenge was encountered using hydrophilic polyvinylidine difluoride (PVDF membranes in a biogas reactor. The more sensitive methane-producing archaea were encapsulated in the membranes, while freely suspended digesting bacteria were present in the culture as well. In this membrane bioreactor (MBR, the free digesting bacteria digested the citrus wastes and produced soluble compounds, which could pass through the membrane and converted to biogas by the encapsulated cell. As a control experiment, similar digestions were carried out in bioreactors containing the identical amount of just free cells. The experiments were carried out in thermophilic conditions at 55 °C, and hydraulic retention time of 30 days. The organic loading rate (OLR was started with 0.3 kg VS/m3/day and gradually increased to 3 kg VS/m3/day. The results show that at the highest OLR, MBR was successful to produce methane at 0.33 Nm3/kg VS, while the traditional free cell reactor reduced its methane production to 0.05 Nm3/kg VS. Approximately 73% of the theoretical methane yield was achieved using the membrane bioreactor.

  3. Denitrifying Bioreactors for Nitrate Removal: A Meta-Analysis.

    Science.gov (United States)

    Addy, Kelly; Gold, Arthur J; Christianson, Laura E; David, Mark B; Schipper, Louis A; Ratigan, Nicole A

    2016-05-01

    Meta-analysis approaches were used in this first quantitative synthesis of denitrifying woodchip bioreactors. Nitrate removal across environmental and design conditions was assessed from 26 published studies, representing 57 separate bioreactor units (i.e., walls, beds, and laboratory columns). Effect size calculations weighted the data based on variance and number of measurements for each bioreactor unit. Nitrate removal rates in bed and column studies were not significantly different, but both were significantly higher than wall studies. In denitrifying beds, wood source did not significantly affect nitrate removal rates. Nitrate removal (mass per volume) was significantly lower in beds with effects with bed temperature; a of 2.15 was quite similar to other studies. Lessons from this meta-analysis can be incorporated into bed designs, especially extending hydraulic retention times to increase nitrate removal under low temperature and high flow conditions. Additional column studies are warranted for comparative assessments, as are field-based studies for assessing in situ conditions, especially in aging beds, with careful collection and reporting of design and environmental data. Future assessment of these systems might take a holistic view, reviewing nitrate removal in conjunction with other processes, including greenhouse gas and other unfavorable by-product production. PMID:27136153

  4. Growing Three-Dimensional Corneal Tissue in a Bioreactor

    Science.gov (United States)

    Spaulding, Glen F.; Goodwin, Thomas J.; Aten, Laurie; Prewett, Tacey; Fitzgerald, Wendy S.; OConnor, Kim; Caldwell, Delmar; Francis, Karen M.

    2003-01-01

    Spheroids of corneal tissue about 5 mm in diameter have been grown in a bioreactor from an in vitro culture of primary rabbit corneal cells to illustrate the production of optic cells from aggregates and tissue. In comparison with corneal tissues previously grown in vitro by other techniques, this tissue approximates intact corneal tissue more closely in both size and structure. This novel three-dimensional tissue can be used to model cell structures and functions in normal and abnormal corneas. Efforts continue to refine the present in vitro method into one for producing human corneal tissue to overcome the chronic shortage of donors for corneal transplants: The method would be used to prepare corneal tissues, either from in vitro cultures of a patient s own cells or from a well-defined culture from another human donor known to be healthy. As explained in several articles in prior issues of NASA Tech Briefs, generally cylindrical horizontal rotating bioreactors have been developed to provide nutrient-solution environments conducive to the 30 NASA Tech Briefs, October 2003 growth of delicate animal cells, with gentle, low-shear flow conditions that keep the cells in suspension without damaging them. The horizontal rotating bioreactor used in this method, denoted by the acronym "HARV," was described in "High-Aspect-Ratio Rotating Cell-Culture Vessel" (MSC-21662), NASA Tech Briefs, Vol. 16, No. 5 (May, 1992), page 150.

  5. Immunological analysis of aerobic bioreactor bovine theileriosis vaccine.

    Directory of Open Access Journals (Sweden)

    Gholamreza Habibi

    2014-09-01

    Full Text Available In this study, the pilot production of aerobic bioreactor tropical theileriosis vaccine was optimized with the aim of immunological assays for further mass production.We have shown earlier the delayed type hypersensitivity (DTH assay could be used for evaluating the immunity and memory cells against specific Theileria antigen in vaccinated animals. In addition, TNF-α is the principle cytokine in modulating the cytotoxic activity of cytotoxic T-lymphocytes (CTL. Immunological analysis of the vaccine was performed by using two cell mediated immunity (CMI in vitro and in vivo DTH test (Theilerin and TNF-α assay.The results of immune responses of susceptible immunized cattle by bioreactor vaccine in comparison with conventional flask vaccine revealed a significant stimulation of immune cells by transcription of high level of TNF-α and positive reaction against Theileria antigen in Theilerin skin test (DTH.The equal immunological results achieved in both above mentioned vaccines verified the satisfactory immunity for aerobic bioreactor theileriosis vaccine for advance mass vaccination in the field on a large-scale.

  6. Simulation of three-phase fluidized bioreactors for denitrification

    International Nuclear Information System (INIS)

    Fluidized-bed bioreactors were developed and operated at three scales (diameters of 0.1, 0.2, and 0.5 m) by the Chemical Technology Division. The performance of these reactors in denitrification was simulated using the following modified form of Monod kinetics to describe the reaction kinetics: rate = V/sub max/ (NO3-/K/sub s/ + NO3-) (% biomass). In the fluids-movement portion of the simulation the tanks-in-series approximation to backmixing was used. This approach yielded a V/sub max/ of 3.5 g/m3-min (% biomass) and a K/sub s/ of 163 g/m3 for the 0.5-m bioreactor. Values of V/sub max/ and K/sub s/ were also determined for data derived from the 0.1-m bioreactor, but inadequate RTD data reduced the confidence level in these results. A complication in denitrification is the multi-step nature of the reduction from nitrate to nitrite to hyponitrite and finally to nitrogen. An experimental study of the effect of biomass loading upon denitrification was begun. It is recommended that the experimental work be continued

  7. Bioreactors for tissue engineering--a new role for perfusionists?

    Science.gov (United States)

    Sistino, Joseph J

    2003-09-01

    Tissue engineering is an exciting new area of medicine with rapid growth and expansion over the last decade. It has the potential to have a profound impact on the practice of medicine and influence the economic development in the industry of biotechnology. In almost every specialty of medicine, the ability to generate replacement cells and develop tissues will change the focus from artificial organs and transplantation to growing replacement organs from the patient's own stem cells. Once these organs are at a size that requires perfusion to maintain oxygen and nutrient delivery, then automated perfusion systems termed "bioreactors" will be necessary to sustain the organ until harvesting. The design of these "bioreactors" will have a crucial role in the maintenance of cellular function throughout the growth period. The perfusion schemes necessary to determine the optimal conditions have not been well elucidated and will undergo extensive research over the next decade. The key to progress in this endeavor will development of long-term perfusion techniques and identifying the ideal pressures, flow rates, type of flow (pulsatile/nonpulsatile), and perfusate solution. Perfusionists are considered experts in the field of whole body perfusion, and it is possible that they can participate in the development and operation of these "bioreactors." Additional education of perfusionists in the area of tissue engineering is necessary in order for them to become integral parts of this exciting new area of medicine. PMID:14653420

  8. Impact of CO2 concentration on autotrophic metabolisms and carbon fate in saline aquifers - A case study

    Science.gov (United States)

    Dupraz, Sebastien; Fabbri, Antonin; Joulian, Catherine; Dictor, Marie-Christine; Battaglia-Brunet, Fabienne; Ménez, Bénédicte; Crouzet, Catherine; Henry, Benoît; Garrido, Francis

    2013-10-01

    The purpose of this study was to identify and quantify the fate and speciation of carbon that can occur in mixtures of geological media (crushed rock) and autotrophic microbial communities. A sulfate reducing bacterium (Desulfotomaculum geothermicum) and a methanogenic archaeon (Methanothermococcus thermolithotrophicus) were both tested separately and together, with and without crushed sedimentary rock (carbonaceous sandstone) for different CO2 partial pressures (0.22, 0.88, 3.52, and 8 bar) at 54 °C in saline artificial groundwater. In order to quantify the respective metabolic activities, the inorganic gases of interest (H2, CH4, H2S and CO2) were measured and the speciation of carbon was assessed by measuring volatile, non-purgeable, total and dissolved organic carbon as well as total and dissolved inorganic carbon. Despite a protective effect of the mineral matrix, the results showed a high sensitivity of autotrophic microorganisms to the stress induced by pressures of CO2 superior to one bar and revealed that a part of this stress was due to direct toxic effects. M. thermolithotrophicus demonstrated a better tolerance to CO2 and was dominating the consortia. This ascendancy was interpreted as resulting from equilibrium displacement due to transport effects of methane between the liquid and gas phases. Abiotic dissolution was observed but some biomineralization processes of carbonates were also identified for D. geothermicum. Both strains displayed very different patterns in their conversion of inorganic carbon: while M. thermolithotrophicus was mainly producing methane, D. geothermicum induced the formation of biomass. The availability of crushed rock increased the proportion of sessile biofilms. All these results were analyzed in correlation with a successful PHREEQC simulation and demonstrate the strong influence of the microbial activities and diversity on the carbon fate in the immediate surroundings of geological CCS storage zones.

  9. Comparative evaluations of organic matters and nitrogen removal capacities of integrated vertical-flow constructed wetlands: Domestic and nitrified wastewater treatment.

    Science.gov (United States)

    Chang, Jun J; Liang, Kang; Wu, Su Q; Zhang, Sheng H; Liang, Wei

    2015-01-01

    Two groups of integrated vertical-flow constructed wetland (IVCW) microcosms were established for treating two types of representative wastewater: domestic and nitrified wastewater under two loading rates (LRs) over about two years. Their removal capacities of organic substance and nitrogen as well as the effects of loading rate (LR), outflow temperature and dissolved oxygen (DO) concentration were investigated and compared. Efficient chemical oxygen demand (COD) eliminations were achieved by the IVCWs, with the mass removal rates increasing linearly with the increasing LRs strongly, achieving average value of 56.07 g m(-2) d(-1) at the highest loading rate. Nevertheless, the effluent COD concentrations also increased, with the average value exceeding Class I A discharge standard (loading rate. Greater total nitrogen (TN) mass removal rates but lower efficiencies were obtained at the high LR for both types of wastewater, and better removal was achieved for nitrified wastewater (NW) in comparison to domestic wastewater (DW), probably due to the prevailing anoxic conditions inside the IVCW beds restricted nitrification process of DW. The influences of LR, temperature and DO on COD removal were slight, but all remarkable on TN reduction. As compared to DO, temperature was more crucial for nitrogen removal, and the temperature dependence coefficient for TN removal of low LR of NW was significantly greater than others. PMID:25901854

  10. Investigation of Archaeal and Bacterial community structure of five different small drinking water networks with special regard to the nitrifying microorganisms.

    Science.gov (United States)

    Nagymáté, Zsuzsanna; Homonnay, Zalán G; Márialigeti, Károly

    2016-01-01

    Total microbial community structure, and particularly nitrifying communities inhabiting five different small drinking water networks characterized with different water physical and chemical parameters was investigated, using cultivation-based methods and sequence aided Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis. Ammonium ion, originated from well water, was only partially oxidized via nitrite to nitrate in the drinking water distribution systems. Nitrification occurred at low ammonium ion concentration (27-46μM), relatively high pH (7.6-8.2) and over a wide range of dissolved oxygen concentrations (0.4-9.0mgL(-1)). The nitrifying communities of the distribution systems were characterized by variable most probable numbers (2×10(2)-7.1×10(4) MPN L(-1)) and probably originated from the non-treated well water. The sequence aided T-RFLP method revealed that ammonia-oxidizing microorganisms and nitrite-oxidizing Bacteria (Nitrosomonas oligotropha, Nitrosopumilus maritimus, and Nitrospira moscoviensis, 'Candidatus Nitrospira defluvii') were present in different ratios in the total microbial communities of the distinct parts of the water network systems. The nitrate generated by nitrification was partly utilized by nitrate-reducing (and denitrifying) Bacteria, present in low MPN and characterized by sequence aided T-RFLP as Comamonas sp. and Pseudomonas spp. Different environmental factors, like pH, chemical oxygen demand, calculated total inorganic nitrogen content (moreover nitrite and nitrate concentration), temperature had important effect on the total bacterial and archaeal community distribution. PMID:27296965

  11. Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying organisms, and enzyme activities in a rice-oilseed rape cropping system

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    DMPP (3,4-dimethylpyrazole phosphate) has been used to reduce nitrogen (N) loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N (NH4+-N and NO3--N) leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone (UA), urea + 1% DMPP (DP), and no fertilizer (CK), have been carried out. The results showed that DP enhanced the mean NH4+-N concentrations by 19.1%-24.3%, but reduced the mean NO3--N concentrations by 44.9%-56.6% in the leachate,under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP.It is proposed that DMPP has the potential to either reduce NO3--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system.

  12. Abundance and diversity of bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants revealed by high-throughput sequencing.

    Directory of Open Access Journals (Sweden)

    Zhu Wang

    Full Text Available Biological nitrification/denitrification is frequently used to remove nitrogen from tannery wastewater containing high concentrations of ammonia. However, information is limited about the bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants (WWTPs due to the low-throughput of the previously used methods. In this study, 454 pyrosequencing and Illumina high-throughput sequencing, combined with molecular methods, were used to comprehensively characterize structures and functions of nitrification and denitrification bacterial communities in aerobic and anaerobic sludge of two full-scale tannery WWTPs. Pyrosequencing of 16S rRNA genes showed that Proteobacteria and Synergistetes dominated in the aerobic and anaerobic sludge, respectively. Ammonia-oxidizing bacteria (AOB amoA gene cloning revealed that Nitrosomonas europaea dominated the ammonia-oxidizing community in the WWTPs. Metagenomic analysis showed that the denitrifiers mainly included the genera of Thauera, Paracoccus, Hyphomicrobium, Comamonas and Azoarcus, which may greatly contribute to the nitrogen removal in the two WWTPs. It is interesting that AOB and ammonia-oxidizing archaea had low abundance although both WWTPs demonstrated high ammonium removal efficiency. Good correlation between the qPCR and metagenomic analysis is observed for the quantification of functional genes amoA, nirK, nirS and nosZ, indicating that the metagenomic approach may be a promising method used to comprehensively investigate the abundance of functional genes of nitrifiers and denitrifiers in the environment.

  13. Influence of edaphic, climatic, and agronomic factors on the composition and abundance of nitrifying microorganisms in the rhizosphere of commercial olive crops.

    Directory of Open Access Journals (Sweden)

    Joan Caliz

    Full Text Available The microbial ecology of the nitrogen cycle in agricultural soils is an issue of major interest. We hypothesized a major effect by farm management systems (mineral versus organic fertilizers and a minor influence of soil texture and plant variety on the composition and abundance of microbial nitrifiers. We explored changes in composition (16S rRNA gene of ammonia-oxidizing archaea (AOA, bacteria (AOB, and nitrite-oxidizing bacteria (NOB, and in abundance of AOA and AOB (qPCR of amoA genes in the rhizosphere of 96 olive orchards differing in climatic conditions, agricultural practices, soil properties, and olive variety. Majority of archaea were 1.1b thaumarchaeota (soil crenarchaeotic group, SCG closely related to the AOA genus Nitrososphaera. Most AOB (97% were identical to Nitrosospira tenuis and most NOB (76% were closely related to Nitrospira sp. Common factors shaping nitrifiers assemblage composition were pH, soil texture, and olive variety. AOB abundance was positively correlated with altitude, pH, and clay content, whereas AOA abundances showed significant relationships with organic nitrogen content and exchangeable K. The abundances of AOA differed significantly among soil textures and olive varieties, and those of AOB among soil management systems and olive varieties. Overall, we observed minor effects by orchard management system, soil cover crop practices, plantation age, or soil organic matter content, and major influence of soil texture, pH, and olive tree variety.

  14. Nitrosomonas Nm143-like ammonia oxidizers and Nitrospira marina-like nitrite oxidizers dominate the nitrifier community in a marine aquaculture biofilm.

    Science.gov (United States)

    Foesel, Bärbel U; Gieseke, Armin; Schwermer, Carsten; Stief, Peter; Koch, Liat; Cytryn, Eddie; de la Torré, José R; van Rijn, Jaap; Minz, Dror; Drake, Harold L; Schramm, Andreas

    2008-02-01

    Zero-discharge marine aquaculture systems are an environmentally friendly alternative to conventional aquaculture. In these systems, water is purified and recycled via microbial biofilters. Here, quantitative data on nitrifier community structure of a trickling filter biofilm associated with a recirculating marine aquaculture system are presented. Repeated rounds of the full-cycle rRNA approach were necessary to optimize DNA extraction and the probe set for FISH to obtain a reliable and comprehensive picture of the ammonia-oxidizing community. Analysis of the ammonia monooxygenase gene (amoA) confirmed the results. The most abundant ammonia-oxidizing bacteria (AOB) were members of the Nitrosomonas sp. Nm143-lineage (6.7% of the bacterial biovolume), followed by Nitrosomonas marina-like AOB (2.2% of the bacterial biovolume). Both were outnumbered by nitrite-oxidizing bacteria of the Nitrospira marina-lineage (15.7% of the bacterial biovolume). Although more than eight other nitrifying populations were detected, including Crenarchaeota closely related to the ammonia-oxidizer 'Nitrosopumilus maritimus', their collective abundance was below 1% of the total biofilm volume; their contribution to nitrification in the biofilter is therefore likely to be negligible. PMID:18093145

  15. Application of high cell density airlift bioreactors to bio-ethanol production – study on optimal bioreactor operation

    OpenAIRE

    Klein, Jaroslav; Vicente, A.A.; Maia, J. M.; Domingues, Lucília; Teixeira, J.A.

    2004-01-01

    In this paper a hydrodynamic and rheological analysis of a continuous airlift bioreactor with high cell density system is presented. A highly flocculating recombinant strain of Sacharomyces cerevisae containing genes for lactose transport (lactose permease) and hydrolysis (β-galactosidase) was exploited to ferment lactose from cheese whey to ethanol. The magnetic particle-tracer method was used to assess the effect of operational conditions (air flow rate, biomass concentration) o...

  16. Artificial Intelligence for the Evaluation of Operational Parameters Influencing Nitrification and Nitrifiers in an Activated Sludge Process.

    Science.gov (United States)

    Awolusi, Oluyemi Olatunji; Nasr, Mahmoud; Kumari, Sheena; Bux, Faizal

    2016-07-01

    Nitrification at a full-scale activated sludge plant treating municipal wastewater was monitored over a period of 237 days. A combination of fluorescent in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qPCR) were used for identifying and quantifying the dominant nitrifiers in the plant. Adaptive neuro-fuzzy inference system (ANFIS), Pearson's correlation coefficient, and quadratic models were employed in evaluating the plant operational conditions that influence the nitrification performance. The ammonia-oxidizing bacteria (AOB) abundance was within the range of 1.55 × 10(8)-1.65 × 10(10) copies L(-1), while Nitrobacter spp. and Nitrospira spp. were 9.32 × 10(9)-1.40 × 10(11) copies L(-1) and 2.39 × 10(9)-3.76 × 10(10) copies L(-1), respectively. Specific nitrification rate (qN) was significantly affected by temperature (r 0.726, p 0.002), hydraulic retention time (HRT) (r -0.651, p 0.009), and ammonia loading rate (ALR) (r 0.571, p 0.026). Additionally, AOB was considerably influenced by HRT (r -0.741, p 0.002) and temperature (r 0.517, p 0.048), while HRT negatively impacted Nitrospira spp. (r -0.627, p 0.012). A quadratic combination of HRT and food-to-microorganism (F/M) ratio also impacted qN (r (2) 0.50), AOB (r (2) 0.61), and Nitrospira spp. (r (2) 0.72), while Nitrobacter spp. was considerably influenced by a polynomial function of F/M ratio and temperature (r (2) 0.49). The study demonstrated that ANFIS could be used as a tool to describe the factors influencing nitrification process at full-scale wastewater treatment plants. PMID:26906468

  17. Meso and micro-scale response of post carbon removal nitrifying MBBR biofilm across carrier type and loading.

    Science.gov (United States)

    Young, Bradley; Banihashemi, Bahman; Forrest, Daina; Kennedy, Kevin; Stintzi, Alain; Delatolla, Robert

    2016-03-15

    This study investigates the effects of three specific moving bed biofilm reactor (MBBR) carrier types and two surface area loading rates on biofilm thickness, morphology and bacterial community structure of post carbon removal nitrifying MBBR systems along with the effects of carrier type and loading on ammonia removal rates and effluent solids settleability. The meso and micro analyses show that the AOB kinetics vary based on loading condition, but irrespective of carrier type. The meso-scale response to increases in loading was shown to be an increase in biofilm thickness with higher surface area carriers being more inclined to develop and maintain thicker biofilms. The pore spaces of these higher surface area to volume carriers also demonstrated the potential to become clogged at higher loading conditions. Although the biofilm thickness increased during higher loading conditions, the relative percentages of both the embedded viable and non-viable cells at high and conventional loading conditions remained stable; indicating that the reduced ammonia removal kinetics observed during carrier clogging events is likely due to the observed reduction in the surface area of the attached biofilm. Microbial community analyses demonstrated that the dominant ammonia oxidizing bacteria for all carriers is Nitrosomonas while the dominant nitrite oxidizing bacteria is Nitrospira. The research showed that filamentous species were abundant under high loading conditions, which likely resulted in the observed reduction in effluent solids settleability at high loading conditions as opposed to conventional loading conditions. Although the settleability of the effluent solids was correlated to increases in abundances of filamentous organisms in the biofilm, analyzed using next generation sequencing, the ammonia removal rate was not shown to be directly correlated to specific meso or micro-scale characteristics. Instead post carbon removal MBBR ammonia removal kinetics were shown to be

  18. Start-up of membrane bioreactor and hybrid moving bed biofilm reactor-membrane bioreactor: kinetic study.

    Science.gov (United States)

    Leyva-Díaz, J C; Poyatos, J M

    2015-01-01

    A hybrid moving bed biofilm reactor-membrane bioreactor (hybrid MBBR-MBR) system was studied as an alternative solution to conventional activated sludge processes and membrane bioreactors. This paper shows the results obtained from three laboratory-scale wastewater treatment plants working in parallel in the start-up and steady states. The first wastewater treatment plant was a MBR, the second one was a hybrid MBBR-MBR system containing carriers both in anoxic and aerobic zones of the bioreactor (hybrid MBBR-MBRa), and the last one was a hybrid MBBR-MBR system which contained carriers only in the aerobic zone (hybrid MBBR-MBRb). The reactors operated with a hydraulic retention time of 30.40 h. A kinetic study for characterizing heterotrophic biomass was carried out and organic matter and nutrients removals were evaluated. The heterotrophic biomass of the hybrid MBBR-MBRb showed the best kinetic performance in the steady state, with yield coefficient for heterotrophic biomass=0.30246 mg volatile suspended solids per mg chemical oxygen demand, maximum specific growth rate for heterotrophic biomass=0.00308 h(-1) and half-saturation coefficient for organic matter=3.54908 mg O2 L(-1). The removal of organic matter was supported by the kinetic study of heterotrophic biomass. PMID:26606088

  19. Containerized Wetland Bioreactor Evaluated for Perchlorate and Nitrate Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Dibley, V R; Krauter, P W

    2004-12-02

    The U.S. Department of Energy (DOE) and Lawrence Livermore Laboratory (LLNL) designed and constructed an innovative containerized wetlands (bioreactor) system that began operation in November 2000 to biologically degrade perchlorate and nitrate under relatively low-flow conditions at a remote location at Site 300 known as Building 854. Since initial start-up, the system has processed over 3,463,000 liters of ground water and treated over 38 grams of perchlorate and 148 kilograms of nitrate. Site 300 is operated by the University of California as a high-explosives and materials testing facility supporting nuclear weapons research. The 11-square mile site located in northern California was added to the NPL in 1990 primarily due to the presence of elevated concentrations of volatile organic compounds (VOCs) in ground water. At the urging of the regulatory agencies, perchlorate was looked for and detected in the ground water in 1999. VOCs, nitrate and perchlorate were released into the soil and ground water in the Building 854 area as the result of accidental leaks during stability testing of weapons or from waste discharge practices that are no longer permitted at Site 300. Design of the wetland bioreactors was based on earlier studies showing that indigenous chlorate-respiring bacteria could effectively degrade perchlorate into nontoxic concentrations of chlorate, chlorite, oxygen, and chloride. Studies also showed that the addition of organic carbon would enhance microbial denitrification. Early onsite testing showed acetic acid to be a more effective carbon source than dried leaf matter, dried algae, or milk replacement starter; a nutrient and carbon source used in a Department of Defense phytoremediation demonstration. No inocula were added to the system. Groundwater was allowed to circulate through the bioreactor for three weeks to acclimate the wetland plants and to build a biofilm from indigenous flora. Using solar energy, ground water is pumped into granular

  20. Optimization of denitrifying bioreactor performance with agricultural residue-based filter media

    Science.gov (United States)

    Denitrification bioreactors are a promising technology for mitigation of nitrate-nitrogen (NO3-N) losses in subsurface drainage water. Bioreactors are constructed with carbon substrates, typically wood chips, to provide a substrate for denitrifying microorganisms. Columns were packed with wood chips...

  1. Treatment of contaminated drilling sludge in a bioreactor; Behandlung von Bohrspuelschlaemmen im Bioreaktorverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Noke, A.

    2003-07-01

    Fine-grained contaminated drilling mud from petroleum production processes was purified in an airlift bioreactor. The process regime of bioreactor treatment was optimized, elements of the process periphery were investigated (e.g. purification of reactor off-air in biofilters as well as mud dehydration), and the hazard of the resulting material was assessed.

  2. Optimizing hydraulic retention times in denitrifying woodchip bioreactors treating recirculating aquaculture system wastewater

    Science.gov (United States)

    The performance of wood-based denitrifying bioreactors to treat high-nitrate wastewaters from aquaculture systems has not previously been demonstrated. Four pilot-scale woodchip bioreactors (approximately 1:10 scale) were constructed and operated for 268 d to determine the optimal range of design hy...

  3. Effects of a perfusion bioreactor activated novel bone substitute in spine fusion in sheep

    DEFF Research Database (Denmark)

    Sørensen, Jesper Roed; Koroma, Kariatta Ester; Ding, Ming; Wendt, David; Jespersen, Stig; Juhl, Maria Vinther; Theilgaard, Naseem; Martin, Ivan; Overgaard, Søren

    2012-01-01

    To evaluate the effect of a large perfusion-bioreactor cell-activated bone substitute, on a two-level large posterolateral spine fusion sheep model.......To evaluate the effect of a large perfusion-bioreactor cell-activated bone substitute, on a two-level large posterolateral spine fusion sheep model....

  4. PERFORMANCE OF NORTH AMERICAN BIOREACTOR LANDFILLS: II. CHEMICAL AND BIOLOGICAL CHARACTERISTICS

    Science.gov (United States)

    The objective of this research was to examine the performance of five North American bioreactor landfills. This paper represents the second of a two part series and addresses biological and chemical aspects of bioreactor performance including gas production and management, and l...

  5. Fluid bed porosity equation for an inverse fluidized bed bioreactor with particles growing biofilm

    International Nuclear Information System (INIS)

    Fluid Bed Bioreactor performance is strongly affected by bed void fraction or bed porosity fluctuations. Particle size enlargement due to biofilm growth is an important factor that is involved in these variations and until now there are no mathematical equations that consider biofilm growth. In this work a mathematical equation is proposed to calculate bed void fraction in an inverse fluid bed bioreactor. (Author)

  6. Evaluation Of Landfill Gas Decay Constant For Municipal Solid Waste Landfills Operated As Bioreactors

    Science.gov (United States)

    Prediction of the rate of gas production from bioreactor landfills is important to optimize energy recovery and to estimate greenhouse gas emissions. Landfill gas (LFG) composition and flow rate were monitored for four years for a conventional and two bioreactor landfill landfil...

  7. Propagation and Dissolution of CO2 bubbles in Algae Photo-bioreactors

    Science.gov (United States)

    Kosaraju, Srinivas

    2015-11-01

    Research grade photo-bioreactors are used to study and cultivate different algal species for biofuel production. In an attempt to study the growth properties of a local algal species in rain water, a custom made bioreactor is designed and being tested. Bio-algae consumes dissolved CO2 in water and during its growth cycle, the consumed CO2 must be replenished. Conventional methods use supply of air or CO2 bubbles in the growth medium. The propagation and dissolution of the bubbles, however, are strongly dependent on the design parameters of the photo-bioreactor. In this paper, we discuss the numerical modeling of the air and CO2 bubble propagation and dissolution in the photo-bioreactor. Using the results the bioreactor design will be modified for maximum productivity.

  8. Membrane bioreactors for enzymatic hydrolysis of lactose; Idrolisi enzimatica del lattosio con bioreattori a membrana

    Energy Technology Data Exchange (ETDEWEB)

    Pizzichini, M.; Pilloton, R. [ENEA, Casaccia (Italy). Area Energia e Innovazione; Pontecorvo, M.; Mignogna, G.; Fortunato, A.; Beone, F.

    1993-03-01

    Bioreactor systems obtained by cell or enzyme immobilization offer many advantages compared with native enzyme, intact cell systems or other biocatalysts. Thus, many attempts have been made to design and use new types of bioreactor systems in order to improve performance, enhance productivity and reduce environmental impacts. Membrane bioreactors, obtained by physical immobilization of biocatalysts, in polymeric membrane support, offer such practical advantages as: a continuous separation and transformation process with low product inhibition and suitable hydraulic configuration (backflushing recycling, ultrafiltrating). Specific membrane modules (Amicon VitaFiber), for bioreactor applications are being commercialized. Beta-galctosidase enzyme has successfully been immobilized in a hollow fiber and in ceramic modules to hydrolyze lactose in waste whey. This technical report presents the general properties and performances (permeability, washing procedures, hydraulic configurations, physical and chemical properties) of both, polymeric and ceramic supports, enzyme kinetics, physical and covalent immobilization, mathematical model of the bioreactor and on-line process monitoring.

  9. Construction and evaluation of urinary bladder bioreactor for urologic tissue-engineering purposes.

    LENUS (Irish Health Repository)

    Davis, Niall F

    2012-01-31

    OBJECTIVE: To design and construct a urinary bladder bioreactor for urologic tissue-engineering purposes and to compare the viability and proliferative activity of cell-seeded extracellular matrix scaffolds cultured in the bioreactor with conventional static growth conditions. MATERIALS AND METHODS: A urinary bladder bioreactor was designed and constructed to replicate physiologic bladder dynamics. The bioreactor mimicked the filling pressures of the human bladder by way of a cyclical low-delivery pressure regulator. In addition, cell growth was evaluated by culturing human urothelial cells (UCs) on porcine extracellular matrix scaffolds in the bioreactor and in static growth conditions for 5 consecutive days. The attachment, viability, and proliferative potential were assessed and compared with quantitative viability indicators and by fluorescent markers for intracellular esterase activity and plasma membrane integrity. Scaffold integrity was characterized with scanning electron microscopy and 4\\

  10. Development of thin-film photo-bioreactor and its application to outdoor culture of microalgae.

    Science.gov (United States)

    Yoo, Jae Jun; Choi, Seung Phill; Kim, Jaoon Y H; Chang, Won Seok; Sim, Sang Jun

    2013-06-01

    Photosynthetic microalgae have received much attention as a microbial source of diverse useful biomaterials through CO(2) fixation and various types of photo-bioreactors have been developed for efficient microalgal cultivation. Herein, we developed a novel thin-film photo-bioreactor, which was made of cast polypropylene film, considering outdoor mass cultivation. To develop optimal design of photo-bioreactor, we tested performance of three shapes of thin-film photo-bioreactors (flat, horizontal and vertical tubular shapes) and various parts in the bioreactor. Collectively, vertical tubular bioreactor with H/D ratio 6:1 and cylindrical stainless steel spargers showed the most outstanding performance. Furthermore, the photo-bioreactor was successfully applied to the cultivation of other microalgae such as Chlamydomonas reinhardtii and Chlorella vulgaris. The scalability of photo-bioreactor was confirmed by gradually increasing culture volume from 4 to 25 L and the biomass productivity of each reactor was quite consistent (0.05-0.07 g/L/day) during the cultivation of H. pluvialis under indoor and outdoor conditions. Especially, we also achieved dry cell weight of 4.64 g/L and astaxanthin yield of 218.16 mg/L through long-term cultivation (100 days) under outdoor condition in 15 L photo-bioreactor using Haematococcus pluvialis, which means that the astaxanthin yield from outdoor cultivation is equal or superior to that obtained from controlled indoor condition. Therefore, these results indicate that we can apply this approach to development of optimal photo-bioreactor for the large-scale culture of microalgae and production of useful biomaterials under outdoor condition. PMID:23361185

  11. Preliminary Study on Airlift Membran-Bioreactor%气升式膜-生物反应器的设计与应用

    Institute of Scientific and Technical Information of China (English)

    徐农; 邢卫红; 徐南平; 时钧

    2002-01-01

    A new type of membrane bioreactor named "airlift membrane-bioreactor" is discussed. For municipal wastewater reclamation, the preliminary study on airlift membrane-bioreactor shows its good performance such as higher flux and lower energy consumption. The airlift membrane-bioreactor is potentially applicable in bioengineering and environmental protection fields.

  12. [Isolation of heterotrophic nitrifiers which can tolerate high concentration of ammonia-nitrogen and the optimization of their nitrogen removal efficiency in wastewater].

    Science.gov (United States)

    Si, Wen-Gong; Lü, Zhi-Gang; Xu, Chao

    2011-11-01

    The removal capabilities and tolerance of high concentration of ammonia-nitrogen of heterotrophic nitrifiers were studied. Methods included multi-point sampling, domestication, gradient dilution of domestication liquid, color indicator as rapid nitrification detection and isolation from streaking plate were conducted to screen heterotrophic nitrifiers. The strains were identified according to the sequence analysis of 16S rDNA. After inoculating the strains into ammonia-nitrogen wastewater, changes of nitrogen compounds were measured in order to understand their denitrification characteristics. The denitrification efficiency was optimized by improving the C/N ratio, changing the compatibility of the strains and mixing the compatible strains with the domesticated bacterial suspension. Finally 8 high-efficiency heterotrohic nitrifiers were obtained, and named as N1-N8 respectively. Phylogenetic analysis showed that 8 strains belonged to Comamonas genus, Rhodococcus genus, Pseudomonos genus, Arthrobacter genus and Paracoccus genus, respectively. When the initial concentration of ammonia nitrogen was 256.9 mg x L(-1) and the C/N was 5.5 of the artificial wastewater, the removal rates of ammonia nitrogen by the strains were about 65%-80%, and the stain N4 was the best. When the C/N ratio of the wastewater increased to 8.0, the ammonia nitrogen removal rates of the strains correspondingly increased to about 80% -90%. As the strains compatibility, the denitrification rate of N4 + N5 + N6 was 88.2% in the artificial wastewater with initial ammonia nitrogen concentration was 261.1 mg x L(-1) and initial C/N ratio was 5.5, which was higher than that of any single strain. The ammonia nitrogen removal rate could reach to 99.8% when N4 + N5 + N6 were combined with the domesticated bacterial suspension. In the artificial wastewater, when the initial ammonia nitrogen increased to 446.9 mg x L(-1) and the C/N ratio decreased to 3.2, the ammonia nitrogen removal rate of the mixed

  13. Trace Gas Emission from in-Situ Denitrifying Bioreactors

    Science.gov (United States)

    Pluer, W.; Walter, M. T.; Geohring, L.

    2014-12-01

    Despite decades of concerted effort to mitigate nonpoint source nitrate (NO3-) pollution from agricultural lands, these efforts have not been sufficient to arrest eutrophication. A primary process for removing excess NO3- from water is denitrification, where denitrifying bacteria use NO3- for respiration in the absence of oxygen. Denitrification results in reduced forms of nitrogen, often dinitrogen gas (N2) but also nitrous oxide (N2O), an aggressive greenhouse gas. A promising solution to NO3- pollution is to intercept agricultural discharges with denitrifying bioreactors (DNBRs). DNBRs provide conditions ideal for denitrifiers: an anaerobic environment, sufficient organic matter, and excess NO3-. These conditions are also ideal for methanogens, which produce methane (CH4), another harmful trace gas. While initial results from bioreactor studies show that they can cost-effectively remove NO3-, trace gas emissions are an unintended consequence. This study's goal was to determine how bioreactor design promotes denitrification while limiting trace gas production. Reactor inflow and outflow water samples were tested for nutrients, including NO3-, and dissolved inflow and outflow gas samples were tested for N2O and CH4. NO3- reduction and trace gas production were evaluated at various residence times, pHs, and inflow NO3- concentrations in field and lab-scale reactors. Low NO3- reduction indicated conditions that stressed denitrifying bacteria while high reductions indicated designs that optimized pollutant treatment for water quality. Several factors influenced high N2O, suggesting non-ideal conditions for the final step of complete denitrification. High CH4 emissions pointed to reactor media choice for discouraging methanogens, which may remove competition with denitrifiers. It is critical to understand all of potential impacts that DNBRs may have, which means identifying processes and design specifications that may affect them.

  14. Production of biopesticides in an in situ cell retention bioreactor.

    Science.gov (United States)

    Prakash, Gunjan; Srivastava, Ashok K

    2008-12-01

    The seeds of Azadirachta indica contain azadirachtin and other limonoids, which can be used as a biopesticide for crop protection. Significant variability and availability of seed only in arid zones has triggered biotechnological production of biopesticides to cope up with its huge requirement. Batch cultivation of A. indica suspension culture was carried out in statistically optimized media (25.0 g/l glucose, 5.7 g/l nitrate, 0.094 g/l phosphate and 5 g/l inoculum) in 3 l stirred tank bioreactor. This resulted in 15.5 g/l biomass and 0.05 g/l azadirachtin production in 10 days leading to productivity of 5 mg l(-1) day(-1). Possible inhibition by the limiting substrates (C, N, P) were also studied and maximum inhibitory concentrations identified. The batch kinetic/inhibitory data were then used to develop and identify an unstructured mathematical model. The batch model was extrapolated to simulate continuous cultivation with and without cell retention in the bioreactor. Several offline computer simulations were done to identify right nutrient feeding strategies (with respect to key limiting substrates; carbon, nitrate and phosphate) to maintain non-limiting and non-inhibitory substrate concentrations in bioreactor. One such continuous culture (with cell retention) simulation was experimentally implemented. In this cultivation, the cells were propagated batch-wise for 8 days. It was then converted to continuous cultivation by feeding MS salts with glucose (75 g/l), nitrate (10 g/l), and phosphate (0.5 g/l) at a feed rate of 500 ml/day and withdrawing the spent medium at the same rate. The above continuous cultivation (with cell retention) demonstrated an improvement in cell growth to 95.8 g/l and intracellular accumulation of 0.38 g/l azadirachtin in 40 days leading to an overall productivity of 9.5 mg l(-1) day(-1). PMID:18392561

  15. Cell Cycle Progression of Human Cells Cultured in Rotating Bioreactor

    Science.gov (United States)

    Parks, Kelsey

    2009-01-01

    Space flight has been shown to alter the astronauts immune systems. Because immune performance is complex and reflects the influence of multiple organ systems within the host, scientists sought to understand the potential impact of microgravity alone on the cellular mechanisms critical to immunity. Lymphocytes and their differentiated immature form, lymphoblasts, play an important and integral role in the body's defense system. T cells, one of the three major types of lymphocytes, play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and natural killer cells by the presence of a special receptor on their cell surface called T cell receptors. Reported studies have shown that spaceflight can affect the expression of cell surface markers. Cell surface markers play an important role in the ability of cells to interact and to pass signals between different cells of the same phenotype and cells of different phenotypes. Recent evidence suggests that cell-cycle regulators are essential for T-cell function. To trigger an effective immune response, lymphocytes must proliferate. The objective of this project is to investigate the changes in growth of human cells cultured in rotating bioreactors and to measure the growth rate and the cell cycle distribution for different human cell types. Human lymphocytes and lymphoblasts will be cultured in a bioreactor to simulate aspects of microgravity. The bioreactor is a cylindrical culture vessel that incorporates the aspects of clinostatic rotation of a solid fluid body around a horizontal axis at a constant speed, and compensates gravity by rotation and places cells within the fluid body into a sustained free-fall. Cell cycle progression and cell proliferation of the lymphocytes will be measured for a number of days. In addition, RNA from the cells will be isolated for expression of genes related in cell cycle regulations.

  16. L-Tryptophan depletion bioreactor, a possible cancer therapy

    Directory of Open Access Journals (Sweden)

    Rolf Bambauer

    2015-04-01

    Full Text Available The cancer therapeutic strategies knownto date are not adequate for all cancer patients. Most of them are followed by a high rate of side effects and complications. The L-tryptophan depletion bioreactor is described as a possible new method of cancer therapy. L-tryptophan is an essential amino acid which has been recognized as an important cancer nutrient and its removal can lead to destruction of the tumour. Normal human cells or tumor cells cannot synthesize L-tryptophan and therefore tumor resistance is unlikely to develop. L-tryptophan is also a constituent for different bio-molecules such as Serotonin, Melatonin, and is needed for other synthesis processes in the cell growth. L-tryptophan degrading enzymes with 3 iso-enzymes called tryptophan side chain oxydase (TSO I, II, III were isolated. The 3 iso-enzymes can be differentiated by tryptic digestion. They have different molecular weights with different effectivenesses. All the TSO enzymes have heme that can catalyze essentially similar reactions involving L-tryptophan as a substrate. The most effective TSO is the type TSO III. A column which contained TSO as a bioreactor was integrated in a plasmapheresis unit and tested it in different animals. In sheep and rabbits L-tryptophan depletion in plasma was shown at 95% and 100% rates respectively by a single pass through the bioreactor. The results in immune supprimized rats with tumors were impressive, too. In 20 different tumor cell lines there were different efficacies. Brest cancer and medulloblastoma showed the greatest efficacy of L-tryptophan degrading. The gene technology of TSO production from Pseudomonas is associated with formation of endotoxins. This disadvantage can be prevented by different washing procedures or by using fungal sources for the TSO production. TSO III is developed to treat cancer diseases successfully, and has low side effects. A combination of L-tryptophan depletion with all available cancer therapies is

  17. Modelling and characterization of an airlift-loop bioreactor.

    OpenAIRE

    Verlaan, P

    1987-01-01

    An airlift-loop reactor is a bioreactor for aerobic biotechnological processes. The special feature of the ALR is the recirculation of the liquid through a downcomer connecting the top and the bottom of the main bubbling section. Due to the high circulation-flow rate, efficient mixing and oxygen transfer is combined with a controlled liquid flow in the absence of mechanical agitators.Liquid velocities and gas hold-ups in an external-loop airlift reactor (ALR) on different scales were modelled...

  18. Mixing and In situ product removal in micro-bioreactors

    OpenAIRE

    Li, X

    2009-01-01

    Summary Of the thesis :’ Mixing and In-situ product removal in micro bioreactors’ by Xiaonan Li The work presented in this thesis is a part of a large cluster project, which was formed between DSM, Organon, Applikon and two university groups (TU Delft and University of Twente), under the ACTS and IBOS program. The aim of this cluster project was to develop a system consisting of parallel bioreactors of 30 to 200 microliter working volume for the cultivation of micro-organisms under well contr...

  19. Estimation of Volumetric Mass Transfer Coefficient in Bioreactor

    OpenAIRE

    Zainab Yaquob Atiya

    2012-01-01

    This study is concentrated to investigate the effects of aeration and stirring speed on the volumetric mass transfer coefficient (KLa). A dynamic technique was used in estimating KLa values in order to achieve the aim of this study.This study was done in 10L bioreactor by using two medias:-1. Dionized water2. Xanthan solution (1 g /L)Moreover, the research covered a comparison between the obtained values of KLa.The Xanthan solution was used because of its higher viscosity in comparison with w...

  20. Biomass effects on oxygen transfer in membrane bioreactors.

    OpenAIRE

    Germain, Eve; Nelles, F.; Drews, A.; Pearce, P; Kraume, M.; Reid, E; Judd, Simon J.; Stephenson, Tom

    2007-01-01

    Ten biomass samples from both municipal and industrial pilot and full scale submerged membrane bioreactors (MBRs) with mixed liquor suspended solids concentrations (MLSS) ranging from 7.2 to 30.2 g L−1 were studied at six air-flow rates (0.7, 1.3, 2.3, 3, 4.4 and 6 m3 m−3 h−1). Statistical analyses were applied to identify the relative impacts of the various bulk biomass characteristics on oxygen transfer. Of the biomass characteristics studied, only solids concentration (correlated with visc...