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Sample records for anaerobic conditions improve

  1. Anaerobic conditions improve germination of a gibberellic acid deficient rice

    NASA Technical Reports Server (NTRS)

    Frantz, Jonathan M.; Bugbee, Bruce

    2002-01-01

    Dwarf plants are useful in research because multiple plants can be grown in a small area. Rice (Oryza sativa L.) is especially important since its relatively simple genome has recently been sequenced. We are characterizing a gibberellic acid (GA) mutant of rice (japonica cv 'Shiokari,' line N-71) that is extremely dwarf (20 cm tall). Unfortunately, this GA mutation is associated with poor germination (70%) under aerobic conditions. Neither exogenous GA nor a dormancy-breaking heat treatment improved germination. However, 95% germination was achieved by germinating the seeds anaerobically, either in a pure N2 environment or submerged in unstirred tap water. The anaerobic conditions appear to break a mild post-harvest dormancy in this rice cultivar. Copyright 2002 Crop Science Society of America.

  2. Improvement of anaerobic soil disinfestation.

    PubMed

    Runia, W T; Molendirk, L P G; Ludeking, D J W; Schomaker, C H

    2012-01-01

    With increasing worldwide restrictions for soil fumigants, growers loose an important tool to control soilborne pests and pathogens. Environmentally friendly alternatives are urgently needed and anaerobic soil disinfestation (ASD) may be one of them. Traditional ASD with fresh grass is already applied in open field vegetables but the mode of action is unknown. Therefore, trials were performed under controlled conditions using soil-filled buckets, in which several processed defined organic materials were incorporated and compared with fresh grass. The effect of inundation was also studied. Target organisms were Pratylenchus penetrans, Meloidogyne hapla, Globodera pallida and Verticillium dahliae. Results showed that grass (traditional ASD) was less effective than the organic materials. All materials proved to be effective at 16 degrees C against all target organisms. However, exposure time, dosages, soil type and the temperature at which the experiments were performed influenced the effectiveness. P. penetrans was eliminated most easily whereas V. dahliae was most difficult to control. Efficacy was higher in sandy soil than in light marine clay. Inundation at 16 degrees C proved to be effective against P. penetrans and G. pallida in both soil types at sufficient exposure times. A soil temperature of 8 degrees C was sometimes too low for efficacy. Gas production of CO2, NH3, H2S, CH4 and N2O and gas consumption of O2 and production of fatty acids during ASD proved to depend on type of organic materials, soil type, temperature, dosage and exposure time. This first step in unravelling the mode of action has already shown several critical parameters for efficacy. Additional knowledge about the complete mechanisms of action may lead to a more reliable, effective and quicker soil disinfestation. PMID:23885444

  3. PCB biohalogenation under anaerobic conditions

    SciTech Connect

    Gauger, W.K.; McCue, J.J.

    1990-01-01

    The Institute of Gas Technology (IGT) is conducting research on the biodehalogenation of polychlorinated biphenyls (PCB's) under anoxic conditions. Reductive dechlorination of PCB's has been observed in treatments inoculated with Hudson River sediments. Differences in gas chromatograms between time 0 and 4-month incubations indicate pattern shifts of the PCB homologs that constitute Aroclor 1242 from highly chlorinated to lesser chlorinated congeners. Changes in distribution patterns of PCB homologs were also evident. PCB homologs containing 4, 5, 6, and 7 chlorine atoms were shown to decrease over the incubation period, whereas PCB homologs containing 2 and 3 chlorines increased in concentration. 10 refs., 5 figs., 1 tab.

  4. Anaerobic biodegradation of cyanide under methanogenic conditions.

    PubMed Central

    Fallon, R D; Cooper, D A; Speece, R; Henson, M

    1991-01-01

    Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of greater than 100 mg liter-1 with a hydraulic retention time of less than 48 h were developed. Methanogenesis was maintained under a variety of feed medium conditions which included ethanol, phenol, or methanol as the primary reduced carbon source. Under optimal conditions, greater than 70% of the inflow free cyanide was removed in the first 30% of the column height. Strongly complexed cyanides were resistant to removal. Ammonia was the nitrogen end product of cyanide transformation. In cell material removed from the charcoal columns, [14C]bicarbonate was the major carbon end product of [14C]cyanide transformation. PMID:1872600

  5. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound. PMID:26676010

  6. Improving products of anaerobic sludge digestion by microaeration.

    PubMed

    Jenicek, P; Celis, C A; Krayzelova, L; Anferova, N; Pokorna, D

    2014-01-01

    Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. Recently, microaeration has been proved to be a relatively simple and highly efficient biological method of sulfide removal in the anaerobic digestion of biosolids, but little attention has been paid to comparing the quality of digested sludge and sludge liquor in the anaerobic and microaerobic digestion and that is why this paper primarily deals with this area of research. The results of the long-term monitoring of digested sludge quality and sludge liquor quality in the anaerobic and microaerobic digesters suggest that products of both technologies are comparable. However, there are several parameters in which the 'microaerobic' products have a significantly better quality such as: sulfide (68% lower) and soluble chemical oxygen demand (COD) (33% lower) concentrations in the sludge liquor and the lower foaming potential of the digested sludge. PMID:24569280

  7. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    PubMed Central

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  8. Degradation of natural and synthetic polyesters under anaerobic conditions.

    PubMed

    Abou-Zeid, D M; Müller, R J; Deckwer, W D

    2001-03-30

    Often, degradability under anaerobic conditions is desirable for plastics claimed to be biodegradable, e.g. in anaerobic biowaste treatment plants, landfills and in natural anaerobic sediments. The biodegradation of the natural polyesters poly(beta-hydroxybutyrate) (PHB), poly(beta-hydroxybutyrate-co-11.6%-beta-hydroxyvalerate) (PHBV) and the synthetic polyester poly(epsilon-caprolactone) (PCL) was studied in two anaerobic sludges and individual polyester degrading anaerobic strains were isolated, characterized and used for degradation experiments under controlled laboratory conditions. Incubation of PHB and PHBV films in two anaerobic sludges exhibited significant degradation in a time scale of 6-10 weeks monitored by weight loss and biogas formation. In contrast to aerobic conditions, PHB was degraded anaerobically more rapidly than the copolyester PHBV, when tested with either mixed cultures or a single strained isolate. PCL tends to degrade slower than the natural polyesters PHB and PHBV. Four PHB and PCL degrading isolates were taxonomically identified and are obviously new species belonging to the genus Clostridium group I. The depolymerizing enzyme systems of PHB and PCL degrading isolates are supposed to be different. Using one isolated strain in an optimized laboratory degradation test with PHB powder, the degradation time was drastically reduced compared to the degradation in sludges (2 days vs. 6-10 weeks). PMID:11245900

  9. Decomposition of organic waste products under aerobic and anaerobic conditions

    SciTech Connect

    Gale, P.M.

    1988-01-01

    The objectives of this research were to determine the kinetics of C and N mineralization under aerobic and anaerobic conditions. These parameters were then used to verify the simulation model, DECOMPOSITION, for the anaerobic system. Incubation experiments were conducted to compare the aerobic and anaerobic decomposition of alfalfa (Medicago sativa L.), a substrate with a low C:N ratio. Under anaerobic conditions the net mineralization of N occurred more rapidly than that under aerobic conditions. However, the rate of C mineralization as measured by CO{sub 2} evolution was much lower. For the anaerobic decomposition of alfalfa, C mineralization was best described as the sum of the CO{sub 2} and CH{sub 4} evolved plus the water soluble organic C formed. The kinetics of C mineralization, as determined by this approach, were used to successfully predict the rate and amount of N mineralization from alfalfa undergoing anaerobic decomposition. The decomposition of paper mill sludge, a high C:N ratio substrate, was also evaluated.

  10. Biodegradability of activated sludge organics under anaerobic conditions.

    PubMed

    Ekama, G A; Sötemann, S W; Wentzel, M C

    2007-01-01

    From an experimental and theoretical investigation of the continuity of activated sludge organic (COD) compounds along the link between the fully aerobic or N removal activated sludge and anaerobic digestion unit operations, it was found that the unbiodegradable particulate organics (i) originating from the influent wastewater and (ii) generated by the activated sludge endogenous process, as determined from response of the activated sludge system, are also unbiodegradable under anaerobic digestion conditions. This means that the activated sludge biodegradable organics that can be anaerobically digested can be calculated from the active fraction of the waste activated sludge based on the widely accepted ordinary heterotrophic organism (OHO) endogenous respiration/death regeneration rates and unbiodegradable fraction. This research shows that the mass balances based steady state and dynamic simulation activated sludge, aerobic digestion and anaerobic digestion models provide internally consistent and externally compatible elements that can be coupled to produce plant wide steady state and dynamic simulation WWTP models. PMID:17045327

  11. Engineered microorganisms capable of producing target compounds under anaerobic conditions

    DOEpatents

    Buelter, Thomas; Meinhold, Peter; Feldman, Reid M. Renny; Hawkins, Andrew C.; Urano, Jun; Bastian, Sabine; Arnold, Frances

    2012-01-17

    The present invention is generally provides recombinant microorganisms comprising engineered metabolic pathways capable of producing C3-C5 alcohols under aerobic and anaerobic conditions. The invention further provides ketol-acid reductoisomerase enzymes which have been mutated or modified to increase their NADH-dependent activity or to switch the cofactor preference from NADPH to NADH and are expressed in the modified microorganisms. In addition, the invention provides isobutyraldehyde dehydrogenase enzymes expressed in modified microorganisms. Also provided are methods of producing beneficial metabolites under aerobic and anaerobic conditions by contacting a suitable substrate with the modified microorganisms of the present invention.

  12. DEVELOPMENT OF IMPROVED ANAEROBIC GROWTH OF BACILLUS MOJAVENSIS STRAIN JF-2 FOR THE PURPOSE OF IMPROVED ANAEROBIC BIOSURFACTANT PRODUCTION FOR ENHANCED OIL RECOVERY

    SciTech Connect

    M.J. McInerney; M. Folmsbee; D. Nagle

    2004-05-31

    Our work focuses on the use of microorganisms to recover petroleum hydrocarbons that remain entrapped after current recovery technologies reach their economic limit. Capillary forces between the hydrocarbon and aqueous phases are largely responsible for trapping the hydrocarbons in the pores of the rock and large reductions in the interfacial tension between the hydrocarbon and aqueous phases are needed for hydrocarbon mobilization (1-3, 10, 11). Microorganisms produce a variety of biosurfactants (4), several of which generate the ultra low interfacial tensions needed for hydrocarbon mobilization (4, 5, 8). In particular, the lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 reduces the interfacial tension between hydrocarbon and aqueous phases to very low levels (<0.016 mN/m) (8) (9). B. mojavensis JF-2 grows under the environmental conditions found in many oil reservoirs, i. e., anaerobic, NaCl concentrations up to 80 g l{sup -1}, and temperatures up to 45 C (6, 7), making it ideally suited for in situ applications. However, anaerobic growth of B. mojavensis JF-2 was inconsistent and difficult to replicate, which limited its use for in situ applications. Our initial studies revealed that enzymatic digests, such as Proteose Peptone, were required for anaerobic growth of Bacillus mojavensis JF-2. Subsequent purification of the growth-enhancing factor in Proteose Peptone resulted in the identification of the growth-enhancing factor as DNA or deoxyribonucleosides. The addition of salmon sperm DNA, herring sperm DNA, E. coli DNA or synthetic DNA (single or double stranded) to Medium E all supported anaerobic growth of JF-2. Further, we found that JF-2 required all four deoxyribonucleosides (deoxyadeonosine, deoxyguanosine, deoxycytidine and thymidine) for growth under strict anaerobic conditions. The requirement for the deoxyribonucleosides did not occur under aerobic growth conditions. DNA was not used as a sole energy source; sucrose was required

  13. Improved anaerobic digestion by staged fermentation and advanced reactor design

    SciTech Connect

    Ghosh, S.; Bostian, H.E.; Henry, M.P.; Sajjad, A.; Farrell, J.B.; Salotto, B.V.

    1985-01-01

    The anaerobic digestion process has taken on new importance and emphasis in recent years because of its potential applications for energy and chemicals production from various types of renewable-carbon resources, and because it can be coupled with certain electrochemical, thermochemical, and biochemical processes to generate electric power, hydrocarbons, methanol, and other high-value products. A number of initiatives have been taken to improve the anaerobic digestion process in keeping with the increasing appreciation for its utility and versatility of application in municipal, industrial, and rural settings.

  14. Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization.

    PubMed

    Tiehm, A; Nickel, K; Zellhorn, M; Neis, U

    2001-06-01

    The pretreatment of waste activated sludge by ultrasonic disintegration was studied in order to improve the anaerobic sludge stabilization. The ultrasound frequency was varied within a range from 41 to 3217 kHz. The impact of different ultrasound intensities and treatment times was examined. Sludge disintegration was most significant at low frequencies. Low-frequency ultrasound creates large cavitation bubbles which upon collapse initiate powerful jet streams exerting strong shear forces in the liquid. The decreasing sludge disintegration efficiency observed at higher frequencies was attributed to smaller cavitation bubbles which do not allow the initiation of such strong shear forces. Short sonication times resulted in sludge floc deagglomeration without the destruction of bacteria cells. Longer sonication brought about the break-up of cell walls, the sludge solids were distintegrated and dissolved organic compounds were released. The anaerobic digestion of waste activated sludge following ultrasonic pretreatment causing microbial cell lysis was significantly improved. There was an increase in the volatile solids degradation as well as an increase in the biogas production. The increase in digestion efficiency was proportional to the degree of sludge disintegration. To a lesser degree the deagglomeration of sludge flocs also augmented the anaerobic volatile solids degradation. PMID:11337847

  15. Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

    PubMed

    Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

    2016-05-01

    Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety. PMID:27155428

  16. Environmental factors affecting indole metabolism under anaerobic conditions

    SciTech Connect

    Madsen, E.L.; Francis, A.J.; Bollag, J.M.

    1988-01-01

    The influence of physiological and environmental factors on the accumulation of oxindole during anaerobic indole metabolism was investigated by high-performance liquid chromatography. Under methanogenic conditions, indole was temporarily converted to oxindole in stoichiometric amounts in media inoculated with three freshwater sediments and an organic soil. In media inoculated with methanogenic sewage sludge, the modest amounts of oxindole detected at 35/sup 0/C reached higher concentrations and persisted longer when the incubation temperature was decreased from 35 to 15/sup 0/C. Also, decreasing the concentration of sewage sludge used as an inoculum from 50 to 1% caused an increase in the accumulation of oxindole from 10 to 75% of the indole added. Under denitrifying conditions, regardless of the concentration or source of the inoculum, oxindole appeared in trace amounts but did not accumulate during indole metabolism. In addition, denitrifying consortia which previously metabolized indole degraded oxindole with no lag period. Our data suggest that oxindole accumulation under methanogenic, but not under denitrifying conditions is caused by differences between relative rates of oxindole production and destruction.

  17. Global Gene Expression Profiles of Bacillus subtilis Grown under Anaerobic Conditions

    PubMed Central

    Ye, Rick W.; Tao, Wang; Bedzyk, Laura; Young, Thomas; Chen, Mario; Li, Liao

    2000-01-01

    Bacillus subtilis can grow under anaerobic conditions, either with nitrate or nitrite as the electron acceptor or by fermentation. A DNA microarray containing 4,020 genes from this organism was constructed to explore anaerobic gene expression patterns on a genomic scale. When mRNA levels of aerobic and anaerobic cultures during exponential growth were compared, several hundred genes were observed to be induced or repressed under anaerobic conditions. These genes are involved in a variety of cell functions, including carbon metabolism, electron transport, iron uptake, antibiotic production, and stress response. Among the highly induced genes are not only those responsible for nitrate respiration and fermentation but also those of unknown function. Certain groups of genes were specifically regulated during anaerobic growth on nitrite, while others were primarily affected during fermentative growth, indicating a complex regulatory circuitry of anaerobic metabolism. PMID:10913079

  18. Microbial degradation of lignin-derived compounds under anaerobic conditions

    SciTech Connect

    Colberg, P.J.

    1983-01-01

    Lignin is the second most abundant form of organic carbon in the biosphere. Recent laboratory studies indicate that a large fraction of polymeric lignin is incompletely degraded by aerobic lignolytic microorganisms and is subsequently released as lignin fragments of reduced molecular size. If such lignin-derived compounds become available in the anaerobic environment, they may serve as potential sources of organic carbon for organisms which release methane precursors. The methanogenic bacteria, in turn, serve as terminal members of the anaerobic food chain, and thus, limit the accumulation of organic carbon in anaerobic sinks. This thesis presents evidence to suggest that lignin-derived compounds which have molecular sizes greater than those of single-ring aromatic compounds (MW > 200) are anaerobically biodegradable to methane. This research involved development of selective enrichment cultures capable of utilizing oligolignols as sole carbon sources. Radiolabeled water-soluble catabolites, released during aerobic lignin degradation by the white rot fungus Phanerochaete chrysosporium, were subjected to anaerobic degradation. The second phase of work involved capillary gas chromatographic analyses of enrichment cultures fed a /sup 14/C-labeled, lignin-derived substrate of average molecular weight 600. 2-Bromoethanesulfonic acid was used to inhibit methane formation and enhance buildup of metabolic intermediates, resulting in the accumulation of volatile fatty acids, phenylacetate, benzoate, catechol, 3-phenyl-propionate, vanillin, syringic acid, vanillic acid, ferulic acid, and caffeic acid. A conceptual model for the anaerobic degradation of two- and three-ring lignin fragments is proposed which overlaps both the ferulate and benzoate degradation pathways at the level of single-ring aromatic compounds.

  19. Metabolism of aniline under different anaerobic electron-accepting and nutritional conditions

    SciTech Connect

    De, M.A.; O'Connor, O.A.; Kosson, D.S. . Dept. of Chemical and Biochemical Engineering)

    1994-02-01

    The biodegradability of aniline was evaluated under two different anaerobic conditions, denitrifying and methanogenic. In addition, under denitrifying conditions, the influence of bicarbonate was studied. Anaerobic sewage digester sludge and estuarine sediment were used as heterogeneous sources of bacteria. Under anaerobic denitrifying conditions amended with bicarbonate, aniline was completely mineralized to CO[sub 2] and N[sub 2]. After an initial lag period, N[sub 2] recoveries of 74 and 100% were obtained for sludge and sediment cultures, respectively. Under anaerobic denitrifying conditions with no bicarbonate, aniline depletion was observed; however, stoichiometric quantities of N[sub 2] were not produced from mineralization and were in fact inhibited below background controls. Under methanogenic conditions, aniline concentration remained unchanged for > 31 weeks. A metabolite of aniline, 4-hydroxybenzoate, was detected in bicarbonate-amended denitrifying cultures.

  20. MICROBIAL DEGRADATION OF NITROGEN, OXYGEN AND SULFUR HETEROCYCLIC COMPOUNDS UNDER ANAEROBIC CONDITIONS: STUDIES WITH AQUIFER SAMPLES

    EPA Science Inventory

    The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible t...

  1. Development of microorganisms in the chernozem under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Polyanskaya, L. M.; Gorbacheva, M. A.; Milanovskii, E. Yu.; Zvyagintsev, D. G.

    2010-03-01

    A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in different horizons of a chernozem. It was revealed that, under aerobic conditions, all the microorganisms grow irrespective of the soil horizon; fungi and bacteria grow at the first succession stages, and actinomycetes grow at the last stages. It was shown that, in the case of a simulated anaerobiosis commonly used to study anaerobic populations of bacteria, the mycelium of micromycetes grows in the upper part of the chernozem’s A horizon. Under anaerobic conditions, the peak of the mycelium development is shifted from the 3rd to 7th days (typical for aerobic conditions) to the 7th to 15th days of incubation. The level of mycelium length’s stabilization under aerobic and anaerobic conditions also differs: it is higher or lower than the initial one, respectively. Under anaerobic conditions, the growth of fungal mycelium, bacteria, and actinomycetes in the lower part of the A horizon and in the B horizon is extremely weak. There was not any observed growth of actinomycetes in all the chernozem’s horizons under anaerobic conditions.

  2. Reduction of Nitrated Diphenylamine Derivatives under Anaerobic Conditions

    PubMed Central

    Drzyzga, O.; Schmidt, A.; Blotevogel, K.

    1995-01-01

    2-Nitrodiphenylamine, 4-nitrodiphenylamine, and 2,4-dinitrodiphenylamine were anaerobically metabolized in sediment-water batch enrichments inoculated with mud from the German North Sea coast. The first intermediate in 2,4-dinitrodiphenylamine degradation was 2-amino-4-nitrodiphenylamine, which appeared in large (nearly stoichiometric) amounts before being completely reduced to 2,4-diaminodiphenylamine. Of the second theoretically expected metabolite, 4-amino-2-nitrodiphenylamine, only traces were detected by gas chromatographic-mass spectrometric analysis in highly concentrated extracts. In addition, low levels of 4-nitrodiphenylamine, which may be the product of ortho deamination of intermediately produced 2-amino-4-nitrodiphenylamine, were observed. 2-Nitrodiphenylamine and 4-nitrodiphenylamine were primarily reduced to 2-aminodiphenylamine and 4-aminodiphenylamine, respectively. Diphenylamine was never detected in any experiment as a theoretically possible intermediate. Results from studies with dense cell suspensions of anaerobic, aromatic-compound-mineralizing bacteria confirmed the transformation reactions, which were carried out by microorganisms indigenous to the anaerobic coastal water sediment. PMID:16535118

  3. An improved medium for the anaerobic growth of Paracoccus denitrificans Pd1222

    PubMed Central

    Hahnke, Stefanie M.; Moosmann, Philipp; Erb, Tobias J.; Strous, Marc

    2014-01-01

    Paracoccus denitrificans is a well studied model organism with respect to its aerobic and anaerobic respiratory enzymes. However, until now, the growth medium for this organism has not been optimized for anaerobic growth. In particular, the requirements of P. denitrificans for trace elements (TEs) are not well known. In the present study we aimed to improve growth rates of P. denitrificans Pd1222 on a defined medium under anoxic conditions. We designed media containing different combinations of TEs at various concentrations, and tested their performance against previously reported media. Our results suggest that growth rate and yield depend on the availability and concentration of TEs in the medium. A chelated TE solution was more suitable than an acidified TE solution. Highest growth rates were achieved with medium comprising the TEs iron, manganese, molybdenum, copper and zinc ranging from 0.1 to 9 μM. On this medium, P. denitrificans Pd1222 grew with a generation time of 4.4 h under anoxic conditions and 2.8 h under oxic conditions. Diauxic growth was clearly shown with respect to nitrate and nitrite reduction under anoxic conditions. PMID:24550891

  4. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions.

    PubMed

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  5. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions

    PubMed Central

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L.

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  6. Anaerobic oxidation of [1,2-14C]dichloroethene under Mn(IV)-reducing conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Dinicola, R.S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.

  7. Nitrous oxide production by Alcaligenes faecalis under transient and dynamic aerobic and anaerobic conditions

    SciTech Connect

    Otte, S.; Grobben, N.G.; Robertson, L.A.; Jetten, M.S.M.; Kuenen, J.G.

    1996-07-01

    Nitrous oxide production contributes to both greenhouse effect and ozone depletion in the stratosphere. A significant part of the global N2O emission can be attributed to microbial processes, especially nitrification and denitrification, used in biological wastewater treatment systems. This study looks at the efficiency of denitrification and the enzymes involved, with the emphasis on N2O production during the transient phase from aerobic to anaerobic conditions and vice versa. The effect of repetitive changing aerobic-anaerobic conditions on N2O was also studied. Alcaligenes faecalis was used as the model denitrofing organism. 35 refs., 3 figs., 1 tab.

  8. Monoaromatic hydrocarbon transformation under anaerobic conditions at Seal Beach, California: Laboratory studies

    SciTech Connect

    Ball, H.A.; Reinhard, M.

    1996-02-01

    Anaerobic biotransformation of several aromatic hydrocarbons found in gasoline including benzene, toluene, ethylbenzene, m-xylene, p-xylene, and o-xylene (BTEX) was studied in batch anaerobic laboratory microcosms. Aquifer sediment and ground water were obtained from the site of a historic gasoline spill at Seal Beach, California. Sulfate is present in the site ground water at 80 mg/L, and sulfate-reducing activity appears to be the dominant intrinsic BTEX bioremediation process where nitrate is absent. In the laboratory, the microcosms were set up with different electron acceptors (sulfate and nitrate) in site ground water and various defined anaerobic media to estimate intrinsic biodegradation rates and to suggest conditions under which anaerobic bioremediation could be enhanced. In unamended microcosms, anaerobic biotransformation of toluene and m + p-xylene occurred at a rate of 7.2 and 4.1 {micro}g/liter hr, respectively, with sulfate as the apparent electron acceptor. Addition of nitrate stimulated nitrate-reducing conditions and increased rates of toluene and m + p-xylene biotransformation to 30.1 and 5.4 {micro}g/liter hr, respectively. The catabolic substrate range was altered to include ethylbenzene in the nitrate-amended microcosms, suggesting an apparent preferential use of different BTEX compounds depending on the electron acceptor available. Under all the conditions studied, more than twice the amount of nitrate or sulfate was used than could be accounted for by the observed BTEX degradation. The results of these experiments indicate that indigenous microorganisms from the Seal Beach aquifer have significant capability to degrade BTEX hydrocarbons and that intrinsic processes in the Seal Beach aquifer may remediate a portion of the hydrocarbon contamination in situ without intervention. However, the data also suggest that intervention by nitrate addition would enhance the rate and extent of anaerobic BTEX biotransformation.

  9. Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions.

    PubMed

    Benadé, Eliska; Stone, Wendy; Mouton, Marnel; Postma, Ferdinand; Wilsenach, Jac; Botha, Alfred

    2016-04-01

    We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria. PMID:26566932

  10. Use of Response Surface Methodology to Optimize Culture Conditions for Hydrogen Production by an Anaerobic Bacterial Strain from Soluble Starch

    NASA Astrophysics Data System (ADS)

    Kieu, Hoa Thi Quynh; Nguyen, Yen Thi; Dang, Yen Thi; Nguyen, Binh Thanh

    2016-05-01

    Biohydrogen is a clean source of energy that produces no harmful byproducts during combustion, being a potential sustainable energy carrier for the future. Therefore, biohydrogen produced by anaerobic bacteria via dark fermentation has attracted attention worldwide as a renewable energy source. However, the hydrogen production capability of these bacteria depends on major factors such as substrate, iron-containing hydrogenase, reduction agent, pH, and temperature. In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by an anaerobic bacterial strain isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8 g L-1 to 12 g L-1), ferrous iron concentration (100 mg L-1 to 200 mg L-1), and l-cysteine concentration (300 mg L-1 to 500 mg L-1). RSM analysis showed that all three factors significantly influenced hydrogen production. Among them, the ferrous iron concentration presented the greatest influence. The optimum hydrogen concentration of 1030 mL L-1 medium was obtained with 10 g L-1 soluble starch, 150 mg L-1 ferrous iron, and 400 mg L-1 l-cysteine after 48 h of anaerobic fermentation. The hydrogen concentration produced by the PL strain was doubled after using RSM. The obtained results indicate that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacterial strain. Hydrogen production from low-cost organic substrates such as soluble starch using anaerobic fermentation methods may be one of the most promising approaches.

  11. Fate of extracellular polymeric substances of anaerobically digested sewage sludge during pre-dewatering conditioning with Acidithiobacillus ferrooxidans culture.

    PubMed

    Murugesan, Kumarasamy; Ravindran, Balasubramani; Selvam, Ammaiyappan; Kurade, Mayur B; Yu, Shuk-Man; Wong, Jonathan W C

    2016-10-01

    This study investigated the fate of extracellular polymeric substances (EPS) of anaerobically digested saline sewage sludge during its preconditioning. Sludge was conditioned with Acidithiobacillus ferrooxidans (AF) culture for 24h in the presence and absence of Fe(2+) as an energy substrate. pH decreased from 7.24 to 3.12 during sludge conditioning process. The capillary suction time (CST) of conditioned sludge significantly decreased to <10s, and specific resistance to filtration (SRF) was reduced by >94% as compared with control within 4h of conditioning with or without Fe(2+), indicating a significant (P<0.001) improvement in sludge dewaterability. A noticeable decrease in extractable EPS was observed in conditioned sludge. The EPS contents showed a significant negative correlation with dewaterability of sludge (P<0.05). The results suggest that bioacidification treatment using A. ferrooxidans effectively improved sludge dewaterability through modification of sludge EPS. PMID:27040507

  12. Phosphorus Release to Floodwater from Calcareous Surface Soils and Their Corresponding Subsurface Soils under Anaerobic Conditions.

    PubMed

    Jayarathne, P D K D; Kumaragamage, D; Indraratne, S; Flaten, D; Goltz, D

    2016-07-01

    Enhanced phosphorus (P) release from soils to overlying water under flooded, anaerobic conditions has been well documented for noncalcareous and surface soils, but little information is available for calcareous and subsurface soils. We compared the magnitude of P released from 12 calcareous surface soils and corresponding subsurface soils to overlying water under flooded, anaerobic conditions and examined the reasons for the differences. Surface (0-15 cm) and subsurface (15-30 cm) soils were packed into vessels and flooded for 8 wk. Soil redox potential and concentrations of dissolved reactive phosphorus (DRP) and total dissolved Ca, Mg, Fe, and Mn in floodwater and pore water were measured weekly. Soil test P was significantly smaller in subsurface soils than in corresponding surface soils; thus, the P release to floodwater from subsurface soils was significantly less than from corresponding surface soils. Under anaerobic conditions, floodwater DRP concentration significantly increased in >80% of calcareous surface soils and in about 40% of subsurface soils. The increase in floodwater DRP concentration was 2- to 17-fold in surface soils but only 4- to 7-fold in subsurface soils. With time of flooding, molar ratios of Ca/P and Mg/P in floodwater increased, whereas Fe/P and Mn/P decreased, suggesting that resorption and/or reprecipitation of P took place involving Fe and Mn. Results indicate that P release to floodwater under anaerobic conditions was enhanced in most calcareous soils. Surface and subsurface calcareous soils in general behaved similarly in releasing P under flooded, anaerobic conditions, with concentrations released mainly governed by initial soil P concentrations. PMID:27380087

  13. Comparison of the transport and deposition of Pseudomonas aeruginosa under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Huixin; Zeng, Hongbo; Ulrich, Ania C.; Liu, Yang

    2016-02-01

    Laboratory-scale columns were employed to study the effect of oxygen and ionic strength on the transport of Pseudomonas aeruginosa PAO1 in porous media. In anaerobic experiments, cells were grown and transport experiments were conducted in a well-controlled anaerobic chamber. Cell surface electrokinetic potentials were measured and surface elemental composition was analyzed using X-ray photoelectron spectroscopy (XPS). Transport experimental results showed reduced travel distance of PAO1 with increased ionic strength under aerobic and anaerobic conditions, consistent with calculated Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The deposition rates of PAO1 were significantly higher in aerobic than in anaerobic condition at higher ionic strength (10 and 100 mM), although the electrokinetic potentials were similar throughout the tested ionic strength (1, 10, and 100 mM). No difference in PAO1 deposition rate was observed at 1 mM. XPS analysis showed that variation in cell surface composition due to different growth conditions played a primary role in determining the different deposition behaviors.

  14. Insights into the global regulation of anaerobic metabolism for improved biohydrogen production.

    PubMed

    Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Xing, Xin-Hui

    2016-01-01

    To improve the biohydrogen yield in bacterial dark fermentation, a new approach of global anaerobic regulation was introduced. Two cellular global regulators FNR and NarP were overexpressed in two model organisms: facultatively anaerobic Enterobacter aerogenes (Ea) and strictly anaerobic Clostridium paraputrificum (Cp). The overexpression of FNR and NarP greatly altered anaerobic metabolism and increased the hydrogen yield by 40%. Metabolic analysis showed that the global regulation caused more reducing environment inside the cell. To get a thorough understanding of the global metabolic regulation, more genes (fdhF, fhlA, ppk, Cb-fdh1, and Sc-fdh1) were overexpressed in different Ea and Cp mutants. For the first time, it demonstrated that there were approximately linear relationships between the relative change of hydrogen yield and the relative change of NADH yield or ATP yield. It implied that cellular reducing power and energy level played vital roles in the biohydrogen production. PMID:26476162

  15. Coenzyme B12 can be produced by engineered Escherichia coli under both anaerobic and aerobic conditions.

    PubMed

    Ko, Yeounjoo; Ashok, Somasundar; Ainala, Satish Kumar; Sankaranarayanan, Mugesh; Chun, Ah Yeong; Jung, Gyoo Yeol; Park, Sunghoon

    2014-12-01

    Coenzyme B12 (Vitamin B12 ) is one of the most complex biomolecules and an essential cofactor required for the catalytic activity of many enzymes. Pseudomonas denitrificans synthesizes coenzyme B12 in an oxygen-dependent manner using a pathway encoded by more than 25 genes that are located in six different operons. Escherichia coli, a robust and suitable host for metabolic engineering was used to produce coenzyme B12 . These genes were cloned into three compatible plasmids and expressed heterologously in E. coli BL21 (DE3). Real-time PCR, SDS-PAGE analysis and bioassay showed that the recombinant E. coli expressed the coenzyme B12 synthetic genes and successfully produced coenzyme B12 . However, according to the quantitative determination by inductively coupled plasma-mass spectrometry, the amount of coenzyme B12 produced by the recombinant E. coli (0.21 ± 0.02 μg/g cdw) was approximately 13-fold lower than that by P. denitrificans (2.75 ± 0.22 μg/g cdw). Optimization of the culture conditions to improve the production of coenzyme B12 by the recombinant E. coli was successful, and the highest titer (0.65 ± 0.03 μg/g cdw) of coenzyme B12 was obtained. Interestingly, although the synthesis of coenzyme B12 in P. denitrificans is strictly oxygen-dependent, the recombinant E. coli could produce coenzyme B12 under anaerobic conditions. PMID:25146562

  16. Improvement of anaerobic digestion of sewage sludge through microwave pre-treatment.

    PubMed

    Serrano, A; Siles, J A; Martín, M A; Chica, A F; Estévez-Pastor, F S; Toro-Baptista, E

    2016-07-15

    Sewage sludge generated in the activated sludge process is a polluting waste that must be treated adequately to avoid important environmental impacts. Traditional management methods, such as landfill disposal or incineration, are being ruled out due to the high content in heavy metal, pathogens, micropolluting compounds of the sewage sludge and the lack of use of resources. Anaerobic digestion could be an interesting treatment, but must be improved since the biomethanisation of sewage sludge entails low biodegradability and low methane production. A microwave pre-treatment at pilot scale is proposed to increase the organic matter solubilisation of sewage sludge and enhance the biomethanisation yield. The operational variables of microwave pre-treatment (power and specific energy applied) were optimised by analysing the physicochemical characteristics of sewage sludge (both total and soluble fraction) under different pre-treatment conditions. According to the variation in the sCOD and TN concentration, the optimal operation variables of the pre-treatment were fixed at 20,000 J/g TS and 700 W. A subsequent anaerobic digestion test was carried out with raw and pre-treated sewage sludge under different conditions (20,000 J/g TS and 700 W; 20,000 J/g TS and 400 W; and 30,000 J/g TS and 400 W). Although stability was maintained throughout the process, the enhancement in the total methane yield was not high (up to 17%). Nevertheless, very promising improvements were determined for the kinetics of the process, where the rG and the OLR increased by 43% and 39%, respectively, after carrying out a pre-treatment at 20,000 J/g TS and 700 W. PMID:27107391

  17. Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature.

    PubMed

    Shao, Liming; Wang, Tianfeng; Li, Tianshui; Lü, Fan; He, Pinjing

    2013-07-01

    Aerobic and anaerobic digestion are popular methods for the treatment of waste activated sludge. However, the differences in degradation of sludge during aerobic and anaerobic digestion remain unclear. In this study, the sludge degradation during aerobic and anaerobic digestion was investigated at mesophilic temperature, focused on protein based on the degradation efficiency and degree of humification. The duration of aerobic and anaerobic digestion was about 90 days. The final degradation efficiency of volatile solid was 66.1 ± 1.6% and 66.4 ± 2.4% under aerobic and anaerobic conditions, respectively. The final degradation efficiency of protein was 67.5 ± 1.4% and 65.1 ± 2.6% under aerobic and anaerobic conditions, respectively. The degradation models of volatile solids were consistent with those of protein under both aerobic and anaerobic conditions. The solubility of protein under aerobic digestion was greater than that under anaerobic digestion. Moreover, the humification index of dissolved organic matter of aerobic digestion was greater than that during anaerobic digestion. PMID:23685650

  18. Detoxification of furfural in Corynebacterium glutamicum under aerobic and anaerobic conditions.

    PubMed

    Tsuge, Yota; Hori, Yoshimi; Kudou, Motonori; Ishii, Jun; Hasunuma, Tomohisa; Kondo, Akihiko

    2014-10-01

    The toxic fermentation inhibitors in lignocellulosic hydrolysates raise serious problems for the microbial production of fuels and chemicals. Furfural is considered to be one of the most toxic compounds among these inhibitors. Here, we describe the detoxification of furfural in Corynebacterium glutamicum ATCC13032 under both aerobic and anaerobic conditions. Under aerobic culture conditions, furfuryl alcohol and 2-furoic acid were produced as detoxification products of furfural. The ratio of the products varied depending on the initial furfural concentration. Neither furfuryl alcohol nor 2-furoic acid showed any toxic effect on cell growth, and both compounds were determined to be the end products of furfural degradation. Interestingly, unlike under aerobic conditions, most of the furfural was converted to furfuryl alcohol under anaerobic conditions, without affecting the glucose consumption rate. Both the NADH/NAD(+) and NADPH/NADP(+) ratio decreased in the accordance with furfural concentration under both aerobic and anaerobic conditions. These results indicate the presence of a single or multiple endogenous enzymes with broad and high affinity for furfural and co-factors in C. glutamicum ATCC13032. PMID:25112225

  19. [Simultaneous Biotransformation of Ammonium and Nitrate via Zero-Valent Iron on Anaerobic Conditions].

    PubMed

    Zhou, Jian; Huang, Yong; Yuan, Yi; Liu, Xin; Li, Xiang; Shen, Jie; Yang, Peng-bing

    2015-12-01

    Zero-valent iron (ZVI) was used to improve the biological autotrophic denitrification process between nitrate and ammonia by anaerobic ammonia oxidation ( ANAMMOX) bacteria. With the addition of ZVI, the biological autotrophic denitrification process could be reacted in the influent condition of pH was 7-8, at 35°C ±0.5°C, the concentration of ammonia was 50-100 mg · L⁻¹ and the concentration of nitrate was 50-100 mg · L⁻¹. The highest conversion rate could be reached to 17.2 mg · (L·h) ⁻¹. With the change of reaction time and the molar ratio of nitrate and ammonia in influent, the final molar conversion ratio of nitrate and ammonia in effluent fluctuated between 1.2-3. 5. The result showed that this autotrophic denitrification process was not belonged to elementary reaction. The mechanism of this autotrophic denitrification process could be summarized that with the reduction of ZVI, the nitrate could be reduced to nitrite. Hereafter, the ANAMMOX process reacted between the nitrite and ammonia. PMID:27011992

  20. Microbial community dynamics in batch high-solid anaerobic digestion of food waste under mesophilic conditions.

    PubMed

    Yi, Jing; Dong, Bin; Xue, Yonggang; Li, Ning; Gao, Peng; Zhao, Yuxin; Dai, Lingling; Dai, Xiaohu

    2014-02-28

    Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g VSremoval. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation. PMID:24150490

  1. Evaluation of the improvement of sonication pre-treatment in the anaerobic digestion of sewage sludge.

    PubMed

    Martín, María Ángeles; González, Inmaculada; Serrano, Antonio; Siles, José Ángel

    2015-01-01

    Sewage sludge is a polluting and hazardous waste generated in wastewater treatment plants with severe management problems. The high content in heavy metal, pathogens and micropolluting compounds limit the implementation of the available management methods. Anaerobic digestion could be an interesting treatment method, but must be improved since the biomethanisation of sewage sludge entails low biodegradability and low methane production. A sonication pre-treatment at lab scale is proposed to increase the organic matter solubilisation of sewage sludge and enhance the biomethanisation yield. Sonication time was optimised by analysing the physicochemical characteristics of sewage sludge (both total and soluble fraction) at different pre-treatment times. The pre-treatment time was fixed at 45 min under the study conditions given that the solubilisation of organic matter did not increase significantly at lower sonication times, whereas the concentration of total nitrogen increased markedly at higher times. The volatile fatty acids generation rate was also evaluated for the pre-treatment conditions. The anaerobic digestion of untreated and pre-treated sewage sludge was subsequently compared and promising results were obtained for loads of 1.0 g VS/L (VS, total volatile solids). The methane yield coefficient increased from 88 to 172 mLSTP/g VS (STP, 0 °C, 1 atm) after the pre-treatment, while biodegradability was found to be around 81% (in VS). Moreover, the allowed organic loading rate and methane production rate observed for the sewage sludge reached values of up to 4.1 kg VS/m(3)·d and 1270 LSTP/m(3)·d, respectively. PMID:25284801

  2. TBA biodegradation in surface-water sediments under aerobic and anaerobic conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

    2002-01-01

    The potential for [U-14C] TBA biodegradation was examined in laboratory microcosms under a range of terminal electron accepting conditions. TBA mineralization to CO2 was substantial in surface-water sediments under oxic, denitrifying, or Mn(IV)-reducing conditions and statistically significant but low under SO4-reducing conditions. Thus, anaerobic TBA biodegradation may be a significant natural attenuation mechanism for TBA in the environment, and stimulation of in situ TBA bioremediation by addition of suitable terminal electron acceptors may be feasible. No degradation of [U-14C] TBA was observed under methanogenic or Fe(III)-reducing conditions.

  3. Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions.

    PubMed Central

    Kästner, M

    1991-01-01

    Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions. PMID:1892393

  4. Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions.

    PubMed

    Kästner, M

    1991-07-01

    Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions. PMID:1892393

  5. Anionic metabolite biosynthesis enhanced by potassium under dark, anaerobic conditions in cyanobacteria

    PubMed Central

    Ueda, Sakiko; Kawamura, Yuhki; Iijima, Hiroko; Nakajima, Mitsuharu; Shirai, Tomokazu; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2016-01-01

    Potassium (K+) is an essential macronutrient for all living organisms including cyanobacteria. Cyanobacteria are a group of bacteria performing oxygenic photosynthesis, widely studied in basic and applied sciences. The primary metabolism of the unicellular cyanobacterium Synechocystis sp. PCC 6803 is altered by environmental conditions, and it excretes organic acids and hydrogen under dark, anaerobic conditions. Here we demonstrated that K+ widely changes the primary carbon metabolism of this cyanobacterium. Succinate and lactate excretion from the cells incubated under dark, anaerobic conditions was enhanced in the presence of K+, while hydrogen production was repressed. The addition of K+ and the genetic manipulation of acetate kinase AckA and an RNA polymerase sigma factor SigE additively increased succinate and lactate production to 141.0 and 217.6 mg/L, which are 11 and 46 times, compared to the wild-type strain without K+, respectively. Intracellular levels of 2-oxoglutarate, succinate, fumarate, and malate increased by K+ under dark, anaerobic conditions. This study provides the evidence of the considerable effect of K+ on the biosynthesis of anionic metabolites in a unicellular cyanobacterium. PMID:27576448

  6. Anionic metabolite biosynthesis enhanced by potassium under dark, anaerobic conditions in cyanobacteria.

    PubMed

    Ueda, Sakiko; Kawamura, Yuhki; Iijima, Hiroko; Nakajima, Mitsuharu; Shirai, Tomokazu; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2016-01-01

    Potassium (K(+)) is an essential macronutrient for all living organisms including cyanobacteria. Cyanobacteria are a group of bacteria performing oxygenic photosynthesis, widely studied in basic and applied sciences. The primary metabolism of the unicellular cyanobacterium Synechocystis sp. PCC 6803 is altered by environmental conditions, and it excretes organic acids and hydrogen under dark, anaerobic conditions. Here we demonstrated that K(+) widely changes the primary carbon metabolism of this cyanobacterium. Succinate and lactate excretion from the cells incubated under dark, anaerobic conditions was enhanced in the presence of K(+), while hydrogen production was repressed. The addition of K(+) and the genetic manipulation of acetate kinase AckA and an RNA polymerase sigma factor SigE additively increased succinate and lactate production to 141.0 and 217.6 mg/L, which are 11 and 46 times, compared to the wild-type strain without K(+), respectively. Intracellular levels of 2-oxoglutarate, succinate, fumarate, and malate increased by K(+) under dark, anaerobic conditions. This study provides the evidence of the considerable effect of K(+) on the biosynthesis of anionic metabolites in a unicellular cyanobacterium. PMID:27576448

  7. Improvement of anaerobic digestion of waste-activated sludge by using H₂O₂ oxidation, electrolysis, electro-oxidation and thermo-alkaline pretreatments.

    PubMed

    Feki, Emna; Khoufi, Sonia; Loukil, Slim; Sayadi, Sami

    2015-10-01

    Disintegration of municipal waste-activated sludge (WAS) is regarded as a prerequisite of the anaerobic digestion process to reduce sludge volume and improve biogas yield. Pretreatment of WAS using thermo-alkaline (TA), H2O2 oxidation, electrolysis and electro-oxidation (EO) processes were investigated and compared in term of COD solubilization and biogas production. For each pretreatment, the influences of different operational variables were studied in detail. At optimum conditions, EO gave the maximum COD solubilization (28 %). The effects of pretreatments under the optimum conditions on anaerobic digestion were experienced with biochemical methane potential assay. Significant increases in biogas yield up to 78 and 40 % were observed respectively in the EO and TA pretreated samples compared to raw sludge. Results clearly revealed that the application of EO is a significant alternative method for the improvement of WAS anaerobic digestion. PMID:25982985

  8. Impact of ultrasonic pretreatment under different operational conditions on the mesophilic anaerobic digestion of sunflower oil cake in batch mode.

    PubMed

    Fernández-Cegrí, V; de la Rubia, M A; Raposo, F; Borja, R

    2012-09-01

    In this study ultrasonic (US) pretreatment was investigated with the aim of improving the anaerobic digestion of sunflower oil cake (SuOC), the solid waste derived from the extraction process of sunflower oil. Five ultrasonic pretreatment assays were conducted at specific energy (SE) and sonication times in a range from 24,000 kJ/kg TS and 16.6 min (assay 1: US1) to 597,600 kJ/kg TS and 331.2 min (assay 5: US5), respectively, all operating at a constant sonication frequency (20 kHz) and ultrasonic power (120 W). As regards ultrasonic pretreatment, the working conditions of the first assay (US1) using samples of SuOC at 2% (w/v) showed to be the most appropriate in terms of both lignin and hemicellulose degradation (57.7% and 66.7%, respectively) and cellulose increase (54% increase with respect to its initial concentration). The percentage of COD solubilization increased from only 14% to 21% when SE was 25 times higher. Results obtained in batch anaerobic digestion experiments (biochemical methane potential - BMP - tests) conducted at 35°C of the solid and liquid fractions released from the different ultrasonic conditions tested, indicated that for the first experiment (US1) the average ultimate methane yield obtained was 53.8% higher than that achieved for untreated SuOC. Finally, the kinetic constants of the anaerobic digestion of the solid and liquid fractions released after the ultrasonic pretreatment were virtually independent of the operation conditions assayed. PMID:22366228

  9. Unconventional anaerobic digester designs for improving methane yields from sea kelp

    SciTech Connect

    Fannin, K F; Srivastava, V J; Chynoweth, D P

    1982-01-01

    Studies were performed as part of an ongoing comprehensive research program to develop and optimize the anaerobic digestion process for producing methane from sea kelp (Macrocystis pyrifera). Laboratory-scale studies focused on digester design and operating techniques applicable toward the goal of increasing methane yields and production rates over those observed in previous studies using conventional stirred tank reactors (STR). Two unconventional anaerobic digesters, an upflow solids reactor and a baffle flow reactor, were used to study the anaerobic digestion performance of kelp; both digesters permit solids retention times that are longer than the hydraulic retention times. The performance of the unconventional digesters was compared with that of the STR on the basis of methane yield and process stability. These studies demonstrated that, although digester performance was markedly affected by kelp variability, the methane yield in both unconventional digesters exceeded 70% of the theoretical yield and was substantialy higher than that of the STR. Utilization of simple digester designs that promoted long solids retention times improved the anaerobic digester performance significantly over that observed in conventional anaerobic digestion processes.

  10. A Hidden Transhydrogen Activity of a FMN-Bound Diaphorase under Anaerobic Conditions

    PubMed Central

    Collins, John; Zhang, Ting; Huston, Scott; Sun, Fangfang; Zhang, Y.-H. Percival; Fu, Jinglin

    2016-01-01

    Background Redox cofactors of NADH/NADPH participate in many cellular metabolic pathways for facilitating the electron transfer from one molecule to another in redox reactions. Transhydrogenase plays an important role in linking catabolism and anabolism, regulating the ratio of NADH/NADPH in cells. The cytoplasmic transhydrogenases could be useful to engineer synthetic biochemical pathways for the production of high-value chemicals and biofuels. Methodology/Principal Findings A transhydrogenase activity was discovered for a FMN-bound diaphorase (DI) from Geobacillus stearothermophilus under anaerobic conditions. The DI-catalyzed hydride exchange were monitored and characterized between a NAD(P)H and a thio-modified NAD+ analogue. This new function of DI was demonstrated to transfer a hydride from NADPH to NAD+ that was consumed by NAD-specific lactate dehydrogenase and malic dehydrogenase. Conclusions/Significance We discover a novel transhydrogenase activity of a FMN-DI by stabilizing the reduced state of FMNH2 under anaerobic conditions. FMN-DI was demonstrated to catalyze the hydride transfer between NADPH and NAD+. In the future, it may be possible to incorporate this FMN-DI into synthetic enzymatic pathways for balancing NADH generation and NADPH consumption for anaerobic production of biofuels and biochemicals. PMID:27145082

  11. Long-term geochemical evolution of acidic mine wastes under anaerobic conditions.

    PubMed

    Lu, Wenzhou; Lin, Chuxia; Ma, Yingqun

    2013-08-01

    A nearly 5-year anaerobic incubation experiment was conducted to observe the geochemical evolution of an acidic mine waste. Long-term storage of the mine waste under strict anaerobic conditions caused marked increase in aqueous sulfur, while aqueous iron showed no remarkable change. Co-existing oxidation and reduction of elemental sulfur appeared to play a central role in controlling the evolutionary trends of aqueous sulfur and iron. Addition of organic matter increased the aqueous Fe concentration, possibly due to enhanced iron mobilization by microbial iron reduction and increased iron solubility by forming organically complexed Fe species. Further addition of CaCO3 resulted in immobilization of aqueous iron and sulfur due to elevated pH and gypsum formation. The chemical behaviors of environmentally significant metals were markedly affected by the added organic matter; Al, Cr, Cu, Ni and Zn tended to be immobilized probably due to elevated pH and complexation with insoluble organic molecules, while As and Pb tended to be mobilized. Jarosite exhibited high stability after nearly 5 years of anaerobic incubation and even under circumneutral pH conditions. Long-term weathering of aluminosilicate through acid attack raised pH, while continuous reaction between the added CaCO3 and mine waste-borne stored acid decreased pH. PMID:23529626

  12. Cadmium removal by Euglena gracilis is enhanced under anaerobic growth conditions.

    PubMed

    Santiago-Martínez, M Geovanni; Lira-Silva, Elizabeth; Encalada, Rusely; Pineda, Erika; Gallardo-Pérez, Juan Carlos; Zepeda-Rodriguez, Armando; Moreno-Sánchez, Rafael; Saavedra, Emma; Jasso-Chávez, Ricardo

    2015-05-15

    The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd(2+)) and biochemically characterized. High biomass (8.5×10(6)cellsmL(-1)) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic environment of 0.7% O₂, which was sufficient to allow mitochondrial respiratory activity: glutamate and malate were fully consumed, whereas 25-33% of the added glucose was consumed. In anaerobic cells, photosynthesis but not respiration was activated by Cd(2+) which induced higher oxidative stress. Malondialdehyde (MDA) levels were 20 times lower in control cells under anaerobiosis than in aerobiosis, although Cd(2+) induced a higher MDA production. Cd(2+) stress induced increased contents of chelating thiols (cysteine, glutathione and phytochelatins) and polyphosphate. Biosorption (90%) and intracellular accumulation (30%) were the mechanisms by which anaerobic cells removed Cd(2+) from medium, which was 36% higher versus aerobic cells. The present study indicated that E. gracilis has the ability to remove Cd(2+) under anaerobic conditions, which might be advantageous for metal removal in sediments from polluted water bodies or bioreactors, where the O₂ concentration is particularly low. PMID:25698571

  13. Kinetics and thermodynamics of biodegradation of hydrolyzed polyacrylamide under anaerobic and aerobic conditions.

    PubMed

    Zhao, Lanmei; Bao, Mutai; Yan, Miao; Lu, Jinren

    2016-09-01

    Kinetics and thermodynamics of hydrolyzed polyacrylamide (HPAM) biodegradation in anaerobic and aerobic activated sludge biochemical treatment systems were explored to determine the maximum rate and feasibility of HPAM biodegradation. The optimal nutrient proportions for HPAM biodegradation were determined to be 0.08g·L(-1) C6H12O6, 1.00g·L(-1) NH4Cl, 0.36g·L(-1) NaH2PO4 and 3.00g·L(-1) K2HPO4 using response surface methodology (RSM). Based on the kinetics, the maximum HPAM biodegradation rates were 16.43385mg·L(-1)·d(-1) and 2.463mg·L(-1)·d(-1) in aerobic and anaerobic conditions, respectively. The activation energy (Ea) of the aerobic biodegradation was 48.9897kJ·mol(-1). Entropy changes (ΔS) of biochemical treatment system decreased from 216.21J·K(-1) to 2.39J·K(-1). Thermodynamic windows of opportunity for HPAM biodegradation were drawn. And it demonstrated HPAM was biodegraded into acetic acid and CO2 under laboratory conditions. Growth-process equations for functional bacteria anaerobically grown on polyacrylic acid were constructed and it confirmed electron equivalence between substrate and product. PMID:27235971

  14. Waste-Activated Sludge Fermentation for Polyacrylamide Biodegradation Improved by Anaerobic Hydrolysis and Key Microorganisms Involved in Biological Polyacrylamide Removal

    PubMed Central

    Dai, Xiaohu; Luo, Fan; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dong, Bin

    2015-01-01

    During the anaerobic digestion of dewatered sludge, polyacrylamide (PAM), a chemical conditioner, can usually be consumed as a carbon and nitrogen source along with other organic matter (e.g., proteins and carbohydrates in the sludge). However, a significant accumulation of acrylamide monomers (AMs) was observed during the PAM biodegradation process. To improve the anaerobic hydrolysis of PAM, especially the amide hydrolysis process, and to avoid the generation of the intermediate product AM, a new strategy is reported herein that uses an initial pH of 9, 200 mg COD/L of PAM and a fermentation time of 17 d. First, response surface methodology (RSM) was applied to optimize PAM removal in the anaerobic digestion of the sludge. The biological hydrolysis of PAM reached 86.64% under the optimal conditions obtained from the RSM. Then, the mechanisms for the optimized parameters that significantly improved the biological hydrolysis of PAM were investigated by the synergistic effect of the main organic compounds in the sludge, the floc size distribution, and the enzymatic activities. Finally, semi-continuous-flow experiments for a microbial community study were investigated based on the determination of key microorganisms involved in the biological hydrolysis of PAM. PMID:26144551

  15. Waste-Activated Sludge Fermentation for Polyacrylamide Biodegradation Improved by Anaerobic Hydrolysis and Key Microorganisms Involved in Biological Polyacrylamide Removal.

    PubMed

    Dai, Xiaohu; Luo, Fan; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dong, Bin

    2015-01-01

    During the anaerobic digestion of dewatered sludge, polyacrylamide (PAM), a chemical conditioner, can usually be consumed as a carbon and nitrogen source along with other organic matter (e.g., proteins and carbohydrates in the sludge). However, a significant accumulation of acrylamide monomers (AMs) was observed during the PAM biodegradation process. To improve the anaerobic hydrolysis of PAM, especially the amide hydrolysis process, and to avoid the generation of the intermediate product AM, a new strategy is reported herein that uses an initial pH of 9, 200 mg COD/L of PAM and a fermentation time of 17 d. First, response surface methodology (RSM) was applied to optimize PAM removal in the anaerobic digestion of the sludge. The biological hydrolysis of PAM reached 86.64% under the optimal conditions obtained from the RSM. Then, the mechanisms for the optimized parameters that significantly improved the biological hydrolysis of PAM were investigated by the synergistic effect of the main organic compounds in the sludge, the floc size distribution, and the enzymatic activities. Finally, semi-continuous-flow experiments for a microbial community study were investigated based on the determination of key microorganisms involved in the biological hydrolysis of PAM. PMID:26144551

  16. Improved ADM1 model for anaerobic digestion process considering physico-chemical reactions.

    PubMed

    Zhang, Yang; Piccard, Sarah; Zhou, Wen

    2015-11-01

    The "Anaerobic Digestion Model No. 1" (ADM1) was modified in the study by improving the bio-chemical framework and integrating a more detailed physico-chemical framework. Inorganic carbon and nitrogen balance terms were introduced to resolve the discrepancies in the original bio-chemical framework between the carbon and nitrogen contents in the degraders and substrates. More inorganic components and solids precipitation processes were included in the physico-chemical framework of ADM1. The modified ADM1 was validated with the experimental data and used to investigate the effects of calcium ions, magnesium ions, inorganic phosphorus and inorganic nitrogen on anaerobic digestion in batch reactor. It was found that the entire anaerobic digestion process might exist an optimal initial concentration of inorganic nitrogen for methane gas production in the presence of calcium ions, magnesium ions and inorganic phosphorus. PMID:26253912

  17. Improvement of mixing patterns in pilot-scale anaerobic ponds treating domestic sewage.

    PubMed

    Peña, M R; Mara, D D; Piguet, J M

    2003-01-01

    Anaerobic ponds are customarily designed as completely mixed reactors. However, evidence from experiments on full-scale facilities shows large deviations from ideal flow models, which in turn cause a reduced process performance. Thus, modified pilot scale anaerobic ponds receiving domestic sewage were developed and studied in parallel. A factorially designed experiment evaluated horizontal and vertical baffling, ponds fitted with cross-sectional plastic nets and a pond with a mixing pit. The hydrodynamic behaviour and process performance of these modified configurations were monitored for four flow rates (1.0, 1.2, 1.5 and 2.0 l/s). The results showed that baffling (vertical and horizontal) and the mixing pit configuration had the best hydrodynamic behaviours and removal efficiencies. Consequently, the development of high-rate anaerobic ponds, through improvements of hydrodynamic behaviour, seems feasible. PMID:14510216

  18. Anaerobic Conditions Induce Expression of Polysaccharide Intercellular Adhesin in Staphylococcus aureus and Staphylococcus epidermidis

    PubMed Central

    Cramton, Sarah E.; Ulrich, Martina; Götz, Friedrich; Döring, Gerd

    2001-01-01

    Products of the intercellular adhesion (ica) operon in Staphylococcus aureus and Staphylococcus epidermidis synthesize a linear β-1,6-linked glucosaminylglycan. This extracellular polysaccharide mediates bacterial cell-cell adhesion and is required for biofilm formation, which is thought to increase the virulence of both pathogens in association with prosthetic biomedical implants. The environmental signal(s) that triggers ica gene product and polysaccharide expression is unknown. Here we demonstrate that anaerobic in vitro growth conditions lead to increased polysaccharide expression in both S. aureus and S. epidermidis, although the regulation is less stringent in S. epidermidis. Anaerobiosis also dramatically stimulates ica-specific mRNA expression in ica- and polysaccharide-positive strains of both S. aureus and S. epidermidis. These data suggest a mechanism whereby ica gene expression and polysaccharide production may act as a virulence factor in an anaerobic environment in vivo. PMID:11349079

  19. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome.

    PubMed

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na(+)). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L(-1) day(-1) organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the "ML635J-40 aquatic group" while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  20. Start-up phase of an anaerobic full-scale farm reactor - Appearance of mesophilic anaerobic conditions and establishment of the methanogenic microbial community.

    PubMed

    Goux, Xavier; Calusinska, Magdalena; Fossépré, Marie; Benizri, Emile; Delfosse, Philippe

    2016-07-01

    The goal of this study was to investigate how the microbial community structure establishes during the start-up phase of a full-scale farm anaerobic reactor inoculated with stale and cold cattle slurry. The 16S/18S high-throughput amplicon sequencing results showed an increase of the bacterial, archaeal and eukaryotic diversity, evenness and richness during the settlement of the mesophilic anaerobic conditions. When a steady performing digestion process was reached, the microbial diversity, evenness and richness decreased, indicating the establishment of a few dominant microbial populations, best adapted to biogas production. Interestingly, among the environmental parameters, the temperature, alkalinity, free-NH3, total solids and O2 content were found to be the main drivers of microbial dynamics. Interactions between eukaryotes, characterized by a high number of unknown organisms, and the bacterial and archaeal communities were also evidenced, suggesting that eukaryotes might play important roles in the anaerobic digestion process. PMID:27099947

  1. Xenobiotic benzotriazoles--biodegradation under meso- and oligotrophic conditions as well as denitrifying, sulfate-reducing, and anaerobic conditions.

    PubMed

    Herzog, Bastian; Lemmer, Hilde; Huber, Bettina; Horn, Harald; Müller, Elisabeth

    2014-02-01

    The intensive use of benzotriazoles as corrosion inhibitors for various applications and their application in dishwasher detergents result in an almost omnipresence of benzotriazole (BTri), 4-methyl- and 5-methyl-benzotriazole (4-TTri and 5-TTri, respectively) in aquatic systems. This study aims on the evaluation of the biodegradation potential of activated sludge communities (ASCs) toward the three benzotriazoles regarding aerobic, anoxic, and anaerobic conditions and different nutrients. ASCs were taken from three wastewater treatment plants with different technologies, namely, a membrane bioreactor (MBR-MH), a conventional activated sludge plant CAS-E (intermittent nitrification/denitrification), and CAS-M (two-stage activated sludge treatment) and used for inoculation of biodegradation setups. All ASCs eliminated up to 30 mg L(-1) 5-TTri and BTri under aerobic conditions within 2-7 and 21-49 days, respectively, but not under anoxic or anaerobic conditions. 4-TTri was refractory at all conditions tested. Significant differences were observed for BTri biodegradation with non-acclimated ASCs from MBR-MH with 21 days, CAS-E with 41 days, and CAS-M with 49 days. Acclimated ASCs removed BTri within 7 days. Furthermore, different carbon and nitrogen concentrations revealed that nitrogen was implicitly required for biodegradation while carbon showed no such effect. The fastest biodegradation occurred for 5-TTri with no need for acclimatization, followed by BTri. BTri showed sludge-specific biodegradation patterns, but, after sludge acclimation, was removed with the same pattern, regardless of the sludge used. Under anaerobic conditions in the presence of different electron acceptors, none of the three compounds showed biological removal. Thus, presumably, aerobic biodegradation is the major removal mechanism in aquatic systems. PMID:24136576

  2. Sulfate-reducing bacteria mediate thionation of diphenylarsinic acid under anaerobic conditions.

    PubMed

    Guan, Ling; Shiiya, Ayaka; Hisatomi, Shihoko; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2015-02-01

    Diphenylarsinic acid (DPAA) is often found as a toxic intermediate metabolite of diphenylchloroarsine or diphenylcyanoarsine that were produced as chemical warfare agents and were buried in soil after the World Wars. In our previous study Guan et al. (J Hazard Mater 241-242:355-362, 2012), after application of sulfate and carbon sources, anaerobic transformation of DPAA in soil was enhanced with the production of diphenylthioarsinic acid (DPTAA) as a main metabolite. This study aimed to isolate and characterize anaerobic soil microorganisms responsible for the metabolism of DPAA. First, we obtained four microbial consortia capable of transforming DPAA to DPTAA at a high transformation rate of more than 80% after 4 weeks of incubation. Sequencing for the bacterial 16S rRNA gene clone libraries constructed from the consortia revealed that all the positive consortia contained Desulfotomaculum acetoxidans species. In contrast, the absence of dissimilatory sulfite reductase gene (dsrAB) which is unique to sulfate-reducing bacteria was confirmed in the negative consortia showing no DPAA reduction. Finally, strain DEA14 showing transformation of DPAA to DPTAA was isolated from one of the positive consortia. The isolate was assigned to D. acetoxidans based on the partial 16S rDNA sequence analysis. Thionation of DPAA was also carried out in a pure culture of a known sulfate-reducing bacterial strain, Desulfovibrio aerotolerans JCM 12613(T). These facts indicate that sulfate-reducing bacteria are microorganisms responsible for the transformation of DPAA to DPTAA under anaerobic conditions. PMID:25228086

  3. Combined anaerobic-aerobic treatment of landfill leachates under mesophilic, submesophilic and psychrophilic conditions.

    PubMed

    Kalyuzhnyi, S; Gladchenko, M; Epov, A

    2003-01-01

    As a first step of treatment of landfill leachates (total COD--1,430-3,810 mg/l, total nitrogen 90-162 mg/l), a performance of laboratory UASB reactors has been investigated under mesophilic (30 degrees C), sub-mesophilic (20 degrees C) and psychrophilic (10 degrees C) conditions. Under hydraulic retention times (HRT) of around 7 h, when the average organic loading rates (OLR) were around 5 g COD/l/day, the total COD removal accounted for 81% (on the average) with the effluent concentrations close to anaerobic biodegradability limit (0.25 g COD/l) for mesophilic and sub-mesophilic regimes. The psychrophilic treatment conducted under the average HRT of 8 h and the average OLR of 4.22 g COD/l/day showed a total COD removal of 47% producing the effluents (0.75 g COD/l) more suitable for subsequent biological nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulphides inside the sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated wastewater. PMID:14640233

  4. Anaerobic digestion of mixed microalgae cultivated in secondary effluent under mesophilic and thermophilic conditions.

    PubMed

    Cea-Barcia, Glenda; Moreno, Gloria; Buitrón, Germán

    2015-01-01

    The anaerobic digestion of mixed indigenous microalgae, grown in a secondary effluent, was evaluated in batch tests at mesophilic (35°C) and thermophilic (50°C) conditions. Under mesophilic conditions, specific methane production varied from 178 to 207 mL CH4/g volatile solids (VS) and the maximum production rate varied from 8.8 to 26.1 mL CH4/(gVS day), depending on the type of microalgae culture. Lower methane parameters were observed in those cultures where Scenedesmus represents more than 95% of the microalge. The culture with the lowest digestion performances under mesophilic conditions was studied under thermophilic conditions. The increase in the incubation temperature significantly increased the specific methane production (390 mL CH4/g VS) and rate (26.0 mL CH4/(gVS day)). However, under thermophilic conditions a lag period of 30 days was observed. PMID:26465311

  5. Laboratory degradation rates of 11 pyrethroids under aerobic and anaerobic conditions.

    PubMed

    Meyer, Brian N; Lam, Chung; Moore, Sean; Jones, Russell L

    2013-05-22

    Degradation of 11 pyrethroids was measured over approximately 100 days in three sediment/water systems under aerobic and anaerobic conditions at 25 °C in the dark. The three California sediments represented a range of textures and organic matter. Test compounds were bifenthrin, cypermethrin, ζ-cypermethrin, cyfluthrin, β-cyfluthrin, deltamethrin, esfenvalerate, fenpropathrin, γ-cyhalothrin, λ-cyhalothrin, and permethrin. A non-standard design was employed to keep conditions essentially the same for all compounds. The test compounds were applied as two test mixtures (six active ingredients per mixture, with bifenthrin common to both) at approximately 50 μg of test compound/kg of sediment (dry weight). Extracts of sediment/water were cleaned up by solid-phase extraction, concentrated, and analyzed by gas chromatography/mass spectrometry (except deltamethrin) against matrix-matched standards, with cyfluthrin-d6 as an internal standard. Deltamethrin was analyzed by liquid chromatography/tandem mass spectrometry using deltamethrin-phenoxy-(13)C6 as an internal standard. Similar degradation rates of bifenthrin and for related isomeric compounds (e.g., cyfluthrin and β-cyfluthrin) were generally measured in both mixtures for each sediment. First-order half-lives under aerobic conditions ranged from 2.9 to greater than 200 days, with a median value of 18 days. Under anaerobic conditions, the range was from 20 to greater than 200 days, with a median value of 70 days. PMID:23641910

  6. NADPH oxidase of guinea-pig macrophages catalyses the reduction of ubiquinone-1 under anaerobic conditions.

    PubMed Central

    Murakami, M; Nakamura, M; Minakami, S

    1986-01-01

    The stimulation-specific NADPH-dependent reduction of ubiquinone-1 (Q-1) in guinea-pig macrophages was studied. The activity was due neither to any modified product of the phagocytosis-specific NADPH oxidase nor to non-specific diaphorases of the cells, since the activity was measured in sonicated or detergent-disrupted cells by subtracting the activity in the resting cells from that in cells activated by phorbol 12-myristate 13-acetate. The activity was not mediated by superoxide anions, since strict anaerobic conditions were employed. The anaerobic reduction of Q-1 was NADPH-specific, like superoxide formation under aerobic conditions, and its maximal velocity was also essentially the same as that of superoxide formation. The oxidase does not directly reduce Q-1 under aerobic conditions [Nakamura, Murakami, Umei & Minakami (1985) FEBS Lett. 186, 215-218], and the electron transfer from NADPH to cytochrome c by the oxidase under aerobic conditions was not enhanced by the addition of Q-1. The observations indicate that the phagocytosis-specific NADPH oxidase reduces Q-1 and that oxygen competes with the reduction of Q-1. Q-1 seems to accept electrons not from the intermediary electron carriers of the oxidase but from the terminal oxygen-reducing site of the enzyme. PMID:3026322

  7. Insight into the mechanism of carbon steel corrosion under aerobic and anaerobic conditions.

    PubMed

    El Mendili, Y; Abdelouas, A; Bardeau, J-F

    2013-06-21

    We particularly focused our study on identifying the corrosion products formed at 30 °C on carbon steel under aerobic and anaerobic conditions and on following their evolution with time due to enhanced microbial activity under environmental and geological conditions. The nature and structural properties of corrosion products were investigated by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) and confocal micro-Raman spectroscopy. Structural characterisation clearly showed the formation of iron oxides (magnetite and maghemite) under aerobic conditions. Under anaerobic conditions, the first corrosion product formed on the steel surface was nanocrystalline mackinawite, which was then followed by a fast transformation process into the pyrrhotite phase, and the Raman spectrum of monoclinic pyrrhotite was proposed for the first time. Finally, this study also shows that in the context of geological disposal of radioactive waste, the corrosion of carbon steel containers in anoxic and sulphidogenic environments sustained by sulphate-reducing bacteria may not be a problem notably due to the formation of a passive layer on the steel surface. PMID:23652337

  8. Anaerobic digestion of raw and thermally hydrolyzed wastewater solids under various operational conditions.

    PubMed

    Wilson, Christopher A; Tanneru, Charan T; Banjade, Sarita; Murthy, Sudhir N; Novak, John T

    2011-09-01

    In this study, high-solids anaerobic digestion of thermally pretreated wastewater solids (THD) was compared with conventional mesophilic anaerobic digestion (MAD). Operational conditions, such as pretreatment temperature (150 to 170 degrees C), solids retention time (15 to 20 days), and digestion temperature (37 to 42 degrees C), were varied for the seven THD systems operated. Volatile solids reduction (VSR) by THD ranged from 56 to 62%, compared with approximately 50% for MAD. Higher VSR contributed to 24 to 59% increased biogas production (m3/kg VSR-d) from THD relative to MAD. The high-solids conditions of the THD feed resulted in high total ammonia-nitrogen (proportional to solids loading) and total alkalinity concentrations in excess of 14 g/L as calcium carbonate (CaCO3). Increased pH in THD reactors caused 5 to 8 times more un-ionized ammonia to be present than in MAD, and this likely led to inhibition of aceticlastic methanogens, resulting in accumulation of residual volatile fatty acids between 2 and 6 g/L as acetic acid. The THD produced biosolids cake that possessed low organic sulfur-based biosolids odor and dewatered to between 33 and 39% total solids. Dual conditioning with cationic polymer and ferric chloride was shown to be an effective strategy for mitigating dissolved organic nitrogen and UV-quenching compounds in the return stream following centrifugal dewatering of THD biosolids. PMID:22073729

  9. Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions.

    PubMed

    Newsome, Laura; Morris, Katherine; Lloyd, Jonathan R

    2015-01-01

    Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions. PMID:26132209

  10. Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions

    PubMed Central

    Newsome, Laura; Morris, Katherine; Lloyd, Jonathan. R.

    2015-01-01

    Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions. PMID:26132209

  11. Increased bactericidal activity of colistin on Pseudomonas aeruginosa biofilms in anaerobic conditions.

    PubMed

    Kolpen, Mette; Appeldorff, Cecilie F; Brandt, Sarah; Mousavi, Nabi; Kragh, Kasper N; Aydogan, Sevtap; Uppal, Haleema A; Bjarnsholt, Thomas; Ciofu, Oana; Høiby, Niels; Jensen, Peter Ø

    2016-02-01

    Tolerance towards antibiotics of Pseudomonas aeruginosa biofilms is recognized as a major cause of therapeutic failure of chronic lung infection in cystic fibrosis (CF) patients. This lung infection is characterized by antibiotic-tolerant biofilms in mucus with zones of O2 depletion mainly due to polymorphonuclear leukocytic activity. In contrast to the main types of bactericidal antibiotics, it has not been possible to establish an association between the bactericidal effects of colistin and the production of detectable levels of OH ˙ on several strains of planktonic P. aeruginosa. Therefore, we propose that production of OH ˙ may not contribute significantly to the bactericidal activity of colistin on P. aeruginosa biofilm. Thus, we investigated the effect of colistin treatment on biofilm of wild-type PAO1, a catalase-deficient mutant (ΔkatA) and a colistin-resistant CF isolate cultured in microtiter plates in normoxic- or anoxic atmosphere with 1 mM nitrate. The killing of bacteria during colistin treatment was measured by CFU counts, and the OH⋅ formation was measured by 3(')-(p-hydroxylphenyl fluorescein) fluorescein (HPF) fluorescence. Validation of the assay was done by hydrogen peroxide treatment. OH⋅ formation was undetectable in aerobic PAO1 biofilms during 3 h of colistin treatment. Interestingly, we demonstrate increased susceptibility of P. aeruginosa biofilms towards colistin during anaerobic conditions. In fact, the maximum enhancement of killing by anaerobic conditions exceeded 2 logs using 4 mg L(-1) of colistin compared to killing at aerobic conditions. PMID:26458402

  12. Influence of extreme ambient temperatures and anaerobic conditions on Peltigera aphthosa (L.) Willd. viability

    NASA Astrophysics Data System (ADS)

    Dyakov, M. Yu.; Insarova, I. D.; Kharabadze, D. E.; Ptushenko, V. V.; Shtaer, O. V.

    2015-11-01

    Lichen are symbiotic systems constituted by heterotrophic fungi (mycobionts) and photosynthetic microorganism (photobionts). These organisms can survive under extreme stress conditions. The aim of this work was to study the influence of low (- 70 °C) or high (+ 70 °C) temperatures, temperature fluctuations from + 70 °C to - 70 °C, and anaerobic conditions on P. aphthosa (L.) Willd. viability. None of the studied stress factors affected significantly photosynthetic and respiratory activity of the thalli. No changes in morphology or ultrastructure of the cells were revealed for both photobiont and mycobiont components after extreme temperature treatment of P. aphthosa thalli. The data show the extreme tolerance of P. aphthosa to some stress factors inherent to the space flight conditions.

  13. Influence of extreme ambient temperatures and anaerobic conditions on Peltigera aphthosa (L.) Willd. viability.

    PubMed

    Dyakov, M Yu; Insarova, I D; Kharabadze, D E; Ptushenko, V V; Shtaer, O V

    2015-11-01

    Lichen are symbiotic systems constituted by heterotrophic fungi (mycobionts) and photosynthetic microorganism (photobionts). These organisms can survive under extreme stress conditions. The aim of this work was to study the influence of low (-70 °C) or high (+70 °C) temperatures, temperature fluctuations from +70 °C to -70 °C, and anaerobic conditions on P. aphthosa (L.) Willd. viability. None of the studied stress factors affected significantly photosynthetic and respiratory activity of the thalli. No changes in morphology or ultrastructure of the cells were revealed for both photobiont and mycobiont components after extreme temperature treatment of P. aphthosa thalli. The data show the extreme tolerance of P. aphthosa to some stress factors inherent to the space flight conditions. PMID:26553640

  14. Improving composting as a post-treatment of anaerobic digestate.

    PubMed

    Zeng, Yang; De Guardia, Amaury; Dabert, Patrick

    2016-02-01

    This work investigated the influences of practical parameters upon composting of digestate. The yardsticks for evaluation were digestate stabilization, nitrogenous emissions mitigation and self-heating potential. The results suggest choosing an "active" bulking agent like dry wood chips (WC) which served as free-water and nitrogen sink through composting. At an optimal volumetric WC:digestate mixing ratio of 4:1, nearly 90% of the initial NH4(+)/NH3 were fixed, which reduced significantly nitrogenous emissions. This mixing ratio also improved the stabilization and self-heating potential. Using small particle size WC increased narrowly O2 consumption and reduced NH3 emission. Storing used WC prior to recycling reduced 40% N2O emission compared to directly recycled WC. Recycling compost helped to decrease NH3 emission, but quadrupled N2O emission. The optimal aeration rate (15Lh(-1)kg OM0) which was lower compared to composting of organic waste, was enough to ensure the O2 supply and ameliorate the self-heating potential through composting of digestate. PMID:26684176

  15. Determination of operating conditions in an anaerobic acid-phase reactor treating dairy wastewater

    SciTech Connect

    Kasapgil, B.; Ince, O.; Anderson, G.K.

    1996-11-01

    Anaerobic digestion of organic material is a multistep process. Two groups of bacteria, namely acidogenic and methanogenic bacteria, are responsible for the acidification and for the methane formation, respectively. The growth requirements of the two groups of bacteria are rather different. In order to create optimum conditions for the process, it was first proposed to separate the process into two phases. Operating variables applicable for the selection and enrichment of microbial populations in phased digesters include digester loading, hydraulic retention time (HRT), pH, temperature, reactor design, and operating mode. By proper manipulation of these operating parameters it is possible to prevent any significant growth of methane bacteria and at the same time achieve the required level of acidification in the first reactor. Further enrichment of two cultures is possible by biomass recycle around each phase. Since the 1970s, phase separation has been introduced into anaerobic digestion technology. However, data concerning the optimization of operating conditions in both acidogenic and methanogenic phase reactors are scarce. This study was therefore carried out for the purposes given below. These were: (1) to determine the best combination of pH and temperature within the ranges studied for the pre-acidification of dairy wastewater; (2) to determine the maximum acidogenic conversion from COD to VFAs, and (3) to determine the changes in the distribution of major VFAs being produced during the pre-acidification of dairy wastewater.

  16. Formation of diphenylthioarsinic acid from diphenylarsinic acid under anaerobic sulfate-reducing soil conditions.

    PubMed

    Hisatomi, Shihoko; Guan, Ling; Nakajima, Mami; Fujii, Kunihiko; Nonaka, Masanori; Harada, Naoki

    2013-11-15

    Diphenylarsinic acid (DPAA) is a toxic phenylarsenical compound often found around sites contaminated with phenylarsenic chemical warfare agents, diphenylcyanoarsine or diphenylchloroarsine, which were buried in soil after the World Wars. This research concerns the elucidation of the chemical structure of an arsenic metabolite transformed from DPAA under anaerobic sulfate-reducing soil conditions. In LC/ICP-MS analysis, the retention time of the metabolite was identical to that of a major phenylarsenical compound synthesized by chemical reaction of DPAA and hydrogen sulfide. Moreover the mass spectra for the two compounds measured using LC/TOF-MS were similar. Subsequent high resolution mass spectral analysis indicated that two major ions at m/z 261 and 279, observed on both mass spectra, were attributable to C12H10AsS and C12H12AsSO, respectively. These findings strongly suggest that the latter ion is the molecular-related ion ([M+H](+)) of diphenylthioarsinic acid (DPTA; (C6H5)2AsS(OH)) and the former ion is its dehydrated fragment. Thus, our results reveal that DPAA can be transformed to DPTA, as a major metabolite, under sulfate-reducing soil conditions. Moreover, formation of diphenyldithioarsinic acid and subsequent dimerization were predicted by the chemical reaction analysis of DPAA with hydrogen sulfide. This is the first report to elucidate the occurrence of DPAA-thionation in an anaerobic soil. PMID:24007995

  17. Breaking The Enzymatic Latch: Do Anaerobic Conditions Constrain Decomposition In Humid Tropical Forest Soil?

    NASA Astrophysics Data System (ADS)

    Hall, S. J.; Silver, W. L.

    2011-12-01

    Anaerobic conditions have been proposed to impose a "latch" on soil organic matter decomposition by inhibiting the activity of extracellular enzymes that catalyze the transformation of organic polymers into monomers for microbial assimilation. Here, we tested the hypothesis that anaerobiosis inhibits soil hydrolytic enzyme activity in a humid tropical forest ecosystem in Puerto Rico. We sampled surface and sub-surface soil from each of 59 plots (n = 118) stratified across distinct topographical zones (ridges, slopes, and valleys) known to vary in soil oxygen (O2) concentrations, and measured the potential activity of five hydrolytic enzymes that decompose carbon (C), nitrogen (N), and phosphorus (P) substrates. We measured reduced iron (Fe (II)) concentrations in soil extractions to provide a spatially and temporally integrated index of anaerobic microbial activity, since iron oxides constitute the dominant anaerobic terminal electron acceptor in this ecosystem. Surprisingly, we observed positive relationships between Fe (II) concentrations and the activity of all enzymes that we assayed. Linear mixed effects models that included Fe (II) concentration, topographic position, and their interaction explained between 30 to 70 % of the variance of enzyme activity of β-1,4-glucosidase, β-cellobiohydrolase, β-xylosidase, N-acetylglucosaminidase, and acid phosphatase. Soils from ridges and slopes contained between 10 and 800 μg Fe (II) g-1 soil, and exhibited consistently positive relationships (p < 0.0001) between Fe (II) and enzyme activity. Valley soils did not display significant relationships between enzyme activity and Fe (II), although they displayed variation in soil Fe (II) concentrations similar to ridges and slopes. Overall, valleys exhibited lower enzyme activity and lower Fe (II) concentrations than ridges or slopes, possibly related to decreased root biomass and soil C. Our data provide no indication that anaerobiosis suppresses soil enzyme activity, but

  18. Effect of imposed anaerobic conditions on metals release from acid-mine drainage contaminated streambed sediments.

    PubMed

    Butler, Barbara A

    2011-01-01

    Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerobic streambed sediments collected from North Fork Clear Creek, Colorado were held under anaerobic conditions for four months. Eh, pH, and concentrations of Cd, Cu, Fe, Mn, and Zn (filtered at 1.5 μm, 0.45 μm, and 0.2 μm), sulfate, and dissolved organic carbon (DOC) were monitored in stream water/sediment slurries. Two sediment size fractions were examined (2 mm-63 μm and <63 μm). Sequential extractions evaluated the mineral phase with which metals were associated in the aerobic sediment. Released Cu was re-sequestered within 5 weeks, while Fe and Mn still were present at 16 weeks. Mn concentration was lower than in the initial stream water at and beyond 14 weeks for the smaller sized sediment. Cd was not released from either sediment size fraction. Zn was released at early times, but concentrations never exceeded those present in the initial stream water and all was re-sequestered over time. The greatest concentrations of Cu, Fe, Mn, and Zn were associated with the Fe/Mn reducible fraction. Sulfate and Fe were strongly correlated (r = 0.90), seeming to indicate anaerobic dissolution of iron oxy-hydroxy-sulfate minerals. DOC and sulfate were strongly correlated (r = 0.81), with iron having a moderately strong correlation with DOC (r = 0.71). Overall concentrations of DOC, sulfate, Cu, Fe, and Zn and pH were significantly higher (p < 0.05) in the water overlying the small sized sediment samples, while the concentrations of Mn released from the larger sized sediment samples were greater. PMID:20709348

  19. Plutonium Oxidation State Distribution under Aerobic and Anaerobic Subsurface Conditions for Metal-Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Reed, D. T.; Swanson, J.; Khaing, H.; Deo, R.; Rittmann, B.

    2009-12-01

    The fate and potential mobility of plutonium in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium is the near-surface contaminant of concern at several DOE sites and continues to be the contaminant of concern for the permanent disposal of nuclear waste. The mobility of plutonium is highly dependent on its redox distribution at its contamination source and along its potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. The redox distribution of plutonium in the presence of facultative metal reducing bacteria (specifically Shewanella and Geobacter species) was established in a concurrent experimental and modeling study under aerobic and anaerobic conditions. Pu(VI), although relatively soluble under oxidizing conditions at near-neutral pH, does not persist under a wide range of the oxic and anoxic conditions investigated in microbiologically active systems. Pu(V) complexes, which exhibit high chemical toxicity towards microorganisms, are relatively stable under oxic conditions but are reduced by metal reducing bacteria under anaerobic conditions. These facultative metal-reducing bacteria led to the rapid reduction of higher valent plutonium to form Pu(III/IV) species depending on nature of the starting plutonium species and chelating agents present in solution. Redox cycling of these lower oxidation states is likely a critical step in the formation of pseudo colloids that may lead to long-range subsurface transport. The CCBATCH biogeochemical model is used to explain the redox mechanisms and final speciation of the plutonium oxidation state distributions observed. These results for microbiologically active systems are interpreted in the context of their importance in defining the overall migration

  20. Growth of silicone-immobilized bacteria on polycarbonate membrane filters, a technique to study microcolony formation under anaerobic conditions.

    PubMed Central

    Højberg, O; Binnerup, S J; Sørensen, J

    1997-01-01

    A technique was developed to study microcolony formation by silicone-immobilized bacteria on polycarbonate membrane filters under anaerobic conditions. A sudden shift to anaerobiosis was obtained by submerging the filters in medium which was depleted for oxygen by a pure culture of bacteria. The technique was used to demonstrate that preinduction of nitrate reductase under low-oxygen conditions was necessary for nonfermenting, nitrate-respiring bacteria, e.g., Pseudomonas spp., to cope with a sudden lack of oxygen. In contrast, nitrate-respiring, fermenting bacteria, e.g., Bacillus and Escherichia spp., formed microcolonies under anaerobic conditions with or without the presence of nitrate and irrespective of aerobic or anaerobic preculture conditions. PMID:9212439

  1. Transposon Mutagenesis Identified Chromosomal and Plasmid Genes Essential for Adaptation of the Marine Bacterium Dinoroseobacter shibae to Anaerobic Conditions

    PubMed Central

    Ebert, Matthias; Laaß, Sebastian; Burghartz, Melanie; Petersen, Jörn; Koßmehl, Sebastian; Wöhlbrand, Lars; Rabus, Ralf; Wittmann, Christoph; Jahn, Dieter

    2013-01-01

    Anaerobic growth and survival are integral parts of the life cycle of many marine bacteria. To identify genes essential for the anoxic life of Dinoroseobacter shibae, a transposon library was screened for strains impaired in anaerobic denitrifying growth. Transposon insertions in 35 chromosomal and 18 plasmid genes were detected. The essential contribution of plasmid genes to anaerobic growth was confirmed with plasmid-cured D. shibae strains. A combined transcriptome and proteome approach identified oxygen tension-regulated genes. Transposon insertion sites of a total of 1,527 mutants without an anaerobic growth phenotype were determined to identify anaerobically induced but not essential genes. A surprisingly small overlap of only three genes (napA, phaA, and the Na+/Pi antiporter gene Dshi_0543) between anaerobically essential and induced genes was found. Interestingly, transposon mutations in genes involved in dissimilatory and assimilatory nitrate reduction (napA, nasA) and corresponding cofactor biosynthesis (genomic moaB, moeB, and dsbC and plasmid-carried dsbD and ccmH) were found to cause anaerobic growth defects. In contrast, mutation of anaerobically induced genes encoding proteins required for the later denitrification steps (nirS, nirJ, nosD), dimethyl sulfoxide reduction (dmsA1), and fermentation (pdhB1, arcA, aceE, pta, acs) did not result in decreased anaerobic growth under the conditions tested. Additional essential components (ferredoxin, cccA) of the anaerobic electron transfer chain and central metabolism (pdhB) were identified. Another surprise was the importance of sodium gradient-dependent membrane processes and genomic rearrangements via viruses, transposons, and insertion sequence elements for anaerobic growth. These processes and the observed contributions of cell envelope restructuring (lysM, mipA, fadK), C4-dicarboxylate transport (dctM1, dctM3), and protease functions to anaerobic growth require further investigation to unravel the

  2. Microbial Ecology in Anaerobic Digestion at Agitated and Non-Agitated Conditions

    PubMed Central

    Tian, Zhuoli; Cabrol, Léa; Ruiz-Filippi, Gonzalo; Pullammanappallil, Pratap

    2014-01-01

    To investigate the distribution and dynamics of microbial community in anaerobic digestion at agitated and non-agitated condition, 454 pyrosequencing of 16s rRNA was conducted. It revealed the distinct community compositions between the two digesters and their progressive shifting over time. Methanogens and syntrophic bacteria were found much less abundant in the agitated digester, which was mainly attributed to the presence of bacterial genera Acetanaerobacterium and Ruminococcus with relatively high abundance. The characterization of the microbial community corroborated the digestion performance affected at the agitated condition, where lower methane yield and delayed methane production rate were observed. This was further verified by the accumulation of propionic acid in the agitated digester. PMID:25313520

  3. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

    PubMed Central

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L−1 day−1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  4. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions

    SciTech Connect

    Kim, Dong-Hoon; Oh, Sae-Eun

    2011-09-15

    Highlights: > High-solids (dry) anaerobic digestion is attracting a lot of attention these days. > One reactor was fed with food waste (FW) and paper waste. > Maximum biogas production rate of 5.0 m{sup 3}/m{sup 3}/d was achieved at HRT 40 d and 40% TS. > The other reactor was fed with FW and livestock waste (LW). > Until a 40% LW content increase, the reactor exhibited a stable performance. - Abstract: With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO{sub 2} emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH{sub 4} production yield (MPY) and VS reduction achieved in this condition were 5.0 m{sup 3}/m{sup 3}/d, 0.25 m{sup 3} CH{sub 4}/g COD{sub added}, and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m{sup 3}/m{sup 3}/d, MPY of 0.26 m{sup 3} CH{sub 4}/g COD{sub added}, and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60

  5. pH-Dependent Uptake of Fumaric Acid in Saccharomyces cerevisiae under Anaerobic Conditions

    PubMed Central

    Jamalzadeh, Elaheh; Verheijen, Peter J. T.; Heijnen, Joseph J.

    2012-01-01

    Microbial production of C4 dicarboxylic acids from renewable resources has gained renewed interest. The yeast Saccharomyces cerevisiae is known as a robust microorganism and is able to grow at low pH, which makes it a suitable candidate for biological production of organic acids. However, a successful metabolic engineering approach for overproduction of organic acids requires an incorporation of a proper exporter to increase the productivity. Moreover, low-pH fermentations, which are desirable for facilitating the downstream processing, may cause back diffusion of the undissociated acid into the cells with simultaneous active export, thereby creating an ATP-dissipating futile cycle. In this work, we have studied the uptake of fumaric acid in S. cerevisiae in carbon-limited chemostat cultures under anaerobic conditions. The effect of the presence of fumaric acid at different pH values (3 to 5) has been investigated in order to obtain more knowledge about possible uptake mechanisms. The experimental results showed that at a cultivation pH of 5.0 and an external fumaric acid concentration of approximately 0.8 mmol · liter−1, the fumaric acid uptake rate was unexpectedly high and could not be explained by diffusion of the undissociated form across the plasma membrane alone. This could indicate the presence of protein-mediated import. At decreasing pH levels, the fumaric acid uptake rate was found to increase asymptotically to a maximum level. Although this observation is in accordance with protein-mediated import, the presence of a metabolic bottleneck for fumaric acid conversion under anaerobic conditions could not be excluded. PMID:22113915

  6. Molecular Dynamics Simulation and Analysis of Interfacial Water at Selected Sulfide Mineral Surfaces under Anaerobic Conditions

    SciTech Connect

    Jin, Jiaqi; Miller, Jan D.; Dang, Liem X.

    2014-04-10

    In this paper, we report on a molecular dynamics simulation (MDS) study of the behavior of interfacial water at selected sulfide mineral surfaces under anaerobic conditions. The study revealed the interfacial water structure and wetting characteristics of the pyrite (100) surface, galena (100) surface, chalcopyrite (012) surface, sphalerite (110) surface, and molybdenite surfaces (i.e., the face, armchair-edge, and zigzag-edge surfaces), including simulated contact angles, relative number density profiles, water dipole orientations, hydrogen-bonding, and residence times. For force fields of the metal and sulfur atoms in selected sulfide minerals used in the MDS, we used the universal force field (UFF) and another set of force fields optimized by quantum chemical calculations for interactions with interfacial water molecules at selected sulfide mineral surfaces. Simulation results for the structural and dynamic properties of interfacial water molecules indicate the natural hydrophobic character for the selected sulfide mineral surfaces under anaerobic conditions as well as the relatively weak hydrophobicity for the sphalerite (110) surface and two molybdenite edge surfaces. Part of the financial support for this study was provided by the U.S. Department of Energy (DOE) under Basic Science Grant No. DE-FG-03-93ER14315. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (BES), of the DOE, funded work performed by Liem X. Dang. Battelle operates Pacific Northwest National Laboratory for DOE. The calculations were carried out using computer resources provided by BES. The authors are grateful to Professor Tsun-Mei Chang for valuable discussions.

  7. Dehalogenation of chlorinated ethenes and immobilization of nickel in anaerobic sediment columns under sulfidogenic conditions.

    PubMed

    Drzyzga, Oliver; El Mamouni, Rachid; Agathos, Spiros N; Gottschal, Jan C

    2002-06-15

    A sediment column study was carried out to demonstrate the bioremediation of chloroethene- and nickel-contaminated sediment in a single anaerobic step under sulfate-reducing conditions. Four columns (one untreated control column and three experimental columns) with sediment from a chloroethene- and nickel-contaminated site were investigated for 1 year applying different treatments. By stimulating the activity of sulfate-reducing bacteria by the addition of sulfate as supplementary electron acceptor, complex anaerobic communities were maintained with lactate as electron donor (with or without methanol), which achieved complete dehalogenation of tetra- and trichloroethenes (PCE and TCE) to ethene and ethane. A few weeks after sulfate addition, production of sulfide increased, indicating an increasing activity of sulfate-reducing bacteria. The nickel concentration in the effluent of one nickel-spiked column was greatly reduced, likely due to the enhanced sulfide production, causing precipitation of nickel sulfide. At the end of the study, 94% of the initial amount of nickel added to that column was recovered in the sediment As compared to the untreated (nonspiked) control column, all chloroethene-spiked columns ladditions of PCE and TCE) showed a permanent release of small chloride ion quantities (approximately 0.5-0.7 mM chloride), which were detected in the effluents a few weeks after sulfide production was observed for the first time. The formation of ethene and ethane as final products after dechlorination of PCE and TCE was detected in some effluents and in some gas phases of the columns. Other metabolites or intermediates (such as DCE isomers) were only detected sporadically in negligible quantities. The results of this study demonstrated thatmicrobial activity stimulated under sulfate-reducing conditions can have a beneficial effect on both the precipitation of heavy metals and the complete dechlorination of organochlorines. The strongly negative redox

  8. Anaerobic biodegradation of nonylphenol in river sediment under nitrate- or sulfate-reducing conditions and associated bacterial community.

    PubMed

    Wang, Zhao; Yang, Yuyin; Dai, Yu; Xie, Shuguang

    2015-04-01

    Nonylphenol (NP) is a commonly detected pollutant in aquatic ecosystem and can be harmful to aquatic organisms. Anaerobic degradation is of great importance for the clean-up of NP in sediment. However, information on anaerobic NP biodegradation in the environment is still very limited. The present study investigated the shift in bacterial community structure associated with NP degradation in river sediment microcosms under nitrate- or sulfate-reducing conditions. Nearly 80% of NP (100 mg kg(-1)) could be removed under these two anaerobic conditions after 90 or 110 days' incubation. Illumina MiSeq sequencing analysis indicated that Proteobacteria, Firmicutes, Bacteroidetes and Chloroflexi became the dominant phylum groups with NP biodegradation. The proportion of Gammaproteobacteria, Deltaproteobacteria and Choloroflexi showed a marked increase in nitrate-reducing microcosm, while Gammaproteobacteria and Firmicutes in sulfate-reducing microcosm. Moreover, sediment bacterial diversity changed with NP biodegradation, which was dependent on type of electron acceptor. PMID:25590825

  9. Antibacterial Action of Nitric Oxide-Releasing Chitosan Oligosaccharides against Pseudomonas aeruginosa under Aerobic and Anaerobic Conditions

    PubMed Central

    Reighard, Katelyn P.

    2015-01-01

    Chitosan oligosaccharides were modified with N-diazeniumdiolates to yield biocompatible nitric oxide (NO) donor scaffolds. The minimum bactericidal concentrations and MICs of the NO donors against Pseudomonas aeruginosa were compared under aerobic and anaerobic conditions. Differential antibacterial activities were primarily the result of NO scavenging by oxygen under aerobic environments and not changes in bacterial physiology. Bacterial killing was also tested against nonmucoid and mucoid biofilms and compared to that of tobramycin. Smaller NO payloads were required to eradicate P. aeruginosa biofilms under anaerobic versus aerobic conditions. Under oxygen-free environments, the NO treatment was 10-fold more effective at killing biofilms than tobramycin. These results demonstrate the potential utility of NO-releasing chitosan oligosaccharides under both aerobic and anaerobic environments. PMID:26239983

  10. Anaerobic power in road cyclists is improved after 10 weeks of whole-body vibration training.

    PubMed

    Oosthuyse, Tanja; Viedge, Alison; McVeigh, Joanne; Avidon, Ingrid

    2013-02-01

    Whole-body vibration (WBV) training has previously improved muscle power in various athletic groups requiring explosive muscle contractions. To evaluate the benefit of including WBV as a training adjunct for improving aerobic and anaerobic cycling performance, road cyclists (n = 9) performed 3 weekly, 10-minute sessions of intermittent WBV on synchronous vertical plates (30 Hz) while standing in a static posture. A control group of cyclists (n = 8) received no WBV training. Before and after the 10-week intervention period, lean body mass (LBM), cycling aerobic peak power (Wmax), 4 mM lactate concentration (OBLA), VO2peak, and Wingate anaerobic peak and mean power output were determined. The WBV group successfully completed all WBV sessions but reported a significant 30% decrease in the weekly cycling training time (pre: 9.4 ± 3.3 h·wk(-1); post: 6.7 ± 3.7 h·wk(-1); p = 0.01) that resulted in a 6% decrease in VO2peak and a 4% decrease in OBLA. The control group reported a nonsignificant 6% decrease in cycling training volume (pre: 9.5 ± 3.6 h·wk(-1); 8.6 ± 2.9 h·wk(-1); p = 0.13), and all measured variables were maintained. Despite the evidence of detraining in the WBV group, Wmax was maintained (pre: 258 ± 53 W; post: 254 ± 57 W; p = 0.43). Furthermore, Wingate peak power increased by 6% (668 ± 189 to 708 ± 220 W; p = 0.055), and Wingate mean power increased by 2% (553 ± 157 to 565 ± 157 W; p = 0.006) in the WBV group from preintervention to postintervention, respectively, without any change to LBM. The WBV training is an attractive training supplement for improving anaerobic power without increasing muscle mass in road cyclists. PMID:22531614

  11. Surfactants in anaerobic digestion of cheese whey, poultry waste, and cattle dung for improved biomethanation

    SciTech Connect

    Desai, M.; Madamwar, D.

    1994-05-01

    To obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung, poultry waste and cheese whey, with enriched methane content, the effect of various surfactants was studied. Among the surfactants tested, Tween 80 and sodium lauryl sulphate showed the maximum enhancement in gas production as well as methane content, indicating better process performance. The Tween 80 dosed digester (300 {mu}L/L) produced about 3.5 L gas/L of digester/d with 70% methane. Results also indicated increased percent COD reduction in the presence of Tween 80. 13 refs., 2 figs.

  12. Reductive dissolution of Pu(IV) by Clostridium sp. under anaerobic conditions.

    PubMed

    Francis, Arokiasamy J; Dodge, Cleveland J; Gillow, Jeffrey B

    2008-04-01

    An anaerobic, gram positive, spore-forming bacterium Clostridium sp., common in soils and wastes, capable of reduction of Fe(III) to Fe(II), Mn(IV) to Mn(II), Tc(VII) to Tc(IV), and U(VI) to U(IV), reduced Pu(IV) to Pu(III). Addition of 242Pu (IV)-nitrate to the bacterial growth medium at pH 6.4 resulted in the precipitation of Pu as amorphous Pu(OH)4 due to hydrolysis and polymerization reactions. The Pu (1 x 10(-5) M) had no effect upon growth of the bacterium as evidenced by glucose consumption; carbon dioxide and hydrogen production; a decrease in pH of the medium from 6.4 to 3.0 due to production of acetic and butyric acids from glucose fermentation; and a change in the Eh of the culture medium from +50 to -180 mV. Commensurate with bacterial growth, Pu was rapidly solubilized as evidenced by an increase in Pu concentration in solution which passed through a 0.03 microm filtration. Selective solvent extraction of the culture by thenoyltrifluoroacetone (TTA) indicated the presence of a reduced Pu species in the soluble fraction. X-ray absorption near edge spectroscopic (XANES) analysis of Pu in the culture sample at the Pu LIII absorption edge (18.054 keV) showed a shift of -3 eV compared to a Pu(IV) standard indicating reduction of Pu(IV) to Pu(III). These results suggestthat, although Pu generally exists as insoluble Pu(IV) in the environment, under appropriate conditions, anaerobic microbial activity could affect the long-term stability and mobility of Pu by its reductive dissolution. PMID:18504965

  13. Candidatus Accumulibacter phosphatis clades enriched under cyclic anaerobic and microaerobic conditions simultaneously use different electron acceptors.

    PubMed

    Camejo, Pamela Y; Owen, Brian R; Martirano, Joseph; Ma, Juan; Kapoor, Vikram; Santo Domingo, Jorge; McMahon, Katherine D; Noguera, Daniel R

    2016-10-01

    Lab- and pilot-scale simultaneous nitrification, denitrification and phosphorus removal-sequencing batch reactors were operated under cyclic anaerobic and micro-aerobic conditions. The use of oxygen, nitrite, and nitrate as electron acceptors by Candidatus Accumulibacter phosphatis during the micro-aerobic stage was investigated. A complete clade-level characterization of Accumulibacter in both reactors was performed using newly designed qPCR primers targeting the polyphosphate kinase gene (ppk1). In the lab-scale reactor, limited-oxygen conditions led to an alternated dominance of Clade IID and IC over the other clades. Results from batch tests when Clade IC was dominant (i.e., >92% of Accumulibacter) showed that this clade was capable of using oxygen, nitrite and nitrate as electron acceptors for P uptake. A more heterogeneous distribution of clades was found in the pilot-scale system (Clades IIA, IIB, IIC, IID, IA, and IC), and in this reactor, oxygen, nitrite and nitrate were also used as electron acceptors coupled to phosphorus uptake. However, nitrite was not an efficient electron acceptor in either reactor, and nitrate allowed only partial P removal. The results from the Clade IC dominated reactor indicated that either organisms in this clade can simultaneously use multiple electron acceptors under micro-aerobic conditions, or that the use of multiple electron acceptors by Clade IC is due to significant microdiversity within the Accumulibacter clades defined using the ppk1 gene. PMID:27340814

  14. Growth of clinical isolates of anaerobic bacteria on agar media: effects of media composition, storage conditions, and reduction under anaerobic conditions.

    PubMed Central

    Murray, P R

    1978-01-01

    The quantitative growth, the colony size, and the rate of growth of 47 clinical anaerobic isolates were compared on five different media, namely Brucella agar, brain heart infusion agar, Columbia agar, Schaedler agar, and tryptic soy agar. There was no significant difference in the quantitative growth of the anaerobes inoculated onto the five media. Although no single medium was superior for the growth of all isolates, 12 of 22 isolates, inoculated onto media stored for 4 weeks or less, grew best on Schaedler agar. The effects of supplementation of the media with reducing agents and reduction of the media before use were also analyzed and were found to be affected by the composition and length of storage of the media, as well as the bacteria tested. PMID:744801

  15. Carbon Isotope Fractionation during Anaerobic Degradation of Methyl tert-Butyl Ether under Sulfate-Reducing and Methanogenic Conditions

    PubMed Central

    Somsamak, Piyapawn; Richnow, Hans H.; Häggblom, Max M.

    2006-01-01

    Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ɛ) estimated for each enrichment were almost identical (−13.4 to −14.6; r2 = 0.89 to 0.99). A ɛ value of −14.4 ± 0.7 was obtained from regression analysis (r2 = 0.97, n = 55, 95% confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation. PMID:16461662

  16. Thermo-chemical pre-treatment to solubilize and improve anaerobic biodegradability of press mud.

    PubMed

    López González, Lisbet Mailin; Vervaeren, Han; Pereda Reyes, Ileana; Dumoulin, Ann; Romero Romero, Osvaldo; Dewulf, Jo

    2013-03-01

    Different pre-treatment severities by thermo-alkaline conditions (100°C, Ca(OH)2) on press mud were evaluated for different pre-treatment time and lime loading. COD solubilization and the methane yield enhancement were assessed. The biochemical methane potential was determined in batch assays under mesophilic conditions (37±1°C). The best pre-treatment resulted in a surplus of 72% of methane yield, adding 10g Ca(OH)2 100g(-1)TS(-1) for 1h. Pre-treatment also increased the COD solubilization, but the optimal severity for COD solubilization as determined by response surface methodology did not ensure the highest methane production. Inhibitory effects on anaerobic digestion were noticed when the severity was increased. These results demonstrate the relevance of thermo-alkaline pre-treatment severity in terms of both lime loading and pre-treatment time to obtain optimal anaerobic biodegradability of lignocellulosic biomass from press mud. PMID:23353040

  17. Changes in microbial community structures due to varying operational conditions in the anaerobic digestion of oxytetracycline-medicated cow manure.

    PubMed

    Turker, Gokhan; Aydin, Sevcan; Akyol, Çağrı; Yenigun, Orhan; Ince, Orhan; Ince, Bahar

    2016-07-01

    Management of manure containing veterinary antibiotics is a major concern in anaerobic treatment systems because of their possible adverse effects on microbial communities. Therefore, the aim of study was to investigate how oxytetracycline (OTC) influences bacteria and acetoclastic and hydrogenotrophic methanogens under varying operational conditions in OTC-medicated and non-medicated anaerobic cow manure digesters. Concentrations of OTC and its metabolites throughout the anaerobic digestion were determined using ultraviolet-high-performance liquid chromatography (UV-HPLC) and tandem liquid chromatography-mass spectrometry (LC/MS/MS), respectively. Fluorescent in situ hybridization, denaturing gradient gel electrophoresis, cloning, and sequencing analyses were used to monitor changes in microbial community structures. According to the results of analytical and molecular approaches, operating conditions highly influence active microbial community dynamics and associate with biogas production and elimination of OTC and its metabolites during anaerobic digestion of cow manure in the presence of an average initial concentration of 2.2 mg OTC/L. The impact of operating conditions has a drastic effect on acetoclastic methanogens than hydrogenotrophic methanogens and bacteria. PMID:27026176

  18. Demonstration of anaerobic stabilization of black water in accumulation systems under tropical conditions.

    PubMed

    Chaggu, Esnati J; Sanders, Wendy; Lettinga, Gatze

    2007-11-01

    The anaerobic digestion of "human waste" was studied at Mlalakuwa residential settlement in Dar-es-Salaam, Tanzania at ambient tropical temperatures (24-31 degrees C). This settlement experiences a high water table with flooding during the rainy season, resulting in a very costly emptying of the latrines once per month. To improve the situation, two plastic tanks (while one is in use, the other one is on stand-by) of 3000 l capacity each, named as Improved Pit-Latrines Without Urine Separation (IMPLWUS), were used as latrine pits. They received faeces+urine+wash water; basically, an accumulation system. Septic tank seed sludge was used. The dissolved chemical oxygen demand (COD(dis)) remaining when the reactor was closed after 380 days was about 8 g COD/l, volatile fatty acids were 100 mg COD/l and total ammonium nitrogen was about 2.8 g N/l, implying the possibility of methanogenesis inhibition. Stability results indicated a need for more degradation time after reactor closure. Estimated biogas production from wastewater generated by 10 people was 544 g COD-CH(4)/day, not enough for cooking purposes. PMID:17175158

  19. Anaerobic degradation of toluene and xylene by aquifer microorganisms under sulfate-reducing conditions.

    PubMed Central

    Edwards, E A; Wills, L E; Reinhard, M; Grbić-Galić, D

    1992-01-01

    Toluene and the three isomers of xylene were completely mineralized to CO2 and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was gasoline-contaminated sediment from Seal Beach, Calif. Evidence confirming that sulfate was the terminal electron acceptor is presented. Benzene and ethylbenzene were not degraded under the experimental conditions used. Successive transfers of the mixed cultures that were enriched from aquifer sediments retained the ability to degrade toluene and xylenes. Greater than 90% of 14C-labeled toluene or 14C-labeled o-xylene was mineralized to 14CO2. The doubling time for the culture grown on toluene or m-xylene was about 20 days, and the cell yield was about 0.1 to 0.14 g of cells (dry weight) per g of substrate. The accumulation of sulfide in the cultures as a result of sulfate reduction appeared to inhibit degradation of aromatic hydrocarbons. PMID:1575482

  20. Dissolution and Mobilization of Uranium in a Reduced Sediment by Natural Humic Substances under Anaerobic Conditions

    SciTech Connect

    Gu, Baohua; Luo, Wensui

    2009-01-01

    Biological reduction and precipitation of uranium (U) has been proposed as a remedial option for immobilizing uranium at contaminated sites, but the long-term stability and mobility of uranium remain a concern because it is neither removed nor destroyed. In this study, the dissolution and mobilization of reduced and oxidized forms of uranium [U(IV) and U(VI)] by natural humic substances were investigated in batch and column flow systems using a bioreduced sediment containing both U(IV) and U(VI). The addition of humic substances significantly increased the dissolution of U(IV) under anaerobic conditions. Humic acid (HA) was found to be more effective than fulvic acid (FA) in dissolving U(IV) in either 1 mM KCl or KHCO3 background solution. However, more U(VI) was dissolved in 1 mM KHCO3 than in 1 mM KCl background electrolytes. The HA also was found to be more effective than FA in mobilizing uranium under reducing and column flow conditions, although an accumulative amount of eluted U(VI) and U(IV) was relatively low (<60 g) after leaching with ~97 pore volumes of the humic solution in 1 mM KHCO3. These observations suggest that natural humic substances could potentially influence the long-term stability of bioreduced U(IV) even under strong reducing environments.

  1. Acute exercise performed close to the anaerobic threshold improves cognitive performance in elderly females.

    PubMed

    Córdova, C; Silva, V C; Moraes, C F; Simões, H G; Nóbrega, O T

    2009-05-01

    The objective of the present study was to compare the effect of acute exercise performed at different intensities in relation to the anaerobic threshold (AT) on abilities requiring control of executive functions or alertness in physically active elderly females. Forty-eight physically active elderly females (63.8 +/- 4.6 years old) were assigned to one of four groups by drawing lots: control group without exercise or trial groups with exercise performed at 60, 90, or 110% of AT (watts) and submitted to 5 cognitive tests before and after exercise. Following cognitive pretesting, an incremental cycle ergometer test was conducted to determine AT using a fixed blood lactate concentration of 3.5 mmol/L as cutoff. Acute exercise executed at 90% of AT resulted in significant (P < 0.05, ANOVA) improvement in the performance of executive functions when compared to control in 3 of 5 tests (verbal fluency, Tower of Hanoi test (number of movements), and Trail Making test B). Exercising at 60% of AT did not improve results of any tests for executive functions, whereas exercise executed at 110% of AT only improved the performance in one of these tests (verbal fluency) compared to control. Women from all trial groups exhibited a remarkable reduction in the Simple Response Time (alertness) test (P = 0.001). Thus, physical exercise performed close to AT is more effective to improve cognitive processing of older women even if conducted acutely, and using a customized exercise prescription based on the anaerobic threshold should optimize the beneficial effects. PMID:19377796

  2. Comparison of Seven Chemical Pretreatments of Corn Straw for Improving Methane Yield by Anaerobic Digestion

    PubMed Central

    Song, Zilin; GaiheYang; Liu, Xiaofeng; Yan, Zhiying; Yuan, Yuexiang; Liao, Yinzhang

    2014-01-01

    Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS −1 in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost. PMID:24695485

  3. Horizontal gene transfer promoted evolution of the ability to propagate under anaerobic conditions in yeasts.

    PubMed

    Gojković, Z; Knecht, W; Zameitat, E; Warneboldt, J; Coutelis, J-B; Pynyaha, Y; Neuveglise, C; Møller, K; Löffler, M; Piskur, J

    2004-05-01

    The ability to propagate under anaerobic conditions is an essential and unique trait of brewer's or baker's yeast ( Saccharomyces cervisiae). To understand the evolution of facultative anaerobiosis we studied the dependence of de novo pyrimidine biosynthesis, more precisely the fourth enzymic activity catalysed by dihydroorotate dehydrogenase (DHODase), on the enzymes of the respiratory chain in several yeast species. While the majority of yeasts possess a mitochondrial DHODase, Saccharomyces cerevisiae has a cytoplasmatic enzyme, whose activity is independent of the presence of oxygen. From the phylogenetic point of view, this enzyme is closely related to a bacterial DHODase from Lactococcus lactis. Here we show that S. kluyveri, which separated from the S. cerevisiae lineage more than 100 million years ago, represents an evolutionary intermediate, having both cytoplasmic and mitochondrial DHODases. We show that these two S. kluyveri enzymes, and their coding genes, differ in their dependence on the presence of oxygen. Only the cytoplasmic DHODase promotes growth in the absence of oxygen. Apparently a Saccharomyces yeast progenitor which had a eukaryotic-like mitochondrial DHODase acquired a bacterial gene for DHODase, which subsequently allowed cell growth gradually to become independent of oxygen. PMID:15014982

  4. Membrane fouling behavior in anaerobic baffled membrane bioreactor under static operating condition.

    PubMed

    Liu, Jiadong; Jia, Xiaolan; Gao, Bo; Bo, Longli; Wang, Lei

    2016-08-01

    A novel AnMBR combined with ABR as the anaerobic baffled membrane bioreactor (ABMBR) was developed for membrane fouling mitigation without any turbulence intensifying strategy to reduce the energy consumption further. The filtration time of this system lasted 14-25days under stable condition only with back-flushing every 48h. The polysaccharide accounted for 6.85±3.1% amount of total filter cake and the protein accounted for 4.12±2.1%, which took 79.12% and 11.12% of total area in laser scanning confocal microscope (CLSM) image. After filtration, 83.72±10.97% of turbidity, 59.28±16.46% of polysaccharide, 16.51% of tryptophan and 37.61% of humic-like substrates were rejected, respectively. The total membrane resistance at the end of each cycle was (4.47±0.99)×10(13)m(-1). And the resistance from filter cake was (4.15±1.00)×10(13)m(-1), which accounted for of 92.6±3.4% of total membrane resistance. PMID:27179954

  5. The anaerobic baffled reactor (ABR) treating communal wastewater under mesophilic conditions: a review.

    PubMed

    Reynaud, N; Buckley, C A

    2016-01-01

    A review concerning the anaerobic baffled reactor (ABR) treating communal wastewater under mesophilic conditions is presented. Existing studies indicate strong resilience of the reactor towards loading variations and shock-loads. The compartmentalisation of the ABR is a strongly stabilising factor with feed fluctuations being evened out across reactor chambers. Significant chemical oxygen demand (COD) reduction occurs almost exclusively in the first three chambers. The hydraulic rather than the organic loading rate is treatment limiting. Laboratory-scale studies show high treatment efficiencies of above 80% COD removal. It was found that most laboratory-scale studies do not factor in important aspects of field operation, such as diurnal fluctuations of feed characteristics, adequate start-up periods and periods of constant loading and optimised chamber outlet design, and never studied the effect of loading on sludge digestion. Performance data on full-scale ABR implementations, however, are extremely scarce, and existing studies are without exception affected by site-specific treatment-limiting factors hindering the extrapolation of generally valid conclusions. In view of a large-scale roll-out, communal ABRs are not sufficiently understood. Current challenges concerning the optimisation of reactor design require numerous well-monitored long-term full-scale reactor investigations. Existing ABR investigations yield encouraging results, supporting that the ABR may be one of the solutions answering the global call for low-maintenance, robust treatment systems. PMID:26877027

  6. In vitro metabolism of rebaudioside B, D, and M under anaerobic conditions: comparison with rebaudioside A.

    PubMed

    Purkayastha, Sidd; Pugh, George; Lynch, Barry; Roberts, Ashley; Kwok, David; Tarka, Stanley M

    2014-03-01

    The hydrolysis of the steviol glycosides rebaudioside A, B, D, and M, as well as of steviolbioside (a metabolic intermediate) to steviol was evaluated in vitro using human fecal homogenates from healthy donors under anaerobic conditions. Incubation of each of the rebaudiosides resulted in rapid hydrolysis to steviol. Metabolism was complete within 24h, with the majority occurring within the first 8h. There were no clear differences in the rate or extent of metabolism of rebaudioside B, D, or M, relative to the comparative control rebaudioside A. The hydrolysis of samples containing 2.0mg/mL of each rebaudioside tended to take slightly longer than solutions containing 0.2mg/mL. There was no apparent gender differences in the amount of metabolism of any of the rebaudiosides, regardless of the concentrations tested. An intermediate in the hydrolysis of rebaudioside M to steviol, steviolbioside, was also found to be rapidly degraded to steviol. The results demonstrate that rebaudiosides B, D, and M are metabolized to steviol in the same manner as rebaudioside A. These data support the use of toxicology data available on steviol, and on steviol glycosides metabolized to steviol (i.e., rebaudioside A) to substantiate the safety of rebaudiosides B, D, and M. PMID:24361573

  7. Juvenile roach (Rutilus rutilus) increase their anaerobic metabolism in response to copper exposure in laboratory conditions.

    PubMed

    Maes, Virginie; Betoulle, Stéphane; Jaffal, Ali; Dedourge-Geffard, Odile; Delahaut, Laurence; Geffard, Alain; Palluel, Olivier; Sanchez, Wilfried; Paris-Palacios, Séverine; Vettier, Aurélie; David, Elise

    2016-07-01

    This study aims to determine the potential impairment of cell energy synthesis processes (glycolysis and respiratory chain pathways) by copper in juvenile roach at different regulation levels by using a multi-marker approach. Juvenile roach were exposed to 0, 10, 50, and 100 µg/L of copper for 7 days in laboratory conditions. The glycolysis pathway was assessed by measuring the relative expression levels of 4 genes encoding glycolysis enzymes. The respiratory chain was studied by assessing the electron transport system and cytochrome c oxidase gene expression. Muscle mitochondria ultrastructure was studied, and antioxidant responses were measured. Furthermore, the main energy reserves-carbohydrates, lipids, and proteins-were measured, and cellular energy was evaluated by measuring ATP, ADP, AMP and IMP concentrations. This study revealed a disturbance of the cell energy metabolism due to copper exposure, with a significant decrease in adenylate energy charge in roach exposed to 10 μg/L of copper after 1 day. Moreover, ATP concentrations significantly decreased in roach exposed to 10 μg/L of copper after 1 day. This significant decrease persisted in roach exposed to 50 µg/L of copper after 7 days. AMP concentrations increased in all contaminated fish after 1 day of exposure. In parallel, the relative expression of 3 genes encoding for glycolysis enzymes increased in all contaminated fish after 1 day of copper exposure. Focusing on the respiratory chain, cytochrome c oxidase gene expression also increased in all contaminated fish at the two time-points. The activity of the electron transport system was not disturbed by copper, except in roach exposed to 100 µg/L of copper after 1 day. Copper induced a metabolic stress. Juvenile roach seemed to respond to the ensuing high energy demand by increasing their anaerobic metabolism, but the energy produced by the anaerobic metabolism is unable to compensate for the stress induced by copper after 7

  8. Comparison of different conditions, substrates and operation modes by dynamic simulation of a full-scale anaerobic SBR plant.

    PubMed

    Rönner-Holm, S G E; Zak, A; Holm, N C

    2012-01-01

    Simulation studies for a full-scale anaerobic unit of a wastewater treatment plant (WWTP) were performed using the anaerobic digestion model no. 1 (ADM1). The anaerobic full-scale plant consists of one mesophilic and one thermophilic digester, operated in an anaerobic sequential batch reactor (ASBR) mode, and sludge enrichment reactors (SER) for each digester. The digesters are fed with a mixture of vegetable waste and process wastewater from the food factory. Characteristics such as COD(total), N(total) and NH(4)-N concentrations in the influent and effluent of the digester and SERs were measured and used for input fractionation. Parameters such as level, pH, biogas amount and composition in the digester were measured online and used for calibration. For simulation studies, different temperatures and operation modes with varying chemical oxygen demand (COD) input loads corresponding to feedstocks such as fruits, vegetables and grain were analysed and compared. Higher gas production and digestion efficiency in the thermophilic reactor and in shorter cycles were found and confirmed at full scale. Serial operation mode increased the gas production, but pH inhibition occurred earlier. Feeding only biosolids into digester I and the effluent of digester I together with process water into digester II further improved gas production in serial operation mode. PMID:22258689

  9. Reactor performance and microbial community dynamics during solid-state anaerobic digestion of corn stover at mesophilic and thermophilic conditions.

    PubMed

    Shi, Jian; Wang, Zhongjiang; Stiverson, Jill A; Yu, Zhongtang; Li, Yebo

    2013-05-01

    Reactor performance and microbial community dynamics were investigated during solid state anaerobic digestion (SS-AD) of corn stover at mesophilic and thermophilic conditions. Thermophilic SS-AD led to faster and greater reductions of cellulose and hemicelluloses during the first 12 days compared to mesophilic SS-AD. However, accumulation of volatile fatty acids (VFAs) was 5-fold higher at thermophilic than mesophilic temperatures, resulting in a large pH drop during days 6-12 in the thermophilic reactors. Culture-based enumeration revealed 10-50 times greater populations of cellulolytic and xylanolytic microbes during thermophilic SS-AD than mesophilic SS-AD. DGGE analysis of PCR amplified 16S rRNA genes showed dynamic shifts, especially during the thermophilic SS-AD, of bacterial and archaeal communities over the 38 days of SS-AD as a result of acclimation of the initial seed microbial consortia to the lignocellulosic feedstock. The findings of this study can guide future studies to improve efficiency and stability of SS-AD. PMID:23567733

  10. Anaerobic hydrocarbon degradation in petroleum-contaminated harbor sediments under sulfate-reducing and artificially imposed iron-reducing conditions

    USGS Publications Warehouse

    Coates, J.D.; Anderson, R.T.; Woodward, J.C.; Phillips, E.J.P.; Lovley, D.R.

    1996-01-01

    The potential use of iron(III) oxide to stimulate in-situ hydrocarbon degradation in anaerobic petroleum-contaminated harbor sediments was investigated. Previous studies have indicated that Fe(III)-reducing bacteria (FeRB) can oxidize some electron donors more effectively than sulfate- reducing bacteria (SRB). In contrast to previous results in freshwater sediments, the addition of Fe(III) to marine sediments from San Diego Bay, CA did not switch the terminal electron-accepting process (TEAP) from sulfate reduction to Fe-(III) reduction. Addition of Fe(III) also did not stimulate anaerobic hydrocarbon oxidation. Exposure of the sediment to air [to reoxidize Fe(II) to Fe(III)] followed by anaerobic incubation of the sediments, resulted in Fe-(III) reduction as the TEAP, but contaminant degradation was not stimulated and in some instances was inhibited. The difference in the ability of FeRB to compete with the SRB in the different sediment treatments was related to relative population sizes. Although the addition of Fe(III) did not stimulate hydrocarbon degradation, the results presented here as well as other recent studies demonstrate that there may be significant anaerobic hydrocarbon degradation under sulfate-reducing conditions in harbor sediments.

  11. Sensitive and selective culture medium for detection of environmental Clostridium difficile isolates without requirement for anaerobic culture conditions.

    PubMed

    Cadnum, Jennifer L; Hurless, Kelly N; Deshpande, Abhishek; Nerandzic, Michelle M; Kundrapu, Sirisha; Donskey, Curtis J

    2014-09-01

    Effective and easy-to-use methods for detecting Clostridium difficile spore contamination would be useful for identifying environmental reservoirs and monitoring the effectiveness of room disinfection. Culture-based detection methods are sensitive for detecting C. difficile, but their utility is limited due to the requirement of anaerobic culture conditions and microbiological expertise. We developed a low-cost selective broth medium containing thioglycolic acid and l-cystine, termed C. difficile brucella broth with thioglycolic acid and l-cystine (CDBB-TC), for the detection of C. difficile from environmental specimens under aerobic culture conditions. The sensitivity and specificity of CDBB-TC (under aerobic culture conditions) were compared to those of CDBB (under anaerobic culture conditions) for the recovery of C. difficile from swabs collected from hospital room surfaces. CDBB-TC was significantly more sensitive than CDBB for recovering environmental C. difficile (36/41 [88%] versus 21/41 [51%], respectively; P = 0.006). C. difficile latex agglutination, an enzyme immunoassay for toxins A and B or glutamate dehydrogenase, and a PCR for toxin B genes were all effective as confirmatory tests. For 477 total environmental cultures, the specificity of CDBB-TC versus that of CDBB based upon false-positive yellow-color development of the medium without recovery of C. difficile was 100% (0 false-positive results) versus 96% (18 false-positive results), respectively. False-positive cultures for CDBB were attributable to the growth of anaerobic non-C. difficile organisms that did not grow in CDBB-TC. Our results suggest that CDBB-TC provides a sensitive and selective medium for the recovery of C. difficile organisms from environmental samples, without the need for anaerobic culture conditions. PMID:24958803

  12. Metabolism of toxic pyrrolizidine alkaloids from tansy ragwort (Senecio jacobaea) in ovine ruminal fluid under anaerobic conditions.

    PubMed Central

    Craig, A M; Latham, C J; Blythe, L L; Schmotzer, W B; O'Connor, O A

    1992-01-01

    The ability of ovine ruminal fluid to metabolize pyrrolizidine alkaloid (PA) from Senecio jacobaea under anaerobic conditions was evaluated. Four fistulated sheep fed PA served as individual sources of ruminal fluid, which was incubated in a defined minimal salts medium under two different anaerobic conditions, denitrifying and methanogenic. Anaerobic cultures amended with ovine ruminal fluids (20%), PA (100 micrograms/ml), and a defined minimal salts medium were monitored for a period of several days. These cultures revealed that while PA was not depleted in sterile, autoclaved controls or under denitrifying conditions, it was metabolized during periods of active methanogenesis under methanogenic conditions. In addition, samples of ruminal fluid were separated by differential centrifugation under anaerobic conditions, and the resultant supernatants were tested for their ability to metabolize PA as compared with those of the respective uncentrifuged control fluids. Uncentrifuged controls exhibited a PA depletion rate of -4.04 +/- 0.17 micrograms of PA per ml per h. Supernatants 1 (centrifuged at 41 x g for 2 min), 2 (centrifuged at 166 x g for 5 min), and 3 (centrifuged at 1,500 x g for 10 min) exhibited significantly slower depletion rates, with slopes of data representing -1.64 +/- 0.16, -1.44 +/- 0.16, and -1.48 +/- 0.16 micrograms of PA metabolized per ml per h, respectively, demonstrating no statistically significant difference among the supernatant cultures. Microscopic evaluations revealed that protozoa were present in the control whole ruminal fluid and to a lesser extent in supernatant 1, while supernatants 2 and 3 contained only bacteria.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1444382

  13. Improved scleroglucan for polymer flooding under harsh reservoir conditions

    SciTech Connect

    Rivenq, R.C.; Donche, A. )

    1992-02-01

    Polymer flooding is commonly used to improve water sweep efficiency in oil reserves. Successful application of this method, however, has been restricted to low-temperature reservoirs because suitable polymers are not available for harsh conditions. Scleroglucan, a polymer produced by fermentation that shows promising properties, forms solutions that are very viscous and highly resistant to shear. Viscosity is insensitive to both salts and pH and only slightly affected by temperature. To facilitate industrial development of scleroglucan polymer, improvements in the filterability of the solutions and better knowledge of their behavior in porous media are necessary. A high-quality scleroglucan was obtained by eliminating the impurities responsible for polymer aggregation. This allowed evaluation of the intrinsic properties of the polymer molecules. Complete elimination of impurities from the polymer solution led to a scleroglucan without any aggregation tendency and with a good filterability, particularly at high temperatures. The performance of this improved scleroglucan in porous media was evaluated by coreflood experiments in Berea cores at temperatures ranging from 30 to 90{degrees} C. Results provided in this paper showed low permeability reduction and a mobility reduction close to relative viscosity. Injection of successive slugs into a Berea core under anaerobic conditions indicated low polymer retention at high temperatures (30 {mu}g/g at 90{degrees} C).

  14. Physiological activities associated with biofilm growth in attached and suspended growth bioreactors under aerobic and anaerobic conditions.

    PubMed

    Naz, Iffat; Seher, Shama; Perveen, Irum; Saroj, Devendra P; Ahmed, Safia

    2015-01-01

    This research work evaluated the biofilm succession on stone media and compared the biochemical changes of sludge in attached and suspended biological reactors operated under aerobic and anaerobic conditions. Stones incubated (30±2°C) with activated sludge showed a constant increase in biofilm weight up to the fifth and seventh week time under anaerobic and aerobic conditions, respectively, where after reduction (>80%) the most probable number index of pathogen indicators on ninth week was recorded. Reduction in parameters such as biological oxygen demand (BOD) (47.7%), chemical oxygen demand (COD, 41%), nitrites (60.2%), nitrates (105.5%) and phosphates (58.9%) and increase in dissolved oxygen (176.5%) of sludge were higher in aerobic attached growth reactors as compared with other settings. While, considerable reductions in these values were also observed (BOD, 53.8%; COD, 2.8%; nitrites, 28.6%; nitrates, 31.7%; phosphates, 41.4%) in the suspended growth system under anaerobic conditions. However, higher sulphate removal was observed in suspended (40.9% and 54.9%) as compared with biofilm reactors (28.2% and 29.3%). Six weeks biofilm on the stone media showed maximum physiological activities; thus, the operational conditions should be controlled to keep the biofilm structure similar to six-week-old biofilm, and can be used in fixed biofilm reactors for wastewater treatment. PMID:25609155

  15. Anaerobic Biodegradation Tests of Poly(lactic acid) under Mesophilic and Thermophilic Conditions Using a New Evaluation System for Methane Fermentation in Anaerobic Sludge

    PubMed Central

    Yagi, Hisaaki; Ninomiya, Fumi; Funabashi, Masahiro; Kunioka, Masao

    2009-01-01

    Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 °C) and mesophilic temperature (35 °C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 °C) and 2.24% (at 35 °C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 °C. On the other hand, the PLA degradation started in 55 days at 35 °C and degradation rate was much slower than at 55 °C. PMID:19865521

  16. Anaerobic biodegradation tests of poly(lactic acid) under mesophilic and thermophilic conditions using a new evaluation system for methane fermentation in anaerobic sludge.

    PubMed

    Yagi, Hisaaki; Ninomiya, Fumi; Funabashi, Masahiro; Kunioka, Masao

    2009-09-01

    Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 degrees C) and mesophilic temperature (35 degrees C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 degrees C) and 2.24% (at 35 degrees C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 degrees C. On the other hand, the PLA degradation started in 55 days at 35 degrees C and degradation rate was much slower than at 55 degrees C. PMID:19865521

  17. Using a tank flow model with PEARL to measure the variation in pesticide persistence between anaerobic and aerobic soil conditions

    NASA Astrophysics Data System (ADS)

    Real, Joaquin; Seiterle-Winn, Natalie; Frances, Felix

    2013-04-01

    Pesticide leaching is very sensitive to the transformation rate (Boesten and Linden, 1991). The values of the transformation rates of the pesticides differ between aerobic and anaerobic soil conditions. The main objective is to determine if there is a significant variation in pesticide persistence between aerobic and anaerobic soil conditions. An auxiliary hydrological model is used with the PEARL model (Leistra et al, 2001). The auxiliary model determines the degree of saturation of the soil at each time step. The value of the degradation rate for a given pesticide in the PEARL model varies depending on the time periods with saturated or unsaturated soil conditions. The proposed auxiliary model has been conceptualized as a static tank flow model based on the actual evapotranspiration of the crop plants. It is based on the RIBAV model (Garcia-Arias et al. 2012) used for the modeling of riparian vegetation zonation. The tank represents a soil column which also includes the superficial root layer. The lower capacity limit of this tank is the permanent wilting moisture of the soil. The upper capacity limit represents the saturated condition of the soil. The tanks input flows are precipitation and irrigation. In contrast, output flows are the actual evapotranspiration and the discharge of the tank. The most relevant model parameters are the soil retention curves, the crop parameters (specially related to root depths and crop coefficients) and the daily meteorological data (such as precipitation and potential evapotranspiration). The main output of the auxiliary model is the relative soil moisture, which determines if the PEARL model should use the transformation rate value for aerobic or for anaerobic conditions. In order to prove the applicability of the model, it was tested with various pesticides, which cover a wide range of transformation rates. The results show that the auxiliary tank model is able to determine the partition of the pesticides degrading in both

  18. Impact of ArcA loss in Shewanella oneidensis revealed by comparative proteomics under aerobic and anaerobic conditions

    SciTech Connect

    Yuan, Jie; Wei, Buyun; Lipton, Mary S.; Gao, Haichun

    2012-06-01

    Shewanella inhabit a wide variety of niches in nature and can utilize a broad spectrum of electron acceptors under anaerobic conditions. How they modulate their gene expression to adapt is poorly understood. ArcA, homologue of a global regulator controlling hundreds of genes involved in aerobic and anaerobic respiration in E. coli, was shown to be important in aerobiosis/anaerobiosis of S. oneidensis as well. Loss of ArcA, in addition to altering transcription of many genes, resulted in impaired growth under aerobic condition, which was not observed in E. coli. To further characterize the impact of ArcA loss on gene expression on the level of proteome under aerobic and anaerobic conditions, liquid-chromatography-mass-spectrometry (LC-MS) based proteomic approach was employed. Results show that ArcA loss led to globally altered gene expression, generally consistent with that observed with transcripts. Comparison of transcriptomic and proteomic data permitted identification of 17 high-confidence ArcA targets. Moreover, our data indicate that ArcA is required for regulation of cytochrome c proteins, and the menaquinone level may play a role in regulating ArcA as in E. coli. Proteomic-data-guided growth assay revealed that the aerobic growth defect of ArcA mutant is presumably due to impaired peptide utilization.

  19. Direct production of organic acids from starch by cell surface-engineered Corynebacterium glutamicum in anaerobic conditions

    PubMed Central

    2013-01-01

    We produced organic acids, including lactate and succinate, directly from soluble starch under anaerobic conditions using high cell-density cultures of Corynebacterium glutamicum displaying α-amylase (AmyA) from Streptococcus bovis 148 on the cell surface. Notably, reactions performed under anaerobic conditions at 35 and 40°C, which are higher than the optimal growth temperature of 30°C, showed 32% and 19%, respectively, higher productivity of the organic acids lactate, succinate, and acetate compared to that at 30°C. However, α-amylase was not stably anchored and released into the medium from the cell surface during reactions at these higher temperatures, as demonstrated by the 61% and 85% decreases in activity, respectively, from baseline, compared to the only 8% decrease at 30°C. The AmyA-displaying C. glutamicum cells retained their starch-degrading capacity during five 10 h reaction cycles at 30°C, producing 107.8 g/l of total organic acids, including 88.9 g/l lactate and 14.0 g/l succinate. The applicability of cell surface-engineering technology for the production of organic acids from biomass by high cell-density cultures of C. glutamicum under anaerobic conditions was demonstrated. PMID:24342107

  20. Direct production of organic acids from starch by cell surface-engineered Corynebacterium glutamicum in anaerobic conditions.

    PubMed

    Tsuge, Yota; Tateno, Toshihiro; Sasaki, Kengo; Hasunuma, Tomohisa; Tanaka, Tsutomu; Kondo, Akihiko

    2013-01-01

    We produced organic acids, including lactate and succinate, directly from soluble starch under anaerobic conditions using high cell-density cultures of Corynebacterium glutamicum displaying α-amylase (AmyA) from Streptococcus bovis 148 on the cell surface. Notably, reactions performed under anaerobic conditions at 35 and 40°C, which are higher than the optimal growth temperature of 30°C, showed 32% and 19%, respectively, higher productivity of the organic acids lactate, succinate, and acetate compared to that at 30°C. However, α-amylase was not stably anchored and released into the medium from the cell surface during reactions at these higher temperatures, as demonstrated by the 61% and 85% decreases in activity, respectively, from baseline, compared to the only 8% decrease at 30°C. The AmyA-displaying C. glutamicum cells retained their starch-degrading capacity during five 10 h reaction cycles at 30°C, producing 107.8 g/l of total organic acids, including 88.9 g/l lactate and 14.0 g/l succinate. The applicability of cell surface-engineering technology for the production of organic acids from biomass by high cell-density cultures of C. glutamicum under anaerobic conditions was demonstrated. PMID:24342107

  1. [Influences of humic acids on the dissimilatory iron reduction of red soil in anaerobic condition].

    PubMed

    Xu, Li-na; Li, Zhong-pei; Che, Yu-ping

    2009-01-01

    Iron oxide is abundant in red soil. Reduction and oxidation of iron oxide are important biogeochemical processes. In this paper, we reported the effects of humic acid on dissimilatory iron reduction (DISSIR) in red soil by adding glucose or humic acid (HA), under an anaerobic condition. Results indicated that DISSIR is weak for the red soil with a low content of organic matter, Glucose that act as electron donators promoted the process of DISSIR in red soil. HA added to soil solely didn't accelerate the DISSIR since it couldn't provide electron donators to microbe. However, adding of both glucose and HA promoted the DISSIR at the beginning of the incubation but then inhibited the process, which maybe caused by the effects of precipitation and adsorption of red soil. Concentrations of HA strongly affected the DISSIR, HA at low concentrations(0.20 and 0.02 g/kg) had weak effects, while HA at a high concentration (2.00 g/kg) promoted the process at the beginning and then inhibited it. HA extracted from different materials had distinct effects on the DISSIR. HA from Weathering coal of Datong in Shanxi Province (HAs), lignite of Gongxian in Henan Province (HAh) and Dianchi Lake sediment in Kunming of Yunnan Province (HAk) all promoted the DISSIR at the beginning of the incubation. However, at the end of incubation, HAk with a low aromaticity still promoted the process, while HAs and HAh with a higher aromaticity weakened the DISSIR. This may be due to the increase in adsorption of soil with the aromaticity of HA. PMID:19353884

  2. BTEX removal in a horizontal-flow anaerobic immobilized biomass reactor under denitrifying conditions.

    PubMed

    Ribeiro, Rogers; de Nardi, Ivana Ribeiro; Fernandes, Bruna Soares; Foresti, Eugenio; Zaiat, Marcelo

    2013-04-01

    Because benzene, toluene, ethylbenzene, and xylenes (BTEX) and ethanol are important contaminants present in Brazilian gasoline, it is essential to develop technology that can be used in the bioremediation of gasoline-contaminated aquifers. This paper evaluates the performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor fed with water containing gasoline constituents under denitrifying conditions. Two HAIB reactors filled with polyurethane foam matrices (5 mm cubes, 23 kg/m(3) density and 95 % porosity) for biomass attachment were assayed. The reactor fed with synthetic substrate containing protein, carbohydrates, sodium bicarbonate and BTEX solution in ethanol, at an Hydraulic retention time (HRT) of 13.5 h, presented hydrocarbon removal efficiencies of 99 % at the following initial concentrations: benzene 6.7 mg/L, toluene 4.9 mg/L, m-xylene and p-xylene 7.2 mg/L, ethylbenzene 3.7 mg/L, and nitrate 60 mg N/L. The HAIB reactor fed with gasoline-contaminated water at an HRT of 20 h showed hydrocarbon removal efficiencies of 96 % at the following initial concentrations: benzene, 4.9 mg/L; toluene, 7.2 mg/L; m-xylene, 3.7 mg/L; and nitrate 400 mg N/L. Microbiological observations along the length of the HAIB reactor fed with gasoline-contaminated water confirmed that in the first segment of the reactor, denitrifying metabolism predominated, whereas from the first sampling port on, the metabolism observed was predominantly methanogenic. PMID:22910812

  3. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment.

    PubMed

    Smith, Adam L; Skerlos, Steven J; Raskin, Lutgarde

    2015-09-01

    Membrane biofilm development was evaluated to improve psychrophilic (15°C) anaerobic membrane bioreactor (AnMBR) treatment of domestic wastewater. An AnMBR containing three replicate submerged membrane housings with separate permeate collection was operated at three levels of membrane fouling by independently controlling biogas sparging for each membrane unit. High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration two to three times the equilibrium concentration predicted by Henry's law. Illumina sequencing of 16S rRNA targeting Bacteria and Archaea and reverse transcription-quantitative polymerase chain reaction targeting the methyl coenzyme-M reductase (mcrA) gene in methanogens indicated that the membrane biofilm was enriched in highly active methanogens and syntrophic bacteria. Restoring fouled membranes to a transmembrane pressure (TMP) near zero by increasing biogas sparging did not disrupt the biofilm's treatment performance, suggesting that microbes in the foulant layer were tightly adhered and did not significantly contribute to TMP. Dissolved methane oversaturation persisted without high TMP, implying that methanogenesis in the biofilm, rather than high TMP, was the primary driving force in methane oversaturation. The results describe an attractive operational strategy to improve treatment performance in low-temperature AnMBR by supporting syntrophy and methanogenesis in the membrane biofilm through controlled membrane fouling. PMID:26238293

  4. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment

    PubMed Central

    Smith, Adam L; Skerlos, Steven J; Raskin, Lutgarde

    2015-01-01

    Membrane biofilm development was evaluated to improve psychrophilic (15°C) anaerobic membrane bioreactor (AnMBR) treatment of domestic wastewater. An AnMBR containing three replicate submerged membrane housings with separate permeate collection was operated at three levels of membrane fouling by independently controlling biogas sparging for each membrane unit. High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration two to three times the equilibrium concentration predicted by Henry’s law. Illumina sequencing of 16S rRNA targeting Bacteria and Archaea and reverse transcription-quantitative polymerase chain reaction targeting the methyl coenzyme-M reductase (mcrA) gene in methanogens indicated that the membrane biofilm was enriched in highly active methanogens and syntrophic bacteria. Restoring fouled membranes to a transmembrane pressure (TMP) near zero by increasing biogas sparging did not disrupt the biofilm’s treatment performance, suggesting that microbes in the foulant layer were tightly adhered and did not significantly contribute to TMP. Dissolved methane oversaturation persisted without high TMP, implying that methanogenesis in the biofilm, rather than high TMP, was the primary driving force in methane oversaturation. The results describe an attractive operational strategy to improve treatment performance in low-temperature AnMBR by supporting syntrophy and methanogenesis in the membrane biofilm through controlled membrane fouling. PMID:26238293

  5. Improving anaerobic digestion of a cellulosic waste via routine bioaugmentation with cellulolytic microorganisms.

    PubMed

    Martin-Ryals, Ana; Schideman, Lance; Li, Peng; Wilkinson, Henry; Wagner, Richard

    2015-01-01

    This study investigated routine bioaugmentation in the acid-phase of a two-phase anaerobic digestion (AD) process treating a largely cellulosic waste material generated from sweet corn processing. A proprietary cellulolytic bioculture was used for bioaugmentation with the aim of increasing substrate hydrolysis to improve overall methanogenic efficiency. In a sequencing batch experiment routine bioaugmentation achieved significantly greater soluble chemical oxygen demand (sCOD) generation (+25%) and methane production (+15%) compared to one-time bioaugmentation. In a continuous bench-scale system, routine bioaugmentation increased acid-phase sCOD by 29-68% and acetic acid concentrations by 31-34%. This benefit to hydrolysis and acetogenesis subsequently led to sustained increase in methane production (+56%) compared to non-bioaugmentation. A cursory economic analysis indicated that routine bioaugmentation could improve the economics of corn waste AD by $27-$34/dry tonne of waste. Overall, routine bioaugmentation showed significant promise for improving AD of corn waste by achieving sustained increases in substrate hydrolysis and methane production. PMID:25864032

  6. Tolerance of anaerobic conditions caused by flooding during germination and early growth in rice (Oryza sativa L.).

    PubMed

    Miro, Berta; Ismail, Abdelbagi M

    2013-01-01

    Rice is semi-aquatic, adapted to a wide range of hydrologies, from aerobic soils in uplands to anaerobic and flooded fields in waterlogged lowlands, to even deeply submerged soils in flood-prone areas. Considerable diversity is present in native rice landraces selected by farmers over centuries. Our understanding of the adaptive features of these landraces to native ecosystems has improved considerably over the recent past. In some cases, major genes associated with tolerance have been cloned, such as SUB1A that confers tolerance of complete submergence and SNORKEL genes that control plant elongation to escape deepwater. Modern rice varieties are sensitive to flooding during germination and early growth, a problem commonly encountered in rainfed areas, but few landraces capable of germination under these conditions have recently been identified, enabling research into tolerance mechanisms. Major QTLs were also identified, and are being targeted for molecular breeding and for cloning. Nevertheless, limited progress has been made in identifying regulatory processes for traits that are unique to tolerant genotypes, including faster germination and coleoptile elongation, formation of roots and leaves under hypoxia, ability to catabolize starch into simple sugars for subsequent use in glycolysis and fermentative pathways to generate energy. Here we discuss the state of knowledge on the role of the PDC-ALDH-ACS bypass and the ALDH enzyme as the likely candidates effective in tolerant rice genotypes. Potential involvement of factors such as cytoplasmic pH regulation, phytohormones, reactive oxygen species scavenging and other metabolites is also discussed. Further characterization of contrasting genotypes would help in elucidating the genetic and biochemical regulatory and signaling mechanisms associated with tolerance. This could facilitate breeding rice varieties suitable for direct seeding systems and guide efforts for improving waterlogging tolerance in other crops

  7. Tolerance of anaerobic conditions caused by flooding during germination and early growth in rice (Oryza sativa L.)

    PubMed Central

    Miro, Berta; Ismail, Abdelbagi M.

    2013-01-01

    Rice is semi-aquatic, adapted to a wide range of hydrologies, from aerobic soils in uplands to anaerobic and flooded fields in waterlogged lowlands, to even deeply submerged soils in flood-prone areas. Considerable diversity is present in native rice landraces selected by farmers over centuries. Our understanding of the adaptive features of these landraces to native ecosystems has improved considerably over the recent past. In some cases, major genes associated with tolerance have been cloned, such as SUB1A that confers tolerance of complete submergence and SNORKEL genes that control plant elongation to escape deepwater. Modern rice varieties are sensitive to flooding during germination and early growth, a problem commonly encountered in rainfed areas, but few landraces capable of germination under these conditions have recently been identified, enabling research into tolerance mechanisms. Major QTLs were also identified, and are being targeted for molecular breeding and for cloning. Nevertheless, limited progress has been made in identifying regulatory processes for traits that are unique to tolerant genotypes, including faster germination and coleoptile elongation, formation of roots and leaves under hypoxia, ability to catabolize starch into simple sugars for subsequent use in glycolysis and fermentative pathways to generate energy. Here we discuss the state of knowledge on the role of the PDC-ALDH-ACS bypass and the ALDH enzyme as the likely candidates effective in tolerant rice genotypes. Potential involvement of factors such as cytoplasmic pH regulation, phytohormones, reactive oxygen species scavenging and other metabolites is also discussed. Further characterization of contrasting genotypes would help in elucidating the genetic and biochemical regulatory and signaling mechanisms associated with tolerance. This could facilitate breeding rice varieties suitable for direct seeding systems and guide efforts for improving waterlogging tolerance in other crops

  8. Microbial Anaerobic Ammonium Oxidation Under Iron Reducing Conditions, Alternative Electron Acceptors

    NASA Astrophysics Data System (ADS)

    Ruiz-Urigüen, M.; Jaffe, P. R.

    2015-12-01

    Autotrophic Acidimicrobiaceae-bacterium named A6 (A6), part of the Actinobacteria phylum have been linked to anaerobic ammonium (NH4+) oxidation under iron reducing conditions. These organisms obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, the TEAs are iron oxides [Fe(III)], which are reduced to Fe(II), this process is known as Feammox. Our studies indicate that alternative forms of TEAs can be used by A6, e.g. iron rich clays (i.e. nontronite) and electrodes in bioelectrochemical systems such as Microbial Electrolysis Cells (MECs), which can sustain NH4+removal and A6 biomass production. Our results show that nontronite can support Feammox and promote bacterial cell production. A6 biomass increased from 4.7 x 104 to 3.9 x 105 cells/ml in 10 days. Incubations of A6 in nontronite resulted in up to 10 times more NH4+ removal and 3 times more biomass production than when ferrihydrite is used as the Fe(III) source. Additionally, Fe in nontronite can be reoxidized by aeration and A6 can reutilize it; however, Fe is still finite in the clay. In contrast, in MECs, A6 harvest electrons from NH4+ and use an anode as an unlimited TEA, as a result current is produced. We operated multiple MECs in parallel using a single external power source, as described by Call & Logan (2011). MECs were run with an applied voltage of 0.7V and different growing mediums always containing initial 5mM NH4+. Results show that current production is favored when anthraquinone-2,6-disulfonate (AQDS), an electron shuttled, is present in the medium as it facilitates the transfer of electrons from the bacterial cell to the anode. Additionally, A6 biomass increased from 1 x 104 to 9.77 x 105cells/ml in 14 days of operation. Due to Acidimicrobiaceae-bacterium A6's ability to use various TEAs, MECs represent an alternative, iron-free form, for optimized biomass production of A6 and its application in NH4

  9. Diversity of methanotrophs in Zoige wetland soils under both anaerobic and aerobic conditions.

    PubMed

    Yun, Juanli; Ma, Anzhou; Li, Yaoming; Zhuang, Guoqiang; Wang, Yanfen; Zhang, Hongxun

    2010-01-01

    Zoige wetland is one of the most important methane emission centers in China. The oxidation of methane in the wetland affects global warming, soil ecology and atmospheric chemistry. Despite their global significance, microorganisms that consume methane in Zoige wetland remain poorly characterized. In this study, we investigated methanotrophs diversity in soil samples from both anaerobic site and aerobic site in Zoige wetland using pmoA gene as a molecular marker. The cloning library was constructed according to the pmoA sequences detected. Four clusters of methanotrophs were detected. The phylogenetic tree showed that all four clusters detected were affiliated to type I methanotrophs. Two novel clusters (cluster 1, cluster 2) were found to relate to none of the recognized genera of methanotrophs. These clusters have no cultured representatives and reveal an ecological adaptation of particular uncultured methanotrophs in Zoige wetland. Two clusters were belonging to Methylobacter and Methylococcus separately. Denaturing gradient gel electrophoresis gel bands pattern retrieved from these two samples revealed that the community compositions of anaerobic soil and aerobic soil were different from each other while anaerobic soil showed a higher metanotrophs diversity. Real-time PCR assays of the two samples demonstrated that aerobic soil sample in Zoige wetland was 1.5 times as much copy numbers as anaerobic soil. These data illustrated that methanotrophs are a group of microorganisms influence the methane consumption in Zoige wetland. PMID:21179963

  10. Effect Of Imposed Anaerobic Conditions On Metals Release From Acid-Mine Drainage Contaminated Streambed Sediments

    EPA Science Inventory

    Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerob...

  11. Effects of Aerobic and Microaerobic Conditions on Anaerobic Ammonium-Oxidizing (Anammox) Sludge

    PubMed Central

    Strous, M.; Van Gerven, E.; Kuenen, J. G.; Jetten, M.

    1997-01-01

    The anaerobic ammonium oxidation (Anammox) process is a promising novel option for removing nitrogen from wastewater. In this study it was shown that the Anammox process was inhibited reversibly by the presence of oxygen. Furthermore, aerobic nitrifiers were shown not to play an important role in the Anammox process. PMID:16535633

  12. Degradation of n-Hexadecane and Its Metabolites by Pseudomonas aeruginosa under Microaerobic and Anaerobic Denitrifying Conditions

    PubMed Central

    Chayabutra, Chawala; Ju, Lu-Kwang

    2000-01-01

    A strategy for sequential hydrocarbon bioremediation is proposed. The initial O2-requiring transformation is effected by aerobic resting cells, thus avoiding a high oxygen demand. The oxygenated metabolites can then be degraded even under anaerobic conditions when supplemented with a highly water-soluble alternative electron acceptor, such as nitrate. To develop the new strategy, some phenomena were studied by examining Pseudomonas aeruginosa fermentation. The effects of dissolved oxygen (DO) concentration on n-hexadecane biodegradation were investigated first. Under microaerobic conditions, the denitrification rate decreased as the DO concentration decreased, implying that the O2-requiring reactions were rate limiting. The effects of different nitrate and nitrite concentrations were examined next. When cultivated aerobically in tryptic soy broth supplemented with 0 to 0.35 g of NO2−-N per liter, cells grew in all systems, but the lag phase was longer in the presence of higher nitrite concentrations. However, under anaerobic denitrifying conditions, even 0.1 g of NO2−-N per liter totally inhibited cell growth. Growth was also inhibited by high nitrate concentrations (>1 g of NO3−-N per liter). Cells were found to be more sensitive to nitrate or nitrite inhibition under denitrifying conditions than under aerobic conditions. Sequential hexadecane biodegradation by P. aeruginosa was then investigated. The initial fermentation was aerobic for cell growth and hydrocarbon oxidation to oxygenated metabolites, as confirmed by increasing dissolved total organic carbon (TOC) concentrations. The culture was then supplemented with nitrate and purged with nitrogen (N2). Nitrate was consumed rapidly initially. The live cell concentration, however, also decreased. The aqueous-phase TOC level decreased by about 40% during the initial active period but remained high after this period. Additional experiments confirmed that only about one-half of the derived TOC was readily

  13. A strategy for aromatic hydrocarbon bioremediation under anaerobic conditions and the impacts of ethanol: a microcosm study.

    PubMed

    Chen, Yu Dao; Barker, James F; Gui, Lai

    2008-02-19

    Increased use of ethanol-blended gasoline (gasohol) and its potential release into the subsurface have spurred interest in studying the biodegradation of and interactions between ethanol and gasoline components such as benzene, toluene, ethylbenzene and xylene isomers (BTEX) in groundwater plumes. The preferred substrate status and the high biological oxygen demand (BOD) posed by ethanol and its biodegradation products suggests that anaerobic electron acceptors (EAs) will be required to support in situ bioremediation of BTEX. To develop a strategy for aromatic hydrocarbon bioremediation and to understand the impacts of ethanol on BTEX biodegradation under strictly anaerobic conditions, a microcosm experiment was conducted using pristine aquifer sand and groundwater obtained from Canadian Forces Base Borden, Canada. The initial electron accepter pool included nitrate, sulfate and/or ferric iron. The microcosms typically contained 400 g of sediment, 600 approximately 800 ml of groundwater, and with differing EAs added, and were run under anaerobic conditions. Ethanol was added to some at concentrations of 500 and 5000 mg/L. Trends for biodegradation of aromatic hydrocarbons for the Borden aquifer material were first developed in the absence of ethanol, The results showed that indigenous microorganisms could degrade all aromatic hydrocarbons (BTEX and trimethylbenzene isomers-TMB) under nitrate- and ferric iron-combined conditions, but not under sulfate-reducing conditions. Toluene, ethylbenzene and m/p-xylene were biodegraded under denitrifying conditions. However, the persistence of benzene indicated that enhancing denitrification alone was insufficient. Both benzene and o-xylene biodegraded significantly under iron-reducing conditions, but only after denitrification had removed other aromatics. For the trimethylbenzene isomers, 1,3,5-TMB biodegradation was found under denitrifying and then iron-reducing conditions. Biodegradation of 1,2,3-TMB or 1,2,4-TMB was

  14. An anaerobic field injection experiment in a landfill leachate plume, Grindsted, Denmark: 2. Deduction of anaerobic (methanogenic, sulfate-, and Fe (III)-reducing) redox conditions

    NASA Astrophysics Data System (ADS)

    Albrechtsen, Hans-JøRgen; Bjerg, Poul L.; Ludvigsen, Liselotte; Rügge, Kirsten; Christensen, Thomas H.

    1999-04-01

    Redox conditions may be environmental factors which affect the fate of the xenobiotic organic compounds. Therefore the redox conditions were characterized in an anaerobic, leachate-contaminated aquifer 15-60 m downgradient from the Grindsted Landfill, Denmark, where an field injection experiment was carried out. Furthermore, the stability of the redox conditions spatially and over time were investigated, and different approaches to deduce the redox conditions were evaluated. The redox conditions were evaluated in a set of 20 sediment and groundwater samples taken from locations adjacent to the sediment samples. Samples were investigated with respect to groundwater chemistry, including hydrogen and volatile fatty acids (VFAs) and sediment geochemistry, and bioassays were performed. The groundwater chemistry, including redox sensitive species for a large number of samples, varied over time during the experimental period of 924 days owing to variations in the leachate from the landfill. However, no indication of change in the redox environment resulting from the field injection experiment or natural variation was observed in the individual sampling points. The methane, Fe(II), hydrogen, and VFA groundwater chemistry parameters strongly indicated a Fe(III)-reducing environment. This was further supported by the bioassays, although methane production and sulfate-reduction were also observed in a few samples close to the landfill. On the basis of the calculated carbon conversion, Fe(III) was the dominant electron acceptor in the region of the aquifer, which was investigated. Because of the complexity of a landfill leachate plume, several redox processes may occur simultaneously, and an array of methods must be applied for redox characterization in such multicomponent systems.

  15. New insights into the key microbial phylotypes of anaerobic sludge digesters under different operational conditions.

    PubMed

    Hao, Liping; Bize, Ariane; Conteau, Delphine; Chapleur, Olivier; Courtois, Sophie; Kroff, Pablo; Desmond-Le Quéméner, Elie; Bouchez, Théodore; Mazéas, Laurent

    2016-10-01

    Analyses on bacterial, archaeal communities at family level and methane-production metabolism were conducted in thirteen full-scale and pilot-scale anaerobic sludge digesters. These digesters were operated at different conditions regarding solids concentration, sludge retention time, organic loading rate and feedstock composition, seeking to optimize digester capacity. Correlations between process parameters and identified microbial phylotypes were evaluated based on relative abundance of these phylotypes determined by Quantitative PCR and 16S rDNA amplicon sequencing. Results showed that, Total Solids concentration (TS), among the evaluated operational parameters, demonstrated the most positive correlation with chemical parameters (including NH3 and VFAs) and significant impact on the abundance of key microbial phylotypes regardless of other factors. Digesters were grouped into 'Higher-TS' with higher stress (TS > 44 g/L, NH3 > 90 mg/L, VFAs > 300 mg/L) and 'Lower-TS' under easier status (TS ≤ 44 g/L, NH3 < 120 mg/L, VFAs < 525 mg/L) in this study. We identified the key microbial phylotypes, i.e. the most abundant and discriminating populations, in 'Higher-TS' digesters with high biogas production rate, which were the class Clostridia, the family Methanosarcinaceae and the order Methanobacteriales. Thermoanaerobacteraceae and Syntrophomonadaceae were identified as key families of Clostridia. Methane was produced both from acetoclastic and hydrogenotrophic methanogenesis. By contrast, in 'Higher-TS' digesters with low biogas production rate, the classes Alpha-, Beta- and Gamma-proteobacteria were detected in higher percentages, of which Rhodobacteraceae, Comamonadaceae and Xanthomonadaceae were the most abundant families respectively, and Methanomicrobiales was the prevailing methanogen order. Consistently, hydrogenotrophic pathway was predominant for methanogenesis, indicating existence of syntrophic acetate oxidation in such 'high-stress', low

  16. Influence of pH on bile sensitivity amongst various strains of Listeria monocytogenes under aerobic and anaerobic conditions

    PubMed Central

    White, Sally J.; McClung, Daniel M.; Wilson, Jessica G.; Roberts, Brandy N.

    2015-01-01

    Listeria monocytogenes is a dangerous bacterium that causes the food-borne disease listeriosis and accounts for nearly 20 % of food-borne deaths. This organism can survive the body's natural defences within the digestive tract, including acidic conditions and bile. Although the bile response has been analysed, limited information is available concerning the ability of L. monocytogenes to resist bile under anaerobic conditions, especially at acidic pH, which mimics conditions within the duodenum. Additionally, it is not known how the bile response varies between serotypes. In this study, the survival of strains representing six serotypes was analysed under aerobic and anaerobic conditions following exposure to bile. Exposure to bile salts at acidic pH increased toxicity of bile, resulting in a significant reduction in survival for all strains tested. However, following this initial reduction, no significant reduction was observed for an additional 2 h except for strain 10403S (P = 0.002). Anaerobic cultivation increased bile resistance, but a significant increase was only observed in virulent strains when exposed to bile at pH 5.5. Exposure to pH 3.0 prior to bile decreased viability amongst avirulent strains in bile in acidic conditions; oxygen availability did not influence viability. Together, the data suggested that being able to sense and respond to oxygen availability may influence the expression of stress response mechanisms, and this response may correspond to disease outcome. Further research is needed on additional strains to determine how L. monocytogenes senses and responds to oxygen and how this varies between invasive and non-invasive strains. PMID:26307079

  17. Influence of pH on bile sensitivity amongst various strains of Listeria monocytogenes under aerobic and anaerobic conditions.

    PubMed

    White, Sally J; McClung, Daniel M; Wilson, Jessica G; Roberts, Brandy N; Donaldson, Janet R

    2015-11-01

    Listeria monocytogenes is a dangerous bacterium that causes the food-borne disease listeriosis and accounts for nearly 20% of food-borne deaths. This organism can survive the body's natural defences within the digestive tract, including acidic conditions and bile. Although the bile response has been analysed, limited information is available concerning the ability of L. monocytogenes to resist bile under anaerobic conditions, especially at acidic pH, which mimics conditions within the duodenum. Additionally, it is not known how the bile response varies between serotypes. In this study, the survival of strains representing six serotypes was analysed under aerobic and anaerobic conditions following exposure to bile. Exposure to bile salts at acidic pH increased toxicity of bile, resulting in a significant reduction in survival for all strains tested. However, following this initial reduction, no significant reduction was observed for an additional 2 h except for strain 10403S (P = 0.002). Anaerobic cultivation increased bile resistance, but a significant increase was only observed in virulent strains when exposed to bile at pH 5.5. Exposure to pH 3.0 prior to bile decreased viability amongst avirulent strains in bile in acidic conditions; oxygen availability did not influence viability. Together, the data suggested that being able to sense and respond to oxygen availability may influence the expression of stress response mechanisms, and this response may correspond to disease outcome. Further research is needed on additional strains to determine how L. monocytogenes senses and responds to oxygen and how this varies between invasive and non-invasive strains. PMID:26307079

  18. Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions.

    PubMed

    Rodríguez, Elisa; Lopes, Alexandre; Fdz-Polanco, María; Stams, Alfons J M; García-Encina, Pedro A

    2012-03-01

    The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was focused on the competitive and syntrophic interactions between the different microbial groups at varying influent substrate to sulfate ratios of 8, 4, and 2 and anaerobic or micro-aerobic conditions. Acetogens detected along the anaerobic phases at substrate to sulfate ratios of 8 and 4 seemed to be mainly involved in the fermentation of glucose and betaine, but they were substituted by other sugar or betaine degraders after oxygen application. Typical fatty acid degraders that grow in syntrophy with methanogens were not detected during the entire reactor run. Likely, sugar and betaine degraders outnumbered them in the DGGE analysis. The detected sulfate-reducing bacteria (SRB) belonged to the hydrogen-utilizing Desulfovibrio. The introduction of oxygen led to the formation of elemental sulfur (S(0)) and probably other sulfur compounds by sulfide-oxidizing bacteria (γ-Proteobacteria). It is likely that the sulfur intermediates produced from sulfide oxidation were used by SRB and other microorganisms as electron acceptors, as was supported by the detection of the sulfur respiring Wolinella succinogenes. Within the Archaea population, members of Methanomethylovorans and Methanosaeta were detected throughout the entire reactor operation. Hydrogenotrophic methanogens mainly belonging to the genus Methanobacterium were detected at the highest substrate to sulfate ratio but rapidly disappeared by increasing the sulfate concentration. PMID:21861082

  19. Performance optimization and validation of ADM1 simulations under anaerobic thermophilic conditions.

    PubMed

    Atallah, Nabil M; El-Fadel, Mutasem; Ghanimeh, Sophia; Saikaly, Pascal; Abou-Najm, Majdi

    2014-12-01

    In this study, two experimental sets of data each involving two thermophilic anaerobic digesters treating food waste, were simulated using the Anaerobic Digestion Model No. 1 (ADM1). A sensitivity analysis was conducted, using both data sets of one digester, for parameter optimization based on five measured performance indicators: methane generation, pH, acetate, total COD, ammonia, and an equally weighted combination of the five indicators. The simulation results revealed that while optimization with respect to methane alone, a commonly adopted approach, succeeded in simulating methane experimental results, it predicted other intermediary outputs less accurately. On the other hand, the multi-objective optimization has the advantage of providing better results than methane optimization despite not capturing the intermediary output. The results from the parameter optimization were validated upon their independent application on the data sets of the second digester. PMID:25463805

  20. Anaerobic digestion of post-hydrothermal liquefaction wastewater for improved energy efficiency of hydrothermal bioenergy processes.

    PubMed

    Zhou, Yan; Schideman, Lance; Zheng, Mingxia; Martin-Ryals, Ana; Li, Peng; Tommaso, Giovana; Zhang, Yuanhui

    2015-01-01

    Hydrothermal liquefaction (HTL) is a promising process for converting wet biomass and organic wastes into bio-crude oil. It also produces an aqueous product referred to as post-hydrothermal liquefaction wastewater (PHWW) containing up to 40% of the original feedstock carbon, which reduces the overall energy efficiency of the HTL process. This study investigated the feasibility of using anaerobic digestion (AD) to treat PHWW, with the aid of activated carbon. Results showed that successful AD occurred at relatively low concentrations of PHWW (≤ 6.7%), producing a biogas yield of 0.5 ml/mg CODremoved, and ∼53% energy recovery efficiency. Higher concentrations of PHWW (≥13.3%) had an inhibitory effect on the AD process, as indicated by delayed, slower, or no biogas production. Activated carbon was shown to effectively mitigate this inhibitory effect by enhancing biogas production and allowing digestion to proceed at higher PHWW concentrations (up to 33.3%), likely due to sequestering toxic organic compounds. The addition of activated carbon also increased the net energy recovery efficiency of AD with a relatively high concentration of PHWW (33.3%), taking into account the energy for producing activated carbon. These results suggest that AD is a feasible approach to treat PHWW, and to improve the energy efficiency of the HTL processes. PMID:26676001

  1. Improvement of COD removal by controlling the substrate degradability during the anaerobic digestion of recalcitrant wastewater.

    PubMed

    Kawai, Minako; Nagao, Norio; Kawasaki, Nobuyuki; Imai, Akio; Toda, Tatsuki

    2016-10-01

    The recalcitrant landfill leachate was anaerobically digested at various mixing ratios with labile synthetic wastewater to evaluate the degradation properties of recalcitrant wastewater. The proportion of leachate to the digestion system was increased in three equal steps, starting from 0% to 100%, and later decreased back to 0% with the same steps. The chemical oxygen demand (COD) for organic carbon and other components were calculated by analyzing the COD and dissolved organic carbon (DOC), and the removal efficiencies of COD carbon and COD others were evaluated separately. The degradation properties of COD carbon and COD others shifted owing to changing of substrate degradability, and the removal efficiencies of COD carbon and COD others were improved after supplying 100% recalcitrant wastewater. The UV absorptive property and total organic carbon (TOC) of each molecular size using high performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) with UVA and TOC detectors were also investigated, and the degradability of different molecular sizes was determined. Although the SEC system detected extracellular polymeric substances (EPS), which are produced by microbes in stressful environments, during early stages of the experiment, EPS were not detected after feeding 100% recalcitrant wastewater. These results suggest that the microbes had acclimatized to the recalcitrant wastewater degradation. The high removal rates of both COD carbon and COD others were sustained when the proportion of labile wastewater in the substrate was 33%, indicating that the effective removal of recalcitrant COD might be controlled by changing the substrate's degradability. PMID:27449962

  2. Routine Testing for Anaerobic Bacteria in Cerebrospinal Fluid Cultures Improves Recovery of Clinically Significant Pathogens

    PubMed Central

    Pittman, Meredith E.; Thomas, Benjamin S.; Wallace, Meghan A.; Weber, Carol J.

    2014-01-01

    In North America, the widespread use of vaccines targeting Haemophilus influenzae type b and Streptococcus pneumoniae have dramatically altered the epidemiology of bacterial meningitis, while the methodology for culturing cerebrospinal fluid (CSF) specimens has remained largely unchanged. The aims of this study were 2-fold: to document the current epidemiology of bacterial meningitis at a tertiary care medical center and to assess the clinical utility of routinely querying for anaerobes in CSF cultures. To that end, we assessed CSF cultures submitted over a 2-year period. A brucella blood agar (BBA) plate, incubated anaerobically for 5 days, was included in the culture procedure for all CSF specimens during the second year of evaluation. In the pre- and postimplementation years, 2,353 and 2,302 CSF specimens were cultured, with 49 and 99 patients having positive culture results, respectively. The clinical and laboratory data for patients with positive cultures were reviewed. Anaerobic bacteria were isolated in the CSF samples from 33 patients post-BBA compared to two patients pre-BBA (P = 0.01). The anaerobic isolates included Bacteroides thetaiotaomicron (n = 1), Propionibacterium species (n = 15), and Propionibacterium acnes (n = 19) isolates; all of these isolates were recovered on the BBA. Eight of the 35 patients from whom anaerobic organisms were isolated received antimicrobial therapy. Although six of these patients had central nervous system hardware, two patients did not have a history of a neurosurgical procedure and had community-acquired anaerobic bacterial meningitis. This study demonstrates that the simple addition of an anaerobically incubated BBA to the culture of CSF specimens enhances the recovery of clinically significant anaerobic pathogens. PMID:24622102

  3. Improvement of methane production from waste activated sludge by on-site photocatalytic pretreatment in a photocatalytic anaerobic fermenter.

    PubMed

    Liu, Chunguang; Shi, Wansheng; Li, Huifang; Lei, Zhongfang; He, Leilei; Zhang, Zhenya

    2014-03-01

    This paper reports a new technology that using on-site TiO2-photocatalytic pretreatment in the anaerobic digestion of waste activated sludge (WAS) can enhance WAS degradation and methane production in a novel photocatalytic anaerobic fermenter. The fermenter consists of a photocatalytic unit and a digestion unit. The photocatalytic unit can constantly supply soluble organics and has less negative effect on the activity of methanogens at the optimal photocatalytic time of 4h per day. After anaerobic digestion for 35days, 1266.7ml/l-sludge of methane, 67.4% of volatile solid (VS) reduction and 60.5% of total chemical oxygen demand (TCOD) removal were achieved in the photocatalytic anaerobic fermenter, compared with 923.2ml/l-sludge of methane, 48.9% of VS reduction and 43.5% TCOD removal in the control fermenter. The results indicate that timely utilization of solubilized organics by methanogens could avoid further mineralization by TiO2-photocatalysis, which not only improves methane production but also enhances WAS degradation. PMID:24462880

  4. Increased temperature in the thermophilic stage in temperature phased anaerobic digestion (TPAD) improves degradability of waste activated sludge.

    PubMed

    Ge, Huoqing; Jensen, Paul D; Batstone, Damien J

    2011-03-15

    Two-stage temperature phased anaerobic digestion (TPAD) is an increasingly popular method to improve stabilisation of sewage waste activated sludge, which normally has inherently poor and slow degradation. However, there has been limited systematic analysis of the impact of the initial thermophilic stage (temperature, pH and retention time) on performance in the main mesophilic stage. In this study, we demonstrate a novel two-stage batch test method for TPAD processes, and use it to optimize operating conditions of the thermophilic stage in terms of degradation extent and methane production. The method determines overall degradability and apparent hydrolysis coefficient in both stages. The overall process was more effective with short pre-treatment retention times (1-2 days) and neutral pH compared to longer retention time (4 days) and low pH (4-5). Degradabilities and apparent hydrolysis coefficients were 0.3-0.5 (fraction degradable) and 0.1-0.4d(-1), respectively, with a margin of error in each measurement of approximately 20% relative (95% confidence). Pre-treatment temperature had a strong impact on the whole process, increasing overall degradability from 0.3 to 0.5 as temperature increased from 50 to 65 °C, with apparent hydrolysis coefficient increasing from 0.1 to 0.4d(-1). PMID:21277081

  5. Effect of music on anaerobic exercise performance.

    PubMed

    Atan, T

    2013-03-01

    For years, mostly the effects of music on cardiorespiratory exercise performance have been studied, but a few studies have examined the effect of music on anaerobic exercise. The purpose of this study was to assess the effect of listening to music and its rhythm on anaerobic exercise: on power output, heart rate and the concentration of blood lactate. 28 male subjects were required to visit the laboratory on 6 occasions, each separated by 48 hours. Firstly, each subject performed the Running-based Anaerobic Sprint Test (RAST) under 3 conditions on separate days: while listening to "slow rhythm music", "fast rhythm music" or "no music". 48 hours after the subjects completed RAST under 3 conditions, Wingate Anaerobic Power (WAN) tests were performed under 3 music conditions. The order of the 3 conditions (slow music, fast music and no music) was selected randomly to prevent an order effect. Results showed no significant differences between 3 conditions in anaerobic power assessments, heart rate or blood lactate (p > 0.05). On the basis of these results it can be said that music cannot improve anaerobic performance. The type of music had no impact on power outputs during RAST and WAN exercise. As a conclusion, listening to music and its rhythm cannot enhance anaerobic performance and cannot change the physiological response to supramaximal exercise. PMID:24744463

  6. EFFECT OF MUSIC ON ANAEROBIC EXERCISE PERFORMANCE

    PubMed Central

    2013-01-01

    For years, mostly the effects of music on cardiorespiratory exercise performance have been studied, but a few studies have examined the effect of music on anaerobic exercise. The purpose of this study was to assess the effect of listening to music and its rhythm on anaerobic exercise: on power output, heart rate and the concentration of blood lactate. 28 male subjects were required to visit the laboratory on 6 occasions, each separated by 48 hours. Firstly, each subject performed the Running-based Anaerobic Sprint Test (RAST) under 3 conditions on separate days: while listening to “slow rhythm music”, “fast rhythm music” or “no music”. 48 hours after the subjects completed RAST under 3 conditions, Wingate Anaerobic Power (WAN) tests were performed under 3 music conditions. The order of the 3 conditions (slow music, fast music and no music) was selected randomly to prevent an order effect. Results showed no significant differences between 3 conditions in anaerobic power assessments, heart rate or blood lactate (p > 0.05). On the basis of these results it can be said that music cannot improve anaerobic performance. The type of music had no impact on power outputs during RAST and WAN exercise. As a conclusion, listening to music and its rhythm cannot enhance anaerobic performance and cannot change the physiological response to supramaximal exercise. PMID:24744463

  7. Tegoprens in anaerobic digestion of a mixture of cheese whey, poultry waste, and cattle dung for improved biomethanation

    SciTech Connect

    Patel, C.; Sastry, V.; Madamwar, D.

    1996-01-01

    To obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung, poultry waste, and cheese whey, the effect of various doses of Tegoprens: T-3012, T-3099, T-5842, T-5843, T-5851, T-5852 has been studied, in bench-scale digesters. Among them, Tegoprens 3022 showed more than a 45% increase in gas production with higher methane content. 18 refs., 1 fig.

  8. Some Improvements in Signal-Conditioning Circuits

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L.

    2004-01-01

    Two documents present wide-ranging discussions of some issues in the design and operation of signal-conditioning circuits. The first document focuses on active low-pass filter circuits that contain resistors, capacitors, and operational amplifiers. It describes design and operational problems encountered previously, deficiencies of prior designs, and four design improvements to overcome the deficiencies. These improvements are as follows: 1. An offset-calibration feature in which an electronic switch isolates a filter capacitor in order to preserve its voltage during a calibration performed to measure the offset voltage of the operational amplifier; 2. Configuring a pair of complementary operational amplifiers to prevent latchup and decrease the degree of nonlinearity in overall response; 3. Minimizing distortion by taking the filter output from the operational-amplifier output nodes instead of from one of the other nodes as in prior designs; and 4. Providing for switching different feedback resistors to change filter break frequencies. The second document addresses topics in the architecture of signal-conditioning and multiplexing circuitry. Improvements are described as being made with respect to greater compactness, increased flexibility in accommodating a variety of inputs, improvements in filter performance, simplification of wiring, and reconfigurability of designs.

  9. Microleakage of human saliva in coronally unsealed obturated root canals in anaerobic conditions.

    PubMed

    Yazdi, K Ashofteh; Bayat-Movahed, S; Aligholi, M; Hayes, S J; Nekoofar, M H

    2009-01-01

    The purpose of this study was to determine the time required for anaerobic bacteria in natural human saliva to contaminate root-filled teeth. Thirty-two single-rooted teeth were cleaned, shaped, filled, and exposed to human saliva for 120 days. Teeth that had not leaked were subjected to polymerise chain reaction examination. Sixty-six percent of the experimental group were totally contaminated. A PCR examination revealed there was no contamination in the apical 3 mm of leakage-free teeth. PMID:19263626

  10. Organic intermediates in the anaerobic biodegradation of coal to methane under laboratory conditions

    USGS Publications Warehouse

    Orem, W.H.; Voytek, M.A.; Jones, E.J.; Lerch, H.E.; Bates, A.L.; Corum, M.D.; Warwick, P.D.; Clark, A.C.

    2010-01-01

    Organic intermediates in coal fluids produced by anaerobic biodegradation of geopolymers in coal play a key role in the production of methane in natural gas reservoirs. Laboratory biodegradation experiments on sub-bituminous coal from Texas, USA, were conducted using bioreactors to examine the organic intermediates relevant to methane production. Production of methane in the bioreactors was linked to acetate accumulation in bioreactor fluid. Long chain fatty acids, alkanes (C19-C36) and various low molecular weight aromatics, including phenols, also accumulated in the bioreactor fluid and appear to be the primary intermediates in the biodegradation pathway from coal-derived geopolymers to acetate and methane. ?? 2010.

  11. Optimization of anaerobic co-digestion of olive mill wastewater and liquid poultry manure in batch condition and semi-continuous jet-loop reactor.

    PubMed

    Khoufi, Sonia; Louhichi, Assawer; Sayadi, Sami

    2015-04-01

    Anaerobic co-digestion of olive mill wastewater (OMW) with liquid poultry manure (LPM) was investigated in a jet-loop reactor (JLR) as a new approach for upgrading the efficiency of bioprocess. Optimum proportion of LPM was evaluated by determining biochemical methane potential. Methane yields were compared by applying one way ANOVA method followed by post hoc Tukey's test with a 0.05 significance level. Results demonstrated that the addition of LPM at proportion of 10% and 30% (v/v) improved methane yield of OMW digestion but differences between these mixtures and raw OMW are not significant. JLR results confirmed that the proportion 30% LPM gives the optimum condition for excellent stability of digester. Methane production was significantly high until an organic loading rate of 9.5 gCOD/L reactor/day. Overall; this study indicates the technical feasibility and effectiveness of using JLR as one-stage anaerobic system for the co-digestion of OMW and LPM. PMID:25682225

  12. Anaerobic-aerobic sequencing bioreactors improve energy efficiency for treatment of personal care product industry wastes.

    PubMed

    Ahammad, S Z; Bereslawski, J L; Dolfing, J; Mota, C; Graham, D W

    2013-07-01

    Personal care product (PCP) industry liquid wastes contain shampoo residues, which are usually treated by aerobic activated sludge (AS). Unfortunately, AS is expensive for PCP wastes because of high aeration and energy demands, whereas potentially energy-positive anaerobic designs cannot meet effluent targets. Therefore, combined anaerobic-aerobic systems may be the best solution. Seven treatment systems were assessed in terms of energy and treatment performance for shampoo wastes, including one aerobic, three anaerobic (HUASB, AHR and AnCSTR) and three anaerobic-aerobic reactor designs. COD removals were highest in the HUASB-aerobic (87.9 ± 0.4%) and AHR-aerobic (86.8±0.5%) systems, which used 69.2% and 62.5% less energy than aerobic AS. However, actual methane production rates were low relative to theoretical in the UASB and AHR units (∼10% methane/COD removed) compared with the AnCSTR unit (∼70%). Anaerobic-aerobic sequence reactors show promise for treating shampoo wastes, but optimal designs depend upon whether methane production or COD removal is most important to operations. PMID:23639409

  13. Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions.

    PubMed

    Yoon, Sang Sun; Coakley, Ray; Lau, Gee W; Lymar, Sergei V; Gaston, Benjamin; Karabulut, Ahmet C; Hennigan, Robert F; Hwang, Sung-Hei; Buettner, Garry; Schurr, Michael J; Mortensen, Joel E; Burns, Jane L; Speert, David; Boucher, Richard C; Hassett, Daniel J

    2006-02-01

    Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2 also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways. PMID:16440061

  14. Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions

    PubMed Central

    Yoon, Sang Sun; Coakley, Ray; Lau, Gee W.; Lymar, Sergei V.; Gaston, Benjamin; Karabulut, Ahmet C.; Hennigan, Robert F.; Hwang, Sung-Hei; Buettner, Garry; Schurr, Michael J.; Mortensen, Joel E.; Burns, Jane L.; Speert, David; Boucher, Richard C.; Hassett, Daniel J.

    2006-01-01

    Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2–) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2– also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways. PMID:16440061

  15. Anaerobic biodegradation of long-chain n-alkanes under sulfate-reducing conditions

    SciTech Connect

    Caldwell, M.E.; Suflita, J.M.; Garrett, R.M.; Prince, R.C.

    1998-07-15

    The ability of anaerobic microorganisms to degrade a wide variety of crude oil components was investigated using chronically hydrocarbon-contaminated marine sediments as the source of inoculum. When sulfate reduction was the predominant electron-accepting process, gas chromatographic analysis revealed almost complete n-alkane removal (C{sub 15}-C{sub 34}) from a weathered oil within 201 d of incubation. No alteration of the oil was detected in sterile control incubations or when nitrate served as an alternate electron acceptor. The amount of sulfate reduced in the oil-amended nonsterile incubations was more than enough to account for the complete mineralization of the n-alkane fraction of the oil; no loss of this anion was observed in sterile control incubations. The mineralization of the alkanes was confirmed using {sup 14}C-14,15-octacosane (C{sub 28}H{sub 58}), with 97% of the radioactivity recovered as {sup 14}CO{sub 2}. These findings extend the range of hydrocarbons known to be amenable to anaerobic biodegradation. Moreover, the rapid and extensive alteration in the n-alkanes can no longer be considered a defining characteristic of aerobic oil biodegradation processes alone.

  16. Effects of solution conditions on the physicochemical properties of stratification components of extracellular polymeric substances in anaerobic digested sludge.

    PubMed

    Yuan, Dongqin; Wang, Yili

    2013-01-01

    The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances (EPS) in anaerobic digested sludge were determined. The total EPS in anaerobic digested sludge were extracted by the cation exchange resin method. Another EPS extraction method, the centrifugation and sonication technique was employed to stratify the EPS into three fractions: slime, loosely bound (LB)-EPS, and tightly bound (TB)-EPS from the outside to the inside of the anaerobic digested sludge. Proteins and polysaccharides were dispersed uniformly across the different EPS fractions, and humic-like substances were mainly partitioned in the slime, with TB-EPS second. Protein was the major constituent of the LB-EPS and TB-EPS, and the corresponding ratios ranged from 54.0% to 65.6%. The hydrophobic part in the EPS chemical components was primarily comprised of protein and DNA, while the hydrophilic part was mainly composed of polysaccharide. In the slime, the hydrophobic values of several EPS chemical components (protein, polysaccharide, humic-like substances and DNA) were all below 50%. The protein/polysaccharide ratio had a significant influence on the Zeta potentials and isoelectric point values of the EPS: the greater the protein/polysaccharide ratio of the EPS was, the greater the Zeta potential and the higher the isoelectric point value were. All Zeta potentials of the EPS showed a decreasing trend with increasing pH. The corresponding isoelectric point values (pH) were 2.8 for total EPS, 2.2 for slime, 2.7 for LB-EPS, and 2.6 for TB-EPS. As the ionic strength increased, the Zeta potentials sharply increased and then gradually became constant without charge reversal. In addition, as the temperature increased (< 40 degrees C), the apparent viscosity of the EPS decreased monotonically and then gradually became stable between 40 and 60 degrees C. PMID:23586310

  17. Reorganization of the bacterial and archaeal populations associated with organic loading conditions in a thermophilic anaerobic digester.

    PubMed

    Hori, Tomoyuki; Haruta, Shin; Sasaki, Daisuke; Hanajima, Dai; Ueno, Yoshiyuki; Ogata, Atsushi; Ishii, Masaharu; Igarashi, Yasuo

    2015-03-01

    Organic loading conditions are an important factor influencing reactor performances in methanogenic bioreactors. Yet the underlying microbiological basis of the process stability, deterioration, and recovery remains to be understood. Here, structural responses of the bacterial and archaeal populations to the change of organic loading conditions in a thermophilic anaerobic digester were investigated by process analyses and 16S rRNA gene-based molecular approaches. The biogas was produced stably without the accumulation of volatile fatty acids (VFAs) at low organic loading rates (OLRs) in the beginning of reactor operation. Increasing OLR in stages disrupted the stable reactor performance, and high OLR conditions continued the deteriorated performance with slight biogas production and high accumulation of VFAs. Thereafter, the gradual decrease of OLR resulted in the recovery from the deterioration, giving rise to the stable performance again. The stable performances before and after the high OLR conditions conducted were associated with compositionally similar but not identical methanogenic consortia. The bacterial and archaeal populations were synchronously changed at both the transient phases toward the deteriorated performance and in recovery process, during which the dynamic shift of aceticlastic and hydrogenotrophic methanogens including the recently identified Methanomassiliicoccus might contribute to the maintenance of the methanogenic activity. The distinctive bacterial population with a high predominance of Methanobacterium formicicum as archaeal member was found for the deteriorated performance. The results in this study indicate the coordinated reorganization of the bacterial and archaeal populations in response to functional states induced by the change of organic loading conditions in the anaerobic digester. PMID:25293692

  18. Characterization of anaerobic sulfite reduction by Salmonella typhimurium and purification of the anaerobically induced sulfite reductase

    SciTech Connect

    Hallenbeck, P.C. ); Clark, M.A.; Barrett, E.L. )

    1989-06-01

    Mutants of Salmonella typhimurium that lack the biosynthetic sulfite reductase (cysI and cysJ mutants) retain the ability to reduce sulfite for growth under anaerobic conditions. Here we report studies of sulfite reduction by a cysI mutant of S. typhimurium and purification of the associated anaerobic sulfite reductase. Sulfite reduction for anaerobic growth did not require a reducing atmosphere but was prevented by an argon atmosphere contaminated with air (<0.33%). It was also prevented by the presence of 0.1 mM nitrate. Anaerobic growth in liquid minimal medium, but not on agar, was found to require additions of trace amounts (10{sup {minus}7} M) of cysteine. Spontaneous mutants that grew under the argon contaminated with air also lost the requirement for 10{sup {minus}7}M cysteine for anaerobic growth in liquid. A role for sulfite reduction in anaerobic energy generation was contraindicated by the findings that sulfite reduction did not improve cell yields, and anaerobic sulfite reductase activity was greatest during the stationary phase of growth. Sulfite reductase was purified from the cytoplasmic fraction of the anaerobically grown cysI mutant and was purified 190-fold. The most effective donor in crude extracts was NADH. NADHP and methyl viologen were, respectively, 40 and 30% as effective as NADH. Oxygen reversibly inhibited the enzyme. The anaerobic sulfite reductase showed some resemblance to the biosynthetic sulfite reductase, but apparently it has a unique, as yet unidentified function.

  19. Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions.

    PubMed

    Johansen, Anders; Nielsen, Henrik B; Hansen, Christian M; Andreasen, Christian; Carlsgart, Josefine; Hauggard-Nielsen, Henrik; Roepstorff, Allan

    2013-04-01

    Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (~1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3h of incubation. Incubation at 37°C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests. PMID:23266071

  20. Sludge reduction and water quality improvement in anaerobic lagoons through influent pre-treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Confined swine production generates large volumes of wastewater typically stored and treated in anaerobic lagoons. These lagoons may require cleanup and closure measures in the future. In practice, liquid and sludge need to be removed by pumping, usually at great expense of energy, and land applied ...

  1. Improvement of anaerobic digester performance by wastewater recirculation through an aerated membrane.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine wastewater from an anaerobic digester was recirculated through a silicone hose located in an external aeration chamber to determine its effect on wastewater malodorants and biogas composition. The silicone hose acted as a semipermeable membrane for the passage of small molecules. In the first...

  2. Improving the cyanide toxicity tolerance of anaerobic reactor: Microbial interactions and toxin reduction.

    PubMed

    Gupta, Pragya; Ahammad, S Z; Sreekrishnan, T R

    2016-09-01

    Anaerobic biological treatment of high organics containing wastewater is amongst the preferred treatment options but poor tolerance to toxins makes its use prohibitive. In this study, efforts have been made to understand the key parameters for developing anaerobic reactor, resilient to cyanide toxicity. A laboratory scale anaerobic batch reactor was set up to treat cyanide containing wastewater. The reactor was inoculated with anaerobic sludge obtained from a wastewater treatment plant and fresh cow dung in the ratio of 3:1. The focus was on acclimatization and development of cyanide-degrading biomass and to understand the toxic effects of cyanide on the dynamic equilibrium between various microbial groups. The sludge exposed to cyanide was found to have higher bacterial diversity than the control. It was observed that certain hydrogenotrophic methanogens and bacterial groups were able to grow and produce methane in the presence of cyanide. Also, it was found that hydrogen utilizing methanogens were more cyanide tolerant than acetate utilizing methanogens. So, effluents from various industries like electroplating, coke oven plant, petroleum refining, explosive manufacturing, and pesticides industries which are having high concentrations of cyanide can be treated by favoring the growth of the tolerant microbes in the reactors. It will provide much better treatment efficiency by overcoming the inhibitory effects of cyanide to certain extent. PMID:27179200

  3. Microbial Dechlorination of 2,3,5,6-Tetrachlorobiphenyl under Anaerobic Conditions in the Absence of Soil or Sediment

    PubMed Central

    Cutter, Leah; Sowers, Kevin R.; May, Harold D.

    1998-01-01

    Bacterial enrichment cultures developed with Baltimore Harbor (BH) sediments were found to reductively dechlorinate 2,3,5,6-tetrachlorobiphenyl (2,3,5,6-CB) when incubated in a minimal estuarine medium containing short-chain fatty acids under anaerobic conditions with and without the addition of sediment. Primary enrichment cultures formed both meta and ortho dechlorination products from 2,3,5,6-CB. The lag time preceding dechlorination decreased from 30 to less than 20 days as the cultures were sequentially transferred into estuarine medium containing dried, sterile BH sediment. In addition, only ortho dechlorination was observed following transfer of the cultures. Sequential transfer into medium without added sediment also resulted in the development of a strict ortho-dechlorinating culture following a lag of more than 100 days. Upon further transfer into the minimal medium without sediment, the lag time decreased to less than 50 days. At this stage all cultures, regardless of the presence of sediment, would produce 2,3,5-CB and 3,5-CB from 2,3,5,6-CB. The strict ortho-dechlorinating activity in the sediment-free cultures has remained stable for more than 1 year through several transfers. These results reveal that the classical microbial enrichment technique using a minimal medium with a single polychlorinated biphenyl (PCB) congener selected for ortho dechlorination of 2,3,5,6-CB. Furthermore, this is the first report of sustained anaerobic PCB dechlorination in the complete absence of soil or sediment. PMID:9687458

  4. Enhancement of sludge anaerobic biodegradability by combined microwave-H2O2 pretreatment in acidic conditions.

    PubMed

    Eswari, Parvathy; Kavitha, S; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

    2016-07-01

    The aim of this study was to increase the sludge disintegration and reduce the cost of microwave (MW) pretreatment. Thermodynamic analysis of MW hydrolysis revealed the best fit with a first-order kinetic model at a specific energy of 18,600 kJ/kg total solids (TS). Combining H2O2 with MW resulted in a significant increment in solubilization from 30 to 50 % at 18,600 kJ/kg TS. The pH of H2O2-assisted MW-pretreated sludge (MW + H2O2) was in the alkaline range (pH 9-10), and it made the sludge unfavorable for subsequent anaerobic digestion and inhibits methane production. In order to nullify the alkaline effect caused by the MW + H2O2 combination, the addition of acid was considered for pH adjustment. H2O2-assisted MW-pretreated sludge in acidic conditions (MW + H2O2 + acid) showed a maximum methane production of 323 mL/g volatile solids (VS) than others during anaerobic biodegradability. A cost analysis of this study reveals that MW + H2O2 + acid was the most economical method with a net profit of 59.90 €/t of sludge. PMID:27026550

  5. Reactor performance of a 750 m(3) anaerobic digestion plant: varied substrate input conditions impacting methanogenic community.

    PubMed

    Wagner, Andreas Otto; Malin, Cornelia; Lins, Philipp; Gstraunthaler, Gudrun; Illmer, Paul

    2014-10-01

    A 750 m(3) anaerobic digester was studied over a half year period including a shift from good reactor performance to a reduced one. Various abiotic parameters like volatile fatty acids (VFA) (formic-, acetic-, propionic-, (iso-)butyric-, (iso-)valeric-, lactic acid), total C, total N, NH4 -N, and total proteins, as well as the organic matter content and dry mass were determined. In addition several process parameters such as temperature, pH, retention time and input of substrate and the concentrations of CH4, H2, CO2 and H2S within the reactor were monitored continuously. The present study aimed at the investigation of the abundance of acetogens and total cell numbers and the microbial methanogenic community as derived from PCR-dHPLC analysis in order to put it into context with the determined abiotic parameters. An influence of substrate quantity on the efficiency of the anaerobic digestion process was found as well as a shift from a hydrogenotrophic in times of good reactor performance towards an acetoclastic dominated methanogenic community in times of reduced reactor performance. After the change in substrate conditions it took the methano-archaeal community about 5-6 weeks to be affected but then changes occurred quickly. PMID:24727280

  6. Inhibition of anaerobic digestion process: a review.

    PubMed

    Chen, Ye; Cheng, Jay J; Creamer, Kurt S

    2008-07-01

    Anaerobic digestion is an attractive waste treatment practice in which both pollution control and energy recovery can be achieved. Many agricultural and industrial wastes are ideal candidates for anaerobic digestion because they contain high levels of easily biodegradable materials. Problems such as low methane yield and process instability are often encountered in anaerobic digestion, preventing this technique from being widely applied. A wide variety of inhibitory substances are the primary cause of anaerobic digester upset or failure since they are present in substantial concentrations in wastes. Considerable research efforts have been made to identify the mechanism and the controlling factors of inhibition. This review provides a detailed summary of the research conducted on the inhibition of anaerobic processes. The inhibitors commonly present in anaerobic digesters include ammonia, sulfide, light metal ions, heavy metals, and organics. Due to the difference in anaerobic inocula, waste composition, and experimental methods and conditions, literature results on inhibition caused by specific toxicants vary widely. Co-digestion with other waste, adaptation of microorganisms to inhibitory substances, and incorporation of methods to remove or counteract toxicants before anaerobic digestion can significantly improve the waste treatment efficiency. PMID:17399981

  7. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    NASA Astrophysics Data System (ADS)

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d-1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  8. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate.

    PubMed

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d(-1)) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

  9. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    PubMed Central

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d−1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

  10. Model based evaluation of a contaminant plume development under aerobic and anaerobic conditions in 2D bench-scale tank experiments.

    PubMed

    Ballarini, E; Beyer, C; Bauer, R D; Griebler, C; Bauer, S

    2014-06-01

    The influence of transverse mixing on competitive aerobic and anaerobic biodegradation of a hydrocarbon plume was investigated using a two-dimensional, bench-scale flow-through laboratory tank experiment. In the first part of the experiment aerobic degradation of increasing toluene concentrations was carried out by the aerobic strain Pseudomonas putida F1. Successively, ethylbenzene (injected as a mixture of unlabeled and fully deuterium-labeled isotopologues) substituted toluene; nitrate was added as additional electron acceptor and the anaerobic denitrifying strain Aromatoleum aromaticum EbN1 was inoculated to study competitive degradation under aerobic /anaerobic conditions. The spatial distribution of anaerobic degradation was resolved by measurements of compound-specific stable isotope fractionation induced by the anaerobic strain as well as compound concentrations. A fully transient numerical reactive transport model was employed and calibrated using measurements of electron donors, acceptors and isotope fractionation. The aerobic phases of the experiment were successfully reproduced using a double Monod kinetic growth model and assuming an initial homogeneous distribution of P. putida F1. Investigation of the competitive degradation phase shows that the observed isotopic pattern cannot be explained by transverse mixing driven biodegradation only, but also depends on the inoculation process of the anaerobic strain. Transient concentrations of electron acceptors and donors are well reproduced by the model, showing its ability to simulate transient competitive biodegradation. PMID:24122285

  11. Anaerobic digestion of pig and dairy manure under photo-dark fermentation condition.

    PubMed

    Yin, Dongxue; Liu, Wei; Zhai, Ningning; Yang, Gaihe; Wang, Xiaojiao; Feng, Yongzhong; Ren, Guangxin

    2014-08-01

    Anaerobic digestion (AD) with livestock manure is a promising way for biogas production. This work presents the influence of photo-dark fermentation on biogas production of pig manure (PM) and dairy manure (DM). All sets were conducted with temperature 35 ± 2 °C and total solid concentrations 8%: PM₁ and DM₁ in transparent reactor under sunlight for photo-dark fermentation, and PM₂ and DM₂ in non-transparent reactor for dark fermentation. DM₂ had the best cumulative biogas production (CBP) of 15,447.5 mL, followed by PM₁ (15,020 mL) with stable pH and low total ammonium nitrogen (TAN) concentration (1384.99 mg/L), and DM₁ and PM₂. The CBP of DM₂ was 5.77 times as much as PM₂. The relationship between CBP and four factors including volatile fatty acid (VFA), TAN, total alkalinity and pH was analyzed. pH gained the maximum determination coefficient with the CBP among all sets and total alkalinity showed negative correlation with CBP of PM₁ and DM₁. PMID:24929281

  12. Comparison of microbial communities during the anaerobic digestion of Gracilaria under mesophilic and thermophilic conditions.

    PubMed

    Azizi, Aqil; Kim, Wonduck; Lee, Jung Hyun

    2016-10-01

    Mesophilic and thermophilic anaerobic digesters (MD and TD, respectively) utilizing Gracilaria and marine sediment as the substrate and inoculum, respectively, were compared by analyzing their performances and microbial community changes. During three successive transfers, the average cumulative methane yields in the MD and TD were 222.6 ± 17.3 mL CH4/g volatile solids (VS) and 246.1 ± 11 mL CH4/g VS, respectively. The higher hydrolysis rate and acidogenesis in the TD resulted in a several fold greater accumulation of volatile fatty acids (acetate, propionate, and butyrate) followed by a larger pH drop with a prolonged recovery than in the MD. However, the operational stability between both digesters remained comparable. Pyrosequencing analyses revealed that the MD had more complex microbial diversity indices and microbial community changes than the TD. Interestingly, Methanomassiliicoccales, the seventh methanogen order was the predominant archaeal order in the MD along with bacterial orders of Clostridiales, Bacteriodales, and Synergistales. Meanwhile, Coprothermobacter and Methanobacteriales dominated the bacterial and archaeal community in the TD, respectively. Although the methane yield is comparable, both MD and TD show a different profile of pH, VFA and the microbial communities. PMID:27562592

  13. Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material.

    PubMed

    Barbieri, Manuela; Carrera, Jesús; Sanchez-Vila, Xavier; Ayora, Carlos; Cama, Jordi; Köck-Schulmeyer, Marianne; López de Alda, Miren; Barceló, Damià; Tobella Brunet, Joana; Hernández García, Marta

    2011-11-01

    The natural processes occurring in subsurface environments have proven to effectively remove a number of organic pollutants from water. The predominant redox conditions revealed to be one of the controlling factors. However, in the case of organic micropollutants the knowledge on this potential redox-dependent behavior is still limited. Motivated by managed aquifer recharge practices microcosm experiments involving aquifer material, settings potentially feasible in field applications, and organic micropollutants at environmental concentrations were carried out. Different anaerobic redox conditions were promoted and sustained in each set of microcosms by adding adequate quantities of electron donors and acceptors. Whereas denitrification and sulfate-reducing conditions are easily achieved and maintained, Fe- and Mn-reduction are strongly constrained by the slower dissolution of the solid phases commonly present in aquifers. The thorough description and numerical modeling of the evolution of the experiments, including major and trace solutes and dissolution/precipitation of solid phases, have been proven necessary to the understanding of the processes and closing the mass balance. As an example of micropollutant results, the ubiquitous beta-blocker atenolol is completely removed in the experiments, the removal occurring faster under more advanced redox conditions. This suggests that aquifers constitute a potentially efficient alternative water treatment for atenolol, especially if adequate redox conditions are promoted during recharge and long enough residence times are ensured. PMID:22115096

  14. Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material

    NASA Astrophysics Data System (ADS)

    Barbieri, Manuela; Carrera, Jesús; Sanchez-Vila, Xavier; Ayora, Carlos; Cama, Jordi; Köck-Schulmeyer, Marianne; López de Alda, Miren; Barceló, Damià; Tobella Brunet, Joana; Hernández García, Marta

    2011-11-01

    The natural processes occurring in subsurface environments have proven to effectively remove a number of organic pollutants from water. The predominant redox conditions revealed to be one of the controlling factors. However, in the case of organic micropollutants the knowledge on this potential redox-dependent behavior is still limited. Motivated by managed aquifer recharge practices microcosm experiments involving aquifer material, settings potentially feasible in field applications, and organic micropollutants at environmental concentrations were carried out. Different anaerobic redox conditions were promoted and sustained in each set of microcosms by adding adequate quantities of electron donors and acceptors. Whereas denitrification and sulfate-reducing conditions are easily achieved and maintained, Fe- and Mn-reduction are strongly constrained by the slower dissolution of the solid phases commonly present in aquifers. The thorough description and numerical modeling of the evolution of the experiments, including major and trace solutes and dissolution/precipitation of solid phases, have been proven necessary to the understanding of the processes and closing the mass balance. As an example of micropollutant results, the ubiquitous beta-blocker atenolol is completely removed in the experiments, the removal occurring faster under more advanced redox conditions. This suggests that aquifers constitute a potentially efficient alternative water treatment for atenolol, especially if adequate redox conditions are promoted during recharge and long enough residence times are ensured.

  15. Requirement of ArcA for redox regulation in Escherichia coli under microaerobic but not anaerobic or aerobic conditions.

    PubMed

    Alexeeva, Svetlana; Hellingwerf, Klaas J; Teixeira de Mattos, M Joost

    2003-01-01

    In Escherichia coli, the two-component regulatory ArcAB system functions as a major control system for the regulation of expression of genes encoding enzymes involved in both aerobic and anaerobic catabolic pathways. Previously, we have described the physiological response of wild-type E. coli to changes in oxygen availability through the complete range from anaerobiosis to full aerobiosis (S. Alexeeva, B. de Kort, G. Sawers, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 182:4934-4940, 2000, and S. Alexeeva, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 184:1402-1406, 2002). Here, we address the question of the contribution of the ArcAB-dependent transcriptional regulation to this response. Wild-type E. coli and a mutant lacking the ArcA regulator were grown in glucose-limited chemostat cultures at controlled levels of oxygen availability ranging from full aerobiosis to complete anaerobiosis. A flux analysis of the distribution of catabolic fluxes over parallel pathways was carried out, and the intracellular redox state (as reflected by the NADH/NAD ratio) was monitored for all steady states. Deletion of ArcA neither significantly altered the in vivo activity of the pyruvate dehydrogenase complex and pyruvate formate lyase nor significantly affected catabolism under fully aerobic and fully anaerobic conditions. In contrast, profound effects of the absence of ArcA were seen under conditions of oxygen-restricted growth: increased respiration, an altered electron flux distribution over the cytochrome o- and d-terminal oxidases, and a significant change in the intracellular redox state were observed. Thus, the ArcA regulator was found to exert major control on flux distribution, and it is concluded that the ArcAB system should be considered a microaerobic redox regulator. PMID:12486057

  16. Intracellular Accumulation of Glycine in Polyphosphate-Accumulating Organisms in Activated Sludge, a Novel Storage Mechanism under Dynamic Anaerobic-Aerobic Conditions

    PubMed Central

    Nguyen, Hien Thi Thu; Kristiansen, Rikke; Vestergaard, Mette; Wimmer, Reinhard

    2015-01-01

    Dynamic anaerobic-aerobic feast-famine conditions are applied to wastewater treatment plants to select polyphosphate-accumulating organisms to carry out enhanced biological phosphorus removal. Acetate is a well-known substrate to stimulate this process, and here we show that different amino acids also are suitable substrates, with glycine as the most promising. 13C-labeled glycine and nuclear magnetic resonance (NMR) were applied to investigate uptake and potential storage products when activated sludge was fed with glycine under anaerobic conditions. Glycine was consumed by the biomass, and the majority was stored intracellularly as free glycine and fermentation products. Subsequently, in the aerobic phase without addition of external substrate, the stored glycine was consumed. The uptake of glycine and oxidation of intracellular metabolites took place along with a release and uptake of orthophosphate, respectively. Fluorescence in situ hybridization combined with microautoradiography using 3H-labeled glycine revealed uncultured actinobacterial Tetrasphaera as a dominant glycine consumer. Experiments with Tetrasphaera elongata as representative of uncultured Tetrasphaera showed that under anaerobic conditions it was able to take up labeled glycine and accumulate this and other labeled metabolites to an intracellular concentration of approximately 4 mM. All components were consumed under subsequent aerobic conditions. Intracellular accumulation of amino acids seems to be a novel storage strategy for polyphosphate-accumulating bacteria under dynamic anaerobic-aerobic feast-famine conditions. PMID:25956769

  17. Intracellular Accumulation of Glycine in Polyphosphate-Accumulating Organisms in Activated Sludge, a Novel Storage Mechanism under Dynamic Anaerobic-Aerobic Conditions.

    PubMed

    Nguyen, Hien Thi Thu; Kristiansen, Rikke; Vestergaard, Mette; Wimmer, Reinhard; Nielsen, Per Halkjær

    2015-07-01

    Dynamic anaerobic-aerobic feast-famine conditions are applied to wastewater treatment plants to select polyphosphate-accumulating organisms to carry out enhanced biological phosphorus removal. Acetate is a well-known substrate to stimulate this process, and here we show that different amino acids also are suitable substrates, with glycine as the most promising. (13)C-labeled glycine and nuclear magnetic resonance (NMR) were applied to investigate uptake and potential storage products when activated sludge was fed with glycine under anaerobic conditions. Glycine was consumed by the biomass, and the majority was stored intracellularly as free glycine and fermentation products. Subsequently, in the aerobic phase without addition of external substrate, the stored glycine was consumed. The uptake of glycine and oxidation of intracellular metabolites took place along with a release and uptake of orthophosphate, respectively. Fluorescence in situ hybridization combined with microautoradiography using (3)H-labeled glycine revealed uncultured actinobacterial Tetrasphaera as a dominant glycine consumer. Experiments with Tetrasphaera elongata as representative of uncultured Tetrasphaera showed that under anaerobic conditions it was able to take up labeled glycine and accumulate this and other labeled metabolites to an intracellular concentration of approximately 4 mM. All components were consumed under subsequent aerobic conditions. Intracellular accumulation of amino acids seems to be a novel storage strategy for polyphosphate-accumulating bacteria under dynamic anaerobic-aerobic feast-famine conditions. PMID:25956769

  18. Evaluation of batch anaerobic co-digestion of palm pressed fiber and cattle manure under mesophilic conditions.

    PubMed

    Bah, Hamidou; Zhang, Wanqin; Wu, Shubiao; Qi, Dandan; Kizito, Simon; Dong, Renjie

    2014-11-01

    Palm pressed fiber (PPF) and cattle manure (CM) are the waste which can be managed properly by anaerobic co-digestion. The biogas production in co-digested PPF and CM at three volatile solids (VS) ratios of 3:1, 1:1, and 1:3 was investigated in a series of batch experiments at an organic loading rate of 30.0 g VS/L under mesophilic (37±1°C) conditions. The highest daily biogas yield of PPF and CM only, was 90.0 mL/g VS(added) at day 12 and 23.4 mL/g VS(added) at day 7. For co-digestion of PPF/CM at mixing ratios of 3:1, 1:1 and 1:3, there were 93.6 mL/g VS(added) at day 11, 86.8 and 26.4 mL/g VS(added) at day 8. VS removal rate for PPF, CM, and co-digestion at mixing ratio of 3:1, 1:1, and 1:3 were 91.1%, 86.0% and 71.0%, respectively. The anaerobic digestion of PPF and CM and their co-digestion systems were stable in operation with low range of volatile fatty acids (VFA)/TIC (total inorganic carbon) of (0.035-0.091). The main volatile fatty acids were propionic, and iso-butyric acids for PPF, iso-butyric and n-butyric acids for CM. The VFAs and ammonium inhibition were not occurred. The modified Gompertz model can be used to perform a better prediction with a lower difference between the measured and predicted biogas yields. A VS ratio of 3:1 is recommended for practice. PMID:25148926

  19. Effect of outdoor conditions on Nannochloropsis salina cultivation in artificial seawater using nutrients from anaerobic digestion effluent.

    PubMed

    Sheets, Johnathon P; Ge, Xumeng; Park, Stephen Y; Li, Yebo

    2014-01-01

    The effects of simulated outdoor seasonal climatic conditions on Nannochloropsis salina (N. salina) grown using nutrients from anaerobic digestion (AD) effluent were evaluated in this study. Under various light exposure (LE) and temperature (10-30 °C) conditions, N. salina specific growth rate (μ) was strongly affected by LE. Light availability (LA) was observed to be crucial for biomass production, with μ values of 0.038±0.013 d(-1), 0.093±0.013 d(-1), and 0.151±0.021 d(-1) for 6-h, 12-h, and 24-h LA conditions, respectively. Temperature (10-25 °C) was not significant in affecting the light dependent growth coefficient (μ/LE), indicating the suitability of culturing this strain in the Ohio climate. Cultures exposed to low illumination had significantly higher unsaturated fatty acid content than those under high illumination, with nearly 29% higher eicosapentaenoic acid (C20:5) content. Using LE and light attenuation resulted in adequate prediction of N. salina growth in a 1000 L open raceway pond. PMID:24291316

  20. Improving Biomethane Production and Mass Bioconversion of Corn Stover Anaerobic Digestion by Adding NaOH Pretreatment and Trace Elements

    PubMed Central

    Liu, ChunMei; Yuan, HaiRong; Zou, DeXun; Liu, YanPing; Zhu, BaoNing; Li, XiuJin

    2015-01-01

    This research applied sodium hydroxide (NaOH) pretreatment and trace elements to improve biomethane production when using corn stover for anaerobic digestion. Full-factor experimental tests identified the best combination of trace elements with the NaOH pretreatment, indicating that the best combination was with 1.0, 0.4, and 0.4 mg·L−1·d−1 of elements Fe, Co, and Ni, respectively. The cumulative biomethane production adding NaOH pretreatment and trace elements was 11,367 mL; total solid bioconversion rate was 55.7%, which was 41.8%–62.2% higher than with NaOH-pretreatment alone and 22.2%–56.3% higher than with untreated corn stover. The best combination was obtained 5–9 days shorter than T90 and maintained good system operation stability. Only a fraction of the trace elements in the best combination was present in the resulting solution; more than 85% of the total amounts added were transferred into the solid fraction. Adding 0.897 g of Fe, 0.389 g of Co, and 0.349 g of Ni satisfied anaerobic digestion needs and enhanced biological activity at the beginning of the operation. The results showed that NaOH pretreatment and adding trace elements improve corn stover biodegradability and enhance biomethane production. PMID:26137469

  1. Improving Biomethane Production and Mass Bioconversion of Corn Stover Anaerobic Digestion by Adding NaOH Pretreatment and Trace Elements.

    PubMed

    Liu, ChunMei; Yuan, HaiRong; Zou, DeXun; Liu, YanPing; Zhu, BaoNing; Li, XiuJin

    2015-01-01

    This research applied sodium hydroxide (NaOH) pretreatment and trace elements to improve biomethane production when using corn stover for anaerobic digestion. Full-factor experimental tests identified the best combination of trace elements with the NaOH pretreatment, indicating that the best combination was with 1.0, 0.4, and 0.4 mg·L(-1)·d(-1) of elements Fe, Co, and Ni, respectively. The cumulative biomethane production adding NaOH pretreatment and trace elements was 11,367 mL; total solid bioconversion rate was 55.7%, which was 41.8%-62.2% higher than with NaOH-pretreatment alone and 22.2%-56.3% higher than with untreated corn stover. The best combination was obtained 5-9 days shorter than T90 and maintained good system operation stability. Only a fraction of the trace elements in the best combination was present in the resulting solution; more than 85% of the total amounts added were transferred into the solid fraction. Adding 0.897 g of Fe, 0.389 g of Co, and 0.349 g of Ni satisfied anaerobic digestion needs and enhanced biological activity at the beginning of the operation. The results showed that NaOH pretreatment and adding trace elements improve corn stover biodegradability and enhance biomethane production. PMID:26137469

  2. Improving the mixing performances of rice straw anaerobic digestion for higher biogas production by computational fluid dynamics (CFD) simulation.

    PubMed

    Shen, Fei; Tian, Libin; Yuan, Hairong; Pang, Yunzhi; Chen, Shulin; Zou, Dexun; Zhu, Baoning; Liu, Yanping; Li, Xiujin

    2013-10-01

    As a lignocellulose-based substrate for anaerobic digestion, rice straw is characterized by low density, high water absorbability, and poor fluidity. Its mixing performances in digestion are completely different from traditional substrates such as animal manures. Computational fluid dynamics (CFD) simulation was employed to investigate mixing performances and determine suitable stirring parameters for efficient biogas production from rice straw. The results from CFD simulation were applied in the anaerobic digestion tests to further investigate their reliability. The results indicated that the mixing performances could be improved by triple impellers with pitched blade, and complete mixing was easily achieved at the stirring rate of 80 rpm, as compared to 20-60 rpm. However, mixing could not be significantly improved when the stirring rate was further increased from 80 to 160 rpm. The simulation results agreed well with the experimental results. The determined mixing parameters could achieve the highest biogas yield of 370 mL (g TS)(-1) (729 mL (g TS(digested))(-1)) and 431 mL (g TS)(-1) (632 mL (g TS(digested))(-1)) with the shortest technical digestion time (T 80) of 46 days. The results obtained in this work could provide useful guides for the design and operation of biogas plants using rice straw as substrates. PMID:23873639

  3. Anaerobic thermophilic culture

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A newly discovered thermophilic anaerobe is described that was isolated in a biologically pure culture and designated Thermoanaerobacter ethanolicus ATCC 3/550. T. Ethanolicus is cultured in aqueous nutrient medium under anaerobic, thermophilic conditions and is used in a novel process for producing ethanol by subjecting carbohydrates, particularly the saccharides, to fermentation action of the new microorganism in a biologically pure culture.

  4. In vitro studies of the mechanism of inhibition of rat liver uroporphyrinogen decarboxylase activity by ferrous iron under anaerobic conditions.

    PubMed

    Mukerji, S K; Pimstone, N R

    1986-02-01

    Human porphyria cutanea tarda (PCT) is an unusual consequence of common hepatic disorders such as alcoholic liver disease and iron overload, where hepatic iron plays a key role in the expression of the metabolic lesion, i.e., defective hepatic decarboxylation of porphyrinogens. In this investigation, kinetic studies on a partially purified rat liver uroporphyrinogen decarboxylase have been conducted under controlled conditions to determine how iron perturbs porphyrinogen decarboxylation in vitro. The enzyme, assayed strictly under anaerobic conditions in the dark, was inhibited progressively by ferrous iron. Approximately 0.45 mM ferrous ammonium sulfate was required to observe about 50% inhibition of enzyme activity measured with uroporphyrinogen I as substrate. We showed that (a) all the steps of enzymatic decarboxylation (octa-, hepta-, hexa-, and pentacarboxylic porphyrinogen of isomer I series) were inhibited by ferrous iron. The inhibition was competitive with respect to uroporphyrinogen I and III substrates; (b) the cations, e.g., Fe3+ and Mg2+, had no effect, whereas sulfhydryl group specific cations and compounds such as Hg2+, Zn2+, p-mercuribenzoate, and 5,5'-dithiobis(2-nitrobenzoate) all inhibited the enzyme; (c) the enzyme could be protected from inhibition by Fe2+ and p-mercuribenzoate by preincubation with pentacarboxylic porphyrinogen, a natural substrate and competitive inhibitor. These data suggest for the first time a direct interaction of ferrous iron with cysteinyl residue(s) located at the active site(s) of the enzyme. PMID:3947082

  5. Interaction between phosphorus removal and hybrid granular sludge formation under low hydraulic selection pressure at alternating anaerobic/aerobic conditions.

    PubMed

    Lang, Longqi; Wan, Junfeng; Zhang, Jing; Wang, Jie; Wang, Yan

    2015-01-01

    The hybrid granular sludge (HGS) formation and its performances on phosphorus removal were investigated in a sequencing batch airlift reactor. Under conditions of low superficial air velocity (SAV = 0.68 cm s(-1)) and relatively long settling time (15-30 min), aerobic granules appeared and coexisted with bio-flocs after 120 days operation. At the stable phase, 54% of total suspended solid (m/m) was granular sludge with the two typical sizes (D(mean) = 1.77 ± 0.33 and 0.89 ± 0.11 mm) in the reactor, where the settling velocity was 98.7 ± 12.4 and 37.8 ± 0.9 m h(-1) for the big and small granules. With progressive extension of anaerobic time from 15 to 60 min before aerobic condition per cycle during the whole experiment, the HGS system can be maintained at a high total phosphorus removal efficiency (ca. 99%) since Day-270. The phosphorus content (wt %) in biomass was respectively 9.54 ± 0.29, 7.60 ± 0.48 and 6.15 ± 0.59 for the big granules, small granules and flocs. PMID:25921951

  6. Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions.

    PubMed

    Costa, Suelen B; Campos, Ana Carolina C; Pereira, Ana Claudia M; de Mattos-Guaraldi, Ana Luiza; Júnior, Raphael Hirata; Rosa, Ana Cláudia P; Asad, Lídia M B O

    2014-09-01

    During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the

  7. Improvement of hydrogen production via ethanol-type fermentation in an anaerobic down-flow structured bed reactor.

    PubMed

    Anzola-Rojas, Mélida del Pilar; Zaiat, Marcelo; De Wever, Heleen

    2016-02-01

    Although a novel anaerobic down-flow structured bed reactor has shown feasibility and stable performance for a long-term compared to other anaerobic fixed bed systems for continuous hydrogen production, the volumetric rates and yields have so far been too low. In order to improve the performance, an operation strategy was applied by organic loading rate (OLR) variation (12-96 g COD L(-1) d(-1)). Different volumetric hydrogen rates, and yields at the same OLR indicated that the system was mainly driven by the specific organic load (SOL). When SOL was kept between 3.8 and 6.2 g sucrose g(-1) VSS d(-1), the volumetric rates raised from 0.1 to 8.9 L H2 L(-1) d(-1), and the yields were stable around 2.0 mol H2 mol(-1) converted sucrose. Furthermore, hydrogen was produced mainly via ethanol-type fermentation, reaching a total energy conversion rate of 23.40 kJ h(-1) L(-1) based on both hydrogen and ethanol production. PMID:26700757

  8. Anaerobic biodegradation of soybean biodiesel and diesel blends under sulfate-reducing conditions.

    PubMed

    Wu, Shuyun; Yassine, Mohamad H; Suidan, Makram T; Venosa, Albert D

    2016-10-01

    Biotransformation of soybean biodiesel and its biodiesel/petrodiesel blends were investigated under sulfate-reducing conditions. Three blends of biodiesel, B100, B50, and B0, were treated using microbial cultures pre-acclimated to B100 (biodiesel only) and B80 (80% biodiesel and 20% petrodiesel). Results indicate that the biodiesel could be effectively biodegraded in the presence or absence of petrodiesel, whereas petrodiesel could not be biodegraded at all under sulfate-reducing conditions. The kinetics of biodegradation of individual Fatty Acid Methyl Ester (FAME) compounds and their accompanying sulfate-reduction rates were studied using a serum bottle test. As for the biodegradation of individual FAME compounds, the biodegradation rates for the saturated FAMEs decreased with increasing carbon chain length. For unsaturated FAMEs, biodegradation rates increased with increasing number of double bonds. The presence of petrodiesel had a greater effect on the rate of biodegradation of biodiesel than on the extent of removal. PMID:27448319

  9. Effects of anaerobic growth conditions on biomass accumulation, root morphology, and efficiencies of nutrient uptake and utilization in seedlings of some southern coastal plain

    SciTech Connect

    Topa, M.A.

    1984-01-01

    Seedlings of pond, and loblolly pines were grown in a non-circulating, continuously-flowing solution culture under anaerobic (0.75 mg/1 O/sub 2/) conditions to determine the effects of anaerobiosis on overall growth, root morphology and efficiencies of nutrient uptake and utilization. Although shoot growth of the 11-week old loblolly and pond was not affected by anaerobic treatment, it did significantly reduce root biomass. Sand pine suffered the largest biomass reduction. Flooding tolerance was positively correlated with morphological changes which enhanced root internal aeration. Oxygen transport from shoot to the root was demonstrated via rhizosphere oxidation experiments using indigo-carmine dye solutions and polarography. Stem and root collar lenticels were found to be the major sites of atmospheric O/sub 2/ entry for submerged roots. Longitudinal and radial pathways for gas diffusion via intercellular spaces in the pericycle and ray parenchyma, respectively, were elucidated histologically. Lenticel and aerenchyma development, and rhizosphere oxidation in roots of anaerobically-grown sand pine seedlings were minimal. Elemental analyses showed that anaerobic conditions interfered with nutrient absorption and utilization. Short-term /sup 32/P uptake experiments with intact seedlings indicated that net absorption decreased because of the reduction in root biomass. Phosphorus absorption rates were negatively correlated with internal tissue phosphorus concentrations, and root and shoot biomass. 315 refs., 25 figs., 14 tabs.

  10. Women and Working Conditions: Prospects for Improvement?

    ERIC Educational Resources Information Center

    Seguret, Marie-Claire

    1983-01-01

    Women's difficult working conditions are due to factors such as the nature and form of women's employment, their reproductive role, and family responsibilities. The relative importance of these factors must be assessed in order to redress inequalities. (SK)

  11. Removal of estrogens in municipal wastewater treatment under aerobic and anaerobic conditions: consequences for plant optimization.

    PubMed

    Joss, Adriano; Andersen, Henrik; Ternes, Thomas; Richle, Philip R; Siegrist, Hansruedi

    2004-06-01

    The removal of estrogens (estrone E1, estradiol E2, and ethinylestradiol EE2) was studied in various municipal wastewater treatment processes equipped for nutrient removal. A biological degradation model is formulated, and kinetic parameters are evaluated with batch experiments under various redox conditions. The resulting model calculations are then compared with sampling campaigns performed on differenttypes of full-scale plant: conventional activated-sludge treatment, a membrane bioreactor, and a fixed-bed reactor. The results show a > 90% removal of all estrogens in the activated sludge processes. (Due to the analytical quantification limit and low influent concentrations, however, this removal efficiency represents only an observable minimum.) The removal efficiencies of 77% and > or = 90% for E1 and E2, respectively, in the fixed-bed reactor represent a good performance in view of the short hydraulic retention time of 35 min. The first-order removal-rate constant in batch experiments observed for E2 varied from 150 to 950 d(-1) for a 1 gSS L(-1) sludge suspension. The removal efficiency of E1 and EE2 clearly depends on the redox conditions, the maximum removal rate occurring under aerobic conditions when E1 was reduced to E2. Sampling campaigns on full-scale plants indicate that the kinetic values identified in batch experiments (without substrate addition) for the natural estrogens may overestimate the actual removal rates. Although this paper does not give direct experimental evidence, it seems that the substrate present in the raw influent competitively inhibits the degradation of E1 and E2. These compounds are therefore removed mainly in activated sludge compartments with low substrate loading. Theoretical evaluation leads us to expect that diffusive mass transfer inside the floc (but not across the laminar boundary layer) appreciably influences the observed degradation rates of E1 and E2, but not of EE2. PMID:15224734

  12. Anaerobic co-digestion of steam-treated Quercus serrata chips and sewage sludge under mesophilic and thermophilic conditions.

    PubMed

    Wang, Feng; Hidaka, Taira; Sakurai, Kensuke; Tsumori, Jun

    2014-08-01

    The biodegradation of Quercus serrata chips was evaluated by anaerobic digestion under various steam explosion conditions. In continuous experiments, untreated chips (W₀) and chips steam-treated at less than 1.0 MPa (W₁) and 2.0 MPa (W₄) were co-digested with sewage sludge (S₁ and S₂) taken from two different wastewater treatment plants. The apparent methane yield of W₁ and W₄ co-digested with S₁ (thermophilic) was 261 dm(3)/kgVS (volatile solids) and 248 dm(3)/kgVS, respectively. The apparent methane yield of W₄ co-digested with S₂ was 258 dm(3)/kgVS (mesophilic) and 271 dm(3)/kgVS (thermophilic). Methane production was inhibited by W₀ due to components released during hydrolysis. The methane conversion ratio of pretreated chips obtained in batch experiments varied from 40.5% to 53.8% (mesophilic) and from 49.0% to 63.7% (thermophilic). The methane conversion ratio increased with decreasing acid-soluble lignin content in the chips. PMID:24926605

  13. Performance evaluation of a completely stirred anaerobic reactor treating pig manure at a low range of mesophilic conditions.

    PubMed

    Guo, Jianbin; Dong, Renjie; Clemens, Joachim; Wang, Wei

    2013-11-01

    Many Chinese biogas plants run in the lower range of mesophilic conditions. This study evaluated the performance of a completely stirred anaerobic reactor treating pig manure at different temperatures (20, 28 and 38°C). The start-up phase of the reactor at 20°C was very long and extremely poor performance was observed with increasing organic loading rate (OLR). At an OLR of 4.3g ODML(-1)d(-1), methane production at 28°C was comparable (3% less) with that at 38°C, but the risk of acidification was high at 28°C. At low OLR (1.3g ODML(-1)d(-1)), the biogas process appeared stable at 28°C and gave same methane yields as compared to the reactor operating at 38°C. The estimated sludge yield at 28°C was 0.065g VSSg(-1) CODremoved, which was higher than that at 38°C (0.016g VSSg(-1) CODremoved). PMID:23842452

  14. Microbial population dynamics during start-up and overload conditions of anaerobic digesters treating municipal solid waste and sewage sludge.

    PubMed

    McMahon, Katherine D; Zheng, Dandan; Stams, Alfons J M; Mackie, Roderick I; Raskin, Lutgarde

    2004-09-30

    Microbial population dynamics were investigated during start-up and during periods of overload conditions in anaerobic co-digesters treating municipal solid waste and sewage sludge. Changes in community structure were monitored using ribosomal RNA-based oligonucleotide probe hybridization to measure the abundance of syntrophic propionate-oxidizing bacteria (SPOB), saturated fatty acid-beta-oxidizing syntrophs (SFAS), and methanogens. These changes were linked to traditional performance parameters such as biogas production and volatile fatty acid (VFA) concentrations. Digesters with high levels of Archaea started up successfully. Methanosaeta concilii was the dominant aceticlastic methanogen in these systems. In contrast, digesters that experienced a difficult start-up period had lower levels of Archaea with proportionally more abundant Methanosarcina spp. Syntrophic propionate-oxidizing bacteria and saturated fatty acid-beta-oxidizing syntrophs were present at low levels in all digesters, and SPOB appeared to play a role in stabilizing propionate levels during start-up of one digester. Digesters with a history of poor performance tolerated a severe organic overload event better than digesters that had previously performed well. It is hypothesized that higher levels of SPOB and SFAS and their methanogenic partners in previously unstable digesters are responsible for this behavior. PMID:15334409

  15. Hydrogen photoproduction by nutrient-deprived Chlamydomonas reinhardtii cells immobilized within thin alginate films under aerobic and anaerobic conditions.

    PubMed

    Kosourov, Sergey N; Seibert, Michael

    2009-01-01

    A new technique for immobilizing H2-photoproducing green algae within a thin (<400 microm) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 microg Chl mL(-1) of matrix), (b) kinetics of H2 photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 micromol mg(-1) Chl h(-1)) of H2 evolution, (d) light conversion efficiencies to H2 of over 1% and (e) unexpectedly high resistance of the H2-photoproducing system to inactivation by atmospheric O2. The algal cells, entrapped in alginate and then placed in vials containing 21% O2 in the headspace, evolved up to 67% of the H2 gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H2-producing system to inactivation by O2 depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O2 in the liquid and headspace and restrict O2 diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications. PMID:18823051

  16. Effect of fermentation conditions on biohydrogen production from cassava starch by anaerobic mixed cultures

    NASA Astrophysics Data System (ADS)

    Tien, Hai M.; Le, Kien A.; Tran, An T.; Le, Phung K.

    2016-06-01

    In this work, a series of batch tests were conducted to investigate the effect of pH, temperature, fermentation time, and inoculums ratio to hydrogen production using cassava starch as a substrate. The statistical analysis of the experiment indicated that the significant effects for the fermentation yield were the main effect of temperature, pH and inoculums ratio. It was fouund that the suitable fermentation conditions of biohydrogen production should be at temperature 40 ° C; pH 6.5, inoculums to medium ratio 10 % and COD operation at 4800 g/mL. The maximum value of hydrogen volume produced was 76.22 mL. These affected has been evaluated and the result can be used as an reference for the pilot or industrial biohydrogen production.

  17. Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

    PubMed Central

    Jin, Jingwei; Dai, Xiaohu

    2014-01-01

    The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

  18. Laboratory Study of Chemical Speciation of Mercury in Lake Sediment and Water under Aerobic and Anaerobic Conditions

    PubMed Central

    Regnell, Olof; Tunlid, Anders

    1991-01-01

    Chemical speciation and partitioning of radiolabeled HgCl2 were studied in model aquatic systems consisting of undisturbed eutrophic lake sediment and water in plastic cylinders. The cylinders were either gradually made anaerobic by a gentle flow of N2-CO2 or kept aerobic by air flow. The proportion of methylated 203Hg was significantly higher, in both water and sediment, in the anaerobic systems than in the aerobic systems. The composition and total concentration of fatty acids originating from bacterial phospholipids, as well as the concentration of vitamin B12, including related cobalamins, were similar in sediments from the anaerobic and aerobic systems. Bacterial cell numbers were, on average, 3.6 times higher in the anaerobic water columns than in the aerobic ones. Volatilization of 203Hg occurred in all systems except in an autoclaved control and was of similar magnitudes in the anaerobic and aerobic systems. Incorporation of 203Hg into the sediment was significantly faster in the aerobic systems than in the anaerobic systems. These results suggest that episodes of anoxia in bottom waters and sediment cause an increase in net mercury methylation and, hence, an increase in bioavailable mercury. PMID:16348444

  19. A Primer on Improving Contingent Faculty Conditions

    ERIC Educational Resources Information Center

    McGrew, Heidi; Untener, Joe

    2010-01-01

    Challenges associated with the increasing use of contingent faculty appointments in American higher education are mounting. The AAUP and other professional groups have identified several major problems: (1) unacceptable conditions and compensation for contingent faculty members; (2) poor learning outcomes for students; and (3) the potential…

  20. Improving Boundary Conditions for Electronic Structure Calculations

    NASA Astrophysics Data System (ADS)

    Benesh, G. A.; Haydock, Roger

    Boundary conditions imposed on a local system joined to a much larger substrate system routinely introduce unphysical reflections that affect the calculation of electronic properties such as energies, charge densities, and densities of states. These problems persist in atomic cluster, slab, and supercell calculations alike. However, wave functions in real, physical systems do not reflect at artificial boundaries. Instead, they carry current smoothly across the surface separating the local system from the underlying medium. Haydock and Nex have derived a non-reflecting boundary condition that works well for discrete systems [Phys. Rev. B 75, 205121 (2006)]. Solutions satisfying their maximal breaking of time-reversal symmetry (MBTS) boundary condition carry current away from the boundary at a maximal rate--in much the same way as exact wave functions in physical systems. The MBTS approach has now been extended to studies employing continuous basis functions. In model systems, MBTS boundary conditions work well for calculating wave functions, eigenenergies, and densities of states. Results are reported for an Al(001) surface. Comparisons are made with slab calculations, embedding calculations, and experiment.

  1. Review of feedstock pretreatment strategies for improved anaerobic digestion: From lab-scale research to full-scale application.

    PubMed

    Carrere, Hélène; Antonopoulou, Georgia; Affes, Rim; Passos, Fabiana; Battimelli, Audrey; Lyberatos, Gerasimos; Ferrer, Ivet

    2016-01-01

    When properly designed, pretreatments may enhance the methane potential and/or anaerobic digestion rate, improving digester performance. This paper aims at providing some guidelines on the most appropriate pretreatments for the main feedstocks of biogas plants. Waste activated sludge was firstly investigated and implemented at full-scale, its thermal pretreatment with steam explosion being most recommended as it increases the methane potential and digestion rate, ensures sludge sanitation and the heat needed is produced on-site. Regarding fatty residues, saponification is preferred for enhancing their solubilisation and bioavailability. In the case of animal by-products, this pretreatment can be optimised to ensure sterilisation, solubilisation and to reduce inhibition linked to long chain fatty acids. With regards to lignocellulosic biomass, the first goal should be delignification, followed by hemicellulose and cellulose hydrolysis, alkali or biological (fungi) pretreatments being most promising. As far as microalgae are concerned, thermal pretreatment seems the most promising technique so far. PMID:26384658

  2. Anaerobic bacteria

    MedlinePlus

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these ... Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's ...

  3. Molecular insight into activated sludge producing polyhydroxyalkanoates under aerobic-anaerobic conditions.

    PubMed

    Ciesielski, Slawomir; Pokoj, Tomasz; Klimiuk, Ewa

    2008-08-01

    One of the options enabling more economic production of polyhydroxyalkanoates compared to pure cultures is the application of mixed cultures. The use of a microbial community in a sequencing batch reactor has a few advantages: a simple process control, no necessity for sterile processing, and possibilities of using cheap substrates as a source of carbon. Nevertheless, while cultivation methods to achieve high PHAs biomass concentration and high productivity in wild and recombinant strains are defined, knowledge about the cultivation strategy for PHAs production by mixed culture and species composition of bacterial communities is still very limited. The main object of this study was to characterize on the molecular level the composition and activity of PHAs producing microorganism in activated sludge cultivated under oxygen limitation conditions. PHAs producers were detected using a PCR technique and the created PHA synthase gene library was analyzed by DNA sequencing. The obtained results indicate that PHAs-producers belonged to Pseudomonas sp., and possessed genes coding for mcl-PHA synthase. The kinetics of mcl-PHA synthase expression was relatively estimated using real-time PCR technology at several timepoints. Performed quantitative and qualitative analysis of total bacterial activity showed that there were differences in total activity during the process but differential expression of various groups of microorganisms examined by using DGGE was not observed. PMID:18418634

  4. The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Gorbacheva, M.

    2012-04-01

    M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for

  5. Effects of temperature on anaerobic decomposition of high-molecular weight organic matter under sulfate-reducing conditions

    NASA Astrophysics Data System (ADS)

    Matsui, Takato; Kojima, Hisaya; Fukui, Manabu

    2013-03-01

    Most sedimentary mineralization occurs along coasts under anaerobic conditions. In the absence of oxygen, high-molecular weight organic matter in marine sediments is gradually decomposed by hydrolysis, fermentation and sulfate reduction. Because of the different responses of the respective steps to temperature, degradation may be specifically slowed or stopped in certain step. To evaluate the effect of temperature on cellobiose degradation, culture experiments were performed at six different temperatures (3 °C, 8 °C, 13 °C, 18 °C, 23 °C, and 28 °C) under sulfate-reducing conditions. This study measured the concentrations of sulfide, dissolved organic carbon (DOC), and organic acids during that degradation. Degradation patterns were divided into three temperature groups: 3 °C, 8/13 °C, and 18/23/28 °C. The decrease in DOC proceeded in two steps, except at 3 °C. The length of the stagnant phase separating these two steps differed greatly between temperatures of 8/13 °C and 18/23/28 °C. In the first step, organic carbon was consumed by hydrolysis, fermentation and sulfate reduction. In the second step, acetate accumulated during the first step was oxidized by sulfate reduction. Bacterial communities in the cultures were analyzed by denaturing gradient gel electrophoresis (DGGE); the major differences among the three temperature groups were attributed to shifts in acetate-using sulfate reducers of the genus Desulfobacter. This suggests that temperature characteristics of dominant acetate oxidizers are important factors in determining the response of carbon flow in coastal marine sediments in relation to the changes in temperature.

  6. [High-solids anaerobic co-digestion of sludge and kitchen garbage under mesophilic conditions].

    PubMed

    Duan, Ni-Na; Dong, Bin; Li, Jiang-Hua; Dai, Ling-Ling; Dai, Xiao-Hu

    2013-01-01

    At solid retention time (SRT) of 20 days, biogas production, volatile solid (VS) degradation and system stability in co-digestion systems of dewatered sludge (DS) and kitchen garbage (KG) were investigated in semi-continuous completely mixed reactors numbered R1-R5 (the DS/KG of their feeding substrate based on wet mass was 1:0, 4:1, 3:2, 2:3 and 0:1, respectively). The results showed that, with larger proportion of KG in feeding substrate, higher methane yield and biogas yield were obtained with lower methane content. For certain reactor at given SRT, KG addition could significantly improve the organic loading rate (OLR) and volume biogas production. System with more KG addition favored higher hydraulic constant k and VS reduction. The hydraulic constant k was 0.25 d(-1), 0.61 d(-1), 1.09 d(-1) and 1.56 d(-1), and the VS reduction was 37.4%, 50.6%, 60.7% and 68.2% for R1-R4, respectively, indicating higher hydrolysis rates with more KG addition, which led to increased VS reductions. With larger KG proportion in feeding substrate, pH, total alkalinity (TA), total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) showed decreasing trend. As KG addition increased by 60%, pH, TA, TAN and FAN decreased by 6%, 16%, 22% and 75%, respectively. FAN and Na+ respectively were potential inhibitory chemicals that threatened the stability of the mono-system of DS and KG. In comparison with the mono-system of DS or KG, the co-system showed higher stability by diluting toxic chemicals like ammonia or Na+ to much lower levels. PMID:23487958

  7. [Influence of extracellular polymeric substance on enzyme hydrolysis of sludge under anaerobic condition].

    PubMed

    Chen, Wei; Jia, Yuan-Yuan; Zheng, Wei; Li, Xiao-Ming; Zhou, Jun; Yang, Qi; Luo, Kun

    2011-08-01

    The effect of extracellular polymeric substance (EPS) on the enzymatic solubilisation of sludge and the changes of chemical components was investigated. Sludge solubilization with and without EPS was studied in the enzymatic system, and in the normal system without enzyme addition, respectively. The result indicated that only EPS could be hydrolyzed when the enzyme addition less than 20 mg/g, while the cell lysis occurred significantly with the doses of enzymes increasing. Treatment with lysozyme for the original sludge was proved to have a higher hydrolysis efficiency, and the SCOD/TCOD rate reached up to 28.14%. And at the enzyme dosage of 60 mg/g, the VSS removal rate increased to 51.66% and the concentration of DNA attained 68.34 mg/g (calculated by VSS) after 48 h reaction, which were 29.01% and 59.63 mg/g higher than the control test, respectively, and were 24.86% and 53.39 mg/g higher than that with EPS removed in advance, respectively. Meanwhile, NH4+ -N, PO4(3-)-P and SCOD showed high dissolution efficiency, and the maximal concentrations achieved to 503 mg/L, 78.9 mg/L and 3171 mg/L, respectively. After removal of extracellular polymers, higher lysis efficiency was also observed by protease and cellulose, by which VSS reduction rate reached to 49.95% and 39.85%, respectively. The concentration of DNA showed a correlation coefficient of more than 0.9 with the concentrations of SCOD, NH4+ -N and PO4(3-)-P. And the highest hydrolysis rate obtained in 6 hours, which was about 3 hours earlier than the control test. Moreover, under those condition, sludge hydrolyzation could be well realized by only small amount of the enzyme addition. PMID:22619959

  8. Kinetics of Fe(II)-catalyzed transformation of 6-line ferrihydrite under anaerobic flow conditions

    SciTech Connect

    Yang, L.; Steefel, C.I.; Marcus, M.A.; Bargar, J.R.

    2010-04-01

    The readsorption of ferrous ions produced by the abiotic and microbially-mediated reductive dissolution of iron oxy-hydroxides drives a series of transformations of the host minerals. To further understand the mechanisms by which these transformations occur and their kinetics within a microporous flow environment, flow-through experiments were conducted in which capillary tubes packed with ferrihydrite-coated glass spheres were injected with inorganic Fe(II) solutions under circumneutral pH conditions at 25 C. Synchrotron X-ray diffraction was used to identify the secondary phase(s) formed and to provide data for quantitative kinetic analysis. At concentrations at and above 1.8 mM Fe(II) in the injection solution, magnetite was the only secondary phase formed (no intermediates were detected), with complete transformation following a nonlinear rate law requiring 28 hours and 150 hours of reaction at 18 and 1.8 mM Fe(II), respectively. However, when the injection solution consisted of 0.36 mM Fe(II), goethite was the predominant reaction product and formed much more slowly according to a linear rate law, while only minor magnetite was formed. When the rates are normalized based on the time to react half of the ferrihydrite on a reduced time plot, it is apparent that the 1.8 mM and 18 mM input Fe(II) experiments can be described by the same reaction mechanism, while the 0.36 input Fe(II) experiment is distinct. The analysis of the transformation kinetics suggest that the transformations involved an electron transfer reaction between the aqueous as well as sorbed Fe(II) and ferrihydrite acting as a semiconductor, rather than a simple dissolution and recrystallization mechanism. A transformation mechanism involving sorbed inner sphere Fe(II) alone is not supported, since the essentially equal coverage of sorption sites in the 18 mM and 1.8 mM Fe(II) injections cannot explain the difference in the transformation rates observed.

  9. Contribution of quinone-reducing microorganisms to the anaerobic biodegradation of organic compounds under different redox conditions.

    PubMed

    Cervantes, Francisco J; Gutiérrez, Claudia H; López, Kitzia Y; Estrada-Alvarado, María Isabel; Meza-Escalante, Edna R; Texier, Anne-Claire; Cuervo, Flor; Gómez, Jorge

    2008-04-01

    The capacity of two anaerobic consortia to oxidize different organic compounds, including acetate, propionate, lactate, phenol and p-cresol, in the presence of nitrate, sulfate and the humic model compound, anthraquinone-2,6-disulfonate (AQDS) as terminal electron acceptors, was evaluated. Denitrification showed the highest respiratory rates in both consortia studied and occurred exclusively during the first hours of incubation for most organic substrates degraded. Reduction of AQDS and sulfate generally started after complete denitrification, or even occurred at the same time during the biodegradation of p-cresol, in anaerobic sludge incubations; whereas methanogenesis did not significantly occur during the reduction of nitrate, sulfate, and AQDS. AQDS reduction was the preferred respiratory pathway over sulfate reduction and methanogenesis during the anaerobic oxidation of most organic substrates by the anaerobic sludge studied. In contrast, sulfate reduction out-competed AQDS reduction during incubations performed with anaerobic wetland sediment, which did not achieve any methanogenic activity. Propionate was a poor electron donor to achieve AQDS reduction; however, denitrifying and sulfate-reducing activities carried out by both consortia promoted the reduction of AQDS via acetate accumulated from propionate oxidation. Our results suggest that microbial reduction of humic substances (HS) may play an important role during the anaerobic oxidation of organic pollutants in anaerobic environments despite the presence of alternative electron acceptors, such as sulfate and nitrate. Methane inhibition, imposed by the inclusion of AQDS as terminal electron acceptor, suggests that microbial reduction of HS may also have important implications on the global climate preservation, considering the green-house effects of methane. PMID:17534721

  10. APOLLO 10: Improvments in Living Conditions

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Living conditions were superior on this flight to any previously. From the film documentary 'APOLLO 10: 'Green Light for a Lunar Landing''. Part of a documentary series made in the early 70's on the APOLLO missions, and narrated by Burgess Meredith. (Actual date created is not known at this time) APOLLO 10: Manned lunar orbital flight with Thomas P Stafford, John W. Young, and Eugene A. Cernan to test all aspects of an actual manned lunar landing except the landing. Mission Duration 192hrs 3mins 23 sec

  11. Anaerobic fermentation of agricultural residue: potential for improvement and implementation. Final report, Volume II

    SciTech Connect

    Jewell, W. J.; Dell'orto, S.; Fanfoni, K. J.; Hayes, T. D.; Leuschner, A. P.; Sherman, D. F.

    1980-04-01

    Earlier studies have shown that although large quantities of agricultural residues are generated on small farms, it was difficult to economically justify use of conventional anaerobic digestion technology, such as used for sewage sludge digestion. A simple, unmixed, earthen-supported structure appeared to be capable of producing significant quantities of biogas at a cost that would make it competitive with many existing fuels. The goal of this study was to define and demonstrate a methane fermentation technology that could be practical and economically feasible on small farms. This study provides the first long term, large scale (reactor volumes of 34 m/sup 3/) parallel testing of the major theory, design, construction, and operation of a low cost approach to animal manure fermentation as compared to the more costly and complex designs. The main objectives were to define the lower limits for successful fermentor operation in terms of mixing, insulation, temperature, feed rate, and management requirements in a cold climate with both pilot scale and full scale fermentors. Over a period of four years, innovative fermentation processes for animal manures were developed from theoretical concept to successful full scale demonstration. Reactors were sized for 50 to 65 dairy animals, or for the one-family dairy size. The results show that a small farm biogas generation system that should be widely applicable and economically feasible was operated successfully for nearly two years. Although this low cost system out-performed the completely mixed unit throughout the study, perhaps the greatest advantage of this approach is its ease of modification, operation, and maintenance.

  12. Hydrogen Photoproduction by Nutrient-Deprived Chalamydomonas reinhardtii Cells Immobilized Within Thin Alginate Films Under Aerobic and Anaerobic Conditions

    SciTech Connect

    Kosourov, S. N.; Seibert, M.

    2009-01-01

    A new technique for immobilizing H{sub 2}-photoproducing green algae within a thin (<400 {micro}m) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 {micro}g Chl mL{sup -1} of matrix), (b) kinetics of H{sub 2} photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 {micro}mol mg{sup -1} Chl h{sup -1}) of H{sub 2} evolution, (d) light conversion efficiencies to H{sub 2} of over 1% and (e) unexpectedly high resistance of the H{sub 2}-photoproducing system to inactivation by atmospheric O{sub 2}. The algal cells, entrapped in alginate and then placed in vials containing 21% O{sub 2} in the headspace, evolved up to 67% of the H{sub 2} gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H{sub 2}-producing system to inactivation by O{sub 2} depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O{sub 2} in the liquid and headspace and restrict O{sub 2} diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications.

  13. Performance evaluation of a completely stirred anaerobic reactor treating pig manure at a low range of mesophilic conditions

    SciTech Connect

    Guo, Jianbin; Dong, Renjie; Clemens, Joachim; Wang, Wei

    2013-11-15

    Highlights: • The biogas process can run stably at 20 °C at extremely low OLR after long-term acclimation of bacteria. • A biogas plant running at 28 °C seems as efficient as that operated at 38 °C at low OLR of 1.3 g ODM L{sup −1} d{sup −1}. • Lower temperature operation is inadvisable for the commercial biogas plant running at rather high OLR. • The estimated sludge yield at 28 °C is higher than that at 38 °C. - Abstract: Many Chinese biogas plants run in the lower range of mesophilic conditions. This study evaluated the performance of a completely stirred anaerobic reactor treating pig manure at different temperatures (20, 28 and 38 °C). The start-up phase of the reactor at 20 °C was very long and extremely poor performance was observed with increasing organic loading rate (OLR). At an OLR of 4.3 g ODM L{sup −1} d{sup −1}, methane production at 28 °C was comparable (3% less) with that at 38 °C, but the risk of acidification was high at 28 °C. At low OLR (1.3 g ODM L{sup −1} d{sup −1}), the biogas process appeared stable at 28 °C and gave same methane yields as compared to the reactor operating at 38 °C. The estimated sludge yield at 28 °C was 0.065 g VSS g{sup −1} COD{sub removed,} which was higher than that at 38 °C (0.016 g VSS g{sup −1} COD{sub removed})

  14. Anaerobic thermophilic bacteria isolated from a Venezuelan oil field and its potential use in microbial improved oil recovery

    SciTech Connect

    Trebbau, G.; Fernandez, B.; Marin, A.

    1995-12-31

    The objective of this work is to determine the ability of indigenous bacteria from a Venezuelan oil field to grow under reservoir conditions inside a porous media, and to produce metabolites capable of recovering residual crude oil. For this purpose, samples of formation waters from a central-eastern Venezuelan oil reservoir were enriched with different carbon sources and a mineral basal media. Formation water was used as a source of trace metals. The enrichments obtained were incubated at reservoir temperature (71{degrees}C), reservoir pressure (1,200 psi), and under anaerobic conditions for both outside and inside porous media (Berea core). Growth and metabolic activity was followed outside porous media by measuring absorbance at 660 nm, increases in pressure, and decreases in pH. Inside porous media bacterial activity was determined by visual examination of the produced waters (gas bubbles and bacterial cells). All the carbohydrates tested outside porous media showed good growth at reservoir conditions. The pH was lowered, gases such as CO{sub 2} and CH{sub 4} were identified by GC. Surface tension was lowered in some enrichments by 30% when compared to controls. Growth was decreased inside porous media, but gases were produced and helped displace oil. In addition, 10% residual oil was recovered from the Berea core. Mathematical modeling was applied to the laboratory coreflood experiment to evaluate the reproducibility of the results obtained.

  15. Anaerobic Thermophiles

    PubMed Central

    Canganella, Francesco; Wiegel, Juergen

    2014-01-01

    The term “extremophile” was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of “extreme” environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally “hot environments” on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has

  16. Anaerobic thermophiles.

    PubMed

    Canganella, Francesco; Wiegel, Juergen

    2014-01-01

    The term "extremophile" was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of "extreme" environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally "hot environments" on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has definitely

  17. Anaerobic digestate from biogas production as a resource for improving soil fertility: effects on crop yield and soil properties

    NASA Astrophysics Data System (ADS)

    Pastorelli, Roberta; Lagomarsino, Alessandra; Vignozzi, Nadia; Valboa, Giuseppe; Papini, Rossella; Fabiani, Arturo; Simoncini, Stefania; Mocali, Stefano; Piccolo, Raimondo

    2013-04-01

    Soil fertility is fundamental in determining crops productivity in all farming systems. Production of biogas through anaerobic digestion of energy crops generates residues that can represent a valuable resource to sustain and improve soil fertility and to increase soil organic matter content. Residues from anaerobic digestion contain organic fractions and available nutrients, that can thus be returned to the cultivation soil as fertilizer and soil conditioner. However, some unknown aspects of digested residues utilization remain to explore: i) the nutrient supply and the real potential for mineral fertilization substitution, ii) the impact on the structure and functioning of soil microbial communities, iii) the direct and indirect effects on soil structure, organic matter and C mineralization. The aim of the present research was to gain a better understanding of these aspects, evaluating the effects of anaerobic digestate application on soil properties and maize yield. With the main focus of comparing mineral fertilization (250 Kg N ha-1) with digested residues addition (at the dose of 25 % and 50 % of mineral fertilizer), a triplicate sets of plots were designed in a field experiment on a silty-clay loam soil in the southern Po Valley (Italy). The amount of applied residues was calculated according to its N content in order to fertilizer each plots with the same amount of total nitrogen. Residues from digestion showed a N content of 0.4 % (60 % as N-NH4) and a C/N ratio of 3. Changes in soil quality after residues application were studied with a holistic approach, involving microbiological, physical and chemical aspects of soil fertility. In particular, we determined: the abundance and diversity of bacterial and fungal soil communities; the soil organic matter content, its distribution within soil aggregates and the C mineralization potential; cation exchange capacity; the main macro and micro nutrients; bulk density; aggregate stability. No significant

  18. Decrease of U(VI) immobilization capability of the facultative anaerobic strain Paenibacillus sp. JG-TB8 under anoxic conditions due to strongly reduced phosphatase activity.

    PubMed

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2014-01-01

    Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

  19. Decrease of U(VI) Immobilization Capability of the Facultative Anaerobic Strain Paenibacillus sp. JG-TB8 under Anoxic Conditions Due to Strongly Reduced Phosphatase Activity

    PubMed Central

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L.

    2014-01-01

    Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

  20. Effect of anaerobic soil disinfestation and vermicompost on soilborne phytopathogenic agents under tree-crop nursery conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD) is a fumigation-independent management strategy for controlling soilborne pathogens. Walnut nurseries currently employ preplant fumigation to control soilborne phytopathogens and weeds, and may be amenable to use ASD instead. We investigated the potential of ASD a...

  1. Inspiratory muscle training improves cycling time-trial performance and anaerobic work capacity but not critical power.

    PubMed

    Johnson, Michael A; Sharpe, Graham R; Brown, Peter I

    2007-12-01

    We examined whether inspiratory muscle training (IMT) improved cycling time-trial performance and changed the relationship between limit work (W (lim)) and limit time (T (lim)), which is described by the parameters critical power (CP) and anaerobic work capacity (AWC). Eighteen male cyclists were assigned to either a pressure-threshold IMT or sham hypoxic-training placebo (PLC) group. Prior to and following a 6 week intervention subjects completed a 25-km cycling time-trial and three constant-power tests to establish the W (lim)-T (lim) relationship. Constant-power tests were prescribed to elicit exercise intolerance within 3-10 (Ex1), 10-20 (Ex2), and 20-30 (Ex3) min. Maximal inspiratory mouth pressure increased by (mean +/- SD) 17.1 +/- 12.2% following IMT (P < 0.01) and was accompanied by a 2.66 +/- 2.51% improvement in 25-km time-trial performance (P < 0.05); there were no changes following PLC. Constant-power cycling endurance was unchanged following PLC, as was CP (pre vs. post: 249 +/- 32 vs. 250 +/- 32 W) and AWC (30.7 +/- 12.7 vs. 30.1 +/- 12.5 kJ). Following IMT Ex1 and Ex3 cycling endurance improved by 18.3 +/- 15.1 and 15.3 +/- 19.1% (P < 0.05), respectively, CP was unchanged (264 +/- 62 vs. 263 +/- 61 W), but AWC increased from 24.8 +/- 5.6 to 29.0 +/- 8.4 kJ (P < 0.05). In conclusion, these data provide novel evidence that improvements in constant-power and cycling time-trial performance following IMT in cyclists may be explained, in part, by an increase in AWC. PMID:17874123

  2. Biochemical and Structural Studies of NADH-Dependent FabG Used To Increase the Bacterial Production of Fatty Acids under Anaerobic Conditions

    PubMed Central

    Javidpour, Pouya; Pereira, Jose H.; Goh, Ee-Been; McAndrew, Ryan P.; Ma, Suzanne M.; Friedland, Gregory D.; Keasling, Jay D.; Chhabra, Swapnil R.; Adams, Paul D.

    2014-01-01

    Major efforts in bioenergy research have focused on producing fuels that can directly replace petroleum-derived gasoline and diesel fuel through metabolic engineering of microbial fatty acid biosynthetic pathways. Typically, growth and pathway induction are conducted under aerobic conditions, but for operational efficiency in an industrial context, anaerobic culture conditions would be preferred to obviate the need to maintain specific dissolved oxygen concentrations and to maximize the proportion of reducing equivalents directed to biofuel biosynthesis rather than ATP production. A major concern with fermentative growth conditions is elevated NADH levels, which can adversely affect cell physiology. The purpose of this study was to identify homologs of Escherichia coli FabG, an essential reductase involved in fatty acid biosynthesis, that display a higher preference for NADH than for NADPH as a cofactor. Four potential NADH-dependent FabG variants were identified through bioinformatic analyses supported by crystallographic structure determination (1.3- to 2.0-Å resolution). In vitro assays of cofactor (NADH/NADPH) preference in the four variants showed up to ∼35-fold preference for NADH, which was observed with the Cupriavidus taiwanensis FabG variant. In addition, FabG homologs were overexpressed in fatty acid- and methyl ketone-overproducing E. coli host strains under anaerobic conditions, and the C. taiwanensis variant led to a 60% higher free fatty acid titer and 75% higher methyl ketone titer relative to the titers of the control strains. With further engineering, this work could serve as a starting point for establishing a microbial host strain for production of fatty acid-derived biofuels (e.g., methyl ketones) under anaerobic conditions. PMID:24212572

  3. Biochemical and structural studies of NADH-dependent FabG used to increase the bacterial production of fatty acids under anaerobic conditions.

    PubMed

    Javidpour, Pouya; Pereira, Jose H; Goh, Ee-Been; McAndrew, Ryan P; Ma, Suzanne M; Friedland, Gregory D; Keasling, Jay D; Chhabra, Swapnil R; Adams, Paul D; Beller, Harry R

    2014-01-01

    Major efforts in bioenergy research have focused on producing fuels that can directly replace petroleum-derived gasoline and diesel fuel through metabolic engineering of microbial fatty acid biosynthetic pathways. Typically, growth and pathway induction are conducted under aerobic conditions, but for operational efficiency in an industrial context, anaerobic culture conditions would be preferred to obviate the need to maintain specific dissolved oxygen concentrations and to maximize the proportion of reducing equivalents directed to biofuel biosynthesis rather than ATP production. A major concern with fermentative growth conditions is elevated NADH levels, which can adversely affect cell physiology. The purpose of this study was to identify homologs of Escherichia coli FabG, an essential reductase involved in fatty acid biosynthesis, that display a higher preference for NADH than for NADPH as a cofactor. Four potential NADH-dependent FabG variants were identified through bioinformatic analyses supported by crystallographic structure determination (1.3- to 2.0-Å resolution). In vitro assays of cofactor (NADH/NADPH) preference in the four variants showed up to ≈ 35-fold preference for NADH, which was observed with the Cupriavidus taiwanensis FabG variant. In addition, FabG homologs were overexpressed in fatty acid- and methyl ketone-overproducing E. coli host strains under anaerobic conditions, and the C. taiwanensis variant led to a 60% higher free fatty acid titer and 75% higher methyl ketone titer relative to the titers of the control strains. With further engineering, this work could serve as a starting point for establishing a microbial host strain for production of fatty acid-derived biofuels (e.g., methyl ketones) under anaerobic conditions. PMID:24212572

  4. Improved volatile fatty acids anaerobic production from waste activated sludge by pH regulation: Alkaline or neutral pH?

    PubMed

    Ma, Huijun; Chen, Xingchun; Liu, He; Liu, Hongbo; Fu, Bo

    2016-02-01

    In this study, the anaerobic fermentation was carried out for volatile fatty acids (VFAs) production at different pH (between 7.0 and 10.0) conditions with untreated sludge and heat-alkaline pretreated waste activated sludge. In the fermentation with untreated sludge, the extent of hydrolysis of organic matters and extent of acidification at alkaline pH are 54.37% and 30.37%, respectively, resulting in the highest VFAs yield at 235.46mg COD/gVS of three pH conditions. In the fermentation with heat-alkaline pretreated sludge, the acidification rate and VFAs yield at neutral pH are 30.98% and 240.14mg COD/gVS, respectively, which are higher than that at other pH conditions. With the glucose or bovine serum albumin as substrate for VFAs production, the neutral pH showed a higher VFAs concentration than the alkaline pH condition. The results of terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the alkaline pH caused low microbial richness. Based on the results in this study, we demonstrated that the alkaline pH is favor of hydrolysis of organic matter in sludge while neutral pH improved the acidogenesis for the VFAs production from sludge. Our finding is obvious different to the previous research and helpful for the understanding of how heat-alkaline pretreatment and alkaline fermentation influence the VFAs production, and beneficial to the development of VFAs production process. PMID:26652215

  5. Use of an algal hydrolysate to improve enzymatic hydrolysis of anaerobically digested fiber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the use of acid hydrolyzed algae to enhance the enzymatic hydrolysis of cellulosic biomass. We first characterized wastewater-grown algal samples and determined the optimal conditions (acid concentration, reaction temperature, and reaction time) for algal hydrolysis using di...

  6. Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste.

    PubMed

    Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can

    2016-11-01

    Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5-8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect. PMID:27497086

  7. Biodegradation of polyacrylamide by anaerobic digestion under mesophilic condition and its performance in actual dewatered sludge system.

    PubMed

    Dai, Xiaohu; Luo, Fan; Yi, Jing; He, Qunbiao; Dong, Bin

    2014-02-01

    Polyacrylamide (PAM) used in sludge dewatering widely exists in high-solid anaerobic digestion. Degradation of polyacrylamide accompanied with accumulation of its toxic monomer is important to disposition of biogas residues. The potential of anaerobic digestion activity in microbial utilization of PAM was investigated in this study. The results indicated that the utilization rate of PAM (as nitrogen source) was influenced by accumulation of ammonia, while cumulative removal of amide group was accorded with zeroth order reaction in actual dewatered system. The adjoining amide group can combined into ether group after biodegradation. PAM can be broken down in different position of its carbon chain backbone. In actual sludge system, the hydrolytic PAM was liable to combined tyrosine-rich protein to form colloid complex, and then consumed as carbon source to form monomer when easily degradable organics were exhausted. The accumulation of acrylamide was leveled off ultimately, accompanied with the yield of methane. PMID:24345566

  8. Impact of high external circulation ratio on the performance of anaerobic reactor treating coal gasification wastewater under thermophilic condition.

    PubMed

    Jia, Shengyong; Han, Hongjun; Zhuang, Haifeng; Hou, Baolin; Li, Kun

    2015-09-01

    A laboratory-scale external circulation anaerobic reactor (ECAR) was developed to treat actual coal gasification wastewater. The external circulation ratio (R) was selected as the main operating variable for analysis. From the results, with the hydraulic retention time of 50h, pH > 8.0 and R of 3, the COD, total phenols, volatile phenol and NH4(+)-N removal efficiencies were remarkably increased to 10 ± 2%, 22 ± 5%, 18 ± 1%, and -1 ± 2%, respectively. Besides, increasing R resulted in more transformation from bound extracellular polymeric substances (EPS) to free EPS in the liquid and the particle size distribution of anaerobic granular sludge accumulated in the middle size range of 1.0-2.5mm. Results showed the genus Saccharofermentans dominanted in the ECAR and the bacterial community shift was observed at different external circulation ratio, influencing the pollutants removal profoundly. PMID:26081627

  9. Improvement of anaerobic digestion of sewage sludge in a wastewater treatment plant by means of mechanical and thermal pre-treatments: Performance, energy and economical assessment.

    PubMed

    Ruffino, Barbara; Campo, Giuseppe; Genon, Giuseppe; Lorenzi, Eugenio; Novarino, Daniel; Scibilia, Gerardo; Zanetti, Mariachiara

    2015-01-01

    Performances of mechanical and low-temperature (<100°C) thermal pre-treatments were investigated to improve the present efficiency of anaerobic digestion (AD) carried out on waste activated sludge (WAS) in the largest Italian wastewater treatment plant (2,300,000p.e.). Thermal pre-treatments returned disintegration rates of one order of magnitude higher than mechanical ones (about 25% vs. 1.5%). The methane specific production increased by 21% and 31%, with respect to untreated samples, for treatment conditions of respectively 70 and 90°C, 3h. Thermal pre-treatments also decreased WAS viscosity. Preliminary energy and economic assessments demonstrated that a WAS final total solid content of 5% was enough to avoid the employment of auxiliary methane for the pre-treatment at 90°C and the subsequent AD process, provided that all the heat generated was transferred to WAS through heat exchangers. Moreover, the total revenues from sale of the electricity produced from biogas increased by 10% with respect to the present scenario. PMID:25459836

  10. Improved anaerobic digestion of a thermally pretreated mixture of physicochemical sludge; broiler excreta and sugar cane wastes (SCW): Effect on organic matter solubilization, biodegradability and bioenergy production.

    PubMed

    Nava-Valente, Noemí; Alvarado-Lassman, Alejandro; Nativitas-Sandoval, Liliana S; Mendez-Contreras, Juan M

    2016-01-01

    Thermal pretreatment effect of a mixture of organic wastes (physicochemical sludge, excreta of broiler chickens and sugarcane wastes (SCW)) in the solubilization and biodegradability organic matter as well as bioenergy production by anaerobic digestion was evaluated. Two different mixtures of physicochemical sludge, excreta of broiler chickens and SCW (70%, 15%, 15% and 60%, 20%, 20% of VS, respectively) were treated at different temperatures (80 °C, 85 °C and 90 °C) and contact time (30, 60 and 90 min). Results indicate that, organic matter solubilization degree increased from 1.14 to 6.56%; subsequently, in the anaerobic digestion process, an increase of 50% in the volatile solids removal and 10% in biogas production was observed, while, retention time decreased from 23 up to 9 days. The results obtained were similar to pilot-scale. In both experimental scales it showed that the synergy produced by the simultaneous anaerobic digestion of different substrates could increase bioenergy production up to 1.3 L bio g(-1) VS removed and 0.82 L CH4 g(-1) VS removed. The treatment conditions presented in this study allow for large residue quantities to be treated and large bioenergy quantities to be produced (10% higher than during conventional treatment) without increasing the anaerobic digester volume. PMID:26819145

  11. Improve the Anaerobic Biodegradability by Copretreatment of Thermal Alkali and Steam Explosion of Lignocellulosic Waste

    PubMed Central

    Siddhu, Muhammad Abdul Hanan; Li, Jianghao; Zhang, Jiafu; Huang, Yan; Wang, Wen; Chen, Chang; Liu, Guangqing

    2016-01-01

    Effective alteration of the recalcitrance properties like crystallization of cellulose, lignin shield, and interlinking of lignocellulosic biomass is an ideal way to utilize the full-scale potential for biofuel production. This study exhibited three different pretreatment effects to enhance the digestibility of corn stover (CS) for methane production. In this context, steam explosion (SE) and thermal potassium hydroxide (KOH-60°C) treated CS produced the maximal methane yield of 217.5 and 243.1 mL/gvs, which were 40.0% and 56.4% more than untreated CS (155.4 mL/gvs), respectively. Copretreatment of thermal potassium hydroxide and steam explosion (CPTPS) treated CS was highly significant among all treatments and improved 88.46% (292.9 mL/gvs) methane yield compared with untreated CS. Besides, CPTPS also achieved the highest biodegradability up to 68.90%. Three kinetic models very well simulated dynamics of methane production yield. Moreover, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses declared the most effective changes in physicochemical properties after CPTPS pretreatment. Thus, CPTPS might be a promising approach to deconstructing the recalcitrance of lignocellulosic structure to improve the biodegradability for AD. PMID:27200370

  12. Improve the Anaerobic Biodegradability by Copretreatment of Thermal Alkali and Steam Explosion of Lignocellulosic Waste.

    PubMed

    Siddhu, Muhammad Abdul Hanan; Li, Jianghao; Zhang, Jiafu; Huang, Yan; Wang, Wen; Chen, Chang; Liu, Guangqing

    2016-01-01

    Effective alteration of the recalcitrance properties like crystallization of cellulose, lignin shield, and interlinking of lignocellulosic biomass is an ideal way to utilize the full-scale potential for biofuel production. This study exhibited three different pretreatment effects to enhance the digestibility of corn stover (CS) for methane production. In this context, steam explosion (SE) and thermal potassium hydroxide (KOH-60°C) treated CS produced the maximal methane yield of 217.5 and 243.1 mL/gvs, which were 40.0% and 56.4% more than untreated CS (155.4 mL/gvs), respectively. Copretreatment of thermal potassium hydroxide and steam explosion (CPTPS) treated CS was highly significant among all treatments and improved 88.46% (292.9 mL/gvs) methane yield compared with untreated CS. Besides, CPTPS also achieved the highest biodegradability up to 68.90%. Three kinetic models very well simulated dynamics of methane production yield. Moreover, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses declared the most effective changes in physicochemical properties after CPTPS pretreatment. Thus, CPTPS might be a promising approach to deconstructing the recalcitrance of lignocellulosic structure to improve the biodegradability for AD. PMID:27200370

  13. Improving volatile fatty acid yield from sludge anaerobic fermentation through self-forming dynamic membrane separation.

    PubMed

    Liu, Hongbo; Wang, Yuanyuan; Yin, Bo; Zhu, Yanfang; Fu, Bo; Liu, He

    2016-10-01

    Self-forming dynamic membrane (SFDM) separation was applied to the conventional sludge fermenter for improving VFA yields. Results indicated SFDM presented good performance in transferring products, retaining substrates, and enriching useful bacteria. The retention ratios of suspended solids, soluble COD, proteins, and polysaccharides reached 99%, 30%, 70%, and 40%, respectively, and more than 90% of the VFAs and ammonia could be transferred in a timely manner. The structure of the microbial community was optimized, which led to enhanced releases of hydrolytic enzymes and accelerated enrichments of functional bacteria. Protease and β-glucosidase activities increased from 1.0 to 5.0U/mL and 15.0 to 23.0μmol/L·h, respectively. VFA yield and sludge conversion ratio increased by 233.3% and 227.9%, respectively. Moreover, SFDM had good operation stability, including a short formation time, a long operation period, and a low transmembrane pressure. These results show VFA yield from sludge fermentation can be greatly improved by SFDM separation. PMID:27347803

  14. Positive feedback of crop residue incorporation on dissolved organic carbon contents under anaerobic conditions in temperate rice paddy soils

    NASA Astrophysics Data System (ADS)

    Said-Pullicino, Daniel; Sodano, Marcella; Bertora, Chiara; Lerda, Cristina; Sacco, Dario; Celi, Luisella

    2016-04-01

    Rice paddy soils are generally characterized by large concentrations and fluxes of DOC in comparison to other ecosystems. Our recent studies have shown that the combination of relatively high pore-water DOC concentrations under anoxic soil conditions (>10-20 mg C l‑1) and important percolation fluxes of water during field flooding may contribute significant organic C inputs into the subsoil (18-51 g C m‑2) over the cropping season. Crop residues incorporated into the soil after harvest represent the main input of organic C into paddy soils, returning about 200-300 g C m‑2 y‑1 in single-cropped rice paddies. The anaerobic decomposition of these residues may supply important amounts of DOC to soil pore waters. Moreover, the supply of electron donors with the input of residue-derived labile OM may further increase DOC contents by stimulating the microbially-catalyzed reductive dissolution of Fe and Mn oxyhydroxides under anoxic conditions, and release of DOC previously stabilized on the mineral matrix (i.e. positive feedback). This could have important implications on organic C inputs into the subsoil as well as substrate availability for methane production. We therefore hypothesized that crop residue management practices that influence the amount of labile organic matter present in the soil at the time of field flooding may strongly influence soil solution DOC concentrations as well as the positive feedback on the release of soil-derived DOC. We tested this hypothesis at field-scale by evaluating variations in the contents and quality of DOC above and beneath the plough pan over the cropping season as a function of crop residue management practices involving: tillage and crop residue incorporation in spring (SPR), tillage and crop residue incorporation in spring, dry seeding and 1 month delayed flooding (DRY), tillage and crop residue incorporation in autumn (AUT), and straw removal after harvest and tillage in spring (REM). Moreover, we linked changes in DOC

  15. The anaerobic co-digestion of sheep bedding and ⩾ 50% cattle manure increases biogas production and improves biofertilizer quality.

    PubMed

    Cestonaro, Taiana; Costa, Mônica Sarolli Silva de Mendonça; Costa, Luiz Antônio de Mendonça; Rozatti, Marcos Antonio Teofilo; Pereira, Dercio Ceri; Lorin, Higor Eisten Francisconi; Carneiro, Leocir José

    2015-12-01

    Sheep manure pellets are peculiarly shaped as small 'capsules' of limited permeability and thus are difficult to degrade. Fragmentation of manure pellets into a homogeneous mass is important for decomposition by microorganisms, and occurs naturally by physical shearing due to animal trampling, when sheep bedding is used. However, the high lignocellulose content of sheep bedding may limit decomposition of sheep manure. Here, we evaluated if co-digestion of sheep bedding with cattle manure would improve the yield and quality of the useful products of anaerobic digestion of sheep bedding--biogas and biofertilizer--by providing a source of nutrients and readily available carbon. Mixtures of sheep bedding and cattle manure in varying proportions (0%, 25%, 50%, 75%, or 100% cattle manure) were added to 6-L digesters, used in a batch system, and analyzed by uni and multivariate statistical tools. PC1, which explained 64.96% of data variability, can be referred to as 'organic fraction/productivity', because higher rates of organic fraction consumption (COD, cellulose and hemicellulose contents) led to higher digester productivity (biogas production, nutrient concentration, and sample stability changes). Therefore, productivity and organic fraction variables were most influenced by manure mixtures with higher (⩾ 50%) or lower (⩽ 25%) ratios of cattle manure, respectively. Increasing the amount of cattle manure up to 50% enhanced the biogas potential production from 142 L kg(-1)TS (0% of cattle manure) to 165, 171, 160 L biogas kg(-1)TS for the mixtures containing 100%, 75% and 50% of cattle manure, respectively. Our results show that the addition of ⩾ 50% cattle manure to the mixture increases biogas production and improves the quality of the final biofertilizer. PMID:26341827

  16. Ecoengineering high rate anaerobic digestion systems: analysis of improved syntrophic biomethanation catalysts.

    PubMed

    Thiele, J H; Wu, W M; Jain, M K; Zeikus, J G

    1990-04-25

    High performance biomethanation granules with operational specific COD removal rates of 7 kg COD removed/kg SS/d were obtained by ecoengineering conventional, granular, UASB digester sludge using a designed protocol of starvation and selection on a defined volatile fatty acid (VFA) based mineral medium. Addition of low (0.15 mM) sulfate levels to this VFA medium increased the maximum shock-load COD removal rate of the ecoengineered biomethanation granules to 9 kg COD/kg SS/d with specific acetate, propionate, and butyrate removal rates of 111, 28, and 64 mol/g SS/d. Addition of moderate (26 mM) calcium levels inhibited growth and altered the structure of granules. The general cellular, growth, stability, and performance features of these ecoengineered granules are described and discussed in relation to their use as improved biomethanation starter cultures. PMID:18588244

  17. Understanding the conditions for improvement: research to discover which context influences affect improvement success.

    PubMed

    Øvretveit, John

    2011-04-01

    Context can be defined as all factors that are not part of a quality improvement intervention itself. More research indicates which aspects are 'conditions for improvement', which influence improvement success. However, little is known about which conditions are most important, whether these are different for different quality interventions or whether some become less or more important at different times in carrying out an improvement. Knowing more about these conditions could help speed up and spread improvements and develop the science. This paper proposes ways to build knowledge about the conditions needed for different changes, and to create conditional-attribution explanations to provide qualified generalisations. It describes theory-based, non-experimental research designs. It also suggests that 'practical improvers' can make their changes more effective by reflecting on and revising their own 'assumption-theories' about the conditions which will help and hinder the improvements they aim to implement. PMID:21450764

  18. The effect of salinization and freshening events in coastal aquifers on nutrient characteristics as deduced from column experiments under aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Russak, A.; Sivan, O.; Herut, B.; Lazar, B.; Yechieli, Y.

    2015-10-01

    This study experimentally quantified the effect of seawater intrusion (salinization) and freshening events in coastal aquifers on nutrient (N, P and DSi) dynamics across the fresh-saline groundwater interface. Laboratory column experiments were conducted under aerobic and anaerobic conditions in order to simulate the processes occurring in the fresh-saline interface. They were performed with aquifer sediments, simulating the natural conditions during alterations of natural fresh groundwater to seawater and vice versa. The salinization and freshening experiments showed that NH4+ and PO43- and DSi were affected mainly by ion exchange processes while microbial activity controlled the nitrogen species NO3- and NO2-. Due to the cation exchange, salinization generated enrichment (above the expected conservative behavior) of NH4+, up to 80 μmol L-1 (an order of magnitude higher than in seawater or fresh groundwater). Under anaerobic conditions NO3- was removed by denitrification, as demonstrated by the decrease in NO3- concentrations, the increase in NO2- concentrations, and the increase in δ15N by 15-25‰. Clear evidence was shown for anion exchange of PO43-, which competes with HCO3- and boron on adsorption sites. DSi seems to take part in the exchange process, similar to PO43-.

  19. Anaerobic α-Amylase Production and Secretion with Fumarate as the Final Electron Acceptor in Saccharomyces cerevisiae

    PubMed Central

    Liu, Zihe; Österlund, Tobias; Hou, Jin; Petranovic, Dina

    2013-01-01

    In this study, we focus on production of heterologous α-amylase in the yeast Saccharomyces cerevisiae under anaerobic conditions. We compare the metabolic fluxes and transcriptional regulation under aerobic and anaerobic conditions, with the objective of identifying the final electron acceptor for protein folding under anaerobic conditions. We find that yeast produces more amylase under anaerobic conditions than under aerobic conditions, and we propose a model for electron transfer under anaerobic conditions. According to our model, during protein folding the electrons from the endoplasmic reticulum are transferred to fumarate as the final electron acceptor. This model is supported by findings that the addition of fumarate under anaerobic (but not aerobic) conditions improves cell growth, specifically in the α-amylase-producing strain, in which it is not used as a carbon source. Our results provide a model for the molecular mechanism of anaerobic protein secretion using fumarate as the final electron acceptor, which may allow for further engineering of yeast for improved protein secretion under anaerobic growth conditions. PMID:23435897

  20. Bioenergy production from diluted poultry manure and microbial consortium inside Anaerobic Sludge Bed Reactor at sub-mesophilic conditions.

    PubMed

    Jaxybayeva, Aigerim; Yangin-Gomec, Cigdem; Cetecioglu, Zeynep; Ozbayram, E Gozde; Yilmaz, Fatih; Ince, Orhan

    2014-01-01

    In this study, anaerobic treatability of diluted chicken manure (with an influent feed ratio of 1 kg of fresh chicken manure to 6 L of tap water) was investigated in a lab-scale anaerobic sludge bed (ASB) reactor inoculated with granular seed sludge. The ASB reactor was operated at ambient temperature (17-25°C) in order to avoid the need of external heating up to higher operating temperatures (e.g., up to 35°C for mesophilic digestion). Since heat requirement for raising the temperature of incoming feed for digestion is eliminated, energy recovery from anaerobic treatment of chicken manure could be realized with less operating costs. Average biogas production rates were calculated ca. 210 and 242 L per kg of organic matter removed from the ASB reactor at average hydraulic retention times (HRTs) of 13 and 8.6 days, respectively. Moreover, average chemical oxygen demand (COD) removal of ca. 89% was observed with suspended solids removal more than 97% from the effluent of the ASB reactor. Influent ammonia, on the other hand, did not indicate any free ammonia inhibition due to dilution of the raw manure while pH and alkalinity results showed stability during the study. Microbial quantification results indicated that as the number of bacterial community decreased, the amount of Archaea increased through the effective digestion volume of the ASB reactor. Moreover, the number of methanogens displayed an uptrend like archaeal community and a strong correlation (-0.645) was found between methanogenic community and volatile fatty acid (VFA) concentration especially acetate. PMID:25065830

  1. Biological sulfate reduction in the acidogenic phase of anaerobic digestion under dissimilatory Fe (III)--reducing conditions.

    PubMed

    Zhang, Jingxin; Zhang, Yaobin; Chang, Jinghui; Quan, Xie; Li, Qi

    2013-04-15

    In this study, a novel approach was developed for sulfate - containing wastewater treatment via dosing Fe₂O₃ in a two - stage anaerobic reactor (A1, S1). The addition of Fe₂O₃ in its second stage i.e. acidogenic sulfate-reducing reactor (S1) resulted in microbial reduction of Fe (III), which significantly enhanced the biological sulfate reduction. In reactor S1, increasing influent sulfate concentration to 1400 mg/L resulted in a higher COD removal (27.3%) and sulfate reduction (57.9%). In the reference reactor without using Fe₂O₃ (S2), the COD and sulfate removal were 15.6% and 29%, respectively. The combined performance of the two-stage anaerobic reactor (A1, S1) also showed a higher COD removal of 74.2%. Denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis showed that the dominant bacteria with high similarity to IRB species as well as sulfate reducer Desulfovibrio and acidogenic bacteria (AB) were enriched in S1. Quantitative Polymerase Chain Reaction (qPCR) analysis presented a higher proportion of sulfate reducer Desulfovibrio marrakechensis and Fe (III) reducer Iron-reducing bacteria HN54 in S1. PMID:23411038

  2. Methanogenic population dynamics and performance of an anaerobic membrane bioreactor (AnMBR) treating swine manure under high shear conditions.

    PubMed

    Padmasiri, Sudini I; Zhang, Jiangzhao; Fitch, Mark; Norddahl, Birgir; Morgenroth, Eberhard; Raskin, Lutgarde

    2007-01-01

    A 6-L, completely mixed anaerobic bioreactor with an external ultrafiltration membrane module was operated for 300 days to evaluate the startup and performance of an anaerobic membrane bioreactor (AnMBR) treating swine manure. The reactor had a successful startup at the initial loading rate of 1g volatile solids (VS)/L/day. After a two-fold increase in loading rate followed by a sudden, two-fold increase in flow velocity through the membrane module on day 75, the performance of the AnMBR deteriorated as measured by volatile fatty acid (VFA) accumulation, decrease in pH, and decrease in biogas production. The methanogenic population dynamics in the reactor were monitored with terminal restriction fragment length polymorphism (T-RFLP). Changes in the relative levels of Methanosarcinaceae and Methanosaetaceae were consistent with changes in VFA concentrations, i.e., high and low levels of acetate corresponded to a high abundance of Methanosarcinaceae and Methanosaetaceae, respectively. The levels of hydrogenotrophic methanogens of the order of Methanomicrobiales increased during decreased reactor performance suggesting that syntrophic interactions involving hydrogenotrophic methanogens remained intact regardless of the degree of shear in the AnMBR. PMID:17109913

  3. Factors controlling the rate of DDE dechlorination to DDMU in Palos Verdes margin sediments under anaerobic conditions.

    PubMed

    Quensen, J F; Tiedje, J M; Jain, M K; Mueller, S A

    2001-01-15

    Marine sediments off the coast of the Palos Verdes Peninsula in California have been designated a Superfund site primarily because of the presence of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethene]. For decades, it was believed that DDE was not microbially transformed, but anaerobic bacteria in the Palos Verdes sediments reductively dechlorinate DDEto DDMU [1-chloro-2,2-bis(p-chlorophenyl)ethene], which is also found in the sediments. The effects of electron donor to sulfate ratio, available carbon, sampling sites, sediment depth, and temperature on the rate and extent of DDE dechlorination in anaerobic Palos Verdes sediment microcosms were investigated. Dechlorination rates varied, depending on the site and depth from which the sediments were collected, but DDE dechlorination occurred with sediments from all locations studied. Sulfate and low temperatures slowed dechlorination, but in the presence of sulfate and at in situ temperature, the dechlorination rates observed in the microcosms agree well with the observed rate of DDE disappearance from the Palos Verdes margin sediments. PMID:11347599

  4. Understanding the conditions for improvement: research to discover which context influences affect improvement success

    PubMed Central

    2011-01-01

    Context can be defined as all factors that are not part of a quality improvement intervention itself. More research indicates which aspects are ‘conditions for improvement’, which influence improvement success. However, little is known about which conditions are most important, whether these are different for different quality interventions or whether some become less or more important at different times in carrying out an improvement. Knowing more about these conditions could help speed up and spread improvements and develop the science. This paper proposes ways to build knowledge about the conditions needed for different changes, and to create conditional-attribution explanations to provide qualified generalisations. It describes theory-based, non-experimental research designs. It also suggests that ‘practical improvers’ can make their changes more effective by reflecting on and revising their own ‘assumption-theories’ about the conditions which will help and hinder the improvements they aim to implement. PMID:21450764

  5. Anaerobic bacteria

    MedlinePlus

    Brook I, Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 297. Stedman's Online ...

  6. Effect of alkaline pretreatment on anaerobic digestion of solid wastes.

    PubMed

    López Torres, M; Espinosa Lloréns, Ma del C

    2008-11-01

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH)2), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH)2/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m3CH4/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW. PMID:18068345

  7. Effect of alkaline pretreatment on anaerobic digestion of solid wastes

    SciTech Connect

    Lopez Torres, M. Espinosa Llorens, Ma. del C.

    2008-11-15

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH){sub 2}), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH){sub 2}/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m{sup 3} CH{sub 4}/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW.

  8. Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

    PubMed Central

    Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

    2014-01-01

    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. PMID:24672798

  9. Characteristics, process parameters, and inner components of anaerobic bioreactors.

    PubMed

    Abdelgadir, Awad; Chen, Xiaoguang; Liu, Jianshe; Xie, Xuehui; Zhang, Jian; Zhang, Kai; Wang, Heng; Liu, Na

    2014-01-01

    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. PMID:24672798

  10. Random UV-C mutagenesis of Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 to improve anaerobic growth on lignocellulosic sugars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yeast strains for anaerobic conversion of lignocellulosic sugars to ethanol were produced from Scheffersomyces (formerly Pichia) stipitis NRRL Y-7124 using UV-C mutagenesis. Random UV-C mutagenesis potentially produces large numbers of mutations broadly and uniformly over the whole genome to genera...

  11. EFFECT OF NONCOLIFORMS ON COLIFORM DETECTION IN POTABLE GROUNDWATER: IMPROVED RECOVERY WITH AN ANAEROBIC MEMBRANE FILTER TECHNIQUE

    EPA Science Inventory

    A total of 529 well and distribution potable water samples were analyzed for total coliforms by the most-probable-number and membrane filter (MF) techniques. Standard plate count bacteria and MF noncoliform bacteria were also enumerated. This anaerobic modification of the standar...

  12. Improved Boundary Conditions for Cell-centered Difference Schemes

    NASA Technical Reports Server (NTRS)

    VanderWijngaart, Rob F.; Klopfer, Goetz H.; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    Cell-centered finite-volume (CCFV) schemes have certain attractive properties for the solution of the equations governing compressible fluid flow. Among others, they provide a natural vehicle for specifying flux conditions at the boundaries of the physical domain. Unfortunately, they lead to slow convergence for numerical programs utilizing them. In this report a method for investigating and improving the convergence of CCFV schemes is presented, which focuses on the effect of the numerical boundary conditions. The key to the method is the computation of the spectral radius of the iteration matrix of the entire demoralized system of equations, not just of the interior point scheme or the boundary conditions.

  13. Zymomonas with improved xylose utilization in stress conditions

    SciTech Connect

    Caimi, Perry G; Emptage, Mark; Li, Xu; Viitanen, Paul V; Chou, Yat-Chen; Franden, Mary Ann; Zhang, Min

    2013-06-18

    Strains of xylose utilizing Zymomonas with improved xylose utilization and ethanol production during fermentation in stress conditions were obtained using an adaptation method. The adaptation involved continuously growing xylose utilizing Zymomonas in media containing high sugars, acetic acid, ammonia, and ethanol.

  14. Anaerobic thermophilic culture system

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A mixed culture system of the newly discovered microorganism Thermoanaerobacter ethanolicus ATCC31550 and the microorganism Clostridium thermocellum ATCC31549 is described. In a mixed nutrient culture medium that contains cellulose, these microorganisms have been coupled and cultivated to efficiently ferment cellulose to produce recoverable quantities of ethanol under anaerobic, thermophilic conditions.

  15. Effect of feed to microbe ratios on anaerobic digestion of Chinese cabbage waste under mesophilic and thermophilic conditions: biogas potential and kinetic study.

    PubMed

    Kafle, Gopi Krishna; Bhattarai, Sujala; Kim, Sang Hun; Chen, Lide

    2014-01-15

    The objective of this study was to investigate the effect of the feed-to-microbe (F/M) ratios on anaerobic digestion of Chinese cabbage waste (CCW) generated from a kimchi factory. The batch test was conducted for 96 days under mesophilic (36.5 °C) (Experiment I) and thermophilic (55 °C) conditions (Experiment II) at F/M ratios of 0.5, 1.0 and 2.0. The first-order kinetic model was evaluated for methane yield. The biogas yield in terms of volatile solids (VS) added increased from 591 to 677 mL/g VS under mesophilic conditions and 434 to 639 mL/g VS under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. Similarly, the volumetric biogas production increased from 1.479 to 6.771 L/L under mesophilic conditions and from 1.086 to 6.384 L/L under thermophilic conditions when F/M ratio increased from 0.5 to 2.0. The VS removal increased from 59.4 to 75.6% under mesophilic conditions and from 63.5 to 78.3% under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The first-order kinetic constant (k, 1/day) decreased under the mesophilic temperature conditions and increased under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The difference between the experimental and predicted methane yield was in the range of 3.4-14.5% under mesophilic conditions and in the range of 1.1-3.0% under thermophilic conditions. The predicted methane yield derived from the first-order kinetic model was in good agreement with the experimental results. PMID:24412592

  16. Improved nitrogen removal in upflow anaerobic sludge blanket (UASB) reactors by incorporation of Anammox bacteria into the granular sludge.

    PubMed

    Schmidt, J E; Batstone, D J; Angelidaki, I

    2004-01-01

    Upflow anaerobic sludge blanket reactors may offer a number of advantages over conventional mixed-tank, SBR, and biofilm reactors, including high space-loading, low footprint, and resistance to shocks and toxins. In this study, we assessed the use of upflow anaerobic sludge blanket (UASB) reactor technology as applied to anaerobic ammonia removal, or Anammox. Four 200 ml UASB reactors were inoculated with 50% (by volume) anaerobic granular sludge and 50% flocular sludge from different sources (all with the potential for containing Anammox organisms). Tools used to assess the reactors included basic analyses, fluorescent in-situ hybridisation, and mathematical modelling, with statistical non-linear parameter estimation. Two of the reactors showed statistically identical Anammox activity (i.e., identical kinetic parameters), with good ammonia and nitrite removal (0.14 kgNHx m(-3) reactor day(-1), with 99% ammonia removal). The third reactor also demonstrated significant Anammox activity, but with poor identifiability of parameters. The fourth reactor had no statistical Anammox activity. Modelling indicated that poor identifiability and performance in the third and fourth reactors were related to an excess of reduced carbon, probably originating in the inoculum. Accumulation of Anammox organisms was confirmed both by a volume loading much lower than the growth rate, and response to a probe specific for organisms previously reported to mediate Anammox processes. Overall, the UASB reactors were effective as Anammox systems, and identifiability of the systems was good, and repeatable (even compared to a previous study in a rotating biological contactor). This indicates that operation, design, and analysis of Anammox UASB reactors specifically, and Anammox systems in general, are reliable and portable, and that UASB systems are an appropriate technology for this process. PMID:15303725

  17. Treatment of domestic wastewater by an integrated anaerobic fluidized-bed membrane bioreactor under moderate to low temperature conditions.

    PubMed

    Gao, Da-Wen; Hu, Qi; Yao, Chen; Ren, Nan-Qi

    2014-05-01

    The performance of a novel integrated anaerobic fluidized-bed membrane bioreactor (IAFMBR) for treating practical domestic wastewater was investigated at a step dropped temperature from 35, 25, to 15°C. The COD removal was 74.0 ± 3.7%, 67.1 ± 2.9% and 51.1 ± 2.6% at 35, 25 and 15°C, respectively. The COD removal depended both on influent strength and operational temperature. The accumulation of VFAs (Volatile Fatty Acids) was affected by temperature, and acetic acid was the most sensitive one to the decrease of temperature. The methanogenic activity of the sludge decreased eventually and the methane yield was dropped from 0.17 ± 0.03, 0.15 ± 0.02 to 0.10 ± 0.01 L/Ld. And as compared with a mesophilic temperature, a low temperature can accelerate membrane biofouling. Proteins were the dominant matters causing membrane fouling at low temperature and membrane fouling can be mitigated by granular active carbon (GAC) through protein absorption. PMID:24650533

  18. Performance and microbial community variations in thermophilic anaerobic digesters treating OTC medicated cow manure under different operational conditions.

    PubMed

    Akyol, Çağrı; Turker, Gokhan; Ince, Orhan; Ertekin, Emine; Üstüner, Oya; Ince, Bahar

    2016-04-01

    This study aimed to determine the fate and effect of oxytetracycline (OTC) and its metabolites during thermophilic anaerobic digestion of cow manure. OTC-medicated and non-medicated digesters were operated at 55°C with different volatile solids (VS) concentrations (4% and 6%) and mixing rates (90 and 120rpm). OTC and its metabolites were measured by HPLC and LC/MS/MS, respectively. Microbial community dynamics were monitored by denaturing gradient gel electrophoresis (DGGE) and real-time PCR (qPCR). Approximately 2mg/L initial OTC concentration caused 10-30% inhibition on biogas production and higher inhibition was observed as mixing rate increased. DGGE results indicated that OTC caused a shift in bacterial community structure and several species became dominant with time. Archaeal community decreased throughout the digestion period. RNA based qPCR analyses showed that gene copy numbers of bacteria and Methanomicrobiales declined in all digesters whereas gene copy numbers of Methanobacteriales and Methanosarcinales increased in high mixing rate digesters. PMID:26826959

  19. The use of laboratory scale reactors to predict sensitivity to changes in operating conditions for full-scale anaerobic digestion treating municipal sewage sludge.

    PubMed

    McLeod, James D; Othman, Maazuza Z; Beale, David J; Joshi, Deepak

    2015-01-01

    Anaerobic digestion of sewage sludge is highly complex and prone to inhibition, which can cause major issues for digester operators. The result is that there have been numerous investigations into changes in operational conditions, however to date all have focused on the qualitative sensitivities, neglecting the quantitative. This study therefore aimed to determine the quantitative sensitivities by using factorial design of experiments and small semi continuous reactors. Analysis showed total and volatile solids removals are chiefly influenced by retention time, with 79% and 59% of the observed results being attributed to retention time respectively, whereas biogas was mainly influenced by loading rate, 38%, and temperature, 22%. Notably the regression model fitted to the experimental data predicted full-scale performance with a high level of precision, indicating that small reactors are subject to the same sensitivity of full-scale digesters and thus can be used to predict changes loading, retention time, and temperature. PMID:25918031

  20. TM0486 from the hyperthermophilic anaerobe Thermotoga maritima is a thiamin binding protein involved in response of the cell to oxidative conditions

    PubMed Central

    Dermoun, Zorah; Foulon, Amélie; Miller, Mitchell D.; Harrington, Daniel J.; Deacon, Ashley M.; Sebban-Kreuzer, Corinne; Roche, Philippe; Lafitte, Daniel; Bornet, Olivier; Wilson, Ian A.; Dolla, Alain

    2010-01-01

    Using the COG database, a comparative genome analysis from anaerobic and aerobic microorganisms, was performed with the aim of identifying proteins specific to the anaerobic way of life. Thirty-three COGs were identified, five of which corresponded to proteins of unknown function. We focused our study on TM0486, from Thermotoga maritima, that belongs to one of these latter COGs of unknown function, namely COG0011. The crystal structure of the protein was determined at 2 Å resolution. The structure adopts a βαββαβ ferredoxin-like fold and assembles as a homotetramer. The structure also revealed the presence of a pocket in each monomer that bound an unidentified ligand NMR and calorimetric experiments revealed that TM0486 specifically bound thiamin with a Kd of 1.58 µM, but not hydroxymethyl pyrimidine (HMP), that was implicated previously as a potential ligand. We demonstrated that the TM0486 gene belongs to the same multicistronic unit as TM0483, TM0484 and TM0485. Although these three genes have already been assigned to the transport of HMP, with TM0484 being the periplasmic thiamin/HMP binding protein and TM0485 and TM0483 the transmembrane and the ATPase components, respectively, our results led us to conclude that this operon encodes for an ABC transporter dedicated to thiamin, with TM0486 transporting charged thiamin in the cytoplasm. Given that this transcriptional unit was up-regulated when T. maritima was exposed to oxidative conditions, we propose that by chelating cytoplasmic thiamin, TM0486 and, by extension, proteins belonging to COG0011 are involved in the response mechanism to stress that could arise during aerobic conditions. PMID:20471400

  1. PARAFFIN CONTROL IN OIL WELLS USING ANAEROBIC MICROORGANISMS

    EPA Science Inventory

    Enrichment and monitoring of the above-described cultures for the ability to degrade waxy paraffins under anaerobic conditions will continue. Experiments will be conducted to determine the nutritional requirements of some of the enrichment cultures to improve growth and deduce...

  2. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions.

    PubMed

    Yuan, Heyang; Miller, Jennifer H; Abu-Reesh, Ibrahim M; Pruden, Amy; He, Zhen

    2016-11-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1-2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R(2)=0.73) and ARGs vs. E. coli (R(2) ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. PMID:27450245

  3. Anaerobic Process.

    PubMed

    Li, Wei-Zun; Qian, Yang; Chang, Chein-Chi; Ju, Meiting

    2015-10-01

    A review of the literature published in 2014 on the focus of Anaerobic Process. It is divided into the following sections. •Pretreatment •Organic waste •multiple-stage co-digestion •Process Methodology and Technology. PMID:26420080

  4. Improved education in musculoskeletal conditions is necessary for all doctors.

    PubMed Central

    Akesson, Kristina; Dreinhöfer, Karsten E.; Woolf, A. D.

    2003-01-01

    It is likely that everyone will, at some time, suffer from a problem related to the musculoskeletal system, ranging from a very common problem such as osteoarthritis or back pain to severely disabling limb trauma or rheumatoid arthritis. Many musculoskeletal problems are chronic conditions. The most common symptoms are pain and disability, with an impact not only on individuals' quality of life but also, importantly, on people's ability to earn a living and be independent. It has been estimated that one in four consultations in primary care is caused by problems of the musculoskeletal system and that these conditions may account for up to 60% of all disability pensions. In contrast, teaching at undergraduate and graduate levels--and the resulting competence and confidence of many doctors--do not reflect the impact of these conditions on individuals and society. Many medical students do not have any clinical training in assessing patients with bone and joint problems. Under the umbrella of the Bone and Joint Decade 2000-2010, experts from all parts of the world with an interest in teaching have developed recommendations for an undergraduate curriculum to improve the teaching of musculoskeletal conditions in medical schools. The goal for each medical school should be a course in musculoskeletal medicine concentrating on clinical assessment, common outpatient musculoskeletal problems and recognition of emergencies. Improving competency in the management of musculoskeletal problems within primary care settings through improved education is the next aim, but there are needs for improvement for all professionals and at all levels within the health care system. PMID:14710510

  5. Anaerobic crystallization and initial X-ray diffraction data of biphenyl 2,3-dioxygenase from Burkholderia xenovorans LB400: addition of agarose improved the quality of the crystals

    PubMed Central

    Kumar, Pravindra; Gómez-Gil, Leticia; Mohammadi, Mahmood; Sylvestre, Michel; Eltis, Lindsay D.; Bolin, Jeffrey T.

    2011-01-01

    Biphenyl 2,3-dioxygenase (BPDO; EC 1.14.12.18) catalyzes the initial step in the degradation of biphenyl and some polychlorinated biphenyls (PCBs). BPDOLB400, the terminal dioxygenase component from Burkholderia xenovorans LB400, a proteobacterial species that degrades a broad range of PCBs, has been crystallized under anaerobic conditions by sitting-drop vapour diffusion. Initial crystals obtained using various polyethylene glycols as precipitating agents diffracted to very low resolution (∼8 Å) and the recorded reflections were diffuse and poorly shaped. The quality of the crystals was significantly improved by the addition of 0.2% agarose to the crystallization cocktail. In the presence of agarose, wild-type BPDOLB400 crystals that diffracted to 2.4 Å resolution grew in space group P1. Crystals of the BPDOP4 and BPDORR41 variants of BPDOLB400 grew in space group P21. PMID:21206025

  6. Biodegradability of leathers through anaerobic pathway.

    PubMed

    Dhayalan, K; Fathima, N Nishad; Gnanamani, A; Rao, J Raghava; Nair, B Unni; Ramasami, T

    2007-01-01

    Leather processing generates huge amounts of both solid and liquid wastes. The management of solid wastes, especially tanned leather waste, is a challenging problem faced by tanners. Hence, studies on biodegradability of leather become imperative. In this present work, biodegradability of untanned, chrome tanned and vegetable tanned leather under anaerobic conditions has been addressed. Two different sources of anaerobes have been used for this purpose. The effect of detanning as a pretreatment method before subjecting the leather to biodegradation has also been studied. It has been found that vegetable tanned leather leads to more gas production than chrome tanned leather. Mixed anaerobic isolates when employed as an inoculum are able to degrade the soluble organics of vegetable tanned material and thus exhibit an increased level of gas production during the initial days, compared to the results of the treatments that received the anaerobic sludge. With chrome tanned materials, there was not much change in the volume of the gas produced from the two different sources. It has been found that detanning tends to improve the biodegradability of both types of leathers. PMID:16740383

  7. Tetrahedral mesh improvement via optimization of the element condition number

    SciTech Connect

    FREITAG,LORI A.; KNUPP,PATRICK

    2000-05-22

    The authors present a new shape measure for tetrahedral elements that is optimal in that it gives the distance of a tetrahedron from the set of inverted elements. This measure is constructed from the condition number of the linear transformation between a unit equilateral tetrahedron and any tetrahedron with positive volume. Using this shape measure, they formulate two optimization objective functions that are differentiated by their goal: the first seeks to improve the average quality of the tetrahedral mesh; the second aims to improve the worst-quality element in the mesh. They review the optimization techniques used with each objective function and presents experimental results that demonstrate the effectiveness of the mesh improvement methods. They show that a combined optimization approach that uses both objective functions obtains the best-quality meshes for several complex geometries.

  8. Flue gas conditioning for improved particle collection in electrostatic precipitators

    SciTech Connect

    Durham, M.D.

    1992-04-27

    The purpose of this research program is to identify and evaluate a variety of additives capable of increasing particle cohesion which could be used for improving collection efficiency in an ESP. A three-phase screening process will be used to provide the, evaluation of many additives in a logical and cost-effective manner. The three step approach involves the following experimental setups: 1. Provide a preliminary screening in the laboratory by measuring the effects of various conditioning agents on reentrainment of flyash particles in an electric field operating at simulated flue gas conditions. 2. Evaluate the successful additives using a 100 acfm bench-scale ESP operating on actual flue gas. 3. Obtain the data required for scaling up the technology by testing the two or three most promising conditioning agents at the pilot scale.

  9. Proteomic, microarray, and signature-tagged mutagenesis analyses of anaerobic Pseudomonas aeruginosa at pH 6.5, likely representing chronic, late-stage cystic fibrosis airway conditions.

    PubMed

    Platt, Mark D; Schurr, Michael J; Sauer, Karin; Vazquez, Gustavo; Kukavica-Ibrulj, Irena; Potvin, Eric; Levesque, Roger C; Fedynak, Amber; Brinkman, Fiona S L; Schurr, Jill; Hwang, Sung-Hei; Lau, Gee W; Limbach, Patrick A; Rowe, John J; Lieberman, Michael A; Barraud, Nicolas; Webb, Jeremy; Kjelleberg, Staffan; Hunt, Donald F; Hassett, Daniel J

    2008-04-01

    Patients suffering from cystic fibrosis (CF) commonly harbor the important pathogen Pseudomonas aeruginosa in their airways. During chronic late-stage CF, P. aeruginosa is known to grow under reduced oxygen tension and is even capable of respiring anaerobically within the thickened airway mucus, at a pH of approximately 6.5. Therefore, proteins involved in anaerobic metabolism represent potentially important targets for therapeutic intervention. In this study, the clinically relevant "anaerobiome" or "proteogenome" of P. aeruginosa was assessed. First, two different proteomic approaches were used to identify proteins differentially expressed under anaerobic versus aerobic conditions. Microarray studies were also performed, and in general, the anaerobic transcriptome was in agreement with the proteomic results. However, we found that a major portion of the most upregulated genes in the presence of NO(3)(-) and NO(2)(-) are those encoding Pf1 bacteriophage. With anaerobic NO(2)(-), the most downregulated genes are those involved postglycolytically and include many tricarboxylic acid cycle genes and those involved in the electron transport chain, especially those encoding the NADH dehydrogenase I complex. Finally, a signature-tagged mutagenesis library of P. aeruginosa was constructed to further screen genes required for both NO(3)(-) and NO(2)(-) respiration. In addition to genes anticipated to play important roles in the anaerobiome (anr, dnr, nar, nir, and nuo), the cysG and dksA genes were found to be required for both anaerobic NO(3)(-) and NO(2)(-) respiration. This study represents a major step in unraveling the molecular machinery involved in anaerobic NO(3)(-) and NO(2)(-) respiration and offers clues as to how we might disrupt such pathways in P. aeruginosa to limit the growth of this important CF pathogen when it is either limited or completely restricted in its oxygen supply. PMID:18203836

  10. Anaerobic transformation of TNT

    SciTech Connect

    Kulpa, C.F.; Roopathy, R.

    1995-12-31

    Most studies on the microbial metabolism of nitroaromatic compounds have used aerobic tempts to degrade nitroaromatics under aerobic microorganisms. In many cases attempts to degrade nitroaromatics under aerobic conditions results in no mineralization and only superficial modifications of the structure. However, under anaerobic sulfate-reducing conditions, the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. Trinitrotoluene under sulfate-reducing conditions is reduced to triaminotoluene presumably by the enzyme nitrite reductase, which is commonly found in many Desulfovibrio spp. The removal of nitrate from trinitrotoluene is achieved by a series of reductive reactions with the production of ammonia and toluene by Desulfovibrio sp. (B strain). Similar metabolic processes could be applied to other nitroaromatic compounds like nitrobenzene, nitrobenzoic acids, nitrophenols, and aniline. This presentation will review the data supporting the anaerobic transformation of TNT and other nitroaromatics.

  11. Improving the transferability of hydrological model parameters under changing conditions

    NASA Astrophysics Data System (ADS)

    Huang, Yingchun; Bárdossy, András

    2014-05-01

    Hydrological models are widely utilized to describe catchment behaviors with observed hydro-meteorological data. Hydrological process may be considered as non-stationary under the changing climate and land use conditions. An applicable hydrological model should be able to capture the essential features of the target catchment and therefore be transferable to different conditions. At present, many model applications based on the stationary assumptions are not sufficient for predicting further changes or time variability. The aim of this study is to explore new model calibration methods in order to improve the transferability of model parameters. To cope with the instability of model parameters calibrated on catchments in non-stationary conditions, we investigate the idea of simultaneously calibration on streamflow records for the period with dissimilar climate characteristics. In additional, a weather based weighting function is implemented to adjust the calibration period to future trends. For regions with limited data and ungauged basins, the common calibration was applied by using information from similar catchments. Result shows the model performance and transfer quantity could be well improved via common calibration. This model calibration approach will be used to enhance regional water management and flood forecasting capabilities.

  12. PCB breakdown by anaerobic microorganisms

    SciTech Connect

    Not Available

    1989-03-01

    Recently, altered PCB cogener distribution patterns observed in anaerobic sediment samples from the upper Hudson River are being attributed to biologically mediated reductive dechlorination. The authors report their successful demonstration of biologically mediated reductive dechlorination of an Aroclor mixture. In their investigation, they assessed the ability of microorganisms from PCB-contaminated Hudson River sediments (60-562 ppm PCBs) to dechlorinate Aroclor 1242 under anaerobic conditions by eluting microorganisms from the PCB- contaminated sediments and transferring them to a slurry of reduced anaerobic mineral medium and PCB-free sediments in tightly stoppered bottles. They observed dechlorination to be the most rapid at the highest PCB concentration tried by them.

  13. Anaerobic sealing

    SciTech Connect

    Hayre, J.

    1986-05-01

    Anaerobic sealants offer an alternative to conventional methods of joint repair on mains operating at low and medium pressures. The method does not require highly skilled personnel who are diligent in ensuring that the necessary standards of preparation and seal application are achieved. British Gas' experience has shown that lead joints that do not contain yarn or where the yarn has deteriorated are difficult to seal. The evidence so far indicates that yarn is important in ensuring that the low viscosity sealant rapidly wicks around the joint during the injection operation. It is obvious that more research and development is needed in this field, but anaerobic sealing of leaking joints in an effective, innovative method of joint repair.

  14. Pulse-jet baghouse performance improvement with flue gas conditioning

    SciTech Connect

    Miller, S.J.; Laudal, D.L.

    1992-10-01

    A pilot study was conducted at the Energy and Environmental Research Center (EERC) at the University of North Dakota to evaluate the effectiveness of flue gas conditioning in reducing tube sheet pressure drop and fine particulate emissions from a pulse-jet fabric filter. The project was jointly funded by the US Department of Energy (DOE), the Electric Power Research Institute (EPRI), and the Canadian Electrical Association (CEA). The work was completed with EERC facilities consisting of a pulverized coal-fired combustor and pilot baghouse. Full-scale pulse-jet bags were employed under conditions similar to large-scale baghouses. The investigation included baseline tests and tests in which ammonia and SO[sub 3] were, injected upstream of the baghouse to determine the effect of conditioning on baghouse performance. The primary independent variables included coal type, conditioning agent concentrations, air-to-cloth (A/C) ratio, and fabric type. The main dependent variables were particulate emissions, bagbouse pressure drop, and cohesive properties of the fly ash. Results demonstrated significant benefits of using conditioning with a pulse-jet baghouse, including a substantial reduction in particulate emissions and a substantial reduction in pressure drop (or the ability to operate at a higher A/C ratio without increasing pressure drop or bag-cleaning frequency). The improvements in fabric filter performance correlate strongly with a shift in the tensile strength and with increases in the aerated and packed porosity of the fly ash. Conditioning appears to be applicable to a wide range of coals and fabrics. Applications for this technology are where there is a need to reduce pressure drop and/or particulate emissions in existing bagbouses, to reduce fine-particle air toxic emissions which may be required in the future, and for new bagbouse installations to allow operation at a higher A/C ratio while providing an ultrahigh fine-particle collection efficiency.

  15. Pulse-jet baghouse performance improvement with flue gas conditioning

    SciTech Connect

    Miller, S.J.; Laudal, D.L.

    1992-10-01

    A pilot study was conducted at the Energy and Environmental Research Center (EERC) at the University of North Dakota to evaluate the effectiveness of flue gas conditioning in reducing tube sheet pressure drop and fine particulate emissions from a pulse-jet fabric filter. The project was jointly funded by the US Department of Energy (DOE), the Electric Power Research Institute (EPRI), and the Canadian Electrical Association (CEA). The work was completed with EERC facilities consisting of a pulverized coal-fired combustor and pilot baghouse. Full-scale pulse-jet bags were employed under conditions similar to large-scale baghouses. The investigation included baseline tests and tests in which ammonia and SO{sub 3} were, injected upstream of the baghouse to determine the effect of conditioning on baghouse performance. The primary independent variables included coal type, conditioning agent concentrations, air-to-cloth (A/C) ratio, and fabric type. The main dependent variables were particulate emissions, bagbouse pressure drop, and cohesive properties of the fly ash. Results demonstrated significant benefits of using conditioning with a pulse-jet baghouse, including a substantial reduction in particulate emissions and a substantial reduction in pressure drop (or the ability to operate at a higher A/C ratio without increasing pressure drop or bag-cleaning frequency). The improvements in fabric filter performance correlate strongly with a shift in the tensile strength and with increases in the aerated and packed porosity of the fly ash. Conditioning appears to be applicable to a wide range of coals and fabrics. Applications for this technology are where there is a need to reduce pressure drop and/or particulate emissions in existing bagbouses, to reduce fine-particle air toxic emissions which may be required in the future, and for new bagbouse installations to allow operation at a higher A/C ratio while providing an ultrahigh fine-particle collection efficiency.

  16. Improvement in separation characteristics of protein precipitates by acoustic conditioning.

    PubMed

    Hoare, M; Titchener, N J; Foster, P R

    1987-01-01

    The effect of acoustic conditioning on the particle size distribution of isoelectric and calcium-ion-precipitated soya protein has been examined in low-residence-time chambers. In a previous study a beat frequency of 5 Hz obtained using a dual-source system of opposing vibrators was determined as giving optimal improvement in particle-settling characteristics for isoelectric soya protein precipitate. In this study the effect of amplitude of vibration, a measure of acoustic power input, and residence time of acoustic conditioning has been examined. Acoustic power input changed the flow pattern in the conditioning chamber from laminar streamline flow to a well-mixed, turbulent pattern. Such a mixing effect promoted the rapid aggregation of fine particles, a process that was modeled on the basis of orthokinetically controlled collisions. The rate of removal of fine particles due to acoustic conditioning was shown to be proportional to a mixing effect that was related to the acoustic power dissipated per unit volume. The consequences of fine-particle aggregation on the centrifugal recovery of the precipitate are discussed. PMID:18561125

  17. Activated sludge mass reduction and biodegradability of the endogenous residues by digestion under different aerobic to anaerobic conditions: Comparison and modeling.

    PubMed

    Martínez-García, C G; Fall, C; Olguín, M T

    2016-03-01

    This study was performed to identify suitable conditions for the in-situ reduction of excess sludge production by intercalated digesters in recycle-activated sludge (RAS) flow. The objective was to compare and model biological sludge mass reduction and the biodegradation of endogenous residues (XP) by digestion under hypoxic, aerobic, anaerobic, and five intermittent-aeration conditions. A mathematical model based on the heterotrophic endogenous decay constant (bH) and including the biodegradation of XP was used to fit the long-term data from the digesters to identify and estimate the parameters. Both the bH constant (0.02-0.05 d(-1)) and the endogenous residue biodegradation constant (bP, 0.001-0.004 d(-1)) were determined across the different mediums. The digesters with intermittent aeration cycles of 12 h-12 h and 5 min-3 h (ON/OFF) were the fastest, compared to the aerobic reactor. The study provides a basis for rating RAS-digester volumes to avoid the accumulation of XP in aeration tanks. PMID:26720137

  18. Anaerobic treatment of tequila vinasses under seasonal operating conditions: start-up, normal operation and restart-up after a long stop and starvation period.

    PubMed

    Jáuregui-Jáuregui, J A; Méndez-Acosta, H O; González-Álvarez, V; Snell-Castro, R; Alcaraz-González, V; Godon, J J

    2014-09-01

    This study examines the performance of an anaerobic fixed-film bioreactor under seasonal operating conditions prevailing in medium and small size Tequila factories: start-up, normal operation and particularly, during the restart-up after a long stop and starvation period. The proposed start-up procedure attained a stable biofilm in a rather short period (28 days) despite unbalanced COD/N/P ratio and the use of non-acclimated inoculum. The bioreactor was restarted-up after being shut down for 6 months during which the inoculum starved. Even when biofilm detachment and bioreactor clogging were detected at the very beginning of restart-up, results show that the bioreactor performed better as higher COD removal and methane yield were attained. CE-SSCP and Q-PCR analyses, conducted on the biofilm prokaryotic communities for each operating condition, confirmed that the high COD removal results after the bioreactor clogging and the severe starvation period were mainly due to the stable archaeal and resilient bacterial populations. PMID:24785790

  19. Methane production improvement by modulation of solid phase immersion in dry batch anaerobic digestion process: Dynamic of methanogen populations.

    PubMed

    André, L; Ndiaye, M; Pernier, M; Lespinard, O; Pauss, A; Lamy, E; Ribeiro, T

    2016-05-01

    Several 60L dry batch anaerobic digestion (AD) reactors were implemented with or without liquid reserve on cattle manure. The immersed part modulation of cattle manure increased the methane flow of about 13%. The quantitative real time PCR and the optimized DNA extraction were implemented and validated to characterize and quantify the methanogen dynamic in dry batch AD process. Final quantities of methanogens converged toward the same level in several inocula at the end of AD. Methanogen dynamic was shown by dominance of Methanosarcinaceae for acetotrophic methanogens and Methanobacteriales for the hydrogenotrophic methanogens. Overall, methanogens populations were stabilized in liquid phase, except Methanosaetaceae. Solid phase was colonized by Methanomicrobiales and Methanosarcinaceae populations giving a support to biofilm development. The methane increase could be explained by a raise of Methanosarcinaceae population in presence of a total contact between solid and liquid phases. Methanosarcinaceae was a bio-indicator of the methane production. PMID:26897414

  20. Microbial aerobic and anaerobic degradation of acrylamide in sludge and water under environmental conditions--case study in a sand and gravel quarry.

    PubMed

    Guezennec, A G; Michel, C; Ozturk, S; Togola, A; Guzzo, J; Desroche, N

    2015-05-01

    Polyacrylamides (PAMs) are used in sand and gravel quarries as water purification flocculants for recycling process water in a recycling loop system where the flocculants remove fine particles in the form of sludge. The PAM-based flocculants, however, contain residual amounts of acrylamide (AMD) that did not react during the polymerization process. This acrylamide is released into the environment when the sludge is discharged into a settling basin. Here, we explore the microbial diversity and the potential for AMD biodegradation in water and sludge samples collected in a quarry site submitted to low AMD concentrations. The microbial diversity, analyzed by culture-dependent methods and the denaturing gradient gel electrophoresis approach, reveals the presence of Proteobacteria, Cyanobacteria, and Actinobacteria, among which some species are known to have an AMD biodegradation activity. Results also show that the two main parts of the water recycling loop-the washing process and the settling basin-display significantly different bacterial profiles. The exposure time with residual AMD could, thus, be one of the parameters that lead to a selection of specific bacterial species. AMD degradation experiments with 0.5 g L(-1) AMD showed a high potential for biodegradation in all parts of the washing process, except the make-up water. The AMD biodegradation potential in samples collected from the washing process and settling basin was also analyzed taking into account on-site conditions: low (12 °C) and high (25 °C) temperatures reflecting the winter and summer seasons, and AMD concentrations of 50 μg L(-1). Batch tests showed rapid (as little as 18 h) AMD biodegradation under aerobic and anaerobic conditions at both the winter and summer temperatures, although there was a greater lag time before activity started with the AMD biodegradation at 12 °C. This study, thus, demonstrates that bacteria present in sludge and water samples exert an in situ and rapid

  1. Anaerobic Biodegradation Of Methyl tert-Butyl Ether Under Iron-Reducing Conditions In Batch And Continuous-Flow Cultures

    EPA Science Inventory

    The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing...

  2. Exercise conditioning in old mice improves skeletal muscle regeneration.

    PubMed

    Joanisse, Sophie; Nederveen, Joshua P; Baker, Jeff M; Snijders, Tim; Iacono, Carlo; Parise, Gianni

    2016-09-01

    Skeletal muscle possesses the ability to regenerate after injury, but this ability is impaired or delayed with aging. Regardless of age, muscle retains the ability to positively respond to stimuli, such as exercise. We examined whether exercise is able to improve regenerative response in skeletal muscle of aged mice. Twenty-two-month-old male C57Bl/6J mice (n = 20) underwent an 8-wk progressive exercise training protocol [old exercised (O-Ex) group]. An old sedentary (O-Sed) and a sedentary young control (Y-Ctl) group were included. Animals were subjected to injections of cardiotoxin into the tibialis anterior muscle. The tibialis anterior were harvested before [O-Ex/O-Sed/Y-Ctl control (CTL); n = 6], 10 d (O-Ex/O-Sed/Y-Ctl d 10; n = 8), and 28 d (O-Ex/O-Sed/Y-Ctl d 28; n = 6) postinjection. Average fiber cross-sectional area was reduced in all groups at d 10 (CTL: O-Ex: 2499 ± 140; O-Sed: 2320 ± 165; Y-Ctl: 2474 ± 269; d 10: O-Ex: 1191 ± 100; O-Sed: 1125 ± 99; Y-Ctl: 1481 ± 167 µm(2); P < 0.05), but was restored to control values in O-Ex and Y-Ctl groups at d 28 (O-Ex: 2257 ± 181; Y-Ctl: 2398 ± 171 µm(2); P > 0.05). Satellite cell content was greater at CTL in O-Ex (2.6 ± 0.4 satellite cells/100 fibers) compared with O-Sed (1.0 ± 0.1% satellite cells/100 fibers; P < 0.05). Exercise conditioning appears to improve ability of skeletal muscle to regenerate after injury in aged mice.-Joanisse, S., Nederveen, J. P., Baker, J. M., Snijders, T., Iacono, C., Parise, G. Exercise conditioning in old mice improves skeletal muscle regeneration. PMID:27306336

  3. Anaerobic digestion process

    SciTech Connect

    Ishida, M.; Haga, R.; Odawara, Y.

    1982-10-19

    An algae culture grown on the water from the digested slurry of a biogasification plant serves as a means of removing CO/sub 2/ from the methane stream while purifying the wastewater and providing more biomass for the anaerobic digestion plant. Tested on a sewage-sludge digestion system, the proposed process improved the methane yield by 32% and methane concentration by 53-98 vol % while lowering the concentration of nitrogen and phosphorus in the final water.

  4. Conditional BDNF release under pathological conditions improves Huntington's disease pathology by delaying neuronal dysfunction

    PubMed Central

    2011-01-01

    Background Brain-Derived Neurotrophic Factor (BDNF) is the main candidate for neuroprotective therapy for Huntington's disease (HD), but its conditional administration is one of its most challenging problems. Results Here we used transgenic mice that over-express BDNF under the control of the Glial Fibrillary Acidic Protein (GFAP) promoter (pGFAP-BDNF mice) to test whether up-regulation and release of BDNF, dependent on astrogliosis, could be protective in HD. Thus, we cross-mated pGFAP-BDNF mice with R6/2 mice to generate a double-mutant mouse with mutant huntingtin protein and with a conditional over-expression of BDNF, only under pathological conditions. In these R6/2:pGFAP-BDNF animals, the decrease in striatal BDNF levels induced by mutant huntingtin was prevented in comparison to R6/2 animals at 12 weeks of age. The recovery of the neurotrophin levels in R6/2:pGFAP-BDNF mice correlated with an improvement in several motor coordination tasks and with a significant delay in anxiety and clasping alterations. Therefore, we next examined a possible improvement in cortico-striatal connectivity in R62:pGFAP-BDNF mice. Interestingly, we found that the over-expression of BDNF prevented the decrease of cortico-striatal presynaptic (VGLUT1) and postsynaptic (PSD-95) markers in the R6/2:pGFAP-BDNF striatum. Electrophysiological studies also showed that basal synaptic transmission and synaptic fatigue both improved in R6/2:pGAP-BDNF mice. Conclusions These results indicate that the conditional administration of BDNF under the GFAP promoter could become a therapeutic strategy for HD due to its positive effects on synaptic plasticity. PMID:21985529

  5. Responses of Alnus glutinosa to anaerobic conditions--mechanisms and rate of oxygen flux into the roots.

    PubMed

    Dittert, K; Wötzel, J; Sattelmacher, B

    2006-03-01

    Upon exposure to waterlogged growing conditions two-year-old alder trees reduced total root mass. Roots were concentrated in the uppermost soil horizon, and only few coarse roots penetrated into deeper soil layers. Root porosity was only slightly affected and did not exceed 8 % in fine roots. Porosity of coarse roots was higher (27 %) but unaffected by growing conditions. The stem base area covered by lenticels increased strongly and so did the cross section diameter of the stem base. The latter showed a highly significant correlation with O (2) transport into the roots, measured by a Clark type oxygen electrode. Exposure of the lower 5 cm of the stem base, where lenticels were concentrated, to pure N (2) led to a cessation of O (2) transport, confirming that lenticels were the major site of air entry into the stem. In alder plants grown under waterlogged conditions, temperature had a pronounced effect on O (2) gas exchange of the root system. The temperature compensation point, i.e., the temperature where O (2) transport equals O (2) consumption by respiration, was 10.5 degrees C for the entire root system, when measured in a range of 0.15 - 0.20 mmol dissolved O (2) L (-1), which is typical for an open water surface equilibrated with air. O (2) net flow was inversely related to O (2) concentration in the rooting media, indicating that higher root and microbial respiration induced higher net fluxes of O (2) into the root system. With 0.04 mmol dissolved O (2) L (-1) nutrient solution, the temperature compensation point increased to 20 degrees C. Measurement of O (2) gradients in the rhizosphere of agar-embedded roots using O (2) microelectrodes showed a preference for O (2) release in the tip region of coarse roots. Increasing stem temperature over air temperature by 5 degrees C stimulated O (2) flux into the roots as suggested by the model of thermo-osmotic gas transport. However determination of stem and air temperature in a natural alder swamp in northern

  6. Anaerobic growth of Corynebacterium glutamicum via mixed-acid fermentation.

    PubMed

    Michel, Andrea; Koch-Koerfges, Abigail; Krumbach, Karin; Brocker, Melanie; Bott, Michael

    2015-11-01

    Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions. PMID:26276118

  7. Anaerobic Growth of Corynebacterium glutamicum via Mixed-Acid Fermentation

    PubMed Central

    Michel, Andrea; Koch-Koerfges, Abigail; Krumbach, Karin; Brocker, Melanie

    2015-01-01

    Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions. PMID:26276118

  8. Prokaryotic diversity and dynamics in a full-scale municipal solid waste anaerobic reactor from start-up to steady-state conditions.

    PubMed

    Cardinali-Rezende, Juliana; Colturato, Luís F D B; Colturato, Thiago D B; Chartone-Souza, Edmar; Nascimento, Andréa M A; Sanz, José L

    2012-09-01

    The prokaryotic diversity of an anaerobic reactor for the treatment of municipal solid waste was investigated over the course of 2 years with the use of 16S rDNA-targeted molecular approaches. The fermentative Bacteroidetes and Firmicutes predominated, and Proteobacteria, Actinobacteria, Tenericutes and the candidate division WWE1 were also identified. Methane production was dominated by the hydrogenotrophic Methanomicrobiales (Methanoculleus sp.) and their syntrophic association with acetate-utilizing and propionate-oxidizing bacteria. qPCR demonstrated the predominance of the hydrogenotrophic over aceticlastic Methanosarcinaceae (Methanosarcina sp. and Methanimicrococcus sp.), and Methanosaetaceae (Methanosaeta sp.) were measured in low numbers in the reactor. According to the FISH and CARD-FISH analyses, Bacteria and Archaea accounted for 85% and 15% of the cells, respectively. Different cell counts for these domains were obtained by qPCR versus FISH analyses. The use of several molecular tools increases our knowledge of the prokaryotic community dynamics from start-up to steady-state conditions in a full-scale MSW reactor. PMID:22750748

  9. Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

    SciTech Connect

    Mendes, Carlos Esquerre, Karla Matos Queiroz, Luciano

    2015-01-15

    Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m{sup 3} day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present study focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m{sup 3} day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge.

  10. In situ and laboratory studies on the fate of specific organic compounds in an anaerobic landfill leachate plume, 1. Experimental conditions and fate of phenolic compounds

    NASA Astrophysics Data System (ADS)

    Nielsen, Per H.; Albrechtsen, Hans-Jørgen; Heron, Gorm; Christensen, Thomas H.

    1995-11-01

    The transformation of specific organic compounds was investigated by in situ and laboratory experiments in an anaerobic landfill leachate pollution plume at four different distances from the landfill. This paper presents the experimental conditions in the in situ microcosm and laboratory batch microcosm experiments performed and the results on the fate of 7 phenolic compounds. Part 2 of this series of papers, also published in this issue, presents the results on the fate of 8 aromatic compounds and 4 chlorinated aliphatic compounds. The redox conditions in the plume were characterized as methanogenic, Fe(III)-reducing and NO 3--reducing by the redox sensitive species present in groundwater and sediment and by bioassays. With a few exceptions the aquifer redox conditions were maintained throughout the experiments as monitored by redox sensitive species present in groundwater during the experiments, by redox sensitive species present in the sediment after the experiments and by bioassays performed after the experiments. Transformation of nitrophenol was very fast close to the landfill in strongly reducing conditions, while transformation was slower in the more oxidized part of the plume. Lag phases for the nitrophenols were short (maximum 10 days). Phenol was only transformed in the more distant part of the plume in experiments where NO 3-, Fe(III) and Mn(IV) reduction was dominant. Lag phases for phenol were either absent or lasted up to 2 months. Dichlorophenols were only transformed in experiments representing strongly reducing, presumably methanogenic, redox conditions close to the landfill after lag phases of up to 3 months. Transformation of o-cresol was not observed in any of the experiments throughout the plume. Generally, there was good accordance between the results obtained by in situ and laboratory experiments, both concerning redox conditions and the fate of the phenolic compounds. However, for phenol and 2,4-dichlorophenol, transformation was observed

  11. Flue gas conditioning for improved particle collection in electrostatic precipitators

    SciTech Connect

    Durham, M.D.

    1993-01-15

    It is concluded that the laboratory tests should be conducted at high levels of SO[sub 3] such that the resulting resistivity is in the range of 10[sup 7]--10[sup 8] ohm-cm. There are several reasons leading to this conclusion. At SO[sub 3] concentrations of 30 ppM and greater, the curves for both dew point and resistivity are relatively flat so that changes in gas phase SO[sub 3] will have minimal impact on particle characteristics. In addition, the electrostatic forces are relatively flat in this range so that changes in flue gas conditions will that result in a change in resistivity by up to two orders of magnitude will have little effect on the magnitude of reentrainment. Finally, at the very low resistivity conditions, reentrainment will be the highest. Since the purpose of the laboratory resistivity tests is to determine the relative ability of the various additives to reduce resistivity, the greater the reentrainment, the easier it will be to measure an improvement. Tests were conducted by first operating at baseline conditions with no additives and then repeating the test with additives. The data collected during each test includes the resistivity of the material, thickness of the collected dust layer, and subjective indications of the dust characteristics. The candidate additives were from the polymer group, cellulose derivatives, starches and gums, and oils. No waxes or synthetic compounds have been tested to date in the laboratory apparatus. Of the seventeen additives tested, eight appeared to have a positive impact on either the ash layer thickness or the physical appearance of the dust layer. Excessive deposits on the discharge electrode resulted during injection of some of the additives. Three of the additives resulted in significant deposits in the injection chamber. The build up on the electrode was interpreted as a positive indicator of increase particle adhesion. The initial observations and comments for the eight additives are listed in Table 1.

  12. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers.

    PubMed

    Han, Young-Soo; Gallegos, Tanya J; Demond, Avery H; Hayes, Kim F

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. PMID:20974481

  13. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers

    USGS Publications Warehouse

    Han, Y.-S.; Gallegos, T.J.; Demond, A.H.; Hayes, K.F.

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. ?? 2010 Elsevier Ltd.

  14. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    PubMed Central

    Liu, Yiwen; Ni, Bing-Jie

    2015-01-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d−1 compared to 0.118 d−1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment. PMID:25644239

  15. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    NASA Astrophysics Data System (ADS)

    Liu, Yiwen; Ni, Bing-Jie

    2015-02-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d-1 compared to 0.118 d-1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment.

  16. Impacts of microalgae pre-treatments for improved anaerobic digestion: thermal treatment, thermal hydrolysis, ultrasound and enzymatic hydrolysis.

    PubMed

    Ometto, Francesco; Quiroga, Gerardo; Pšenička, Pavel; Whitton, Rachel; Jefferson, Bruce; Villa, Raffaella

    2014-11-15

    Anaerobic digestion (AD) of microalgae is primarily inhibited by the chemical composition of their cell walls containing biopolymers able to resist bacterial degradation. Adoption of pre-treatments such as thermal, thermal hydrolysis, ultrasound and enzymatic hydrolysis have the potential to remove these inhibitory compounds and enhance biogas yields by degrading the cell wall, and releasing the intracellular algogenic organic matter (AOM). This work investigated the effect of four pre-treatments on three microalgae species, and their impact on the quantity of soluble biomass released in the media and thus on the digestion process yields. The analysis of the composition of the soluble COD released and of the TEM images of the cells showed two main degradation actions associated with the processes: (1) cell wall damage with the release of intracellular AOM (thermal, thermal hydrolysis and ultrasound) and (2) degradation of the cell wall constituents with the release of intracellular AOM and the solubilisation of the cell wall biopolymers (enzymatic hydrolysis). As a result of this, enzymatic hydrolysis showed the greatest biogas yield increments (>270%) followed by thermal hydrolysis (60-100%) and ultrasounds (30-60%). PMID:25150520

  17. Biogas production improvement and C/N control by natural clinoptilolite addition into anaerobic co-digestion of Phragmites australis, feces and kitchen waste.

    PubMed

    Wang, Xiaowei; Zhang, Lieyu; Xi, Beidou; Sun, Wenjun; Xia, Xunfeng; Zhu, Chaowei; He, Xiaosong; Li, Mingxiao; Yang, Tianxue; Wang, Pengfei; Zhang, Zhonglei

    2015-03-01

    Anaerobic co-digestion (A co-D) performance of Phragmites australis, feces and kitchen waste with addition of clinoptilolite (one main kind of zeolite) was investigated to evaluate the improvement of biogas/methane production and internal mechanism of nitrogen and organics control. A better biogas/methane production was observed by 10% clinoptilolite (v/v) than bentonite and diatomite, with the shortest lag phase of 0.070d(-1), the max rate of 15.89L/(kgVSday) and ultimate biogas production of 308.2L/kgVS as the modified Gompertz equation predicted. Accordingly, the content of methane in the biogas was increased from 44.10% to 65.30%. Furthermore, the clinoptilolite inhibited the acidification of digestion liquid (optimum pH 7.0-7.5) and enhanced the VFAs (acetic acid, propionic acid and butyric acid) destruction. Moreover, 10% of clinoptilolite optimally enhanced the microbial utilization of Ca(2+)/Mg(2+), controlled the C/N ratio, and improved the biogas production as well as NH3-N/NO3-N inhibition efficiency. PMID:25603527

  18. Model-based design of an agricultural biogas plant: application of anaerobic digestion model no.1 for an improved four chamber scheme.

    PubMed

    Wett, B; Schoen, M; Phothilangka, P; Wackerle, F; Insam, H

    2007-01-01

    Different digestion technologies for various substrates are addressed by the generic process description of Anaerobic Digestion Model No. 1. In the case of manure or agricultural wastes a priori knowledge about the substrate in terms of ADM1 compounds is lacking and influent characterisation becomes a major issue. The actual project has been initiated for promotion of biogas technology in agriculture and for expansion of profitability also to rather small capacity systems. In order to avoid costly individual planning and installation of each facility a standardised design approach needs to be elaborated. This intention pleads for bio kinetic modelling as a systematic tool for process design and optimisation. Cofermentation under field conditions was observed, quality data and flow data were recorded and mass flow balances were calculated. In the laboratory different substrates have been digested separately in parallel under specified conditions. A configuration of four ADM1 model reactors was set up. Model calibration identified disintegration rate, decay rates for sugar degraders and half saturation constant for sugar as the three most sensitive parameters showing values (except the latter) about one order of magnitude higher than default parameters. Finally, the model is applied to the comparison of different reactor configurations and volume partitions. Another optimisation objective is robustness and load flexibility, i.e. the same configuration should be adaptive to different load situations only by a simple recycle control in order to establish a standardised design. PMID:17564366

  19. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    PubMed

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  20. Optimizing anaerobic soil disinfestation: an alternative to soil fumigation?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil disinfestation methods using anaerobic decomposition of organic matter were developed in the Netherlands and Japan as an ecological alternative to MeBr. Anaerobic soil disinfestation (ASD) works by creating a combination of anaerobic soil conditions and readily available carbon pools to stimula...

  1. Improved design of anaerobic digesters for household biogas production in indonesia: one cow, one digester, and one hour of cooking per day.

    PubMed

    Usack, Joseph G; Wiratni, Wiratni; Angenent, Largus T

    2014-01-01

    A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼ 1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27 ± 1 °C, a volatile solids loading rate of 2.0 g VS · L(-1) · day(-1), and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies. PMID:24715809

  2. Eliminating methanogenic activity in hydrogen reactor to improve biogas production in a two-stage anaerobic digestion process co-digesting municipal food waste and sewage sludge.

    PubMed

    Zhu, Heguang; Parker, Wayne; Conidi, Daniela; Basnar, Robert; Seto, Peter

    2011-07-01

    Laboratory scale two-stage anaerobic digestion process model was operated for 280 days to investigate the feasibility to produce both hydrogen and methane from a mixture feedstock (1:1 (v/v)) of municipal food waste and sewage sludge. The maximum hydrogen and methane yields obtained in the two stages were 0.93 and 9.5 mL/mL feedstock. To eliminate methanogenic activity and obtain substantial hydrogen production in the hydrogen reactor, both feedstock and mixed liquor required treatment. The heat treatment (100°C, 10 min) for feedstock and a periodical treatment (every 2-5 weeks, either heating, removal of biomass particles or flushing with air) for mixed liquor were effective in different extent. The methane production in the second stage was significantly improved by the hydrogen production in the first stage. The maximum methane production obtained in the period of high hydrogen production was more than 2-fold of that observed in the low hydrogen production period. PMID:21592783

  3. Improving pollutants removal by microalgae Chlorella PY-ZU1 with 15% CO2 from undiluted anaerobic digestion effluent of food wastes with ozonation pretreatment.

    PubMed

    Cheng, Jun; Ye, Qing; Xu, Jiao; Yang, Zongbo; Zhou, Junhu; Cen, Kefa

    2016-09-01

    In order to purify various pollutants (3108mg COD/L, 2120mg NH3-N/L) in the undiluted anaerobic digestion effluent of food wastes (UADEFW), ozonation pretreatment was employed to improve pollutants removal by microalgae mutant Chlorella PY-ZU1 with 15% CO2. Ozonation pretreatment broke CC bonds and benzene rings of refractory organics such as unsaturated fatty acids and phenols in UADEFW and degraded them into low-molecular-weight organics such as methanoic acid and methanal, but excessive ozone induced the accumulation of toxic by-products. The microalgal growth rate and biomass yield markedly increased to the peaks of 456mg/L/d and 4.3g/L, respectively, when the UADEFW was pretreated with 2mg-O3/mg-C of ozone. The removal efficiencies of NH3-N, TP and COD reached 99%, 99% and 68%, respectively. The lipid and carbohydrate contents of microalgal biomass increased because of the relative lack of nitrogen when microalgae was cultured with 15% CO2 to purify the UADEFW with ozonation pretreatment. PMID:27243605

  4. Improved Design of Anaerobic Digesters for Household Biogas Production in Indonesia: One Cow, One Digester, and One Hour of Cooking per Day

    PubMed Central

    Usack, Joseph G.; Wiratni, Wiratni; Angenent, Largus T.

    2014-01-01

    A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27 ± 1°C, a volatile solids loading rate of 2.0 g VS·L−1·day−1, and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies. PMID:24715809

  5. Improved Monitoring of Semi-Continuous Anaerobic Digestion of Sugarcane Waste: Effects of Increasing Organic Loading Rate on Methanogenic Community Dynamics

    PubMed Central

    Leite, Athaydes Francisco; Janke, Leandro; Lv, Zuopeng; Harms, Hauke; Richnow, Hans-Hermann; Nikolausz, Marcell

    2015-01-01

    The anaerobic digestion of filter cake and its co-digestion with bagasse, and the effect of gradual increase of the organic loading rate (OLR) from start-up to overload were investigated. Understanding the influence of environmental and technical parameters on the development of particular methanogenic pathway in the biogas process was an important aim for the prediction and prevention of process failure. The rapid accumulation of volatile organic acids at high OLR of 3.0 to 4.0 gvs·L−1·day−1 indicated strong process inhibition. Methanogenic community dynamics of the reactors was monitored by stable isotope composition of biogas and molecular biological analysis. A potential shift toward the aceticlastic methanogenesis was observed along with the OLR increase under stable reactor operating conditions. Reactor overloading and process failure were indicated by the tendency to return to a predominance of hydrogenotrophic methanogenesis with rising abundances of the orders Methanobacteriales and Methanomicrobiales and drop of the genus Methanosarcina abundance. PMID:26404240

  6. Improved Monitoring of Semi-Continuous Anaerobic Digestion of Sugarcane Waste: Effects of Increasing Organic Loading Rate on Methanogenic Community Dynamics.

    PubMed

    Leite, Athaydes Francisco; Janke, Leandro; Lv, Zuopeng; Harms, Hauke; Richnow, Hans-Hermann; Nikolausz, Marcell

    2015-01-01

    The anaerobic digestion of filter cake and its co-digestion with bagasse, and the effect of gradual increase of the organic loading rate (OLR) from start-up to overload were investigated. Understanding the influence of environmental and technical parameters on the development of particular methanogenic pathway in the biogas process was an important aim for the prediction and prevention of process failure. The rapid accumulation of volatile organic acids at high OLR of 3.0 to 4.0 gvs·L⁻¹·day⁻¹ indicated strong process inhibition. Methanogenic community dynamics of the reactors was monitored by stable isotope composition of biogas and molecular biological analysis. A potential shift toward the aceticlastic methanogenesis was observed along with the OLR increase under stable reactor operating conditions. Reactor overloading and process failure were indicated by the tendency to return to a predominance of hydrogenotrophic methanogenesis with rising abundances of the orders Methanobacteriales and Methanomicrobiales and drop of the genus Methanosarcina abundance. PMID:26404240

  7. Anaerobic Infections

    MedlinePlus

    ... Health Issues Conditions Abdominal ADHD Allergies & Asthma Autism Cancer Chest & Lungs Chronic Conditions Cleft & Craniofacial Developmental Disabilities Ear Nose & Throat Emotional Problems Eyes Fever From Insects or Animals Genitals and Urinary Tract Glands & Growth ...

  8. Flue gas conditioning for improved particle collection in electrostatic precipitators

    SciTech Connect

    Durham, M.D.

    1993-04-16

    Several tasks have been completed in a program to evaluate additives to improve fine particle collection in electrostatic precipitators. Screening tests and laboratory evaluations of additives are summarized in this report. Over 20 additives were evaluated; four were found to improve flyash precipitation rates. The Insitec particle analyzer was also evaluated; test results show that the analyzer will provide accurate sizing and counting information for particles in the size range of [le] 10 [mu]m dia.

  9. [Anaerobic bacteria 150 years after their discovery by Pasteur].

    PubMed

    García-Sánchez, José Elías; García-Sánchez, Enrique; Martín-Del-Rey, Ángel; García-Merino, Enrique

    2015-02-01

    In 2011 we celebrated the 150th anniversary of the discovery of anaerobic bacteria by Louis Pasteur. The interest of the biomedical community on such bacteria is still maintained, and is particularly focused on Clostridium difficile. In the past few years important advances in taxonomy have been made due to the genetic, technological and computing developments. Thus, a significant number of new species related to human infections have been characterised, and some already known have been reclassified. At pathogenic level some specimens of anaerobic microflora, that had not been isolated from human infections, have been now isolated in some clinical conditions. There was emergence (or re-emergence) of some species and clinical conditions. Certain anaerobic bacteria have been associated with established infectious syndromes. The virulence of certain strains has increased, and some hypotheses on their participation in certain diseases have been given. In terms of diagnosis, the routine use of MALDI-TOF has led to a shortening of time and a cost reduction in the identification, with an improvement directly related to the improvement of data bases. The application of real-time PCR has been another major progress, and the sequencing of 16srRNA gene and others is currently a reality for several laboratories. Anaerobes have increased their resistance to antimicrobial agents, and the emergence of resistance to carbapenems and metronidazole, and multi-resistance is a current reality. In this situation, linezolid could be an effective alternative for Bacteroides. Fidaxomicin is the only anti-anaerobic agent introduced in the recent years, specifically for the diarrhoea caused by C.difficile. Moreover, some mathematical models have also been proposed in relation with this species. PMID:23648369

  10. Improving the sludge conditioning potential of moringa seed

    NASA Astrophysics Data System (ADS)

    Ademiluyi, Joel O.; Eze, Romanus M.

    1990-01-01

    In the search for a cheaper material to effectively condition sludge, oil-free moringa seed was prepared and tested. A Soxhlet apparatus was used to extract the oil from moringa seed ( Moringa oleifera). The oil-free seed (marc) has been found to have higher conditioning potential than the ordinary moringa seed. However, the traditional ferric chloride is still a better sludge conditioner than moringa seed marc. For the digested domestic sludge used, optimum conditioning dosages were found to be 0.6, 0.80, and 1.10% of the total solids for ferric chloride, marc of the moringa seed, and ordinary moringa seed, respectively. Since little or no operational material is lost in the extraction process, the moringa seed marc is a promising conditioner in place of the ordinary seed.

  11. Assessing Engineering Competencies: The Conditions for Educational Improvement

    ERIC Educational Resources Information Center

    Musekamp, Frank; Pearce, Jacob

    2015-01-01

    Low-stakes assessment is supposed to improve educational practice by providing feedback to different actors in educational systems. However, the process of assessment from design to the point of a final impact on student learning outcomes is complex and diverse. It is hard to identify reasons for substandard achievement on assessments, let alone…

  12. The Facilities Audit. A Process for Improving Facilities Conditions.

    ERIC Educational Resources Information Center

    Kaiser, Harvey H.

    The problems of deferred maintenance and decaying campus infrastructure have troubled higher education for the past two decades. This book, designed to be a tool for facilities managers, describes a process for inspecting and reporting conditions of buildings and infrastructure. The audit process is meant to be a routine part of maintenance…

  13. Anaerobic microbial transformations in subsurface environments

    SciTech Connect

    Bollag, J.M.; Berry, D.F.; Chanmugathas, P.

    1985-04-01

    The first draft of a literature review article entitled, ''Metabolism of Homocyclic (Benzenoid) and Heterocyclic Aromatic Compounds by Microorganisms Under Anaerobic Conditions'' is completed. The article covers biodegradation of both heterocyclic and homocyclic aromatic compounds under a variety of conditions including nitrate reducing, fermentation, sulfate reducing, and methanogensis. Laboratory experiments have been designed to study the anaerobic biotransformation processes involving organic substance derived from energy residual wastes. The test compounds selected for the initial anaerobic biodegradation experiments include aniline, indole, and pyridine. A Hungate apparatus is presently in operation.

  14. Antimicrobial Treatment Improves Mycobacterial Survival in Nonpermissive Growth Conditions

    PubMed Central

    Turapov, Obolbek; Waddell, Simon J.; Burke, Bernard; Glenn, Sarah; Sarybaeva, Asel A.; Tudo, Griselda; Labesse, Gilles; Young, Danielle I.; Young, Michael; Andrew, Peter W.; Butcher, Philip D.; Cohen-Gonsaud, Martin

    2014-01-01

    Antimicrobials targeting cell wall biosynthesis are generally considered inactive against nonreplicating bacteria. Paradoxically, we found that under nonpermissive growth conditions, exposure of Mycobacterium bovis BCG bacilli to such antimicrobials enhanced their survival. We identified a transcriptional regulator, RaaS (for regulator of antimicrobial-assisted survival), encoded by bcg1279 (rv1219c) as being responsible for the observed phenomenon. Induction of this transcriptional regulator resulted in reduced expression of specific ATP-dependent efflux pumps and promoted long-term survival of mycobacteria, while its deletion accelerated bacterial death under nonpermissive growth conditions in vitro and during macrophage or mouse infection. These findings have implications for the design of antimicrobial drug combination therapies for persistent infectious diseases, such as tuberculosis. PMID:24590482

  15. Test/QA Plan For Verification Of Anaerobic Digester For Energy Production And Pollution Prevention

    EPA Science Inventory

    The ETV-ESTE Program conducts third-party verification testing of commercially available technologies that improve the environmental conditions in the U.S. A stakeholder committee of buyers and users of such technologies guided the development of this test on anaerobic digesters...

  16. The curing agent sodium nitrite, used in the production of fermented sausages, is less inhibiting to the bacteriocin-producing meat starter culture Lactobacillus curvatus LTH 1174 under anaerobic conditions.

    PubMed

    Verluyten, Jurgen; Messens, Winy; De Vuyst, Luc

    2003-07-01

    Curvacin A is a listericidal bacteriocin produced by Lactobacillus curvatus LTH 1174, a strain isolated from fermented sausage. The response of this strain to an added curing agent (sodium nitrite) in terms of cell growth and bacteriocin production was investigated in vitro by laboratory fermentations with modified MRS broth. The strain was highly sensitive to nitrite; even a concentration of 10 ppm of curing agent inhibited its growth and both volumetric and specific bacteriocin production. A meat simulation medium containing 5 ppm of sodium nitrite was tested to investigate the influence of the gas phase on the growth and bacteriocin production of L. curvatus LTH 1174. Aerating the culture during growth had no effect on biomass formation, but the oxidative stress caused a higher level of specific bacteriocin production and led to a metabolic shift toward acetic acid production. Anaerobic conditions, on the other hand, led to an increased biomass concentration and less growth inhibition. Also, higher maximum volumetric bacteriocin activities and a higher level of specific bacteriocin production were obtained in the presence of sodium nitrite than in fermentations under aerobic conditions or standard conditions of air supply. These results indicate that the inhibitory effect of the curing agent is at least partially masked under anaerobic conditions. PMID:12839751

  17. Acclimation strategy to increase phenol tolerance of an anaerobic microbiota.

    PubMed

    Madigou, Céline; Poirier, Simon; Bureau, Chrystelle; Chapleur, Olivier

    2016-09-01

    A wide variety of inhibitory substances can induce anaerobic digester upset or failure. In this work the possibility to improve the resistance of an anaerobic microbiota to a common pollutant, the phenol, was evaluated in a lab-scale semi-continuous bioreactor. An acclimation strategy, consisting in a regular step-wise adaptation of the microbiota to stressful condition was employed. Degradation performances were monitored and molecular tools (16S sequencing and ARISA fingerprinting technique) were used to track changes in the microbial community. The acclimation strategy progressively minimized the effect of phenol on degradation performances. After 3 successive disturbance episodes, microbiota resistance was considerably developed and total inhibition threshold increased from 895 to 1942mg/L of phenol. Microbiota adaptation was characterized by the selection of the most resistant Archaea OTU from Methanobacterium genus and an important elasticity of Bacteria, especially within Clostridiales and Bacteroidales orders, that probably enabled the adaptation to more and more stressful conditions. PMID:27233100

  18. Multimodal cues improve prey localization under complex environmental conditions.

    PubMed

    Rhebergen, F; Taylor, R C; Ryan, M J; Page, R A; Halfwerk, W

    2015-09-01

    Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog (Physalaemus pustulosus) to test prey assessment by fringe-lipped bats (Trachops cirrhosus). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog (Dendropsophus ebraccatus). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them. PMID:26336176

  19. Multimodal cues improve prey localization under complex environmental conditions

    PubMed Central

    Rhebergen, F.; Taylor, R. C.; Ryan, M. J.; Page, R. A.; Halfwerk, W.

    2015-01-01

    Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog (Physalaemus pustulosus) to test prey assessment by fringe-lipped bats (Trachops cirrhosus). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog (Dendropsophus ebraccatus). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them. PMID:26336176

  20. Autogenic feedback training improves pilot performance during emergency flying conditions.

    PubMed

    Kellar, M A; Folen, R A; Cowings, P S; Toscano, W B; Hisert, G L

    1993-01-01

    Studies have shown that autonomous mode behavior (AMB) is one cause of aircraft fatalities caused by pilot error. In AMB cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. The following study, conducted under the auspices of the U.S. National Aeronautics and Space Administration's (NASA) Ames Research Center, examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. PMID:11537902

  1. Redesigning Escherichia coli Metabolism for Anaerobic Production of Isobutanol▿†

    PubMed Central

    Trinh, Cong T.; Li, Johnny; Blanch, Harvey W.; Clark, Douglas S.

    2011-01-01

    Fermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design an Escherichia coli strain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism of E. coli was decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growth E. coli cannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesigned E. coli strain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producing E. coli strain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production. PMID:21642415

  2. Use of 13C Labeled Carbon Tetrachloride to Demonstrate the Transformation to Carbon Dioxide under Anaerobic Conditions in a Continuous Flow Column

    NASA Astrophysics Data System (ADS)

    Semprini, L.; Azizian, M.

    2012-12-01

    The demonstration of transformation of chlorinated aliphatic compounds (CAHs) in the subsurface is a challenge, especially when the products are carbon dioxide (CO2) and chloride ion. The groundwater contaminant carbon tetrachloride (CT) is of particular interest since a broad range of transformation products can be potentially formed under anaerobic conditions. The ability to demonstrate the transformation of CT to CO2 as a non toxic endproduct, is also of great interest. Results will be presented from a continuous flow column study where 13C labeled CT was used to demonstrate its transformation to CO2. The column was packed with a quartz sand and bioaugmented the Evanite Culture (EV) that is capable of transforming tetrachloroethene (PCE) to ethene. The column was continously fed a synthetic groundwater that was amended with PCE (0.10 mM) and either formate (1.5 mM) or lactate (1.1 mM), which ferments to produce hydrogen (H2) as the ultimate electron donor. Earlier CT transformation studies with the column, in the absence of sulfate reduction, and with formate added as a donor found CT (0.015 mM) was over 98% transformed with about 20% converted to chloroform (CF) (0.003 mM) and with a transient detection of chloromethane (CM). Methane and carbon disulfide, as potential products, were not detected. Neither CT nor CF inhibited the reductive dehalogenation of PCE to ethene. A series of transient studies conducted after these initial CT transformation tests, but in the absence of CT, showed formate remained an effective substrate for maintaining sulfate reduction and PCE transformation. Lactate, which was effectively fermented prior to CT addition, was not effectively fermented, with propionate accumulating as a fermentation product. When lactate was added, PCE was mainly transformed to cis-dichloroethene (cis-DCE) and VC, and sulfate reduction did not occur. In order to restore effective lactate fermentation the column was then bioaugmented with an EV culture that

  3. Defining cell culture conditions to improve human norovirus infectivity assays.

    PubMed

    Straub, T M; Hutchison, J R; Bartholomew, R A; Valdez, C O; Valentine, N B; Dohnalkova, A; Ozanich, R M; Bruckner-Lea, C J

    2013-01-01

    Significant difficulties remain for determining whether human noroviruses (hNoV) recovered from water, food, and environmental samples are infectious. Three-dimensional (3-D) tissue culture of human intestinal cells has shown promise in developing an infectivity assay, but reproducibility, even within a single laboratory, remains problematic. From the literature and our observations, we hypothesized that the common factors that lead to more reproducible hNoV infectivity in vitro requires that the cell line be (1) of human gastrointestinal origin, (2) expresses apical microvilli, and (3) be a positive secretor cell line. The C2BBe1 cell line, which is a brush-border producing clone of Caco-2, meets these three criteria. When challenged with Genogroup II viruses, we observed a 2 Log(10) increase in viral RNA titer. A passage experiment with GII viruses showed evidence of the ability to propagate hNoV by both quantitative reverse transcription polymerase chain reaction (qRT-PCR) and microscopy. In our hands, using 3-D C2BBe1 cells improves reproducibility of the infectivity assay for hNoV, but the assay can still be variable. Two sources of variability include the cells themselves (mixed phenotypes of small and large intestine) and initial titer measurements using qRT-PCR that measures all RNA vs. plaque assays that measure infectious virus. PMID:23306266

  4. Defining cell culture conditions to improve human norovirus infectivity assays

    SciTech Connect

    Straub, Tim M.; Hutchison, Janine R.; Bartholomew, Rachel A.; Valdez, Catherine O.; Valentine, Nancy B.; Dohnalkova, Alice; Ozanich, Richard M.; Bruckner-Lea, Cindy J.

    2013-01-10

    Significant difficulties remain for determining whether human noroviruses (hNoV) recovered from water, food, and environmental samples are infectious. Three-dimensional tissue culture of human intestinal cells has shown promise in developing an infectivity assay, but reproducibility, even within a single laboratory, remains problematic. From the literature and our observations, we hypothesized that the common factors that leads to more reproducible hNoV infectivity in vitro requires that the cell line be 1) of human gastrointestinal origin, 2) expresses apical microvilli, and 3) be a positive secretor cell line. The C2BBe1 cell line, which is a brush-border producing clone of Caco-2, meets these three criteria. When challenged with Genogroup II viruses, we observed a 2 Log10 increase in viral RNA titer. A passage experiment with GII viruses showed evidence of the ability to propagate hNoV by both reverse transcription quantitative PCR (qRT-PCR) and microscopy. Using 3-D C2BBe1 cells improves reproducibility of the infectivity assay for hNoV, but the assay can still be variable. Two sources of variability include the cells themselves (mixed phenotypes of small and large intestine) and initial titer measurements using quantitative reverse transcription PCR (qRT-PCR) that measures all RNA vs. plaque assays that measure infectious virus.

  5. APPARATUS FOR IMPROVING HYDRODYNAMIC CONDITIONS WITHIN A CONDUIT

    DOEpatents

    Furgerson, W.T.; Samuels, G. Jr.

    1962-03-27

    An improved header is designed for eliminating the phenomena of boundary growth, boundary separation, and boundary flow reversal within a divergent passageway having an equivalent cone angle greater than 20 deg . The header is disposed at the inlet end of an annular divergency and adapted to distribute a rotational fluid flow across that inlet end. Vane means are mounted adjacent the inlet end to establish within the divergent passageway a solid body rotation having both a rotational component of fluid velocity and an axial component of fluid velocity in the direction of the divergence. The vane means are so constructed as to direct a substantial portion of the inlet flow toward both walls of the divergence and a drag ring on the bottom of the vanes will cause a substantially greater portion of the inlet flow to be directed toward one wall than toward the other wall of the annuiar passageway to eliminate any defects which were not eliminated by solid body flow. (AEC)

  6. Crop improvement using life cycle datasets acquired under field conditions

    PubMed Central

    Mochida, Keiichi; Saisho, Daisuke; Hirayama, Takashi

    2015-01-01

    Crops are exposed to various environmental stresses in the field throughout their life cycle. Modern plant science has provided remarkable insights into the molecular networks of plant stress responses in laboratory conditions, but the responses of different crops to environmental stresses in the field need to be elucidated. Recent advances in omics analytical techniques and information technology have enabled us to integrate data from a spectrum of physiological metrics of field crops. The interdisciplinary efforts of plant science and data science enable us to explore factors that affect crop productivity and identify stress tolerance-related genes and alleles. Here, we describe recent advances in technologies that are key components for data driven crop design, such as population genomics, chronological omics analyses, and computer-aided molecular network prediction. Integration of the outcomes from these technologies will accelerate our understanding of crop phenology under practical field situations and identify key characteristics to represent crop stress status. These elements would help us to genetically engineer “designed crops” to prevent yield shortfalls because of environmental fluctuations due to future climate change. PMID:26442053

  7. [Enhancement for anaerobic digestion of sewage sludge pretreated by microwave and its combined processes ].

    PubMed

    Liu, Ji-bao; Ni, Xiao-tang; Wei, Yuan-song; Tong, Juan; Wang, Ya-wei

    2014-09-01

    To improve anaerobic digestion and dewatering of sludge, impacts of sludge pretreated by microwave (MW) and its combined processes on sludge anaerobic digestion and dewatering were investigated. The results showed that microwave and its combined processes could effectively enhance anaerobic sludge digestion. Not only the cumulative methane production in the test of the MW-H2O2-alkaline (0. 2) was increased by 13. 34% compared with the control, but also its methane production rate was much higher than that of the control. Compared with the single MW process, the addition of both H2O2 and alkaline enhanced the solubilization of particle COD( >0. 45 micron) , indicating that synergistically generated soluble organics were faster to biodegrade which resulted in the enhancement of anaerobic digestion. The MW-acid process was effective in improving sludge dewaterability, e. g. , Capillary Suction Time (CST) at only 9. 85 s. The improvement of sludge dewatering was significantly correlated with sludge physical properties such as zeta potential, surface charge density and particle size. Under different sludge pretreatment conditions, the sludge dewatering after anaerobic digestion was similar, though the difference of sludge dewatering to some degrees was observed for pretreated sludge. PMID:25518665

  8. Aerobic and anaerobic cellulase production by Cellulomonas uda.

    PubMed

    Poulsen, Henrik Vestergaard; Willink, Fillip Wolfgang; Ingvorsen, Kjeld

    2016-10-01

    Cellulomonas uda (DSM 20108/ATCC 21399) is one of the few described cellulolytic facultative anaerobes. Based on these characteristics, we initiated a physiological study of C. uda with the aim to exploit it for cellulase production in simple bioreactors with no or sporadic aeration. Growth, cellulase activity and fermentation product formation were evaluated in different media under both aerobic and anaerobic conditions and in experiments where C. uda was exposed to alternating aerobic/anaerobic growth conditions. Here we show that C. uda behaves as a true facultative anaerobe when cultivated on soluble substrates such as glucose and cellobiose, but for reasons unknown cellulase activity is only induced under aerobic conditions on insoluble cellulosic substrates and not under anaerobic conditions. These findings enhance knowledge on the limited number of described facultative cellulolytic anaerobes, and in addition it greatly limits the utility of C. uda as an 'easy to handle' cellulase producer with low aeration demands. PMID:27154570

  9. 42 CFR 418.58 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) HOSPICE CARE Conditions of...) Identify opportunities and priorities for improvement. (3) The frequency and detail of the data...

  10. Anaerobic digestion of horse dung mixed with different bedding materials in an upflow solid-state (UASS) reactor at mesophilic conditions.

    PubMed

    Böske, Janina; Wirth, Benjamin; Garlipp, Felix; Mumme, Jan; Van den Weghe, Herman

    2014-04-01

    Aim of this study was to investigate the use of upflow anaerobic solid-state (UASS) digestion for treating horse manure. Biochemical methane potential (BMP) tests conducted for varying mixtures of dung (hay and silage feed) and bedding material (wheat straw, flax, hemp, wood chips) showed that straw mixed with hay horse dung has the highest potential of [Formula: see text] . Continuous mesophilic digestion was conducted for 238 days using a single-stage UASS reactor (27 L) and a two-stage UASS system with an anaerobic filter (AF, 21 L). Increasing the organic loading rate (OLR) from 2.5 to 4.5 g vs L(-1)d(-1) enhanced the methane rate of the single-stage reactor from 0.262 to 0.391 LL(-1)d(-1) while the methane yield declined from 104.8 to 86.9 L kg vs(-1). The two-stage system showed similar yields. Thus, for solid-state digestion of horse manure a single-stage UASS reactor appears sufficient. PMID:24583222

  11. Long-term operation of a pilot scale anaerobic membrane bioreactor (AnMBR) for the treatment of municipal wastewater under psychrophilic conditions.

    PubMed

    Gouveia, J; Plaza, F; Garralon, G; Fdz-Polanco, F; Peña, M

    2015-06-01

    The performance of a pilot scale anaerobic membrane bioreactor (AnMBR), comprising an upflow anaerobic sludge blanket (UASB) reactor coupled to an external ultrafiltration membrane treating municipal wastewater at 18±2°C, was evaluated over three years of stable operation. The reactor was inoculated with a mesophilic inoculum without acclimation. The AnMBR supported a tCOD removal efficiency of 87±1% at hydraulic retention time (HRT) of 7h, operating at a volumetric loading rate (VLR) of between 2 and 2.5kgtCOD/m(3)d, reaching effluent tCOD concentrations of 100-120mg/L and BOD5 concentrations of 35-50mgO2/L. Specific methane yield varied from 0.18 to 0.23Nm(3)CH4/kgCODremoved depending on the recirculation between the membrane module and the UASB reactor. The permeate flow rate, using cycles of 15s backwash, 7.5min filtration, and continuous biogas sparging (40-60m/h), ranged from 10 to 14Lm(2)/h with trans-membrane pressure (TMP) values of 400-550mbar. PMID:25770470

  12. UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 strain for improved anaerobic growth at elevated temperature on pentose and hexose sugars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More robust industrial yeast strains from Kluyveromyces marxianus NRRL Y-1109 and have been produced using UV-C irradiation specifically for anaerobic conversion of lignocellulosic sugar streams to fuel ethanol at elevated temperature (45°C). This type of random mutagenesis offers the possibility o...

  13. Influence of thermal pretreatment on physical and chemical properties of kitchen waste and the efficiency of anaerobic digestion.

    PubMed

    Jin, Yiying; Li, Yangyang; Li, Jinhui

    2016-09-15

    The effects of thermal pretreatment at moderate temperatures (70, 80 and 90 °C) and high temperatures (120, 140 and 160 °C) over heating durations of 10-120 min on the physical and chemical properties of kitchen waste and on anaerobic digestion were investigated. The results show that thermal pretreatment significantly enhances the solubilisation of organic compounds (chemical oxygen demand, crude proteins, crude fats and volatile fatty acids) and their biodegradability during subsequent anaerobic digestion. High temperature and long heating duration are beneficial for the release and reduction of organic compounds, and the efficiency of subsequent anaerobic digestion is improved markedly under these conditions. Moreover, both the methane production rate and methane yield were observed to increase significantly at moderate treatment temperatures when the anaerobic digestion time was longer than 50 h. PMID:27240205

  14. Waste heat utilization in an anaerobic digestion system

    NASA Astrophysics Data System (ADS)

    Boissevain, Brett

    Anaerobic digestion has great potential as an energy source. Not only does it provide an effective method for waste mitigation, but it has the potential to generate significant quantities of fuel and electricity. In order to ensure efficient digestion and biomass utilization, however, the system must be continuously maintained at elevated temperatures. It is technically feasible to supplement such a system with outside energy, but it is more cost effective to heat the system using only the produced biogas. While there is considerable literature covering the theory of anaerobic digestion, there are very few practical studies to show how heat utilization affects system operation. This study considers the effect of major design variables (i.e. heat exchanger efficiencies and biogas conditioning) on promoting a completely self-sustaining digestion system. The thesis considers a real world system and analyzes how it can be improved to avoid the need of an external energy source.

  15. A Putative ABC Transporter Permease Is Necessary for Resistance to Acidified Nitrite and EDTA in Pseudomonas aeruginosa under Aerobic and Anaerobic Planktonic and Biofilm Conditions

    PubMed Central

    McDaniel, Cameron; Su, Shengchang; Panmanee, Warunya; Lau, Gee W.; Browne, Tristan; Cox, Kevin; Paul, Andrew T.; Ko, Seung-Hyun B.; Mortensen, Joel E.; Lam, Joseph S.; Muruve, Daniel A.; Hassett, Daniel J.

    2016-01-01

    Pseudomonas aeruginosa (PA) is an important airway pathogen of cystic fibrosis and chronic obstructive disease patients. Multiply drug resistant PA is becoming increasing prevalent and new strategies are needed to combat such insidious organisms. We have previously shown that a mucoid, mucA22 mutant PA is exquisitely sensitive to acidified nitrite (A-NO2−, pH 6.5) at concentrations that are well tolerated in humans. Here, we used a transposon mutagenesis approach to identify PA mutants that are hypersensitive to A-NO2−. Among greater than 10,000 mutants screened, we focused on PA4455, in which the transposon was found to disrupt the production of a putative cytoplasmic membrane-spanning ABC transporter permease. The PA4455 mutant was not only highly sensitive to A-NO2−, but also the membrane perturbing agent, EDTA and the antibiotics doxycycline, tigecycline, colistin, and chloramphenicol, respectively. Treatment of bacteria with A-NO2− plus EDTA, however, had the most dramatic and synergistic effect, with virtually all bacteria killed by 10 mM A-NO2−, and EDTA (1 mM, aerobic, anaerobic). Most importantly, the PA4455 mutant was also sensitive to A-NO2− in biofilms. A-NO2− sensitivity and an anaerobic growth defect was also noted in two mutants (rmlC and wbpM) that are defective in B-band LPS synthesis, potentially indicating a membrane defect in the PA4455 mutant. Finally, this study describes a gene, PA4455, that when mutated, allows for dramatic sensitivity to the potential therapeutic agent, A-NO2− as well as EDTA. Furthermore, the synergy between the two compounds could offer future benefits against antibiotic resistant PA strains. PMID:27064218

  16. Arsenic, Anaerobes, and Autotrophy.

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.

    2008-12-01

    That microbes have resistance to the toxic arsenic oxyanions arsenite [As(III)] and arsenate [As(V)] has been recognized for some time. More recently it was shown that certain prokaryotes can demonstrate As- dependent growth by conserving the energy gained from the aerobic oxidation of As(III) to As(V), or from the reduction of As(V) to As(III) under anaerobic conditions. During the course of our field studies of two alkaline, hypersaline soda lakes (Mono Lake and Searles Lake, CA) we have discovered several new anaerobic chemo- and photo-autotrophic bacteria that can center their energy gain around the redox reactions between As(III) and As(V). Alkalilimnicola ehrlichii, isolated from the water column of Mono Lake is a nitrate-respiring, As(III)-oxidizing chemoautotroph of the gamma-proteobacteria that has a highly flexible metabolism. It can function either as a facultative anaerobe or as a chemo-autotroph, or as a heterotroph (Hoeft et al., 2007). In contrast, strain MLMS-1 of the delta-proteobacteria was also isolated from Mono Lake, but to date is the first example of an obligate As(V)-respirer that is also an obligate chemo-autotroph, gaining its energy via the oxidation of sulfide to sulfate (Hoeft et al., 2004). Strain SLAS-1, isolated from salt-saturated Searles Lake is a member of the Halananerobiales, and can either grow as a heterotroph (lactate e-donor) or chemo- autotroph (sulfide e-donor) while respiring As(V). The fact that it can achieve this feat at salt-saturation (~ 340 g/L) makes it a true extremophile (Oremland et. al., 2005). Finally, strain PHS-1 isolated from a hot spring on Paoha island in Mono Lake is the first example of a photosynthetic bacterium of the gamma- proteobacteria able to link its growth to As(III)-dependent anoxygenic photosynthesis (Kulp et al., 2008). These novel microbes give us new insights into the evolution of arsenic-based metabolism and their role in the biogeochemical cycling of this toxic element. Hoeft, S.E., et

  17. 42 CFR 403.732 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Condition of participation: Quality assessment and... Health Care Institutions-Benefits, Conditions of Participation, and Payment § 403.732 Condition of participation: Quality assessment and performance improvement. The RNHCI must develop, implement, and maintain...

  18. 42 CFR 403.732 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Condition of participation: Quality assessment and... Health Care Institutions-Benefits, Conditions of Participation, and Payment § 403.732 Condition of participation: Quality assessment and performance improvement. The RNHCI must develop, implement, and maintain...

  19. 42 CFR 403.732 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Condition of participation: Quality assessment and... Health Care Institutions-Benefits, Conditions of Participation, and Payment § 403.732 Condition of participation: Quality assessment and performance improvement. The RNHCI must develop, implement, and maintain...

  20. 42 CFR 403.732 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Condition of participation: Quality assessment and... Health Care Institutions-Benefits, Conditions of Participation, and Payment § 403.732 Condition of participation: Quality assessment and performance improvement. The RNHCI must develop, implement, and maintain...

  1. 42 CFR 403.732 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Condition of participation: Quality assessment and... Health Care Institutions-Benefits, Conditions of Participation, and Payment § 403.732 Condition of participation: Quality assessment and performance improvement. The RNHCI must develop, implement, and maintain...

  2. Voluntary exercise improves both learning and consolidation of cued conditioned fear in C57 mice.

    PubMed

    Falls, William A; Fox, James H; MacAulay, Christina M

    2010-03-01

    Exercise is associated with improved cognitive function in humans as well as improved learning across a range of tasks in rodents. Although these studies provide a strong link between exercise and learning, to date studies have largely focused on tasks that principally involve the hippocampus. However, exercise has been shown to produce alterations in other brain areas suggesting that the cognitive enhancing effects of exercise may be more general. Therefore we set out to examine the effects of voluntary exercise on cued Pavlovian fear conditioning, a form of learning that is critically dependent on the amygdala. In Experiment 1 we showed that mice given 2 weeks of access to a running wheel prior to tone and foot shock fear conditioning showed enhanced conditioned fear as measured by fear-potentiated startle. This effect was not the result of altered shock reactivity nor was it to due to reduced baseline startle amplitude in exercising mice. In subsequent experiments we sought to examine whether the enhanced cued conditioned fear was the result of an improvement in learning, consolidation or retrieval of conditioned fear. In separate groups of mice, two weeks of access to a running wheel was begun either prior to fear conditioning, immediately after fear conditioning (consolidation period) or 2 weeks after fear conditioning. Compared to sedentary mice, mice that exercised either prior to fear conditioning, or immediately after fear conditioning, showed enhanced cued conditioned fear. Fear conditioning was not enhanced in mice that began exercising 2 weeks after fear conditioning. Taken together these results suggest that voluntary exercise improves the learning and consolidation of cued conditioned fear but does not improve the retrieval or performance of conditioned fear. Because a great deal is known about the neural circuit for cued conditioned fear, it is now possible to examine the cellular, molecular and pharmacological changes associated with exercise in

  3. Anaerobic bag culture method.

    PubMed

    Rosenblatt, J E; Stewart, P R

    1975-06-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method. PMID:1100671

  4. Anaerobic bag culture method.

    PubMed Central

    Rosenblatt, J E; Stewart, P R

    1975-01-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method. Images PMID:1100671

  5. [Effect of carbon substrate concentration on N2, N2O, NO, CO2, and CH4 emissions from a paddy soil in anaerobic condition].

    PubMed

    Chen, Nuo; Liao, Ting-ting; Wang, Rui; Zheng, Xun-hua; Hu, Rong-gui; Butterbach-Bahl, Klaus

    2014-09-01

    Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen (N2) , nitrous oxide (N2O) and nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model(s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon substrate concentration on the emissions of the denitrification gases, CO2 and CH4 from anaerobically incubated soils by setting two treatments: control (CK) with initial soil nitrate and dissolved organic carbon (DOC) concentrations of ~ 50 mg.kg-1 and -28 mg kg-1 , respectively; and DOC added (C + ) with initial soil nitrate and DOC concentrations of ~50 mg.kg-1 and ~300 mg.kg-1 , respectively. The emissions of denitrification gases, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each treatment were dynamically measured, using the gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that CH4 emission was not observed in CK treatment while observed in C treatment. Aggregate emission of greenhouse gases for C + treatment was significantly higher comparing with the CK treatment (P <0. 01). The mass fractions of NO, N20 and N2 emissions in total nitrogen gases emissions were approximately 9% , 35% and 56% for CK treatment, respectively; and approximately 31% , 50% and 19% for C+ treatment, respectively, with significant differences between these two treatments (P < 0.01). The results indicated that carbon substrate concentrations can significantly change the composition of nitrogen gas emissions. The results also implicated

  6. Combination of process and vibration data for improved condition monitoring of industrial systems working under variable operating conditions

    NASA Astrophysics Data System (ADS)

    Ruiz-Cárcel, C.; Jaramillo, V. H.; Mba, D.; Ottewill, J. R.; Cao, Y.

    2016-01-01

    The detection and diagnosis of faults in industrial processes is a very active field of research due to the reduction in maintenance costs achieved by the implementation of process monitoring algorithms such as Principal Component Analysis, Partial Least Squares or more recently Canonical Variate Analysis (CVA). Typically the condition of rotating machinery is monitored separately using vibration analysis or other specific techniques. Conventional vibration-based condition monitoring techniques are based on the tracking of key features observed in the measured signal. Typically steady-state loading conditions are required to ensure consistency between measurements. In this paper, a technique based on merging process and vibration data is proposed with the objective of improving the detection of mechanical faults in industrial systems working under variable operating conditions. The capabilities of CVA for detection and diagnosis of faults were tested using experimental data acquired from a compressor test rig where different process faults were introduced. Results suggest that the combination of process and vibration data can effectively improve the detectability of mechanical faults in systems working under variable operating conditions.

  7. Anaerobic specimen transport device.

    PubMed Central

    Wilkins, T D; Jimenez-Ulate, F

    1975-01-01

    A device is described and evaluated for the anaerobic transport of clinical specimens. The device limits the amount of oxygen entering with the sample to a maximum of 2%, which is rapidly removed by reacting with hydrogen in the presence of a palladium catalyst. The viability on swabs of 12 species of anaerobes, four strains of facultative anaerobes and a strain of Pseudomonas aeruginosa, was maintained during the length of the tests (24 or 48 h). The results demonstrated that this device protected even the more oxygen-sensitive clinical anaerobes from death due to oxygen exposure. This device can be used for swabs as well as for anaerobic collection and liquid and solid specimens. Images PMID:1104656

  8. DEHALOGENATION: A NOVEL PATHWAY FOR THE ANAEROBIC BIODEGRADATION OF HALOAROMATIC COMPOUNDS

    EPA Science Inventory

    Microorganisms of lake sediment and sewage sludge anaerobically metabolize halobenzoates by a novel pathway. The primary degradative event was loss of the aryl halide without the alteration of the aromatic ring. Dehalogenation required strict anaerobic conditions and depended on ...

  9. Acute effects of jaw clenching using a customized mouthguard on anaerobic ability and ventilatory flows.

    PubMed

    Morales, Jose; Buscà, Bernat; Solana-Tramunt, Mònica; Miró, Adrià

    2015-12-01

    The latest findings on the ergogenic effects of a dentistry-design, bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters. This paper was aimed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics, 30-s Wingate Anaerobic Test performance parameters. Twenty-eight healthy and physically-active male subjects (age: 24.50 ± 3.32, height: 181.34 ± 7.4, weight: 78.14 ± 8.21), were voluntarily studied. The subjects were first briefed on the test protocols, and then performed the 30s Wingate test and Spirometer test. The experimental trials were performed in a random counterbalanced order. We evaluate maximum expiratory volume (VEmax L min(-1)), mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), rate to fatigue (Ws(-1)) and lactate production (mMol L(-1)), rate of perceived exertion (RPE). There were significant differences between mouthguard and no-mouthguard conditions in mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), and rate to fatigue (Ws(-1)) for the 30-s Wingate Anaerobic Test. Significantly lower lactate production (mMol L(-1)) was observed, in mouthguard condition but no significant differences were found in RPE. In airflow dynamics, the VEmax L min(-1) was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions. In conclusion, wearing a customized mouthguard improves anaerobic ability and increases forced expiratory volume. This study will help practitioners improve athlete's performance in anaerobic activities where high intensity action might provoke jaw-clenching, contributing in reductions of lactate and fatigue, and improving ventilatory parameters. PMID:26415095

  10. Metagenome of an Anaerobic Microbial Community Decomposing Poplar Wood Chips

    SciTech Connect

    van der Lelie, D.; Taghavi, S.; McCorkle, S. M.; Li, L. L.; Malfatti, S. A.; Monteleone, D.; Donohoe, B. S.; Ding, S. Y.; Adney, W. S.; Himmel, M. E.; Tringe, S. G.

    2012-05-01

    This study describes the composition and metabolic potential of a lignocellulosic biomass degrading community that decays poplar wood chips under anaerobic conditions. We examined the community that developed on poplar biomass in a non-aerated bioreactor over the course of a year, with no microbial inoculation other than the naturally occurring organisms on the woody material. The composition of this community contrasts in important ways with biomass-degrading communities associated with higher organisms, which have evolved over millions of years into a symbiotic relationship. Both mammalian and insect hosts provide partial size reduction, chemical treatments (low or high pH environments), and complex enzymatic 'secretomes' that improve microbial access to cell wall polymers. We hypothesized that in order to efficiently degrade coarse untreated biomass, a spontaneously assembled free-living community must both employ alternative strategies, such as enzymatic lignin depolymerization, for accessing hemicellulose and cellulose and have a much broader metabolic potential than host-associated communities. This would suggest that such a community would make a valuable resource for finding new catalytic functions involved in biomass decomposition and gaining new insight into the poorly understood process of anaerobic lignin depolymerization. Therefore, in addition to determining the major players in this community, our work specifically aimed at identifying functions potentially involved in the depolymerization of cellulose, hemicelluloses, and lignin, and to assign specific roles to the prevalent community members in the collaborative process of biomass decomposition. A bacterium similar to Magnetospirillum was identified among the dominant community members, which could play a key role in the anaerobic breakdown of aromatic compounds. We suggest that these compounds are released from the lignin fraction in poplar hardwood during the decay process, which would point to

  11. In situ detection of anaerobic alkane metabolites in subsurface environments

    PubMed Central

    Agrawal, Akhil; Gieg, Lisa M.

    2013-01-01

    Alkanes comprise a substantial fraction of crude oil and refined fuels. As such, they are prevalent within deep subsurface fossil fuel deposits and in shallow subsurface environments such as aquifers that are contaminated with hydrocarbons. These environments are typically anaerobic, and host diverse microbial communities that can potentially use alkanes as substrates. Anaerobic alkane biodegradation has been reported to occur under nitrate-reducing, sulfate-reducing, and methanogenic conditions. Elucidating the pathways of anaerobic alkane metabolism has been of interest in order to understand how microbes can be used to remediate contaminated sites. Alkane activation primarily occurs by addition to fumarate, yielding alkylsuccinates, unique anaerobic metabolites that can be used to indicate in situ anaerobic alkane metabolism. These metabolites have been detected in hydrocarbon-contaminated shallow aquifers, offering strong evidence for intrinsic anaerobic bioremediation. Recently, studies have also revealed that alkylsuccinates are present in oil and coal seam production waters, indicating that anaerobic microbial communities can utilize alkanes in these deeper subsurface environments. In many crude oil reservoirs, the in situ anaerobic metabolism of hydrocarbons such as alkanes may be contributing to modern-day detrimental effects such as oilfield souring, or may lead to more beneficial technologies such as enhanced energy recovery from mature oilfields. In this review, we briefly describe the key metabolic pathways for anaerobic alkane (including n-alkanes, isoalkanes, and cyclic alkanes) metabolism and highlight several field reports wherein alkylsuccinates have provided evidence for anaerobic in situ alkane metabolism in shallow and deep subsurface environments. PMID:23761789

  12. Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens

    NASA Technical Reports Server (NTRS)

    Nealson, K. H.; Moser, D. P.; Saffarini, D. A.

    1995-01-01

    Shewanella putrefaciens MR-1 can grow either aerobically or anaerobically at the expense of many different electron acceptors and is often found in abundance at redox interfaces in nature. Such redox interfaces are often characterized by very strong gradients of electron acceptors resulting from rapid microbial metabolism. The coincidence of S. putrefaciens abundance with environmental gradients prompted an examination of the ability of MR-1 to sense and respond to electron acceptor gradients in the laboratory. In these experiments, taxis to the majority of the electron acceptors that S. putrefaciens utilizes for anaerobic growth was seen. All anaerobic electron acceptor taxis was eliminated by the presence of oxygen, nitrate, nitrite, elemental sulfur, or dimethyl sulfoxide, even though taxis to the latter was very weak and nitrate and nitrite respiration was normal in the presence of dimethyl sulfoxide. Studies with respiratory mutants of MR-1 revealed that several electron acceptors that could not be used for anaerobic growth nevertheless elicited normal anaerobic taxis. Mutant M56, which was unable to respire nitrite, showed normal taxis to nitrite, as well as the inhibition of taxis to other electron acceptors by nitrite. These results indicate that electron acceptor taxis in S. putrefaciens does not conform to the paradigm established for Escherichia coli and several other bacteria. Carbon chemo-taxis was also unusual in this organism: of all carbon compounds tested, the only positive response observed was to formate under anaerobic conditions.

  13. Anaerobic Digestion and its Applications

    EPA Science Inventory

    Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

  14. 42 CFR 418.58 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... collected to do the following: (i) Monitor the effectiveness and safety of services and quality of care. (ii..., patient safety, and quality of care. (2) Performance improvement activities must track adverse patient...: Patient Care § 418.58 Condition of participation: Quality assessment and performance improvement....

  15. 42 CFR 418.58 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... collected to do the following: (i) Monitor the effectiveness and safety of services and quality of care. (ii..., patient safety, and quality of care. (2) Performance improvement activities must track adverse patient...: Patient Care § 418.58 Condition of participation: Quality assessment and performance improvement....

  16. 42 CFR 486.348 - Condition: Quality assessment and performance improvement (QAPI).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Condition: Quality assessment and performance improvement (QAPI). 486.348 Section 486.348 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION CONDITIONS FOR COVERAGE OF SPECIALIZED SERVICES FURNISHED BY...

  17. 42 CFR 486.348 - Condition: Quality assessment and performance improvement (QAPI).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Condition: Quality assessment and performance improvement (QAPI). 486.348 Section 486.348 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION CONDITIONS FOR COVERAGE OF SPECIALIZED SERVICES FURNISHED BY...

  18. 42 CFR 482.96 - Condition of participation: Quality assessment and performance improvement (QAPI).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Condition of participation: Quality assessment and performance improvement (QAPI). 482.96 Section 482.96 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION CONDITIONS OF PARTICIPATION FOR HOSPITALS Requirements...

  19. 42 CFR 482.96 - Condition of participation: Quality assessment and performance improvement (QAPI).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Condition of participation: Quality assessment and performance improvement (QAPI). 482.96 Section 482.96 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION CONDITIONS OF PARTICIPATION FOR HOSPITALS Requirements...

  20. 33 CFR 329.8 - Improved or natural conditions of the waterbody.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Improved or natural conditions of the waterbody. 329.8 Section 329.8 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF... or natural conditions of the waterbody. Determinations are not limited to the natural or...

  1. 42 CFR 416.43 - Conditions for coverage-Quality assessment and performance improvement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 3 2014-10-01 2014-10-01 false Conditions for coverage-Quality assessment and performance improvement. 416.43 Section 416.43 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) AMBULATORY SURGICAL SERVICES Specific Conditions for Coverage §...

  2. 42 CFR 416.43 - Conditions for coverage-Quality assessment and performance improvement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 3 2013-10-01 2013-10-01 false Conditions for coverage-Quality assessment and performance improvement. 416.43 Section 416.43 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) AMBULATORY SURGICAL SERVICES Specific Conditions for Coverage §...

  3. 42 CFR 416.43 - Conditions for coverage-Quality assessment and performance improvement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 3 2012-10-01 2012-10-01 false Conditions for coverage-Quality assessment and performance improvement. 416.43 Section 416.43 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) AMBULATORY SURGICAL SERVICES Specific Conditions for Coverage §...

  4. 42 CFR 416.43 - Conditions for coverage-Quality assessment and performance improvement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 3 2011-10-01 2011-10-01 false Conditions for coverage-Quality assessment and performance improvement. 416.43 Section 416.43 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM AMBULATORY SURGICAL SERVICES Specific Conditions for Coverage § 416.43...

  5. 33 CFR 329.8 - Improved or natural conditions of the waterbody.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Improved or natural conditions of... or natural conditions of the waterbody. Determinations are not limited to the natural or original... navigable capacity of nearby waters as to nevertheless be subject to certain regulatory authorities. (b)...

  6. Anaerobic Metabolism and Bioremediation of Explosives-Contaminated Soil

    NASA Astrophysics Data System (ADS)

    Boopathy, Raj

    Nitroaromatic compounds pollute soil, water, and food via use of pesticides, plastics, pharmaceuticals, landfill dumping of industrial wastes, and the military use of explosives. Biotransformation of trinitrotoluene and other nitroaromatics by aerobic bacteria in the laboratory has been frequently reported, but the anaerobic bacterial metabolism of nitroaromatics has not been studied as extensively perhaps due to the difficulty in working with anaerobic cultures and the slow growth of anaerobes. Sulfate-reducing and methanogenic bacteria can metabolize nitroaromatic compounds under anaerobic conditions if appropriate electron donors and electron acceptors are present in the environment.

  7. Clinical review: Bacteremia caused by anaerobic bacteria in children

    PubMed Central

    Brook, Itzhak

    2002-01-01

    This review describes the microbiology, diagnosis and management of bacteremia caused by anaerobic bacteria in children. Bacteroides fragilis, Peptostreptococcus sp., Clostridium sp., and Fusobacterium sp. were the most common clinically significant anaerobic isolates. The strains of anaerobic organisms found depended, to a large extent, on the portal of entry and the underlying disease. Predisposing conditions include: malignant neoplasms, immunodeficiencies, chronic renal insufficiency, decubitus ulcers, perforation of viscus and appendicitis, and neonatal age. Organisms identical to those causing anaerobic bacteremia can often be recovered from other infected sites that may have served as a source of persistent bacteremia. When anaerobes resistant to penicillin are suspected or isolated, antimicrobial drugs such as clindamycin, chloramphenicol, metronidazole, cefoxitin, a carbapenem, or the combination of a beta-lactamase inhibitor and a penicillin should be administered. The early recognition of anaerobic bacteremia and administration of appropriate antimicrobial and surgical therapy play a significant role in preventing mortality and morbidity in pediatric patients. PMID:12133179

  8. ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER

    SciTech Connect

    John R. Gallagher

    2001-07-31

    reactor. Batch tests were conducted to examine naphthenic acid biodegradability under several conditions. The conditions used were seed from the anaerobic reactor, wetland sediments under aerobic and anaerobic conditions, and a sterile control. The naphthenic acid was from a commercial source isolated from Gulf Coast petroleum as was dosed at 2 mg/mL. The incubations were for 30 days at 30 C. The results showed that the naphthenic acids were not biodegraded under anaerobic conditions, but were degraded under aerobic conditions. Despite poor performance of the anaerobic reactor, it remains likely that anaerobic treatment of acetate, toluene, and, potentially, other produced-water components is feasible.

  9. Hyperthyroidism Improves the Pathological Condition of Nonalcoholic Steatohepatitis: A Case of Nonalcoholic Steatohepatitis with Graves' Disease.

    PubMed

    Miyake, Teruki; Matsuura, Bunzo; Furukawa, Shinya; Todo, Yasuhiko; Yamamoto, Shin; Yoshida, Osamu; Imai, Yusuke; Watanabe, Takao; Yamamoto, Yasunori; Hirooka, Masashi; Tokumoto, Yoshio; Kumagi, Teru; Abe, Masanori; Seike, Hirotaka; Miyauchi, Shozo; Hiasa, Yoichi

    2016-01-01

    3,5,3'-triiodo-L-thyronine regulates the glucose metabolism, lipid metabolism, and hepatic steatosis. Several groups have shown the relationships between hypothyroidism and nonalcoholic fatty liver and hypothyroidism and nonalcoholic steatohepatitis (NASH). However, the effect of hyperthyroidism on NASH has not yet been investigated. We herein report effects of thyroid hormone on the pathological condition of NASH in a patient with NASH complicated by Graves' disease. In our case, the liver enzyme level improved with the increasing thyroid hormone level; however, the liver enzyme level was aggravated with the improving thyroid hormone level. Therefore, hyperthyroidism may improve the pathological condition of NASH. PMID:27477408

  10. Anaerobic xylose fermentation by Spathaspora passalidarum.

    PubMed

    Hou, X

    2012-04-01

    A cost-effective conversion of lignocellulosic biomass into bioethanol requires that the xylose released from the hemicellulose fraction (20-40% of biomass) can be fermented. Baker's yeast, Saccharomyces cerevisiae, efficiently ferments glucose but it lacks the ability to ferment xylose. Xylose-fermenting yeast such as Pichia stipitis requires accurately controlled microaerophilic conditions during the xylose fermentation, rendering the process technically difficult and expensive. In this study, it is demonstrated that under anaerobic conditions Spathaspora passalidarum showed high ethanol production yield, fast cell growth, and rapid sugar consumption with xylose being consumed after glucose depletion, while P. stipitis was almost unable to utilize xylose under these conditions. It is further demonstrated that for S. passalidarum, the xylose conversion takes place by means of NADH-preferred xylose reductase (XR) and NAD(+)-dependent xylitol dehydrogenase (XDH). Thus, the capacity of S. passalidarum to utilize xylose under anaerobic conditions is possibly due to the balance between the cofactor's supply and demand through this XR-XDH pathway. Only few XRs with NADH preference have been reported so far. 2-Deoxy glucose completely inhibited the conversion of xylose by S. passalidarum under anaerobic conditions, but only partially did that under aerobic conditions. Thus, xylose uptake by S. passalidarum may be carried out by different xylose transport systems under anaerobic and aerobic conditions. The presence of glucose also repressed the enzymatic activity of XR and XDH from S. passalidarum as well as the activities of those enzymes from P. stipitis. PMID:22124720

  11. Membrane controlled anaerobic digestion

    NASA Astrophysics Data System (ADS)

    Omstead, D. R.

    In response to general shortages of energy, examination of the anaerboic digestion process as a potential source of a combustible, methane-rich fuel has intensified in recent years. It has been suggested that orgaic intermediates (such as fatty acids), produced during digestion, might also be recovered for use as chemical feedstocks. This investigation has been concerned with combining ultrafiltration separation techniques with anaerobic digestion for the development of a process in which the total production of acetic acid (the most valuable intermediate in anaerobic digestion) and methane are optimized. Enrichment cultures, able to utilize glucose as a sole carbon source, were adapted from sewage digesting cultures using conventional techniques. An ultrafiltration system was constructed and coupled to an anaerobic digester culture vessel which contained the glucose enrichment. The membrane controlled anaerobic digester appears to show promise as a means of producing high rates of both methane gas and acetic acid.

  12. Anaerobic brain abscess

    PubMed Central

    Sudhaharan, Sukanya; Chavali, Padmasri

    2016-01-01

    Background and Objectives: Brain abscess remains a potentially fatal central nervous system (CNS) disease, especially in developing countries. Anaerobic abscess is difficult to diagnose because of cumbersome procedures associated with the isolation of anaerobes. Materials and Methods: This is a hospital-based retrospective microbiological analysis of 430 brain abscess materials (purulent aspirates and/or tissue), for anaerobic organisms, that were received between 1987–2014, by the Microbiology Laboratory in our Institute. Results: Culture showed growth of bacteria 116/430 (27%) of the cases of which anaerobes were isolated in 48/116 (41.1%) of the cases. Peptostreptococcus (51.4 %), was the predominant organism isolated in four cases followed by Bacteroides and Peptococcus species. Conclusion: Early diagnosis and detection of these organisms would help in the appropriate management of these patients. PMID:27307977

  13. Anaerobic Soil Disinfestation and Soil Borne Pest Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD; also referred to as Biological Soil Disinfestation (BSD)) is a pre-plant soil treatment method developed to control plant disease and manage yield decline in many crop production systems. The practice involves induction of anaerobic soil conditions by increasing m...

  14. Aerobic and anaerobic microbial degradation of crude (4-methylcyclohexyl)methanol in river sediments.

    PubMed

    Yuan, Li; Zhi, Wei; Liu, Yangsheng; Smiley, Elizabeth; Gallagher, Daniel; Chen, Xi; Dietrich, Andrea; Zhang, Husen

    2016-03-15

    Cyclohexane and some of its derivatives have been a major concern because of their significant adverse human health effects and widespread occurrence in the environment. The 2014 West Virginia chemical spill has raised public attention to (4-methylcyclohexyl)methanol (4-MCHM), one cyclohexane derivative, which is widely used in coal processing but largely ignored. In particular, the environmental fate of its primary components, cis- and trans-4-MCHM, remains largely unexplored. This study aimed to investigate the degradation kinetics and mineralization of cis- and trans-4-MCHM by sediment microorganisms under aerobic and anaerobic conditions. We found the removal of cis- and trans-4-MCHM was mainly attributed to biodegradation with little contribution from sorption. A nearly complete aerobic degradation of 4-MCHM occurred within 14 days, whereas the anaerobic degradation was reluctant with residual percentages of 62.6% of cis-4-MCHM and 85.0% of trans-4-MCHM after 16-day incubation. The cis-4-MCHM was degraded faster than the trans under both aerobic and anaerobic conditions, indicating an isomer-specific degradation could occur during the 4-MCHM degradation. Nitrate addition enhanced 4-MCHM mineralization by about 50% under both aerobic and anaerobic conditions. Both cis- and trans-4-MCHM fit well with the first-order kinetic model with respective degradation rates of 0.46-0.52 and 0.19-0.31 day(-)(1) under aerobic condition. Respective degradation rates of 0.041-0.095 and 0.013-0.052 day(-)(1) occurred under anaerobic condition. One bacterial strain capable of effectively degrading 4-MCHM isomers was isolated from river sediments and identified as Bacillus pumilus at the species level based on 16S rRNA gene sequence and 97% identity. Our findings will provide critical information for improving the prediction of the environmental fate of 4-MCHM and other cyclohexane derivatives with similar structure as well as enhancing the development of feasible treatment

  15. Improvement of wall conditioning of the tandem mirror GAMMA 10 by ECR discharge cleaning

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Ichimura, M.; Imai, Y.; Inutake, M.; Mase, A.; Miyoshi, S.; Tsuboi, F.; Tsubouchi, D.; Yamaguchi, N.; Yatsu, K.; Sakamoto, Y.; Okazaki, K.; Peranich, L.; Leikind, B.

    1989-04-01

    Wall conditioning and results of ECR discharge cleaning (ECR-DC) in GAMMA 10 are described. Improvement of the wall condition is evaluated quantitatively in terms of residual gas analyses, dynamic pressure, visible spectroscopy and plasma parameters. These results show that light impurities and gas desorption from the wall by plasma discharges are reduced by more than one order of magnitude during a great number of plasma shots. The ECR-DC for 30 h with simultaneous baking considerably improves the wall condition. Light impurities and gas desorption are observed to be strongly reduced to lower levels which have not been attained without ECR-DC. Spectroscopic and diamagnetic loop measurements indicate that the electron temperature as well as ion temperature increases. Consequently, ECR-DC shortens dramatically the wall conditioning period by 2 to 3 weeks which corresponds to more than 1000 pulsed plasma shots.

  16. Affine Projection Algorithm with Improved Data-Selective Method Using the Condition Number

    NASA Astrophysics Data System (ADS)

    Ban, Sung Jun; Lee, Chang Woo; Kim, Sang Woo

    Recently, a data-selective method has been proposed to achieve low misalignment in affine projection algorithm (APA) by keeping the condition number of an input data matrix small. We present an improved method, and a complexity reduction algorithm for the APA with the data-selective method. Experimental results show that the proposed algorithm has lower misalignment and a lower condition number for an input data matrix than both the conventional APA and the APA with the previous data-selective method.

  17. A systematic review of strength and conditioning programmes designed to improve fitness characteristics in golfers.

    PubMed

    Smith, Christopher J; Callister, Robin; Lubans, David R

    2011-06-01

    It has been suggested that conditioning programmes have the potential to improve golf performance through fitness adaptations. The primary aim of this systematic review was to evaluate the effectiveness of conditioning programmes on measures of golf-related fitness and golf performance. Four electronic library databases were searched and the quality of the studies was assessed using criteria adapted from the Consolidated Standard of Reporting Trials statement. Thirteen studies satisfied our criteria for inclusion. Nine studies involved middle-aged to older male recreational golfers and four studies used younger more skilled golfers. Conditioning programmes involved the use of machine weights, free weights, medicine balls, and elastic bands, and most studies included a flexibility component. Most studies assessed changes in fitness characteristics and generally resulted in improvements. All but two of the studies assessed changes in club head speed and reported increases. The findings from this review suggest that strength and conditioning programmes can have a positive effect on the golf swing and fitness characteristics of golfers. The majority of studies in this review evaluated the effects of generic conditioning programmes on fitness characteristics and club head speed. Future studies should investigate the effects of more golf-specific strength and conditioning programmes to improve fitness and overall golf performance. PMID:21547836

  18. Biological pretreatment enhances biogas production in the anaerobic digestion of pulp and paper sludge.

    PubMed

    Lin Yunqin; Wang Dehan; Wang Lishang

    2010-09-01

    High efficient resource recovery from pulp and paper sludge (PPS) has been the focus of attention. The objective of this research was to develop a bio-pretreatment process prior to anaerobic digestion of PPS to improve the methane productivity. Active and inactive mushroom compost extracts (MCE) were used for pretreating PPS, followed by anaerobic digestion with monosodium glutamate waste liquor (MGWL). Laboratory-scale experiments were carried out in completely mixed bioreactors, 1-L capacity with 700 ml useful capacity. Optimal amount of active MCE for organics' solubilization in the step of pretreatment was 250 A.U./gVS( sludge). Under this condition, the PPS floc structure was well disrupted, resulting in void rate and fibre size diminishment after pretreatment. In addition, SCOD and VS removal were found to be 56% and 43.6%, respectively, after anaerobic digestion, being the peak value of VFA concentration determined as 1198 mg acetic acid L(-1). The anaerobic digestion efficiency of PPS with and without pretreatment was evaluated. The highest methane yield under optimal pretreatment conditions was 0.23 m(3) CH4/kgVS(add), being 134.2% of the control. The results indicated that MCE bio-pretreatment could be a cost-effective and environmentally sound method for producing methane from PPS. PMID:20147578

  19. Gender comparisons in anaerobic power and anaerobic capacity tests.

    PubMed Central

    Maud, P J; Shultz, B B

    1986-01-01

    The purpose of the study was to compare anaerobic power and anaerobic capacity test scores between young active men and women. Three performance measures of anaerobic power and two of anaerobic capacity were administered to a sample comprising 52 male and 50 female college students (means age = 21.4 yrs). Results indicated significant differences between men and women in body height, weight and per cent fat, in fat free mass (FFM), anaerobic power, and anaerobic capacity when recorded as gross work completed and relative to body weight. However, these differences are reduced when data is adjusted for body weight and further reduced when corrected for FFM. The study found no significant differences between men and women in either anaerobic power or anaerobic capacity when values were given relative to FFM. PMID:3730753

  20. Energy transduction by anaerobic ferric iron respiration in Thiobacillus ferrooxidans

    SciTech Connect

    Pronk, J.T.; Liem, K.; Bos, P.; Kuenen, J.G. )

    1991-07-01

    Formate-grown cells of the obligately chemolithoautotrophic acidophile Thiobacillus ferrooxidans were capable of formate- and elemental sulfur-dependent reduction of ferric iron under anaerovic conditions. Under aerobic conditions, both oxygen and ferric iron could be simultaneously used as electron acceptors. To investigate whether anaerobic ferric iron respiration by T. ferrooxidans is an energy-transducing process, uptake of amino acids was studied. Glycine uptake by starved cells did not occur in the absence of an electron donor, neither under aerobic conditions nor under anaerobic conditions. Uptake of glycine could be driven by formate- and ferrous iron-dependent oxygen uptake. Under anaerobic conditions, ferric iron respiration with the electron donors formate and elemental sulfur could energize glycine uptake. Glycine uptake was inhibited by the uncoupler 2,4-dinitrophenol. The results indicate that anaerobic ferric iron respiration can contribute to the energy budget of T. ferrooxidans.

  1. Conditional Sox9 ablation improves locomotor recovery after spinal cord injury by increasing reactive sprouting.

    PubMed

    McKillop, William M; York, Elisa M; Rubinger, Luc; Liu, Tony; Ossowski, Natalie M; Xu, Kathy; Hryciw, Todd; Brown, Arthur

    2016-09-01

    The absence of axonal regeneration after spinal cord injury (SCI) has been attributed to the up-regulation of axon-repelling molecules, such as chondroitin sulfate proteoglycans (CSPGs) present in the glial scar that forms post-SCI. We previously identified the transcription factor SOX9 as a key up-regulator of CSPG production and also demonstrated that conditional Sox9 ablation leads to decreased CSPG levels and improved recovery of hind limb function after SCI. We herein demonstrate increased neural input onto spinal neurons caudal to the lesion in spinal cord injured Sox9 conditional knock out mice as indicated by increased levels of the presynaptic markers synaptophysin and vesicular glutamate transporter 1 (VGLUT1) compared to controls. Axonal sparing, long-range axonal regeneration and reactive sprouting were investigated as possible explanations for the increase in neural inputs caudal to the lesion and for the improved locomotor outcomes in spinal cord-injured Sox9 conditional knock out mice. Whereas retrograde tract-tracing studies failed to reveal any evidence for increased axonal sparing or for long-range regeneration in the Sox9 conditional knock out mice, anterograde tract-tracing experiments demonstrated increased reactive sprouting caudal to the lesion after SCI. Finally we demonstrate that application of a broad spectrum MMP inhibitor to reduce CSPG degradation in Sox9 conditional knock out mice prevents the improvements in locomotor recovery observed in untreated Sox9 conditional knock out mice. These results suggest that improved recovery of locomotor function in Sox9 conditional knock out mice after SCI is due to increased reactive sprouting secondary to reduced CSPG levels distal to the lesion. PMID:27235933

  2. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Science Inventory

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  3. Methods for improved forewarning of condition changes in monitoring physical processes

    DOEpatents

    Hively, Lee M.

    2013-04-09

    This invention teaches further improvements in methods for forewarning of critical events via phase-space dissimilarity analysis of data from biomedical equipment, mechanical devices, and other physical processes. One improvement involves objective determination of a forewarning threshold (U.sub.FW), together with a failure-onset threshold (U.sub.FAIL) corresponding to a normalized value of a composite measure (C) of dissimilarity; and providing a visual or audible indication to a human observer of failure forewarning and/or failure onset. Another improvement relates to symbolization of the data according the binary numbers representing the slope between adjacent data points. Another improvement relates to adding measures of dissimilarity based on state-to-state dynamical changes of the system. And still another improvement relates to using a Shannon entropy as the measure of condition change in lieu of a connected or unconnected phase space.

  4. 33 CFR 329.8 - Improved or natural conditions of the waterbody.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... condition of the waterbody. Navigability may also be found where artificial aids have been or may be used to make the waterbody suitable for use in navigation. (a) Existing improvements: artificial waterbodies. (1) An artificial channel may often constitute a navigable water of the United States, even though...

  5. 33 CFR 329.8 - Improved or natural conditions of the waterbody.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... condition of the waterbody. Navigability may also be found where artificial aids have been or may be used to make the waterbody suitable for use in navigation. (a) Existing improvements: artificial waterbodies. (1) An artificial channel may often constitute a navigable water of the United States, even though...

  6. 42 CFR 482.21 - Condition of participation: Quality assessment and performance improvement program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... must use the data collected to— (i) Monitor the effectiveness and safety of services and quality of... performance improvement program. 482.21 Section 482.21 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION CONDITIONS OF...

  7. What is the Business Case for Improving Care for Patients with Complex Conditions?

    PubMed Central

    Parkerton, Patricia; Hagigi, Fred

    2007-01-01

    INTRODUCTION Patients with complex conditions account for a disproportionate share of health care spending. Although evidence indicates that care for these patients could be provided more efficiently, the financial impact of mechanisms to improve the care they receive is unclear. DESIGN/METHODS Numerous mechanisms—emphasizing patient self-management, care coordination, and evidence-based guidelines—aim to improve the quality of care and outcomes for patients with complex conditions. Assessing the overall “business case” for these mechanisms requires carefully estimating all relevant costs and financial benefits, then comparing them in present value terms. Mechanisms that are not cost-saving may still be implemented if they are cost-effective. We reviewed articles in peer-reviewed journals, as well as reports available on publicly accessible websites, which contained data about the business case for mechanisms to improve care for patients with complex conditions. MAIN RESULTS Published studies do not provide clear evidence that current mechanisms are cost saving. This literature also has several major methodological shortcomings with respect to providing an understanding of the business case for these mechanisms. CONCLUSIONS Further research using standardized methodologies is needed to understand the business case for mechanisms to improve care for patients with complex conditions. Implications for VA business case analyses include the necessity of establishing appropriate time horizons, scope of services, and target populations, as well as considering the impact of existing VA systems. PMID:18026808

  8. 42 CFR 418.58 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... collected to do the following: (i) Monitor the effectiveness and safety of services and quality of care. (ii..., patient safety, and quality of care. (2) Performance improvement activities must track adverse patient... Participation: Patient Care § 418.58 Condition of participation: Quality assessment and performance...

  9. 42 CFR 418.58 - Condition of participation: Quality assessment and performance improvement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... collected to do the following: (i) Monitor the effectiveness and safety of services and quality of care. (ii..., patient safety, and quality of care. (2) Performance improvement activities must track adverse patient... Participation: Patient Care § 418.58 Condition of participation: Quality assessment and performance...

  10. Anaerobes: a new aetiology in cavitary pneumoconiosis.

    PubMed Central

    del Campo, J M; Hitado, J; Gea, G; Colmeiro, A; Lanza, A M; Muñoz, J A; Mosquera, J A

    1982-01-01

    The role of mycobacteria in the cavitation of large pneumoconiotic masses is well established. In other cases softness is attributed to an ischaemic or aseptic necrosis. Five cases are described in which cavitation of the pulmonary masses was caused by anaerobic bacteria, confirmed by the growth of such bacterial in cultures after transtracheal or transpleural puncture. Repeated cultures for mycobacteria gave negative results. Two cases were acute, having serious complications such as bronchopleural fistula, empyema, and serious respiratory insufficiency. The role of anaerobes in cavitary pneumoconiosis has not been recognised previously, probably because of the special conditions required to culture these bacteria and the infrequent use of transtracheal puncture in the diagnosis of this entity. The prevalence of anaerobes as agents capable of cavitating pneumoconiotic masses remains to be established. Images PMID:6128024

  11. Microbiological mechanism of the improved nitrogen and phosphorus removal by embedding microbial fuel cell in Anaerobic-Anoxic-Oxic wastewater treatment process.

    PubMed

    Xie, Beizhen; Liu, Bojie; Yi, Yue; Yang, Lige; Liang, Dawei; Zhu, Ying; Liu, Hong

    2016-05-01

    Anaerobic-Anoxic-Oxic (AA/O) wastewater treatment process is a widely used wastewater treatment process for simultaneous nitrogen and phosphorus removal. Microbial fuel cell (MFC) can generate electricity and treat the organic wastewater simultaneously. Our previous research showed that embedding MFC in AA/O wastewater treatment process could enhance the pollutants removal efficiency. However, the mechanism was not clear. In this study, a lab-scale corridor-style AA/O reactor with MFC embedded was operated and both the total nitrogen and total phosphorus removal efficiencies were enhanced. DGGE and Illumina Miseq results demonstrated that both the microbial community structures on the surface of the cathode and in the suspensions of cathode chamber have been changed. The percentage of Thauera and Emticicia, identified as denitrifying bacteria, increased significantly in the suspension liquid when the MFC was embedded in the AA/O reactor. Moreover, the genus Rheinheimera were significantly enriched on the cathode surface, which might contribute to both the nitrogen removal enhancement and electricity generation. PMID:26874439

  12. THERMOPHILIC ANAEROBIC BIODEGRADATION OF PHENOLICS

    EPA Science Inventory

    The report gives results of a series of anaerobic microbial acclimation and treatment performance tests with synthetic phenolic substrates. The research is a feasibility level assessment of substituting anaerobic biodegradation of phenolics for solvent extraction. The tests showe...

  13. Comparison of Aerobic and Anaerobic Biodegradation of Sugarcane Vinasse.

    PubMed

    Mota, V T; Araújo, T A; Amaral, M C S

    2015-07-01

    Vinasse is the main liquid waste from ethanol production, and it has a considerable pollution potential. Biological treatment is a promising alternative to reduce its organic load. The aim of this study was to analyze the biodegradation of sugarcane juice vinasse in aerobic and anaerobic conditions. The content of carbohydrates, proteins and volatile fatty acids was evaluated. Vinasse samples showed a high biodegradability (>96.5 %) and low percentage of inert chemical oxygen demand (COD) (<3.2 %) in both aerobic and anaerobic conditions. The rates of substrate utilization were slightly higher in aerobic reactors, but COD stabilization occurred simultaneously in the anaerobic reactors, confirming its suitability for anaerobic digestion. Inert COD in anaerobic conditions was lower than in aerobic conditions. On the other hand, COD from metabolic products in the anaerobic reactors was higher than in the aerobic ones, indicating an increased release of soluble microbial products (SMPs) by anaerobic microorganisms. The results indicated that carbohydrates were satisfactorily degraded and protein-like substances were the major components remaining after biological degradation of vinasse. PMID:25957273

  14. Anaerobic degradation of linear alkylbenzene sulfonate.

    PubMed

    Mogensen, Anders S; Haagensen, Frank; Ahring, Birgitte K

    2003-04-01

    Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C12 LAS), which show that C12 LAS was biodegradable under methanogenic conditions. Sorption of C12 LAS on sewage sludge was described with a Freundlich isotherm. The C12 LAS sorption was determined with different concentrations of total solids (TS). In the semi-continuously stirred tank reactor, 18% of the added C12 LAS was bioavailable and 20% was biotransformed when spiking with 100 mg/L of C12 LAS and a TS concentration of 14.2 mg/L. Enhanced bioavailability of C12 LAS was obtained in an upflow anaerobic sludge blanket (UASB) reactor inoculated with granular sludge and sewage sludge. Biodegradation under thermophilic conditions was 37% with LAS as sole carbon source. Benzaldehyde was produced in the UASB reactor during LAS transformation. PMID:12685701

  15. Application of Novel Amino-Functionalized NZVI@SiO2 Nanoparticles to Enhance Anaerobic Granular Sludge Removal of 2,4,6-Trichlorophenol

    PubMed Central

    Guan, Zeyu; Wan, Jinquan; Ma, Yongwen; Wang, Yan; Shu, Yajie

    2015-01-01

    A novel amino-functionalized silica-coated nanoscale zerovalent iron (NZVI@SiO2-NH2) was successfully synthesized by using one-step liquid-phase method with the surface functionalization of nanoscale zerovalent iron (NZVI) to enhance degradation of chlorinated organic contaminants from anaerobic microbial system. NZVI@SiO2-NH2 nanoparticles were synthesized under optimal conditions with the uniform core-shell structure (80–100 nm), high loading of amino functionality (~0.9 wt%), and relatively large specific surface area (126.3 m2/g). The result demonstrated that well-dispersed NZVI@SiO2-NH2 nanoparticle with nFe0-core and amino-functional silicon shell can effectively remove 2,4,6-trichlorophenol (2,4,6-TCP) in the neutral condition, much higher than that of NZVI. Besides, the surface-modified nanoparticles (NZVI@SiO2-NH2) in anaerobic granule sludge system also showed a positive effect to promote anaerobic biodechlorination system. More than 94.6% of 2,4,6-TCP was removed from the combined NZVI@SiO2-NH2-anaerobic granular sludge system during the anaerobic dechlorination processes. Moreover, adding the appropriate concentration of NZVI@SiO2-NH2 in anaerobic granular sludge treatment system can decrease the toxicity of 2,4,6-TCP to anaerobic microorganisms and improved the cumulative amount of methane production and electron transport system activity. The results from this study clearly demonstrated that the NZVI@SiO2-NH2/anaerobic granular sludge system could become an effective and promising technology for the removal of chlorophenols in industrial wastewater. PMID:26060427

  16. Metabolic modelling of syntrophic-like growth of a 1,3-propanediol producer, Clostridium butyricum, and a methanogenic archeon, Methanosarcina mazei, under anaerobic conditions.

    PubMed

    Bizukojc, Marcin; Dietz, David; Sun, Jibin; Zeng, An-Ping

    2010-05-01

    Clostridium butyricum can convert glycerol into 1,3-propanediol, thereby generating unfortunately a high amount of acetate, formate and butyrate as inhibiting by-products. We have proposed a novel mixed culture comprising C. butyricum and a methane bacterium, Methanosarcina mazei, to relieve the inhibition and to utilise the by-products for energy production. In order to examine the efficiency of such a mixed culture, metabolic modelling of the culture system was performed in this work. The metabolic networks for the organisms were reconstructed from genomic and physiological data. Several scenarios were analysed to examine the preference of M. mazei in scavenging acetate and formate under conditions of different substrate availability, including methanol as a co-substrate, since it may exist in glycerol solution from biodiesel production. The calculations revealed that if methanol is present, the methane production can increase by 130%. M. mazei can scavenge over 70% of the acetate secreted by C. butyricum. PMID:19680695

  17. Improved Gauge Conditions and Evolution Techniques for Puncture Black Hole Simulations

    NASA Astrophysics Data System (ADS)

    Etienne, Zachariah; Baker, John; Paschalidis, Vasileios; Shapiro, Stuart; Kelly, Bernard

    2014-03-01

    Robust spacetime gauge conditions are critically important to the stability and accuracy of numerical relativity (NR) simulations involving puncture black holes. Most of the NR community continues to use the highly-robust--though nearly decade-old--``moving-puncture gauge conditions'' for such simulations. We present improved gauge conditions and evolution techniques that reduce constraint violations by more than an order of magnitude on adaptive-mesh refinement (AMR) grids. It has been found that high-frequency waves propagating away from puncture black holes (e.g., in binary systems) cross progressively lower levels of refinement until they become under-resolved and reflect off an AMR boundary, leading to noisy gravitational waveforms. Such noise does not converge away cleanly with increasing resolution, effectively setting a hard upper limit on waveform accuracy using puncture techniques at computationally feasible resolutions. We demonstrate that our improved puncture gauge conditions reduce this noise by nearly an order of magnitude, and point to possible directions for future improvements.

  18. The anaerobic digestion process

    SciTech Connect

    Rivard, C.J.; Boone, D.R.

    1996-01-01

    The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.

  19. Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

    PubMed Central

    Carmona, Manuel; Zamarro, María Teresa; Blázquez, Blas; Durante-Rodríguez, Gonzalo; Juárez, Javier F.; Valderrama, J. Andrés; Barragán, María J. L.; García, José Luis; Díaz, Eduardo

    2009-01-01

    Summary: Aromatic compounds belong to one of the most widely distributed classes of organic compounds in nature, and a significant number of xenobiotics belong to this family of compounds. Since many habitats containing large amounts of aromatic compounds are often anoxic, the anaerobic catabolism of aromatic compounds by microorganisms becomes crucial in biogeochemical cycles and in the sustainable development of the biosphere. The mineralization of aromatic compounds by facultative or obligate anaerobic bacteria can be coupled to anaerobic respiration with a variety of electron acceptors as well as to fermentation and anoxygenic photosynthesis. Since the redox potential of the electron-accepting system dictates the degradative strategy, there is wide biochemical diversity among anaerobic aromatic degraders. However, the genetic determinants of all these processes and the mechanisms involved in their regulation are much less studied. This review focuses on the recent findings that standard molecular biology approaches together with new high-throughput technologies (e.g., genome sequencing, transcriptomics, proteomics, and metagenomics) have provided regarding the genetics, regulation, ecophysiology, and evolution of anaerobic aromatic degradation pathways. These studies revealed that the anaerobic catabolism of aromatic compounds is more diverse and widespread than previously thought, and the complex metabolic and stress programs associated with the use of aromatic compounds under anaerobic conditions are starting to be unraveled. Anaerobic biotransformation processes based on unprecedented enzymes and pathways with novel metabolic capabilities, as well as the design of novel regulatory circuits and catabolic networks of great biotechnological potential in synthetic biology, are now feasible to approach. PMID:19258534

  20. Corrosion of iron and low alloyed steel within a water saturated brick of clay under anaerobic deep geological disposal conditions: An integrated experiment

    NASA Astrophysics Data System (ADS)

    Martin, F. A.; Bataillon, C.; Schlegel, M. L.

    2008-09-01

    The aim of this study was to determine the corrosion behaviour of iron and low alloyed steels under simulated geological disposal conditions, related to long-term disposal of nuclear wastes in the site of Bure (Meuse-Haute Marne, Champagne, France). The dedicated experiment was a fully integrated set-up: three different bars of material (iron, steel or nickel) have been introduced inside a solid block of clay, which has been saturated with synthetic Bure water and maintained at 90 °C during 8 months. Two types of clay have been tested: first, a compacted MX80 (Wyoming, USA) and second, argilite directly taken from the Bure site (Callovo-Oxfordian). In situ electrochemistry has been performed: impedance spectra, chronopotentiometry… The samples have been analysed using a combination of techniques, such as SEM, XRD, EDS, μXAS, μRaman, gravimetry after desquamation. In both cases, the steel or the iron seemed to passivate in contact with the clay. Post-processing of the EIS determined the corrosion rates and the changes in the kinetics have been noticed. The post mortem analysis of the corrosion products showed in both cases the presence of an internal layer made of magnetite (Raman, EDX). The external layer was made of partially Ca-substituted siderite (Fe 1-xCa xCO 3), which could play an extra role in the passivation. Moreover, the samples embedded in the Bure argilite presented an intermediate unique layer containing Fe, O, Na and Si. This study suggests the corrosion products started to react with the silica issued from the dissolution of the Bure clay minerals, resulting in clay minerals neo-formation and in corrosion kinetic changes.

  1. Isotopic Disequilibrium Between Carbon Fixed and Released in a Rice Paddy Ecosystem as Influenced by Methanogenesis From CO2 Under Anaerobic Conditions

    NASA Astrophysics Data System (ADS)

    Han, G. H.; Yoshikoshi, H.; Nagai, H.; Yamada, T.; Ono, K.; Miyata, A.; Harazono, Y.

    2004-12-01

    Stable carbon isotope ratios of various ecosystem components and ecosystem respiration (\\deltaR) were measured in a Japanese rice paddy. An automated air sampling system was used to collect nighttime air samples to estimate \\deltaR by means of Keeling plot. Throughout the growing season in 2003, significantly (3\\permil to 4\\permil) higher \\delta13C values were observed in \\deltaR than those observed in plant tissue samples, indicating a strong decoupling process for carbon assimilated and respired in the ecosystem. It is well known that production of methane from CO2 exhibits a larger isotope fractionation than that can be found in equilibration of CO2 with soil water. CO2 entrapped in soil showed 5.5\\permil to 7.5\\permil higher \\delta13C values than \\deltaR. Given these isotopic differences, we partitioned total ecosystem respiration into plant respiration and soil (including root) respiration components with an assumption that there is no isotope fractionation associated with respiratory processes of rice plant. The estimated proportion of soil respiration to total ecosystem respiration was about 30% under flooded conditions, but increased to about 40% by floodwater drainage. The partitioned respiratory fluxes from soil contributed to reducing the discrepancy between measured plant biomass increase and accumulated net ecosystem exchange (NEE) for the entire growing season. Partitioning NEE into photosynthetic assimilation and ecosystem respiration based on the isoflux approach revealed that floodwater drainage increased daytime respiratory fluxes greater than the estimated respiratory fluxes from an exponential relationship between nocturnal NEE and air temperature.

  2. The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions.

    PubMed

    Wang, Shaofeng; He, Xin Yu; Pan, Rongrong; Xu, Liying; Wang, Xin; Jia, Yongfeng

    2016-04-01

    The effect of microbial sulfidogenesis on As transformation and mobilization in solid phase with low Fe/As ratio is still not well known. In this study, microbial transformation and mobilization of As in the As-Fe coprecipitate with different sulfate levels were investigated using chemical extraction and K-edge XANES of As and S. Results showed that approximately 2.7, 24.4, and 83.7 % of total As were released into the aqueous phase in the low-, mid-, and high-sulfate treatments, respectively, indicating that the presence of large amounts of sulfate could enhance microbial arsenic mobilization in the As-Fe coprecipitate. In the low-sulfate treatment, As mobilization was primarily attributed to the reductive dissolution of the Fe (oxy)hydroxides and the As reduction and desorption. In the mid- and high-sulfate treatments, the reduction of arsenate and ferric iron was significantly enhanced. Complete ferric iron reduction was observed in the solid phase, implying that Fe (oxy)hydroxide was transformed to secondary minerals and may be the one of the primary causes for the enhanced As mobilization. Thermodynamic calculations predicted the formation of thioarsenite species after 35 days of incubation based on the concentration of dissolved As(III) and S(-II). Since thioarsenic species is more mobile, its formation may be one of the most important factors enhancing the As release in the high-sulfate system. The result of this study is of significance to completely predict the environmental behavior of As associated with Fe (hydr)oxides in the presence of microbial sulfidogenesis under anoxic conditions. PMID:26676545

  3. An ergonomic approach to improve work conditions of older employees in social housing.

    PubMed

    Biquand, Sylvain; Heddad, Nadia

    2012-01-01

    French companies are legally required to develop action plans to improve employment and work conditions for older workers ("plans seniors"). These plans contain measures oriented towards recruiting, career evolution, skills developme1nt, knowledge transmission and improvement of work conditions. A tool for assessing work situations experienced by council buildings caretakers ("gardiens") was used in such a plan on behalf of the main agency of council housing in Paris, and we developed. This assessment tool was developed after ergonomic work analysis on a sample of 36 older caretakers (age > 57 y.o). The technical inspectors in charge of technical interventions on buildings and managing caretakers were trained to use the assessment tool and apply it to all caretakers aged 50 and over. PMID:22316754

  4. Advancing medical-surgical nursing practice: improving management of the changing patient condition.

    PubMed

    Monroe, Heidi; Plylar, Peggy; Krugman, Mary

    2014-01-01

    Higher patient acuities and more novice nurses on medical-surgical units have Educators focused on achieving positive outcomes with changes in patient condition. An educational program was developed to enhance nurses' knowledge, skill, and confidence in assessing hemodynamics, recognizing early signs of instability, and administering vasoactive medications. The program was successful with significant knowledge improvement as well as an increased use of the Medical Emergency Team while maintaining a low number of code calls. PMID:25407973

  5. Anaerobic digestion for household organics

    SciTech Connect

    Sinclair, R.; Kelleher, M.

    1995-04-01

    Considerable success in using anaerobic technology for processing household organics is being reported by several recently constructed facilities in Europe. Organic residuals collected separately in a Belgian town are processed to produce biogas and a compost-like material in less than one month. The dry anaerobic conversion process (DRANCO) was developed by Organic Waste Systems (OWS) in the 1980s, with the collaboration of Professor Willy Verstraete at the University of Ghent`s Laboratory of Applied Microbial Ecology. The patented process converts solid and semisolid organic residuals into biogas (for energy recovery) and a stable humus like product. The plant has competing odor sources such as the active landfill and the surrounding farmland - in fact, the smell of livestock manure is quite prevalent in this heavily agricultural area. Addition of the nonrecyclable paper fraction to the feedstock improves the carbon/nitrogen ratio, soaks up moisture, and absorbs odor. The entire Brecht facility does not occupy much space and total material retention time at the site is one month, compared to a number of months for aerobic systems. It also has a low staffing requirement, provides energy self-sufficiency, and the final soil enhancement product meets established quality standards.

  6. Antimicrobials therapy of anaerobic infections.

    PubMed

    Brook, Itzhak

    2016-06-01

    Anaerobes predominant in the normal human skin and mucous membranes bacterial flora are often a cause of endogenous infections. Anaerobic bacteria are difficult to isolate from infectious sites, and are often overlooked. Anaerobic infections caused by anaerobes can occur in all body sites, including the central nervous system (CNS), oral cavity, head and neck, chest, abdomen, pelvis, skin and soft tissues. The treatment of these infections is complicated by the slow growth of these organisms, their polymicrobial nature and the growing resistance of anaerobes to antimicrobials agents. Antimicrobials are frequently the only form of therapy needed, but in others, they are an important adjunct to surgical drainage and correction of pathology. Because anaerobes are often recovered with aerobic and facultative bacteria, the chosen antimicrobials should cover all pathogens. The antimicrobials effective against anaerobic organisms are metronidazole, carbapenems, combinations of a beta-lactam and a beta-lactamase inhibitor, chloramphenicol, tigecycline and clindamycin. PMID:26365224

  7. Defined enzyme cocktail from the anaerobic fungus Orpinomyces sp. strain C1A effectively releases sugars from pretreated corn stover and switchgrass.

    PubMed

    Morrison, Jessica M; Elshahed, Mostafa S; Youssef, Noha H

    2016-01-01

    The anaerobic fungus Orpinomyces strain C1A is capable of growth on various types of lignocellulosic substrates, and harbors an impressive reservoir of carbohydrate active enzymes (CAZymes). Using a minimum enzyme cocktail strategy, we constituted a four-component lignocellulolytic cocktail derived from highly transcribed C1A, and evaluated its efficacy against pretreated corn stover and switchgrass. Hydrolysis yields ranged between 65-77.4%, depending on the lignocellulosic substrate and pretreatment applied. Addition of a highly expressed anaerobic fungal swollenin improved hydrolysis yields by up to 7%. Compared to the commercial cocktail CTec2, these anaerobic fungal cocktails provided comparable or slightly lower hydrolysis yields. Further, the differences in efficacy between commercial and anaerobic cocktails were often only realized after extended (168 hr) incubations. Under certain conditions, the hydrolysis yields of the anaerobic fungal cocktail was slightly superior to that realized by CTec2. We attribute the observed high hydrolysis yields to the high specific activity and affinity of the individual enzymes of the cocktail, as well as the high level of synergy and multi-functionality observed in multiple components. Collectively, this effort provides a novel platform for constructing highly effective enzymes for biofuel production and represents the first lignocellulolytic enzyme cocktail created from anaerobic fungal enzymes. PMID:27381262

  8. Defined enzyme cocktail from the anaerobic fungus Orpinomyces sp. strain C1A effectively releases sugars from pretreated corn stover and switchgrass

    PubMed Central

    Morrison, Jessica M.; Elshahed, Mostafa S.; Youssef, Noha H.

    2016-01-01

    The anaerobic fungus Orpinomyces strain C1A is capable of growth on various types of lignocellulosic substrates, and harbors an impressive reservoir of carbohydrate active enzymes (CAZymes). Using a minimum enzyme cocktail strategy, we constituted a four-component lignocellulolytic cocktail derived from highly transcribed C1A, and evaluated its efficacy against pretreated corn stover and switchgrass. Hydrolysis yields ranged between 65–77.4%, depending on the lignocellulosic substrate and pretreatment applied. Addition of a highly expressed anaerobic fungal swollenin improved hydrolysis yields by up to 7%. Compared to the commercial cocktail CTec2, these anaerobic fungal cocktails provided comparable or slightly lower hydrolysis yields. Further, the differences in efficacy between commercial and anaerobic cocktails were often only realized after extended (168 hr) incubations. Under certain conditions, the hydrolysis yields of the anaerobic fungal cocktail was slightly superior to that realized by CTec2. We attribute the observed high hydrolysis yields to the high specific activity and affinity of the individual enzymes of the cocktail, as well as the high level of synergy and multi-functionality observed in multiple components. Collectively, this effort provides a novel platform for constructing highly effective enzymes for biofuel production and represents the first lignocellulolytic enzyme cocktail created from anaerobic fungal enzymes. PMID:27381262

  9. Aeration of anaerobically digested sewage sludge for COD and nitrogen removal: optimization at large-scale.

    PubMed

    Parravicini, V; Svardal, K; Hornek, R; Kroiss, H

    2008-01-01

    The paper will report about the experiences at an Austrian large wastewater treatment plant of 720,000 population equivalents, where anaerobically digested sewage sludge is further stabilised under aerobic conditions. Enhanced stabilisation of the anaerobically digested sludge was required at the plant in order to get a permit for landfill disposal of the dewatered stabilized sludge. By implementing a post-aeration treatment (SRT approximately 6d; 36 degrees C) after anaerobic digestion the organic content of the anaerobically well digested sludge can be decreased by 16%. Investigations on site showed that during digested sludge post-aeration anoxic phases for denitrification are needed to provide stable process conditions. In this way the pH value can be kept in a more favourable range for micro-organisms and concrete structures. Additionally, inhibition of the biological process due to nitrite accumulation can be avoided. By optimising the aeration/pause ratio approximately 45% of total nitrogen in digested sludge can be removed. This significantly improves nitrogen removal efficiency at the wastewater treatment plant. NH(4)-removal occurs mainly through nitritation and denitritation with an efficiency of 98%. The costs/benefit analysis shows that post-aeration of digested sludge results in an increase of total annual costs for wastewater treatment of only 0.84%, corresponding to 0.19 Euro/pe/a. Result of molecular biological analyses (DGGE) indicate that all four ammonium-oxidizing bacteria species present in activated sludge can survive anaerobic digestion, but only two of them can adapt in the digested sludge post-aeration tanks. Additionally, in the post-aerated digested sludge a further ammonium-oxidizing bacteria species was identified. PMID:18235180

  10. Flue gas conditioning for improved particle collection in electrostatic precipitators. Quarterly technical report

    SciTech Connect

    Durham, M.D.

    1992-04-27

    The purpose of this research program is to identify and evaluate a variety of additives capable of increasing particle cohesion which could be used for improving collection efficiency in an ESP. A three-phase screening process will be used to provide the, evaluation of many additives in a logical and cost-effective manner. The three step approach involves the following experimental setups: 1. Provide a preliminary screening in the laboratory by measuring the effects of various conditioning agents on reentrainment of flyash particles in an electric field operating at simulated flue gas conditions. 2. Evaluate the successful additives using a 100 acfm bench-scale ESP operating on actual flue gas. 3. Obtain the data required for scaling up the technology by testing the two or three most promising conditioning agents at the pilot scale.

  11. Calorimetric studies of the growth of anaerobic microbes.

    PubMed

    Miyake, Hideo; Maeda, Yukiko; Ishikawa, Takashi; Tanaka, Akiyoshi

    2016-09-01

    This article aims to validate the use of calorimetry to measure the growth of anaerobic microbes. It has been difficult to monitor the growth of strict anaerobes while maintaining optimal growth conditions. Traditionally, optical density and ATP concentration are usually used as measures of the growth of anaerobic microbes. However, to take these measurements it is necessary to extract an aliquot of the culture, which can be difficult while maintaining anaerobic conditions. In this study, calorimetry was used to continuously and nondestructively measure the heat generated by the growth of anaerobic microbes as a function of time. Clostridium acetobutylicum, Clostridium beijerinckii, and Clostridium cellulovorans were used as representative anaerobic microbes. Using a multiplex isothermal calorimeter, we observed that peak time (tp) of C. acetobutylicum heat evolution increased as the inoculation rate decreased. This strong correlation between the inoculation rate and tp showed that it was possible to measure the growth rate of anaerobic microbes by calorimetry. Overall, our results showed that there is a very good correlation between heat evolution and optical density/ATP concentration, validating the use of the method. PMID:27012376

  12. Improving wait times to care for individuals with multimorbidities and complex conditions using value stream mapping

    PubMed Central

    Sampalli, Tara; Desy, Michel; Dhir, Minakshi; Edwards, Lynn; Dickson, Robert; Blackmore, Gail

    2015-01-01

    Background: Recognizing the significant impact of wait times for care for individuals with complex chronic conditions, we applied a LEAN methodology, namely – an adaptation of Value Stream Mapping (VSM) to meet the needs of people with multiple chronic conditions and to improve wait times without additional resources or funding. Methods: Over an 18-month time period, staff applied a patient-centric approach that included LEAN methodology of VSM to improve wait times to care. Our framework of evaluation was grounded in the needs and perspectives of patients and individuals waiting to receive care. Patient centric views were obtained through surveys such as Patient Assessment of Chronic Illness Care (PACIC) and process engineering based questions. In addition, LEAN methodology, VSM was added to identify non-value added processes contributing to wait times. Results: The care team successfully reduced wait times to 2 months in 2014 with no wait times for care anticipated in 2015. Increased patient engagement and satisfaction are also outcomes of this innovative initiative. In addition, successful transformations and implementation have resulted in resource efficiencies without increase in costs. Patients have shown significant improvements in functional health following Integrated Chronic Care Service (ICCS) intervention. The methodology will be applied to other chronic disease management areas in Capital Health and the province. Conclusion: Wait times to care in the management of multimoribidities and other complex conditions can add a significant burden not only on the affected individuals but also on the healthcare system. In this study, a novel and modified LEAN methodology has been applied to embed the voice of the patient in care delivery processes and to reduce wait times to care in the management of complex chronic conditions. PMID:26188810

  13. Why Would Plant Species Become Extinct Locally If Growing Conditions Improve?

    PubMed Central

    Kramer, Koen; Bijlsma, Rienk-Jan; Hickler, Thomas; Thuiller, Wilfried

    2012-01-01

    Two assumptions underlie current models of the geographical ranges of perennial plant species: 1. current ranges are in equilibrium with the prevailing climate, and 2. changes are attributable to changes in macroclimatic factors, including tolerance of winter cold, the duration of the growing season, and water stress during the growing season, rather than to biotic interactions. These assumptions allow model parameters to be estimated from current species ranges. Deterioration of growing conditions due to climate change, e.g. more severe drought, will cause local extinction. However, for many plant species, the predicted climate change of higher minimum temperatures and longer growing seasons means, improved growing conditions. Biogeographical models may under some circumstances predict that a species will become locally extinct, despite improved growing conditions, because they are based on an assumption of equilibrium and this forces the species range to match the species-specific macroclimatic thresholds. We argue that such model predictions should be rejected unless there is evidence either that competition influences the position of the range margins or that a certain physiological mechanism associated with the apparent improvement in growing conditions negatively affects the species performance. We illustrate how a process-based vegetation model can be used to ascertain whether such a physiological cause exists. To avoid potential modelling errors of this type, we propose a method that constrains the scenario predictions of the envelope models by changing the geographical distribution of the dominant plant functional type. Consistent modelling results are very important for evaluating how changes in species areas affect local functional trait diversity and hence ecosystem functioning and resilience, and for inferring the implications for conservation management in the face of climate change. PMID:22991500

  14. Anaerobic Antimicrobial Therapy After Necrotizing Enterocolitis in VLBW Infants

    PubMed Central

    Autmizguine, Julie; Hornik, Christoph P.; Benjamin, Daniel K.; Laughon, Matthew M.; Clark, Reese H.; Cotten, C. Michael; Cohen-Wolkowiez, Michael; Benjamin, Daniel K.

    2015-01-01

    OBJECTIVE: To evaluate the effect of anaerobic antimicrobial therapy for necrotizing enterocolitis (NEC) on clinical outcomes in very low birth weight (≤1500 g) infants. METHODS: We identified very low birth weight infants with NEC from 348 US NICUs from 1997 to 2012. Anaerobic antimicrobial therapy was defined by antibiotic exposure on the first day of NEC. We matched (1:1) infants exposed to anaerobic antimicrobial therapy with infants who were not exposed by using a propensity score stratified by NEC severity (medical and surgical). The primary composite outcome was in-hospital death or intestinal stricture. We assessed the relationship between anaerobic antimicrobial therapy and outcome by using a conditional logistic regression on the matched cohort. RESULTS: A total of 1390 infants exposed to anaerobic antimicrobial therapy were matched with 1390 infants not exposed. Mean gestational age and birth weight were 27 weeks and 946 g, respectively, and were similar in both groups. We found no significant difference in the combined outcome of death or strictures, but strictures as a single outcome were more common in the anaerobic antimicrobial therapy group (odds ratio 1.73; 95% confidence interval, 1.11–2.72). Among infants with surgical NEC, mortality was less common with anaerobic antimicrobial therapy (odds ratio 0.71; 95% confidence interval, 0.52–0.95). CONCLUSIONS: Anaerobic antimicrobial therapy was not associated with the composite outcome of death or strictures but was associated with an increase in intestinal strictures. This higher incidence of intestinal strictures may be explained by the fact that death is a competing outcome for intestinal strictures, and mortality was slightly lower in the anaerobic cohort. Infants with surgical NEC who received anaerobic antimicrobial therapy had lower mortality. PMID:25511117

  15. Anaerobic biodegradation of surrogate naphthenic acids.

    PubMed

    Clothier, Lindsay N; Gieg, Lisa M

    2016-03-01

    Surface bitumen extraction from the Alberta's oil sands region generates large settling basins known as tailings ponds. The oil sands process-affected water (OSPW) stored in these ponds contain solid and residual bitumen-associated compounds including naphthenic acids (NAs) that can potentially be biodedgraded by indigenous tailings microorganisms. While the biodegradation of some NAs is known to occur under aerobic conditions, little is understood about anaerobic NA biodegradation even though tailings ponds are mainly anoxic. Here, we investigated the potential for anaerobic NA biodegradation by indigenous tailings microorganisms. Enrichment cultures were established from anoxic tailings that were amended with 5 single-ringed surrogate NAs or acid-extractable organics (AEO) from OSPW and incubated under nitrate-, sulfate-, iron-reducing, and methanogenic conditions. Surrogate NA depletion was observed under all anaerobic conditions tested to varying extents, correlating to losses in the respective electron acceptor (sulfate or nitrate) or the production of predicted products (Fe(II) or methane). Tailings-containing cultures incubated under the different electron-accepting conditions resulted in the enrichment and putative identification of microbial community members that may function in metabolizing surrogate NAs under the various anoxic conditions. In addition, more complex NAs (in the form of AEO) was observed to drive sulfate and iron reduction relative to controls. Overall, this study has shown that simple surrogate NAs can be biodegraded under a variety of anoxic conditions, a key first step in understanding the potential anaerobic metabolism of NAs in oil sands tailings ponds and other industrial wastewaters. PMID:26724449

  16. OPERANT CONDITIONING OF A SPINAL REFLEX CAN IMPROVE LOCOMOTION AFTER SPINAL CORD INJURY IN HUMANS

    PubMed Central

    Thompson, Aiko K.; Pomerantz, Ferne; Wolpaw, Jonathan R.

    2013-01-01

    Operant conditioning protocols can modify the activity of specific spinal cord pathways and can thereby affect behaviors that use these pathways. To explore the therapeutic application of these protocols, we studied the impact of down-conditioning the soleus H-reflex in people with impaired locomotion caused by chronic incomplete spinal cord injury. After a baseline period in which soleus H-reflex size was measured and locomotion was assessed, subjects completed either 30 H-reflex down-conditioning sessions (DC subjects) or 30 sessions in which the H-reflex was simply measured (Unconditioned (UC) subjects), and locomotion was reassessed. Over the 30 sessions, the soleus H-reflex decreased in two-thirds of the DC subjects (a success rate similar to that in normal subjects) and remained smaller several months later. In these subjects, locomotion became faster and more symmetrical, and the modulation of EMG activity across the step-cycle increased bilaterally. Furthermore, beginning about halfway through the conditioning sessions, all of these subjects commented spontaneously that they were walking faster and farther in their daily lives, and several noted less clonus, easier stepping, and/or other improvements. The H-reflex did not decrease in the other DC subjects or in any of the UC subjects; and their locomotion did not improve. These results suggest that reflex conditioning protocols can enhance recovery of function after incomplete spinal cord injuries and possibly in other disorders as well. Because they are able to target specific spinal pathways, these protocols could be designed to address each individual’s particular deficits, and might thereby complement other rehabilitation methods. PMID:23392666

  17. Isolation and characterization of brewer's yeast variants with improved fermentation performance under high-gravity conditions.

    PubMed

    Blieck, Lies; Toye, Geert; Dumortier, Françoise; Verstrepen, Kevin J; Delvaux, Freddy R; Thevelein, Johan M; Van Dijck, Patrick

    2007-02-01

    To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated better-performing variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22 degrees Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11 degrees C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous. PMID:17158628

  18. Improving condition severity classification with an efficient active learning based framework.

    PubMed

    Nissim, Nir; Boland, Mary Regina; Tatonetti, Nicholas P; Elovici, Yuval; Hripcsak, George; Shahar, Yuval; Moskovitch, Robert

    2016-06-01

    Classification of condition severity can be useful for discriminating among sets of conditions or phenotypes, for example when prioritizing patient care or for other healthcare purposes. Electronic Health Records (EHRs) represent a rich source of labeled information that can be harnessed for severity classification. The labeling of EHRs is expensive and in many cases requires employing professionals with high level of expertise. In this study, we demonstrate the use of Active Learning (AL) techniques to decrease expert labeling efforts. We employ three AL methods and demonstrate their ability to reduce labeling efforts while effectively discriminating condition severity. We incorporate three AL methods into a new framework based on the original CAESAR (Classification Approach for Extracting Severity Automatically from Electronic Health Records) framework to create the Active Learning Enhancement framework (CAESAR-ALE). We applied CAESAR-ALE to a dataset containing 516 conditions of varying severity levels that were manually labeled by seven experts. Our dataset, called the "CAESAR dataset," was created from the medical records of 1.9 million patients treated at Columbia University Medical Center (CUMC). All three AL methods decreased labelers' efforts compared to the learning methods applied by the original CAESER framework in which the classifier was trained on the entire set of conditions; depending on the AL strategy used in the current study, the reduction ranged from 48% to 64% that can result in significant savings, both in time and money. As for the PPV (precision) measure, CAESAR-ALE achieved more than 13% absolute improvement in the predictive capabilities of the framework when classifying conditions as severe. These results demonstrate the potential of AL methods to decrease the labeling efforts of medical experts, while increasing accuracy given the same (or even a smaller) number of acquired conditions. We also demonstrated that the methods included in

  19. Neural fuzzy modeling of anaerobic biological wastewater treatment systems

    SciTech Connect

    Tay, J.H.; Zhang, X.

    1999-12-01

    Anaerobic biological wastewater treatment systems are difficult to model because their performance is complex and varies significantly with different reactor configurations, influent characteristics, and operational conditions. Instead of conventional kinetic modeling, advanced neural fuzzy technology was employed to develop a conceptual adaptive model for anaerobic treatment systems. The conceptual neural fuzzy model contains the robustness of fuzzy systems, the learning ability of neural networks, and can adapt to various situations. The conceptual model was used to simulate the daily performance of two high-rate anaerobic wastewater treatment systems with satisfactory results obtained.

  20. Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

    PubMed Central

    Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

    2015-01-01

    We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

  1. Anaerobic lung infections.

    PubMed

    Vincent, M T; Goldman, B S

    1994-06-01

    Aspiration is the leading cause of anaerobic lung infections. Risk factors for these infections include a depressed level of consciousness, a history of seizure, general anesthesia, central nervous system or neuromuscular disease, cerebrovascular accident, impaired swallowing and use of a tracheal or nasogastric tube. Clinical presentation includes fever, weight loss, malaise and cough productive of foul-smelling sputum. Diagnosis is based on radiographic findings, clinical features and a characteristic morphology of mixed flora on Gram stain of uncontaminated pulmonary specimens. The diagnosis is confirmed by isolation of organisms, usually polymicrobial, on culture. Treatment includes proper drainage, debridement of necrotic tissue and an antibiotic regimen (often initially empiric) with an agent active against anaerobic and aerobic organisms. PMID:8203319

  2. A new approach for improving reliability of personal navigation devices under harsh GNSS signal conditions.

    PubMed

    Dhital, Anup; Bancroft, Jared B; Lachapelle, Gérard

    2013-01-01

    In natural and urban canyon environments, Global Navigation Satellite System (GNSS) signals suffer from various challenges such as signal multipath, limited or lack of signal availability and poor geometry. Inertial sensors are often employed to improve the solution continuity under poor GNSS signal quality and availability conditions. Various fault detection schemes have been proposed in the literature to detect and remove biased GNSS measurements to obtain a more reliable navigation solution. However, many of these methods are found to be sub-optimal and often lead to unavailability of reliability measures, mostly because of the improper characterization of the measurement errors. A robust filtering architecture is thus proposed which assumes a heavy-tailed distribution for the measurement errors. Moreover, the proposed filter is capable of adapting to the changing GNSS signal conditions such as when moving from open sky conditions to deep canyons. Results obtained by processing data collected in various GNSS challenged environments show that the proposed scheme provides a robust navigation solution without having to excessively reject usable measurements. The tests reported herein show improvements of nearly 15% and 80% for position accuracy and reliability, respectively, when applying the above approach. PMID:24212120

  3. Oral Administration of Fermented Probiotics Improves the Condition of Feces in Adult Horses

    PubMed Central

    ISHIZAKA, Saori; MATSUDA, Akira; AMAGAI, Yosuke; OIDA, Kumiko; JANG, Hyosun; UEDA, Yuko; TAKAI, Masaki; TANAKA, Akane; MATSUDA, Hiroshi

    2014-01-01

    ABSTRACT The effects of probiotics on horses are still controversial. The present study was a randomized, double-blinded, placebo-controlled crossover study designed to evaluate the ability of probiotics to improve intestinal conditions in adult horses. Fermented probiotics were administered to 10 healthy adult geldings for 28 days. The clinical condition of the horses was monitored daily, and the blood and feces were biochemically analyzed every 14 days. In the probiotic-treated group, the concentration of carboxylic acids in the feces was increased at days 14 and 28. In contrast to the fecal pH in the control group, which increased at days 14 and 28, the fecal pH in the probiotic-treated group did not increase. Additionally, the relative amounts of enteropathogenic bacterial DNA were diminished in the probiotic-treated group. These results suggest that probiotic bacteria proliferated in the equine intestine. No instances of abnormal clinical conditions or abnormal values in blood tests were observed throughout the study. Oral administration of fermented probiotics may have the ability to improve the intestinal environment biochemically and microbiologically without the risk of adverse effects. PMID:25558179

  4. A New Approach for Improving Reliability of Personal Navigation Devices under Harsh GNSS Signal Conditions

    PubMed Central

    Dhital, Anup; Bancroft, Jared B.; Lachapelle, Gérard

    2013-01-01

    In natural and urban canyon environments, Global Navigation Satellite System (GNSS) signals suffer from various challenges such as signal multipath, limited or lack of signal availability and poor geometry. Inertial sensors are often employed to improve the solution continuity under poor GNSS signal quality and availability conditions. Various fault detection schemes have been proposed in the literature to detect and remove biased GNSS measurements to obtain a more reliable navigation solution. However, many of these methods are found to be sub-optimal and often lead to unavailability of reliability measures, mostly because of the improper characterization of the measurement errors. A robust filtering architecture is thus proposed which assumes a heavy-tailed distribution for the measurement errors. Moreover, the proposed filter is capable of adapting to the changing GNSS signal conditions such as when moving from open sky conditions to deep canyons. Results obtained by processing data collected in various GNSS challenged environments show that the proposed scheme provides a robust navigation solution without having to excessively reject usable measurements. The tests reported herein show improvements of nearly 15% and 80% for position accuracy and reliability, respectively, when applying the above approach. PMID:24212120

  5. Anaerobic digestion of pulp and paper mill wastewater and sludge.

    PubMed

    Meyer, Torsten; Edwards, Elizabeth A

    2014-11-15

    Pulp and paper mills generate large amounts of waste organic matter that may be converted to renewable energy in form of methane. The anaerobic treatment of mill wastewater is widely accepted however, usually only applied to few selected streams. Chemical oxygen demand (COD) removal rates in full-scale reactors range between 30 and 90%, and methane yields are 0.30-0.40 m(3) kg(-1) COD removed. Highest COD removal rates are achieved with condensate streams from chemical pulping (75-90%) and paper mill effluents (60-80%). Numerous laboratory and pilot-scale studies have shown that, contrary to common perception, most other mill effluents are also to some extent anaerobically treatable. Even for difficult-to-digest streams such as bleaching effluents COD removal rates range between 15 and 90%, depending on the extent of dilution prior to anaerobic treatment, and the applied experimental setting. Co-digestion of different streams containing diverse substrate can level out and diminish toxicity, and may lead to a more robust microbial community. Furthermore, the microbial population has the ability to become acclimated and adapted to adverse conditions. Stress situations such as toxic shock loads or temporary organic overloading may be tolerated by an adapted community, whereas they could lead to process disturbance with an un-adapted community. Therefore, anaerobic treatment of wastewater containing elevated levels of inhibitors or toxicants should be initiated by an acclimation/adaptation period that can last between a few weeks and several months. In order to gain more insight into the underlying processes of microbial acclimation/adaptation and co-digestion, future research should focus on the relationship between wastewater composition, reactor operation and microbial community dynamics. The potential for engineering and managing the microbial resource is still largely untapped. Unlike in wastewater treatment, anaerobic digestion of mill biosludge (waste activated

  6. Characterizing the anaerobic response of Chlamydomonas reinhardtii by quantitative proteomics.

    PubMed

    Terashima, Mia; Specht, Michael; Naumann, Bianca; Hippler, Michael

    2010-07-01

    The versatile metabolism of the green alga Chlamydomonas reinhardtii is reflected in its complex response to anaerobic conditions. The anaerobic response is also remarkable in the context of renewable energy because C. reinhardtii is able to produce hydrogen under anaerobic conditions. To identify proteins involved during anaerobic acclimation as well as to localize proteins and pathways to the powerhouses of the cell, chloroplasts and mitochondria from C. reinhardtii in aerobic and anaerobic (induced by 8 h of argon bubbling) conditions were isolated and analyzed using comparative proteomics. A total of 2315 proteins were identified. Further analysis based on spectral counting clearly localized 606 of these proteins to the chloroplast, including many proteins of the fermentative metabolism. Comparative quantitative analyses were performed with the chloroplast-localized proteins using stable isotopic labeling of amino acids ([(13)C(6)]arginine/[(12)C(6)]arginine in an arginine auxotrophic strain). The quantitative data confirmed proteins previously characterized as induced at the transcript level as well as identified several new proteins of unknown function induced under anaerobic conditions. These proteins of unknown function provide new candidates for further investigation, which could bring insights for the engineering of hydrogen-producing alga strains. PMID:20190198

  7. Process configuration role in anaerobic biotransformations

    SciTech Connect

    Speece, R.E.

    1998-07-01

    Defining the environmental conditions which would enable anaerobic processes to consistently produce effluents containing only non-detectable concentrations of degradable organics would remove one of the main drawbacks to wider application of this important treatment technology. Recently specific metabolic intermediates formed in the anaerobic biotransformation of complex organics have been found to enhance or curtail process performance. Using acrylate and acrolein as representative hazardous chemicals, modifications in staging and reactor operation procedures have been observed in the author's laboratory to profoundly impact the rate and completeness of the biotransformation process. Specific metabolic intermediates formed in the biotransformation of complex substrates to a large extent will control a given process performance and process configuration greatly impacts the metabolic pathway, thus impacting the intermediates formed as well. There is a growing body of literature to indicate that process performance in anaerobic biotransformation is greatly impacted by reactor configuration. There is also some evidence that metabolic precursors impact the subsequent efficiency of conversion of volatile fatty acids (VFA) ultimately to CH{sub 4}. But although profound differences in the performance of anaerobic biotransformation are reported for various process configurations, there are no published criteria to guide the rational design of stages/phased processes. Clarification of the relative merits of single stage, two stage, two phase, granules and biofilms as well as CSTR and plug flow modes in the biotransformation of hazardous pollutants would be foundational for future research and development.

  8. Autogenic-feedback training improves pilot performance during emergency flying conditions

    NASA Technical Reports Server (NTRS)

    Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

    1993-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. The effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance was examined. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised four pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight physiological data were recorded for each crewmember and individual crew performance and rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  9. Autogenic-feedback training improves pilot performance during emergency flying conditions

    NASA Technical Reports Server (NTRS)

    Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

    1994-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised three pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight, physiological data were recorded for each crew member and individual crew performance was rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  10. Improving image quality in poor visibility conditions using a physical model for contrast degradation.

    PubMed

    Oakley, J P; Satherley, B L

    1998-01-01

    In daylight viewing conditions, image contrast is often significantly degraded by atmospheric aerosols such as haze and fog. This paper introduces a method for reducing this degradation in situations in which the scene geometry is known. Contrast is lost because light is scattered toward the sensor by the aerosol particles and because the light reflected by the terrain is attenuated by the aerosol. This degradation is approximately characterized by a simple, physically based model with three parameters. The method involves two steps: first, an inverse problem is solved in order to recover the three model parameters; then, for each pixel, the relative contributions of scattered and reflected flux are estimated. The estimated scatter contribution is simply subtracted from the pixel value and the remainder is scaled to compensate for aerosol attenuation. This paper describes the image processing algorithm and presents an analysis of the signal-to-noise ratio (SNR) in the resulting enhanced image. This analysis shows that the SNR decreases exponentially with range. A temporal filter structure is proposed to solve this problem. Results are presented for two image sequences taken from an airborne camera in hazy conditions and one sequence in clear conditions. A satisfactory agreement between the model and the experimental data is shown for the haze conditions. A significant improvement in image quality is demonstrated when using the contrast enhancement algorithm in conjuction with a temporal filter. PMID:18267391

  11. Considerations of Environmentally Relevant Test Conditions for Improved Evaluation of Ecological Hazards of Engineered Nanomaterials.

    PubMed

    Holden, Patricia A; Gardea-Torresdey, Jorge L; Klaessig, Fred; Turco, Ronald F; Mortimer, Monika; Hund-Rinke, Kerstin; Cohen Hubal, Elaine A; Avery, David; Barceló, Damià; Behra, Renata; Cohen, Yoram; Deydier-Stephan, Laurence; Ferguson, P Lee; Fernandes, Teresa F; Herr Harthorn, Barbara; Henderson, W Matthew; Hoke, Robert A; Hristozov, Danail; Johnston, John M; Kane, Agnes B; Kapustka, Larry; Keller, Arturo A; Lenihan, Hunter S; Lovell, Wess; Murphy, Catherine J; Nisbet, Roger M; Petersen, Elijah J; Salinas, Edward R; Scheringer, Martin; Sharma, Monita; Speed, David E; Sultan, Yasir; Westerhoff, Paul; White, Jason C; Wiesner, Mark R; Wong, Eva M; Xing, Baoshan; Steele Horan, Meghan; Godwin, Hilary A; Nel, André E

    2016-06-21

    Engineered nanomaterials (ENMs) are increasingly entering the environment with uncertain consequences including potential ecological effects. Various research communities view differently whether ecotoxicological testing of ENMs should be conducted using environmentally relevant concentrations-where observing outcomes is difficult-versus higher ENM doses, where responses are observable. What exposure conditions are typically used in assessing ENM hazards to populations? What conditions are used to test ecosystem-scale hazards? What is known regarding actual ENMs in the environment, via measurements or modeling simulations? How should exposure conditions, ENM transformation, dose, and body burden be used in interpreting biological and computational findings for assessing risks? These questions were addressed in the context of this critical review. As a result, three main recommendations emerged. First, researchers should improve ecotoxicology of ENMs by choosing test end points, duration, and study conditions-including ENM test concentrations-that align with realistic exposure scenarios. Second, testing should proceed via tiers with iterative feedback that informs experiments at other levels of biological organization. Finally, environmental realism in ENM hazard assessments should involve greater coordination among ENM quantitative analysts, exposure modelers, and ecotoxicologists, across government, industry, and academia. PMID:27177237

  12. Opportunities for improving leaf water use efficiency under climate change conditions.

    PubMed

    Gago, Jorge; Douthe, Cyril; Florez-Sarasa, Igor; Escalona, Jose M; Galmes, Jeroni; Fernie, Alisdair R; Flexas, Jaume; Medrano, Hipolito

    2014-09-01

    WUEi (intrinsic water use efficiency) is a complex (multi)-trait, that depends on several physiological processes, driving plant productivity and its relation with a changing environment. Climatic change predictions estimate increases in temperature and drought in the semi-arid regions, rendering improved water use efficiency is a mandatory objective to maintain the current global food supply. The aims of this review were (i) to identify through a meta-analysis the leaf traits mostly related to intrinsic water use efficiency (WUEi, the ratio between A - net photosynthesis and gs - stomatal conductance), based on a newly compiled dataset covering more than 200 species/varieties and 106 genus of C3 plants (ii) to describe the main potential targets for WUEi improvement via biotechnological manipulations and (iii) to introduce emergent and innovative technologies including UAVs (Unmanned Aerial Vehicles) to scale up levels from leaf to whole plant water status. We confirmed that increases in gm/gs and Vcmax/gs ratios are systematically related with increases in WUEi maintained across species, habitats, and environmental conditions. Other emergent opportunities to improve WUEi are described such as the relationship between photosynthesis and respiration and their link with metabolomics. Finally, we outline our hypothesis that we are observing the advent of a "smart" agriculture, wherein new technologies, such as UAVs equipped with remote sensors will rapidly facilitate an efficient water use regulating the irrigation schedule and determination, under field conditions, of cultivars with improved water use efficiency. We, therefore, conclude that the multi-disciplinary challenge toward WUE has only just begun. PMID:25113456

  13. Modeling for Anaerobic Fixed-Bed Biofilm Reactors

    SciTech Connect

    Liu, B. Y. M.; Pfeffer, J. T.

    1989-06-01

    The specific objectives of this research were: 1. to develop an equilibrium model for chemical aspects of anaerobic reactors; 2. to modify the equilibrium model for non-equilibrium conditions; 3. to incorporate the existing biofilm models into the models above to study the biological and chemical behavior of the fixed-film anaerobic reactors; 4. to experimentally verify the validity of these models; 5. to investigate the biomass-holding ability of difference packing materials for establishing reactor design criteria.

  14. Bioaugmentation of overloaded anaerobic digesters restores function and archaeal community.

    PubMed

    Tale, V P; Maki, J S; Zitomer, D H

    2015-03-01

    Adding beneficial microorganisms to anaerobic digesters for improved performance (i.e. bioaugmentation) has been shown to decrease recovery time after organic overload or toxicity upset. Compared to strictly anaerobic cultures, adding aerotolerant methanogenic cultures may be more practical since they exhibit higher methanogenic activity and can be easily dried and stored in ambient air for future shipping and use. In this study, anaerobic digesters were bioaugmented with both anaerobic and aerated, methanogenic propionate enrichment cultures after a transient organic overload. Digesters bioaugmented with anaerobic and moderately aerated cultures recovered 25 and 100 days before non-bioaugmented digesters, respectively. Increased methane production due to bioaugmentation continued a long time, with 50-120% increases 6 to 12 SRTs (60-120 days) after overload. In contrast to the anaerobic enrichment, the aerated enrichments were more effective as bioaugmentation cultures, resulting in faster recovery of upset digester methane and COD removal rates. Sixty days after overload, the bioaugmented digester archaeal community was not shifted, but was restored to one similar to the pre-overload community. In contrast, non-bioaugmented digester archaeal communities before and after overload were significantly different. Organisms most similar to Methanospirillum hungatei had higher relative abundance in well-operating, undisturbed and bioaugmented digesters, whereas organisms similar to Methanolinea tarda were more abundant in upset, non-bioaugmented digesters. Bioaugmentation is a beneficial approach to increase digester recovery rate after transient organic overload events. Moderately aerated, methanogenic propionate enrichment cultures were more beneficial augments than a strictly anaerobic enrichment. PMID:25528544

  15. Effects of thermo-chemical pre-treatment on anaerobic biodegradability and hydrolysis of lignocellulosic biomass.

    PubMed

    Fernandes, T V; Bos, G J Klaasse; Zeeman, G; Sanders, J P M; van Lier, J B

    2009-05-01

    The effects of different thermo-chemical pre-treatment methods were determined on the biodegradability and hydrolysis rate of lignocellulosic biomass. Three plant species, hay, straw and bracken were thermo-chemically pre-treated with calcium hydroxide, ammonium carbonate and maleic acid. After pre-treatment, the plant material was anaerobically digested in batch bottles under mesophilic conditions for 40 days. From the pre-treatment and subsequent anaerobic digestion experiments, it was concluded that when the lignin content of the plant material is high, thermo-chemical pre-treatments have a positive effect on the biodegradability of the substrate. Calcium hydroxide pre-treatment improves the biodegradability of lignocellulosic biomass, especially for high lignin content substrates, like bracken. Maleic acid generates the highest percentage of dissolved COD during pre-treatment. Ammonium pre-treatment only showed a clear effect on biodegradability for straw. PMID:19144515

  16. Anaerobic Codigestion of Sludge: Addition of Butcher's Fat Waste as a Cosubstrate for Increasing Biogas Production.

    PubMed

    Martínez, E J; Gil, M V; Fernandez, C; Rosas, J G; Gómez, X

    2016-01-01

    Fat waste discarded from butcheries was used as a cosubstrate in the anaerobic codigestion of sewage sludge (SS). The process was evaluated under mesophilic and thermophilic conditions. The codigestion was successfully attained despite some inhibitory stages initially present that had their origin in the accumulation of volatile fatty acids (VFA) and adsorption of long-chain fatty acids (LCFA). The addition of a fat waste improved digestion stability and increased biogas yields thanks to the higher organic loading rate (OLR) applied to the reactors. However, thermophilic digestion was characterized by an effluent of poor quality and high VFA content. Results from spectroscopic analysis suggested the adsorption of lipid components onto the anaerobic biomass, thus disturbing the complete degradation of substrate during the treatment. The formation of fatty aggregates in the thermophilic reactor prevented process failure by avoiding the exposure of biomass to the toxic effect of high LCFA concentrations. PMID:27071074

  17. Sulfate addition as an effective method to improve methane fermentation performance and propionate degradation in thermophilic anaerobic co-digestion of coffee grounds, milk and waste activated sludge with AnMBR.

    PubMed

    Li, Qian; Li, Yu-You; Qiao, Wei; Wang, Xiaochang; Takayanagi, Kazuyuki

    2015-06-01

    This study was conducted to investigate the effects of sulfate on propionate degradation and higher organic loading rate (OLR) achievement in a thermophilic AnMBR for 373days using coffee grounds, milk and waste activated sludge (WAS) as the co-substrate. Without the addition of sulfate, the anaerobic system failed at an OLR of 14.6g-COD/L/d, with propionate accumulating to above 2.23g-COD/L, and recovery by an alkalinity supplement was not successful. After sulfate was added into substrates at a COD/SO4(2-) ratio of 200:1 to 350:1, biogas production increased proportionally with OLR increasing from 4.06 to 15.2g-COD/L/d. Propionic acid was maintained at less than 100mg-COD/L due to the effective conversion of propionic acid to methane after the sulfate supplement was added. The long-term stable performance of the AnMBR indicated that adding sulfate was beneficial for the degradation of propionate and achieving a higher OLR under the thermophilic condition. PMID:25791749

  18. The microbiological quality of air improves when using air conditioning systems in cars

    PubMed Central

    2010-01-01

    Background Because of better comfort, air conditioning systems are a common feature in automobiles these days. However, its impact on the number of particles and microorganisms inside the vehicle - and by this its impact on the risk of an allergic reaction - is yet unknown. Methods Over a time period of 30 months, the quality of air was investigated in three different types of cars (VW Passat, VW Polo FSI, Seat Alhambra) that were all equipped with a automatic air conditioning system. Operation modes using fresh air from outside the car as well as circulating air from inside the car were examined. The total number of microorganisms and the number of mold spores were measured by impaction in a high flow air sampler. Particles of 0.5 to 5.0 μm diameter were counted by a laser particle counter device. Results Overall 32 occasions of sampling were performed. The concentration of microorganisms outside the cars was always higher than it was inside the cars. Few minutes after starting the air conditioning system the total number of microorganisms was reduced by 81.7%, the number of mold spores was reduced by 83.3%, and the number of particles was reduced by 87.8%. There were no significant differences neither between the types of cars nor between the types of operation mode of the air conditioning system (fresh air vs. circulating air). All parameters that were looked for in this study improved during utilization of the car's air conditioning system. Conclusions We believe that the risk of an allergic reaction will be reduced during use also. Nevertheless, we recommend regular maintenance of the system and replacement of older filters after defined changing intervals. PMID:20515449

  19. Improvement of titanium alloy for biomedical applications by nitriding and carbonitriding processes under glow discharge conditions.

    PubMed

    Czarnowska, E; Wierzchoń, T; Maranda-Niedbała, A; Karczmarewicz, E

    2000-02-01

    Although titanium alloys are used in medicine, they present low wear resistance. In this paper we present the results of studies on surface layers produced by nitriding at three different temperatures, and by carbonitriding under glow discharge conditions in order to improve wear resistance, hardness, and to modulate microstructure and chemical composition of surface layers. A cell culture model using human fibroblasts was chosen to study the effect of such treatments on the cytocompatibility of these materials. The results showed that nitrided and carbonitrided surface layers were cytocompatible. Modulation of surface microstructure by temperature in the nitriding process and chemical composition of surface layers by carbonitriding led to differences in cellular behaviour. Cell proliferation appeared to be slightly reduced from the 6th day of culture on nitrided surfaces produced at 730 degrees C and 1000 degrees C, however after 12 days of culture, the best growth was on surface layers produced at 850 degrees C. The best viability was observed on the carbonitrided layer. The orientation and shape of the cells corresponded to surface topography. Nitriding and carbonitriding under glow discharge conditions may constitute interesting techniques allowing the formation of surface layers on parts with sophisticated shapes. They may also permit modulating surface topography in a way improving the features of titanium alloys for various applications in medicine. PMID:15348050

  20. Carbon and Hydrogen Isotopic Fractionation during Anaerobic Biodegradation of Benzene

    PubMed Central

    Mancini, Silvia A.; Ulrich, Ania C.; Lacrampe-Couloume, Georges; Sleep, Brent; Edwards, Elizabeth A.; Sherwood Lollar, Barbara

    2003-01-01

    Compound-specific isotope analysis has the potential to distinguish physical from biological attenuation processes in the subsurface. In this study, carbon and hydrogen isotopic fractionation effects during biodegradation of benzene under anaerobic conditions with different terminal-electron-accepting processes are reported for the first time. Different enrichment factors (ɛ) for carbon (range of −1.9 to −3.6‰) and hydrogen (range of −29 to −79‰) fractionation were observed during biodegradation of benzene under nitrate-reducing, sulfate-reducing, and methanogenic conditions. These differences are not related to differences in initial biomass or in rates of biodegradation. Carbon isotopic enrichment factors for anaerobic benzene biodegradation in this study are comparable to those previously published for aerobic benzene biodegradation. In contrast, hydrogen enrichment factors determined for anaerobic benzene biodegradation are significantly larger than those previously published for benzene biodegradation under aerobic conditions. A fundamental difference in the previously proposed initial step of aerobic versus proposed anaerobic biodegradation pathways may account for these differences in hydrogen isotopic fractionation. Potentially, C-H bond breakage in the initial step of the anaerobic benzene biodegradation pathway may account for the large fractionation observed compared to that in aerobic benzene biodegradation. Despite some differences in reported enrichment factors between cultures with different terminal-electron-accepting processes, carbon and hydrogen isotope analysis has the potential to provide direct evidence of anaerobic biodegradation of benzene in the field. PMID:12513995

  1. Hog farm in California uses anaerobic digestion

    SciTech Connect

    Swanson, D.

    1995-12-31

    This article describes a system of covered lagoons which help address the waste management problems of hog farmers as well as producing methane used to power generators. Four advantages of anaerobic digestion are described along with the system: energy production from methane; fertilizer for fields; economic development in rural areas; and improved water quality through reduction of nonpoint source pollution. Address for full report is given.

  2. Engineering and two-stage evolution of a lignocellulosic hydrolysate-tolerant Saccharomyces cerevisiae strain for anaerobic fermentation of xylose from AFEX pretreated corn stover.

    PubMed

    Parreiras, Lucas S; Breuer, Rebecca J; Avanasi Narasimhan, Ragothaman; Higbee, Alan J; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B; Bice, Benjamin D; Bonfert, Brandi L; Pinhancos, Rebeca C; Balloon, Allison J; Uppugundla, Nirmal; Liu, Tongjun; Li, Chenlin; Tanjore, Deepti; Ong, Irene M; Li, Haibo; Pohlmann, Edward L; Serate, Jose; Withers, Sydnor T; Simmons, Blake A; Hodge, David B; Westphall, Michael S; Coon, Joshua J; Dale, Bruce E; Balan, Venkatesh; Keating, David H; Zhang, Yaoping; Landick, Robert; Gasch, Audrey P; Sato, Trey K

    2014-01-01

    The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH. PMID:25222864

  3. Engineering and Two-Stage Evolution of a Lignocellulosic Hydrolysate-Tolerant Saccharomyces cerevisiae Strain for Anaerobic Fermentation of Xylose from AFEX Pretreated Corn Stover

    PubMed Central

    Parreiras, Lucas S.; Breuer, Rebecca J.; Avanasi Narasimhan, Ragothaman; Higbee, Alan J.; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B.; Bice, Benjamin D.; Bonfert, Brandi L.; Pinhancos, Rebeca C.; Balloon, Allison J.; Uppugundla, Nirmal; Liu, Tongjun; Li, Chenlin; Tanjore, Deepti; Ong, Irene M.; Li, Haibo; Pohlmann, Edward L.; Serate, Jose; Withers, Sydnor T.; Simmons, Blake A.; Hodge, David B.; Westphall, Michael S.; Coon, Joshua J.; Dale, Bruce E.; Balan, Venkatesh; Keating, David H.; Zhang, Yaoping; Landick, Robert; Gasch, Audrey P.; Sato, Trey K.

    2014-01-01

    The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH. PMID:25222864

  4. Biogas generation in anaerobic wastewater treatment under tetracycline antibiotic pressure

    PubMed Central

    Lu, Meiqing; Niu, Xiaojun; Liu, Wei; Zhang, Jun; Wang, Jie; Yang, Jia; Wang, Wenqi; Yang, Zhiquan

    2016-01-01

    The effect of tetracycline (TC) antibiotic on biogas generation in anaerobic wastewater treatment was studied. A lab-scale Anaerobic Baffled Reactor (ABR) with three compartments was used. The reactor was operated with synthetic wastewater in the absence of TC and in the presence of 250 μg/L TC for 90 days, respectively. The removal rate of TC, volatile fatty acids (VFAs), biogas compositions (hydrogen (H2), methane (CH4), carbon dioxide (CO2)), and total biogas production in each compartment were monitored in the two operational conditions. Results showed that the removal rate of TC was 14.97–67.97% in the reactor. The presence of TC had a large negative effect on CH4 and CO2 generation, but appeared to have a positive effect on H2 production and VFAs accumulation. This response indicated that the methanogenesis process was sensitive to TC presence, but the acidogenesis process was insensitive. This suggested that the presence of TC had less influence on the degradation of organic matter but had a strong influence on biogas generation. Additionally, the decrease of CH4 and CO2 generation and the increase of H2 and VFAs accumulation suggest a promising strategy to help alleviate global warming and improve resource recovery in an environmentally friendly approach. PMID:27341657

  5. Biogas generation in anaerobic wastewater treatment under tetracycline antibiotic pressure.

    PubMed

    Lu, Meiqing; Niu, Xiaojun; Liu, Wei; Zhang, Jun; Wang, Jie; Yang, Jia; Wang, Wenqi; Yang, Zhiquan

    2016-01-01

    The effect of tetracycline (TC) antibiotic on biogas generation in anaerobic wastewater treatment was studied. A lab-scale Anaerobic Baffled Reactor (ABR) with three compartments was used. The reactor was operated with synthetic wastewater in the absence of TC and in the presence of 250 μg/L TC for 90 days, respectively. The removal rate of TC, volatile fatty acids (VFAs), biogas compositions (hydrogen (H2), methane (CH4), carbon dioxide (CO2)), and total biogas production in each compartment were monitored in the two operational conditions. Results showed that the removal rate of TC was 14.97-67.97% in the reactor. The presence of TC had a large negative effect on CH4 and CO2 generation, but appeared to have a positive effect on H2 production and VFAs accumulation. This response indicated that the methanogenesis process was sensitive to TC presence, but the acidogenesis process was insensitive. This suggested that the presence of TC had less influence on the degradation of organic matter but had a strong influence on biogas generation. Additionally, the decrease of CH4 and CO2 generation and the increase of H2 and VFAs accumulation suggest a promising strategy to help alleviate global warming and improve resource recovery in an environmentally friendly approach. PMID:27341657

  6. Biogas generation in anaerobic wastewater treatment under tetracycline antibiotic pressure

    NASA Astrophysics Data System (ADS)

    Lu, Meiqing; Niu, Xiaojun; Liu, Wei; Zhang, Jun; Wang, Jie; Yang, Jia; Wang, Wenqi; Yang, Zhiquan

    2016-06-01

    The effect of tetracycline (TC) antibiotic on biogas generation in anaerobic wastewater treatment was studied. A lab-scale Anaerobic Baffled Reactor (ABR) with three compartments was used. The reactor was operated with synthetic wastewater in the absence of TC and in the presence of 250 μg/L TC for 90 days, respectively. The removal rate of TC, volatile fatty acids (VFAs), biogas compositions (hydrogen (H2), methane (CH4), carbon dioxide (CO2)), and total biogas production in each compartment were monitored in the two operational conditions. Results showed that the removal rate of TC was 14.97–67.97% in the reactor. The presence of TC had a large negative effect on CH4 and CO2 generation, but appeared to have a positive effect on H2 production and VFAs accumulation. This response indicated that the methanogenesis process was sensitive to TC presence, but the acidogenesis process was insensitive. This suggested that the presence of TC had less influence on the degradation of organic matter but had a strong influence on biogas generation. Additionally, the decrease of CH4 and CO2 generation and the increase of H2 and VFAs accumulation suggest a promising strategy to help alleviate global warming and improve resource recovery in an environmentally friendly approach.

  7. Ergonomic strategies for improving working conditions in some developing countries in Asia.

    PubMed

    Kawakami, T; Batino, J M; Khai, T T

    1999-04-01

    Ergonomic action is growing in Asia in response to increasing local needs. Recent studies in some developing countries in Asia commonly developed and applied widely-applicable measures for assessing local needs in field conditions including small enterprises and agriculture. For this purpose, carefully examining the actual workplace conditions of the local people was essential. Consequently, a number of field studies could contributed to improving the working conditions of the local people in materials handling, workstation design, work organization and work environment by using available local resources. Building on local capacity and practice, action-oriented ergonomics training has also been developing and spreading into many workplaces. Various non-expert human resources including local government units, trade unions, industrial associations and the agricultural sectors have been mobilized to act as participatory trainers in the action-oriented ergonomic training programmes. Training tools such as action checklists, good local examples and group work dynamics have been developed and applied to such training activities. Learning from local achievements and focusing on locally available resources, ergonomists have facilitated these local action processes by developing action-oriented training tools and training local trainers. It was confirmed that a number of ergonomic improvements could be formulated by the self-help initiative of the local people when participatory action tools and training were provided. Developing flexible and dynamic ergonomic research and training methods to meet the diversifying needs of the local people will continuously be important. Ergonomists' efforts to cover the wider population and workplaces need to be strengthened and accelerated. PMID:10319567

  8. Improving forecast skill by assimilation of quality-controlled AIRS temperature retrievals under partially cloudy conditions

    NASA Astrophysics Data System (ADS)

    Reale, O.; Susskind, J.; Rosenberg, R.; Brin, E.; Liu, E.; Riishojgaard, L. P.; Terry, J.; Jusem, J. C.

    2008-04-01

    The National Aeronautics and Space Administration (NASA) Atmospheric Infrared Sounder (AIRS) on board the Aqua satellite is now recognized as an important contributor towards the improvement of weather forecasts. At this time only a small fraction of the total data produced by AIRS is being used by operational weather systems. In fact, in addition to effects of thinning and quality control, the only AIRS data assimilated are radiance observations of channels unaffected by clouds. Observations in mid-lower tropospheric sounding AIRS channels are assimilated primarily under completely clear-sky conditions, thus imposing a very severe limitation on the horizontal distribution of the AIRS-derived information. In this work it is shown that the ability to derive accurate temperature profiles from AIRS observations in partially cloud-contaminated areas can be utilized to further improve the impact of AIRS observations in a global model and forecasting system. The analyses produced by assimilating AIRS temperature profiles obtained under partial cloud cover result in a substantially colder representation of the northern hemisphere lower midtroposphere at higher latitudes. This temperature difference has a strong impact, through hydrostatic adjustment, in the midtropospheric geopotential heights, which causes a different representation of the polar vortex especially over northeastern Siberia and Alaska. The AIRS-induced anomaly propagates through the model's dynamics producing improved 5-day forecasts.

  9. Improving Forecast Skill by Assimilation of Quality-controlled AIRS Temperature Retrievals under Partially Cloudy Conditions

    NASA Technical Reports Server (NTRS)

    Reale, O.; Susskind, J.; Rosenberg, R.; Brin, E.; Riishojgaard, L.; Liu, E.; Terry, J.; Jusem, J. C.

    2007-01-01

    The National Aeronautics and Space Administration (NASA) Atmospheric Infrared Sounder (AIRS) on board the Aqua satellite has been long recognized as an important contributor towards the improvement of weather forecasts. At this time only a small fraction of the total data produced by AIRS is being used by operational weather systems. In fact, in addition to effects of thinning and quality control, the only AIRS data assimilated are radiance observations of channels unaffected by clouds. Observations in mid-lower tropospheric sounding AIRS channels are assimilated primarily under completely clear-sky conditions, thus imposing a very severe limitation on the horizontal distribution of the AIRS-derived information. In this work it is shown that the ability to derive accurate temperature profiles from AIRS observations in partially cloud-contaminated areas can be utilized to further improve the impact of AIRS observations in a global model and forecasting system. The analyses produced by assimilating AIRS temperature profiles obtained under partial cloud cover result in a substantially colder representation of the northern hemisphere lower midtroposphere at higher latitudes. This temperature difference has a strong impact, through hydrostatic adjustment, in the midtropospheric geopotential heights, which causes a different representation of the polar vortex especially over northeastern Siberia and Alaska. The AIRS-induced anomaly propagates through the model's dynamics producing improved 5-day forecasts.

  10. Improving the range of UHF RFID transponders using solar energy harvesting under low light conditions

    NASA Astrophysics Data System (ADS)

    Ascher, A.; Lehner, M.; Eberhardt, M.; Biebl, E.

    2015-11-01

    The sensitivity of passive UHF RFID transponders (Radio Frequency Identification) is the key issue, which determines the maximum read range of an UHF RFID system. During this work the ability of improving the sensitivity using solar energy harvesting, especially for low light conditions, is shown. To use the additional energy harvested from the examined silicon and organic solar cells, the passive RFID system is changed into a semi-active one. This needs no changes on the reader hardware itself, only the used RFIC (Radio Frequency Integrated Circuit) of the transponder has to possess an additional input pin for an external supply voltage. The silicon and organic cells are evaluated and compared to each other regarding their low light performance. The different cells are examined in a shielded box, which is protected from the environmental lighting. Additionally, a demonstrator is shown, which makes the measurement of the extended read range with respect to the lighting conditions possible. If the cells are completely darkened, the sensitivity gain is ascertained using high capacity super caps. Due to the measurements an enhancement in range up to 70 % could be guaranteed even under low light conditions.

  11. Improving variational mass-consistent models of hydrodynamic flows via boundary conditions

    NASA Astrophysics Data System (ADS)

    Núñez, M. A.

    2012-04-01

    Variational mass-consistent models for the velocity field v have been used by mesoscale meteorological community to modeling the wind field from an observed field v 0 in a bounded region Ω with boundary Γ. Variational calculus reduces the problem to the solution of an elliptic equation for a Lagrange multiplier λ subject to Dirichlet Boundary Condition (DBC) on flow-through boundaries. In this work, it is shown that DBC decreases the regularity of λ and this in turn decreases the accuracy with which the velocity field satisfies the mass-balance. The boundary condition (BC) v · n = v T · ngiven by the true field v T on the whole boundary Γ, leads only to a Neumann boundary condition (NBC) for λ. Approximations of this BC are studied. Analytic and numerical results show that the velocity field U 0 obtained from v 0 by direct integration of the continuity equation, yields a NBC that improves significantly the fields obtained with DBC's.

  12. Interleukin-18 Antagonism Improved Histopathological Conditions of Malaria Infection in Mice

    PubMed Central

    JABBARZARE, Marzieh; CHIN, Voon Kin; TALIB, Herni; YAM, Mun Fei; ADAM, Siti Khadijah; HASSAN, Haniza; ABDUL MAJID, Roslaini; MAT TAIB, Che Norma; MOHD MOKLAS, Mohamad Aris; TAUFIK HIDAYAT, Mohamad; MOHD SIDEK, Hasidah; BASIR, Rusliza

    2015-01-01

    Background: Interleukin 18 (IL-18) exerts pleiotropic roles in many inflammatory-related diseases including parasitic infection. Previous studies have demonstrated the promising therapeutic potential of modulating IL-18 bioactivity in various pathological conditions. However, its involvement during malaria infection has yet to be established. In this study, we demonstrated the effect of modulating IL-18 on the histopathological conditions of malaria infected mice. Methods: Plasmodium berghei ANKA infection in male ICR mice was used as a model for malaria infection. Modulation of IL-18 release was carried out by treatment of malarial mice with recombinant mouse IL-18 (rmIL-18) and recombinant mouse IL-18 Fc chimera (rmIL-18Fc) intravenously. Histopathological study and analysis were performed on major organs including brain, liver, spleen, lungs and kidney. Results: Treatment with rmIL-18Fc resulted in significant improvements on the histopathological conditions of the organs in malaria-infected mice. Conclusion: IL-18 is an important mediator of malaria pathogenesis and targeting IL-18 could prove beneficial in malaria-infected host. PMID:26622294

  13. Improvement of Initial Conditions of Sea Fog Modeling with Cycling 3DVAR-WRF

    NASA Astrophysics Data System (ADS)

    Gao, S.; Fu, G.; Wu, W.; Xu, X.

    2010-07-01

    Among the seas of China, the Yellow Sea (YS) experiences sea fog most frequently, especially during the spring and summer seasons. Recent studies of sea fog modeling over YS have suggested that data assimilation is a key important issue for sea fog modeling, because simulation result is significantly sensitive to initial conditions. In this talk, a heavy sea fog over YS occurred from 6 to 7 March 2006 is carefully studied by using Weather Research and Forecasting (WRF) model. The evolution of sea fog area is demonstrated by the Multi-functional Transport Satellite (MTSAT)-1R visible imagery and infrared data using dual channel difference method. A cycling 3DVAR scheme with 12-h assimilation window is designed and employed to generate the initial conditions for this sea fog simulation. The result shows that the simulated sea fog area is greatly improved compared to the result without cycling 3DVAR. Additionally, the initial conditions with cycling 3DVAR-WRF are also used to force the Regional Atmospheric Modeling System (RAMS) model to simulate this sea fog case. We find that the simulated sea fog coverage is much better than the result with RAMS original isentropic analysis.

  14. IL-12-conditioning improves retrovirally-mediated transduction efficiency of CD8+ T cells

    PubMed Central

    Andrijauskaite, Kristina; Suriano, Samantha; Cloud, Colleen A.; Li, Mingli; Kesarwani, Pravin; Stefanik, Leah S.; Moxley, Kelly M.; Salem, Mohamed L; Garrett-Mayer, Elizabeth; Paulos, Chrystal M.; Mehrotra, Shikhar; Kochenderfer, James N.; Cole, David J.; Rubinstein, Mark P.

    2016-01-01

    The ability to genetically modify T cells is a critical component to many immunotherapeutic strategies and research studies. However, the success of these approaches is often limited by transduction efficiency. Since retroviral vectors require cell division for integration, transduction efficiency is dependent on the appropriate activation and culture conditions for T cells. Naïve CD8+ T cells which are quiescent must be first activated to induce cell division to allow genetic modification. To optimize this process, we activated mouse T cells with a panel of different cytokines, including IL-2, IL-4, IL-6, IL-7, IL-12, IL-15 and IL-23, known to act on T cells. After activation, cytokines were removed, and activated T cells were retrovirally transduced. We found that IL-12 pre-conditioning of mouse T cells greatly enhanced transduction efficiency while preserving function and expansion potential. We also observed a similar transduction enhancing effect of IL-12 pre-conditioning on human T cells. These findings provide a simple method to improve the transduction efficiencies of CD8+ T cells. PMID:26182912

  15. Two-stage anaerobic and post-aerobic mesophilic digestion of sewage sludge: Analysis of process performance and hygienization potential.

    PubMed

    Tomei, M Concetta; Mosca Angelucci, Domenica; Levantesi, Caterina

    2016-03-01

    Sequential anaerobic-aerobic digestion has been demonstrated to be effective for enhanced sludge stabilization, in terms of increased solid reduction and improvement of sludge dewaterability. In this study, we propose a modified version of the sequential anaerobic-aerobic digestion process by operating the aerobic step under mesophilic conditions (T=37 °C), in order to improve the aerobic degradation kinetics of soluble and particulate chemical oxygen demand (COD). Process performance has been assessed in terms of "classical parameters" such as volatile solids (VS) removal, biogas production, COD removal, nitrogen species, and polysaccharide and protein fate. The aerobic step was operated under intermittent aeration to achieve nitrogen removal. Aerobic mesophilic conditions consistently increased VS removal, providing 32% additional removal vs. 20% at 20 °C. Similar results were obtained for nitrogen removal, increasing from 64% up to 99% at the higher temperature. Improved sludge dewaterability was also observed with a capillary suction time decrease of ~50% during the mesophilic aerobic step. This finding may be attributable to the decreased protein content in the aerobic digested sludge. The post-aerobic digestion exerted a positive effect on the reduction of microbial indicators while no consistent improvement of hygienization related to the increased temperature was observed. The techno-economic analysis of the proposed digestion layout showed a net cost saving for sludge disposal estimated in the range of 28-35% in comparison to the single-phase anaerobic digestion. PMID:26760266

  16. Anaerobic wastewater treatment using anaerobic baffled bioreactor: a review

    NASA Astrophysics Data System (ADS)

    Hassan, Siti Roshayu; Dahlan, Irvan

    2013-09-01

    Anaerobic wastewater treatment is receiving renewed interest because it offers a means to treat wastewater with lower energy investment. Because the microorganisms involved grow more slowly, such systems require clever design so that the microbes have sufficient time with the substrate to complete treatment without requiring enormous reactor volumes. The anaerobic baffled reactor has inherent advantages over single compartment reactors due to its circulation pattern that approaches a plug flow reactor. The physical configuration of the anaerobic baffled reactor enables significant modifications to be made; resulting in a reactor which is proficient of treating complex wastewaters which presently require only one unit, ultimately significant reducing capital costs. This paper also concerns about mechanism, kinetic and hydrodynamic studies of anaerobic digestion for future application of the anaerobic baffled reactor for wastewater treatment.

  17. Improving Primary Health Care in Chronic Musculoskeletal Conditions through Digital Media: The PEOPLE Meeting

    PubMed Central

    Cott, Cheryl; Jones, C Allyson; Badley, Elizabeth M; Davis, Aileen M

    2013-01-01

    Background Musculoskeletal (MSK) conditions are the most common cause of severe chronic pain and disability worldwide. Despite the impact of these conditions, disparity exists in accessing high quality basic care. As a result, effective treatments do not always reach people who need services. The situation is further hampered by the current models of care that target resources to a limited area of health services (eg, joint replacement surgery), rather than the entire continuum of MSK health, which includes services provided by primary care physicians and health professionals. The use of digital media offers promising solutions to improve access to services. However, our knowledge in this field is limited. To advance the use of digital media in improving MSK care, we held a research planning meeting entitled “PEOPLE: Partnership to Enable Optimal Primary Health Care by Leveraging Digital Media in Musculoskeletal Health”. This paper reports the discussion during the meeting. Objective The objective of this study was to: (1) identify research priorities relevant to using digital media in primary health care for enhancing MSK health, and (2) develop research collaboration among researchers, clinicians, and patient/consumer communities. Methods The PEOPLE meeting included 26 participants from health research, computer science/digital media, clinical communities, and patient/consumer groups. Based on consultations with each participant prior to the meeting, we chose to focus on 3 topics: (1) gaps and issues in primary health care for MSK health, (2) current application of digital media in health care, and (3) challenges to using digital media to improve MSK health in underserviced populations. Results The 2-day discussion led to emergence of 1 overarching question and 4 research priorities. A main research priority was to understand the characteristics of those who are not able to access preventive measures and treatment for early MSK diseases. Participants

  18. Anaerobic bioassay of methane potential of microalgal biomass

    NASA Astrophysics Data System (ADS)

    Yen, Hong-Wei

    This study was undertaken to investigate the feasibility of using anaerobic digestion as a technique to recover solar energy embodied in excess algal biomass production harvested from Clemson University's high rate algal based Partitioned Aquaculture System (PAS) as an energy source to support PAS operations. In this study, four different organic substrates were loaded to anaerobic digesters in eight experimental trials, to ascertain the optimal combination of operational variables and effect of algal, or modified algal substrate upon methane production rate. The four substrates used in this study were: (1) a synthetic feedstock consisting of molasses and dog food, (2) a commercially obtained, readily degradable algal biomass (Spirulina ) in dry form, (3) PAS harvested and dewatered algal sludge, and (4) algal biomass blended with shredded waste paper or molasses as a carbon supplement for the adjustment of algal C/N ratio. Eight experimental trials using combinations of the four substrates were conducted in 15 liter digesters to investigate the effects of controlled digester parameters upon digester performance. Digesters operating at 20 days HRT, mesophilic digestion (35°C), and twice per day mixing at maximal loading rates produced maximal methane gas using PAS algal sludge. However, under these conditions overall methane production was less than 1000 ml CH4/l day. This low level of energy recovery from the fermentation of algal biomass (alone) is not energetically or economically favorable. Co-digestion of algal sludge and waste paper was investigated as a way to increase methane production. The data obtained from these trials suggest an optimum C/N ratio for co-digestion of algal sludge and waste paper in the range of 20--25/l. A balanced C/N ratio along with the stimulated increase in cellulase activity is suggested as likely reasons for increased methane production seen in co-digestion of algal sludge and waste paper. Yeast extract addition to anaerobic

  19. Culturing and Maintaining Clostridium difficile in an Anaerobic Environment

    PubMed Central

    Edwards, Adrianne N.; Suárez, Jose M.; McBride, Shonna M.

    2013-01-01

    Clostridium difficile is a Gram-positive, anaerobic, sporogenic bacterium that is primarily responsible for antibiotic associated diarrhea (AAD) and is a significant nosocomial pathogen. C. difficile is notoriously difficult to isolate and cultivate and is extremely sensitive to even low levels of oxygen in the environment. Here, methods for isolating C. difficile from fecal samples and subsequently culturing C. difficile for preparation of glycerol stocks for long-term storage are presented. Techniques for preparing and enumerating spore stocks in the laboratory for a variety of downstream applications including microscopy and animal studies are also described. These techniques necessitate an anaerobic chamber, which maintains a consistent anaerobic environment to ensure proper conditions for optimal C. difficile growth. We provide protocols for transferring materials in and out of the chamber without causing significant oxygen contamination along with suggestions for regular maintenance required to sustain the appropriate anaerobic environment for efficient and consistent C. difficile cultivation. PMID:24084491

  20. THIAMINE AND NICOTINIC ACID: ANAEROBIC GROWTH FACTORS FOR MUCOR ROUXII

    PubMed Central

    Bartnicki-Garcia, S.; Nickerson, Walter J.

    1961-01-01

    Bartnicki-Garcia, S. (Rutgers, the State University, New Brunswick, N. J.), and Walter J. Nickerson. Thiamine and nicotinic acid: Anaerobic growth factors for Mucor rouxii. J. Bacteriol. 82:142–148. 1961.—Mucor rouxii requires preformed thiamine and nicotinic acid for anaerobic growth. Such requirements are not manifested during aerobic incubation. Aerobically, the fungus was shown to be able to synthesize both vitamins. The yeastlike form and the filamentous form of anaerobically grown M. rouxii exhibit the same vitamin requirements. Thiamine can be substituted by its thiazole moiety. Under certain conditions, nicotinic acid was partly substituted by tryptophan, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid. Anaerobically. the fungus (thiamine requiring) was about ten times more susceptible to pyrithiamine antagonism than the same organism grown aerobically (thiamine independent). PMID:16561911

  1. Comparison of microbial activity in anaerobic and microaerobic digesters.

    PubMed

    Jenicek, P; Celis, C A; Koubova, J; Pokorna, D

    2011-01-01

    Microaerobic alternative of anaerobic digestion offers many advantages especially when sulfide concentration in the digester is high. For better understanding of the microaerobic technology more detailed characterization of biomass activity is needed. Two equal digesters were operated under the same condition except of microaeration in one of them. During long term operation of anaerobic and microaerobic digesters the sludge quality and the biomass activity was monitored. The activity of sulfide oxidizing bacteria of microaerobic biomass was significantly higher in comparison with anaerobic biomass. The activity of sulfate reducing bacteria was comparable. The activity of methanogenic bacteria activity depended on sulfide concentration more than on microaeration. The extent of foaming problems was lower in the microaerobic than in the anaerobic digester. PMID:21977645

  2. Enhanced methane production from microalgal biomass by anaerobic bio-pretreatment.

    PubMed

    He, Shuai; Fan, Xiaolei; Katukuri, Naveen Reddy; Yuan, Xianzheng; Wang, Fei; Guo, Rong-Bo

    2016-03-01

    Anaerobic digestion (AD) of microalgal biomass is one of the most energy efficient technologies to convert microalgae to biofuels. In order to improve the biogas productivity, breaking up the tough and rigid cell wall of microalgae by pretreatment is necessary. In this work, Bacillus licheniformis, a facultative anaerobic bacterial with hydrolytic and acidogenic activities, was adopted to pretreat Chlorella sp. In the established pretreatment process, pure bacterial culture (0%, 1%, 2%, 4%, 8%, v/v) were used to pretreat Chlorella sp. under anaerobic condition at 37°C for 60 h. The soluble chemical oxygen demands (SCOD) content was increased by 16.4-43.4%, while volatile fatty acids (VFAs) were improved by 17.3-44.2%. Furthermore, enhancement of methane production (9.2-22.7%) was also observed in subsequent AD. The results indicated that the more dosages of bacteria were used to pretreat the microalgal biomass in the range of 1-8%, the more methane was produced. PMID:26773949

  3. A new dynamic model for bioavailability and cometabolism of micropollutants during anaerobic digestion.

    PubMed

    Delgadillo-Mirquez, Liliana; Lardon, Laurent; Steyer, Jean-Philippe; Patureau, Dominique

    2011-10-01

    Organic micropollutants (OMPs) are present in wastewater and sludge. Their possible impact to the environment contributes to their increasing scientific and social interest. Anaerobic digestion has been shown as a potential biological process for removal of these compounds. An accurate description of OMP distribution in the environmental system can be used to better understand which compartment is used for degradation and to improve their depletion in conventional wastewater treatment technologies. In this work, we proposed a dynamical model with a four-compartment distribution to describe the Polycyclic Aromatic Hydrocarbons (PAHs) fate during anaerobic digestion. The model is calibrated and validated using experimental data obtained from two continuous reactors fed with primary and secondary sludge operated under mesophilic conditions. A non-linear least square method was used to optimize the model parameters. The resulted model is in accordance with the experimental data. The PAH biodegradation rate is well modeled when considering the aqueous fraction (including free and sorbed to dissolved/colloidal matter PAHs) as the bioavailable compartment. It was also demonstrated in the simulations that the PAHs biodegradation is linked to a mechanism of cometabolism. The model proposed is potentially useful to better understand the micropollutant distribution, predict the fate of PAHs under anaerobic condition and help to optimize the operation process for their depletion. PMID:21719065

  4. Oxygen tolerance capacity of upflow anaerobic solid-state (UASS) with anaerobic filter (AF) system.

    PubMed

    Meng, Yao; Jost, Carsten; Mumme, Jan; Wang, Kaijun; Linke, Bernd

    2016-07-01

    In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state (UASS) with anaerobic filter (AF) system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0-431mL O2/gvs were conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431mL O2/gvs increased the methane yield by 82.2%. Aeration intensities of 0-355mL O2/gvs were conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen (DO) of UASS and AF reactors kept around 1.39±0.27 and 0.99±0.38mg/L, respectively. pH was relatively stable around 7.11±0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85±7mL/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity. PMID:27372134

  5. Improving the performance of gold nanohole array biosensors by controlling the optical collimation conditions.

    PubMed

    Weber de Menezes, Jacson; Thesing, Anderson; Valsecchi, Chiara; Armas, Luis E G; Brolo, Alexandre G

    2015-07-20

    An experimental investigation on how the bulk and surface sensitivities of gold nanohole arrays fabricated by interference lithography affect the degree of white light beam collimation is presented. The optical transmission response of nanohole arrays has been recorded by focused and collimated beam transmission spectra. The results show that both the bulk and surface sensitivities for the collimated case are much larger than for the focused case. In particular, the shape of the spectra was dependent on the degree of beam collimation. The results showed that improved sensing performance (around 3.5 times) and higher figure of merit (around 4.4 times) can be obtained by simply adjusting the incident/collection experimental conditions in transmission measurements. PMID:26367835

  6. Improved stability conditions for uncertain neutral-type systems with time-varying delays

    NASA Astrophysics Data System (ADS)

    Ren, Yu; Feng, Zhiguang; Sun, Guanghui

    2016-06-01

    This paper investigates the robust stability problem for a class of uncertain neutral-type delayed systems. The systems under consideration contain parameter uncertainties and time-varying delays. We aim at designing less conservative robust stability criteria for such systems. A new second-order reciprocally convex inequality is first proposed in order to deal with double integral terms. Then, by constructing a new Lyapunov- Krasovskii functional and employing the improved Wirtinger-based integral inequality and the reciprocally convex combination approaches, novel stability criteria are obtained. Moreover, the stability conditions for standard time-delay system are obtained as by-product results. Comparisons in three numerical examples illustrate the effectiveness of our results.

  7. Improved Prediction of Quasi-Global Vegetation Conditions Using Remotely-Sensed Surface Soil Moisture

    NASA Technical Reports Server (NTRS)

    Bolten, John; Crow, Wade

    2012-01-01

    The added value of satellite-based surface soil moisture retrievals for agricultural drought monitoring is assessed by calculating the lagged rank correlation between remotely-sensed vegetation indices (VI) and soil moisture estimates obtained both before and after the assimilation of surface soil moisture retrievals derived from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) into a soil water balance model. Higher soil moisture/VI lag correlations imply an enhanced ability to predict future vegetation conditions using estimates of current soil moisture. Results demonstrate that the assimilation of AMSR-E surface soil moisture retrievals substantially improve the performance of a global drought monitoring system - particularly in sparsely-instrumented areas of the world where high-quality rainfall observations are unavailable.

  8. Mapping ergonomics application to improve SMEs working condition in industrially developing countries: a critical review.

    PubMed

    Hermawati, Setia; Lawson, Glyn; Sutarto, Auditya Purwandini

    2014-01-01

    In industrially developing countries (IDC), small and medium enterprises (SMEs) account for the highest proprotion of employment. Unfortunately, the working conditions in SMEs are often very poor and expose employees to a potentially wide range of health and safety risks. This paper presents a comprehensive review of 161 articles related to ergonomics application in SMEs, using Indonesia as a case study. The aim of this paper is to investigate the extent of ergonomics application and identify areas that can be improved to promote effective ergonomics for SMEs in IDC. The most urgent issue found is the need for adopting participatory approach in contrast to the commonly implemented top-down approach. Some good practices in ergonomics application were also revealed from the review, e.g. a multidisciplinary approach, unsophisticated and low-cost solutions, and recognising the importance of productivity. The review also found that more work is still required to achieve appropriate cross-cultural adaptation of ergonomics application. PMID:25216158

  9. Improved Global Soft Decision Incorporating Second-Order Conditional MAP in Speech Enhancement

    NASA Astrophysics Data System (ADS)

    Kum, Jong-Mo; Chang, Joon-Hyuk

    In this paper, we propose a novel method based on the second-order conditional maximum a posteriori (CMAP) to improve the performance of the global soft decision in speech enhancement. The conventional global soft decision scheme is found through investigation to have a disadvantage in that the global speech absence probability (GSAP) in that scheme is adjusted by a fixed parameter, which could be a restrictive assumption in the consecutive occurrences of speech frames. To address this problem, we devise a method to incorporate the second-order CMAP in determining the GSAP, which is clearly different from the previous approach in that not only current observation but also the speech activity decisions of the previous two frames are exploited. Performances of the proposed method are evaluated by a number of tests in various environments and show better results than previous work.

  10. Improved Relationships for the Thermodynamic Properties of Carbon Phases at Detonation Conditions

    NASA Astrophysics Data System (ADS)

    Stiel, Leonard; Baker, Ernest; Murphy, Daniel

    2013-06-01

    In order to improve the procedures utilized in the Jaguar thermochemical program for carbon, volumetric and heat capacity relationships have been developed for graphite, diamond, and liquid carbon forms. Available experimental thermodynamic property and Hugoniot data have been analyzed to establish optimum equations of state for the carbon phases. The appropriate carbon form or multiple forms at equilibrium results from the minimization of the Gibbs free energy of the system. The resulting relationships are utilized to examine the phase behavior of carbon at elevated temperatures and pressures. The behavior of metastable carbon states is optimized by analyses of Hugoniot data for hydrocarbons, and C-J and cylinder velocities for a database of CHNO explosives. The accuracy of the resulting relationships is demonstrated by comparisons for several properties, including the Hugoniot behavior of oxygen-deficient explosives at overdriven conditions.

  11. Economic viability of anaerobic digestion

    SciTech Connect

    Wellinger, A.

    1996-01-01

    The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters - type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates - define the investment and operating costs of an anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters is somewhat higher than that of anaerobic digestion, but the investment costs 1 1/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.

  12. Hydrologic modification to improve habitat in riverine lakes: Management objectives, experimental approach, and initial conditions

    USGS Publications Warehouse

    Johnson, Barry L.; Barko, John W.; Gerasimov, Yuri; James, William F.; Litvinov, Alexander; Naimo, Teresa J.; Wiener, James G.; Gaugush, Robert F.; Rogala, James T.; Rogers, Sara J.

    1996-01-01

    The Finger Lakes habitat-rehabilitation project is intended to improve physical and chemical conditions for fish in six connected back water lakes in Navigation Pool 5 of the upper Missouri River. The primary management objective is to improve water temperature, dissolved oxygen concentration and current velocity during winter for bluegills, Lepomis macrochirus, and black crappies, Pomoxis nigromaculatus, two of the primary sport fishes in the lakes. The lakes will be hydrologically altered by Installing culverts to Introduce controlled flows of oxygenated water into four lakes, and an existing unregulated culvert on a fifth lake will be equipped with a control gate to regulate inflow. These habitat modifications constitute a manipulative field experiment that will compare pre-project (1991 to summer 1993) and post-project (fall 1993 to 1996) conditions in the lakes, including hydrology, chemistry, rooted vegetation, and fish and macroinvertebrate communities. Initial data indicate that the Finger Lakes differ in water chemistry, hydrology, and macrophyte abundance. Macroinvertebrate communities also differed among lakes: species diversity was highest in lakes with dense aquatic macrophytes. The system seems to support a single fish community, although some species concentrated in individual lakes at different times. The introduction of similar flows into five of the lakes will probably reduce the existing physical and chemical differences among lakes. However, our ability to predict the effects of hydrologic modification on fish populations is limited by uncertainties concerning both the interactions of temperature, oxygen and current in winter and the biological responses of primary and secondary producers. Results from this study should provide guidance for similar habitat-rehabilitation projects in large rivers.

  13. Anaerobic biodegradation of aromatic compounds.

    PubMed

    Jothimani, P; Kalaichelvan, G; Bhaskaran, A; Selvaseelan, D Augustine; Ramasamy, K

    2003-09-01

    Many aromatic compounds and their monomers are existing in nature. Besides they are introduced into the environment by human activity. The conversion of these aromatic compounds is mainly an aerobic process because of the involvement of molecular oxygen in ring fission and as an electron acceptor. Recent literatures indicated that ring fission of monomers and obligomers mainly occurs in anaerobic environments through anaerobic respiration with nitrate, sulphate, carbon dioxide or carbonate as electron acceptors. These anaerobic processes will help to work out the better situation for bioremediation of contaminated environments. While there are plenty of efforts to reduce the release of these chemicals to the environment, already contaminated sites need to be remediated not only to restore the sites but to prevent the leachates spreading to nearby environment. Basically microorganisms are better candidates for breakdown of these compounds because of their wider catalytic mechanisms and the ability to act even in the absence of oxygen. These microbes can be grouped based on their energy mechanisms. Normally, the aerobic counterparts employ the enzymes like mono-and-dioxygenases. The end product is basically catechol, which further may be metabolised to CO2 by means of quinones reductases cycles. In the absense of reductases compounds, the reduced catechols tend to become oxidised to form many quinone compounds. The quinone products are more recalcitrant and lead to other aesthetic problems like colour in water, unpleasant odour, etc. On the contrary, in the reducing environment this process is prevented and in a cascade of pathways, the cleaved products are converted to acetyl co-A to be integrated into other central metabolite paths. The central metabolite of anaerobic degradation is invariably co-A thio-esters of benzoic acid or hydroxy benzoic acid. The benzene ring undergoes various substitution and addition reactions to form chloro-, nitro-, methyl- compounds

  14. Conditional economic incentives to improve HIV treatment adherence: literature review and theoretical considerations

    PubMed Central

    Galárraga, Omar; Genberg, Becky L.; Martin, Rosemarie A.; Laws, M. Barton; Wilson, Ira B.

    2013-01-01

    We present selected theoretical issues regarding conditional economic incentives (CEI) for HIV treatment adherence. High HIV treatment adherence is essential not only to improve individual health for persons living with HIV, but also to reduce transmission. The incentives literature spans several decades and various disciplines, thus we selectively point out useful concepts from economics, psychology and HIV clinical practice to elucidate the complex interaction between socio-economic issues, psychological perspectives and optimal treatment adherence. Appropriately-implemented CEI can help patients improve their adherence to HIV treatment in the short-term, while the incentives are in place. However, more research is needed to uncover mechanisms that can increase habit formation or maintenance effects in the longer-term. We suggest some potentially fruitful avenues for future research in this area, including the use of concepts from self-determination theory. This general framework may have implications for related research among disadvantaged communities with high rates of HIV/AIDS infection. PMID:23370833

  15. Improvement of Plasma Performance with Lithium Wall Conditioning in Aditya Tokamak

    NASA Astrophysics Data System (ADS)

    B. Chowdhuri, M.; Manchanda, R.; Ghosh, J.; B. Bhatt, S.; Ajai, Kumar; K. Das, B.; A. Jadeja, K.; A. Raijada, P.; Manoj, Kumar; Banerjee, S.; Nilam, Ramaiya; Aniruddh, Mali; Ketan, M. Patel; Vinay, Kumar; Vasu, P.; Bhattacharyay, R.; L. Tanna, R.; Y. Shankara, Joisa; K. Atrey, P.; V. S. Rao, C.; Chenna Reddy, D.; K. Chattopadhyay, P.; Jha, R.; C. Saxena, Y.; Aditya Team

    2013-02-01

    Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ~100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal (up to ~40% to 50%) and a 20% to 30% decrease of Hα signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Zeff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.

  16. Improvement of submerged culture conditions to produce colorants by Penicillium purpurogenum.

    PubMed

    Santos-Ebinuma, Valéria Carvalho; Roberto, Inês Conceição; Teixeira, Maria Francisca Simas; Pessoa, Adalberto

    2014-01-01

    Safety issues related to the employment of synthetic colorants in different industrial segments have increased the interest in the production of colorants from natural sources, such as microorganisms. Improved cultivation technologies have allowed the use of microorganisms as an alternative source of natural colorants. The objective of this work was to evaluate the influence of some factors on natural colorants production by a recently isolated from Amazon Forest, Penicillium purpurogenum DPUA 1275 employing statistical tools. To this purpose the following variables: orbital stirring speed, pH, temperature, sucrose and yeast extract concentrations and incubation time were studied through two fractional factorial, one full factorial and a central composite factorial designs. The regression analysis pointed out that sucrose and yeast extract concentrations were the variables that influenced more in colorants production. Under the best conditions (yeast extract concentration around 10 g/L and sucrose concentration of 50 g/L) an increase of 10, 33 and 23% respectively to yellow, orange and red colorants absorbance was achieved. These results show that P. purpurogenum is an alternative colorants producer and the production of these biocompounds can be improved employing statistical tool. PMID:25242965

  17. Improvement of submerged culture conditions to produce colorants by Penicillium purpurogenum

    PubMed Central

    Santos-Ebinuma, Valéria Carvalho; Roberto, Inês Conceição; Teixeira, Maria Francisca Simas; Pessoa, Adalberto

    2014-01-01

    Safety issues related to the employment of synthetic colorants in different industrial segments have increased the interest in the production of colorants from natural sources, such as microorganisms. Improved cultivation technologies have allowed the use of microorganisms as an alternative source of natural colorants. The objective of this work was to evaluate the influence of some factors on natural colorants production by a recently isolated from Amazon Forest, Penicillium purpurogenum DPUA 1275 employing statistical tools. To this purpose the following variables: orbital stirring speed, pH, temperature, sucrose and yeast extract concentrations and incubation time were studied through two fractional factorial, one full factorial and a central composite factorial designs. The regression analysis pointed out that sucrose and yeast extract concentrations were the variables that influenced more in colorants production. Under the best conditions (yeast extract concentration around 10 g/L and sucrose concentration of 50 g/L) an increase of 10, 33 and 23% respectively to yellow, orange and red colorants absorbance was achieved. These results show that P. purpurogenum is an alternative colorants producer and the production of these biocompounds can be improved employing statistical tool. PMID:25242965

  18. Citrulline Supplementation Improves Organ Perfusion and Arginine Availability under Conditions with Enhanced Arginase Activity

    PubMed Central

    Wijnands, Karolina A.P.; Meesters, Dennis M.; van Barneveld, Kevin W.Y.; Visschers, Ruben G.J.; Briedé, Jacob J.; Vandendriessche, Benjamin; van Eijk, Hans M.H.; Bessems, Babs A.F.M.; van den Hoven, Nadine; von Wintersdorff, Christian J.H.; Brouckaert, Peter; Bouvy, Nicole D.; Lamers, Wouter H.; Cauwels, Anje; Poeze, Martijn

    2015-01-01

    Enhanced arginase-induced arginine consumption is believed to play a key role in the pathogenesis of sickle cell disease-induced end organ failure. Enhancement of arginine availability with l-arginine supplementation exhibited less consistent results; however, l-citrulline, the precursor of l-arginine, may be a promising alternative. In this study, we determined the effects of l-citrulline compared to l-arginine supplementation on arginine-nitric oxide (NO) metabolism, arginine availability and microcirculation in a murine model with acutely-enhanced arginase activity. The effects were measured in six groups of mice (n = 8 each) injected intraperitoneally with sterile saline or arginase (1000 IE/mouse) with or without being separately injected with l-citrulline or l-arginine 1 h prior to assessment of the microcirculation with side stream dark-field (SDF)-imaging or in vivo NO-production with electron spin resonance (ESR) spectroscopy. Arginase injection caused a decrease in plasma and tissue arginine concentrations. l-arginine and l-citrulline supplementation both enhanced plasma and tissue arginine concentrations in arginase-injected mice. However, only the citrulline supplementation increased NO production and improved microcirculatory flow in arginase-injected mice. In conclusion, the present study provides for the first time in vivo experimental evidence that l-citrulline, and not l-arginine supplementation, improves the end organ microcirculation during conditions with acute arginase-induced arginine deficiency by increasing the NO concentration in tissues. PMID:26132994

  19. Using Dynamic Risk to Enhance Conditional Release Decisions in Prisoners to Improve Their Outcomes.

    PubMed

    Serin, Ralph C; Gobeil, Renée; Lloyd, Caleb D; Chadwick, Nick; Wardrop, Kaitlyn; Hanby, Laura

    2016-03-01

    Advances in criminal risk assessment have increased sufficiently that inclusion of valid risk measures to anchor assessments is considered a best practice in release decision-making and community supervision by many paroling authorities and probation agencies. This article highlights how decision accuracy at several key stages of the offender's release and supervision process could be further enhanced by the inclusion of dynamic factors. In cases where the timing of release is discretionary and not legislated, the utilization of a validated decision framework can improve transparency and potentially reduce decision errors. In cases where release is by statute, there is still merit in using dynamic risk assessment and case analysis to inform the assignment of release conditions, thereby attending to re-entry and public safety considerations. Finally, preliminary results from a recent study are presented to highlight the fact that community supervision outcomes may be improved by incorporating changes in dynamic risk into case planning and risk management, although this work requires replication with larger populations reflecting diverse groups of offenders. Nonetheless, these decision strategies have implications for both resource allocation and client outcomes, as outlined here. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26992091

  20. Conditional economic incentives to improve HIV treatment adherence: literature review and theoretical considerations.

    PubMed

    Galárraga, Omar; Genberg, Becky L; Martin, Rosemarie A; Barton Laws, M; Wilson, Ira B

    2013-09-01

    We present selected theoretical issues regarding conditional economic incentives (CEI) for HIV treatment adherence. High HIV treatment adherence is essential not only to improve individual health for persons living with HIV, but also to reduce transmission. The incentives literature spans several decades and various disciplines, thus we selectively point out useful concepts from economics, psychology and HIV clinical practice to elucidate the complex interaction between socio-economic issues, psychological perspectives and optimal treatment adherence. Appropriately-implemented CEI can help patients improve their adherence to HIV treatment in the short-term, while the incentives are in place. However, more research is needed to uncover mechanisms that can increase habit formation or maintenance effects in the longer-term. We suggest some potentially fruitful avenues for future research in this area, including the use of concepts from self-determination theory. This general framework may have implications for related research among disadvantaged communities with high rates of HIV/AIDS infection. PMID:23370833

  1. CrossTalk proposal: Heat acclimatization does improve performance in a cool condition.

    PubMed

    Minson, Christopher T; Cotter, James D

    2016-01-15

    We believe available data support the thesis that HA can improve performance in cool conditions, and perhaps with less expense and fewer side-effects than hypoxia (Dempsey & Morgan, 2015), but its utility is unresolved and may be modest or absent in some settings and individuals. A few key issues are becoming clear, however. First, HA must be of sufficient stimulus and duration, with key evidence indicating longer is better. Second, individual variability in response to HA as an ergogenic aid needs to be considered. Third, key training aspects such as speed and intensity may need to be maintained, and ideally performed in a cooler environment to maximize gains and minimize fatigue (including the effects of matched absolute versus relative work rates on adaptations). Alternatively, passive heating should be considered (e.g. immediately after training). Fourth, there is no evidence that HA impairs cool weather performance, and thus HA is a useful strategy when the competitive environmental conditions are potentially hot or unknown. Fifth, much remains unknown about ideal timing for competition following HA and its decay. Lastly, an ergogenic effect of HA has yet to be studied in truly elite athletes. PMID:26668072

  2. Magnetic fluids improving effect in in vitro regenerates in hypogravity conditions

    NASA Astrophysics Data System (ADS)

    Butnaru, Gallia; Terteac, Dumitru; Potencz, Iosif

    1999-07-01

    The previous in vitro experiments done with different types of magnetic fluids (MFs) pointed out the favorable effect upon dedifferentiation and redifferentiation. Finally, regeneration of an embryo and of plantlets from a single vegetative plant cell was successfully performed. The two processes are the most spectacular aspects of development involving the formation of different distinct cells and of tissue which increase the potential for variability to new conditions. These advancements generated the idea that the MFs could have a favorable effect on cell morphology and tissue structural organization. This study addressed the question of whether or not Magnetic Fluids could have a protective effect on plants grown under different stress conditions as well as in simulated hypogravity influence. In simulated hypogravity two possible patterns of influence were postulated: reversible and irreversible cell modifications. The presence of the magnetic particles (MPs) in the growth medium improved the cell and the anatomical leaf structure. The favorable effect was the enrichment of the density, due to MPs penetration in cytoplasm, or due to the change in the cell water potential. We presume both.

  3. Effect of steeping conditions on the amylolytic development of some Nigerian improved sorghum cultivars.

    PubMed

    Ukwuru, M U

    2010-01-01

    Nigerian improved sorghum cultivars 'L538', 'YG5760', 'L1499', 'SSH1' and 'SSH3' were investigated for the effect of steeping conditions on their amylolytic development. The grains were steeped using 3 steep regimes SR 1, SR 2 and SR 3 which involved steeping and re-steeping in cold distilled and de-ionized water for 36, 45 and 54 h respectively. Grains in each SR were divided into 4 portions and further steeped for 6 h using final warm steep temperatures (FWST) of 30, 35, 40 and 45°C. α-and β-Amylase as well as diastatic activity were determined at different FWST. SR and FWST were correlated with enzyme development. Steeping conditions significantly (p<0.05) affected amylolytic development of the sorghum malts. Optimum moisture content (48%) was obtained at FWST of 35°C. α-Amylase was the predominant enzyme. All enzyme activities were at a peak at FWST of 30 and 35°C and at SR 2. The highest enzyme activity was recorded by cultivar 'YG5760' malt-(α-amylase 272, β-Amylase 169 μg equivalent glucose). High relationship existed between α-amylase and moderate relationship between β-Amylase and SR. Similar relationship existed between enzyme development and FWST. PMID:23572602

  4. Microbial inoculants and organic amendment improves plant establishment and soil rehabilitation under semiarid conditions.

    PubMed

    Mengual, Carmen; Schoebitz, Mauricio; Azcón, Rosario; Roldán, Antonio

    2014-02-15

    The re-establishment of autochthonous shrub species is an essential strategy for recovering degraded soils under semiarid Mediterranean conditions. A field assay was carried out to determine the combined effects of the inoculation with native rhizobacteria (Bacillus megaterium, Enterobacter sp, Bacillus thuringiensis and Bacillus sp) and the addition of composted sugar beet (SB) residue on physicochemical soil properties and Lavandula dentata L. establishment. One year after planting, Bacillus sp. and B. megaterium + SB were the most effective treatments for increasing shoot dry biomass (by 5-fold with respect to control) and Enterobacter sp + SB was the most effective treatments for increasing dry root biomass. All the treatments evaluated significantly increased the foliar nutrient content (NPK) compared to control values (except B. thuringiensis + SB). The organic amendment had significantly increased available phosphorus content in rhizosphere soil by 29% respect to the control. Enterobacter sp combined with sugar beet residue improved total N content in soil (by 46% respect to the control) as well as microbiological and biochemical properties. The selection of the most efficient rhizobacteria strains and their combined effect with organic residue seems to be a critical point that drives the effectiveness of using these biotechnological tools for the revegetation and rehabilitation of degraded soils under semiarid conditions. PMID:24463051

  5. Chitosan/siCkip-1 biofunctionalized titanium implant for improved osseointegration in the osteoporotic condition

    PubMed Central

    Zhang, Li; Wu, Kaimin; Song, Wen; Xu, Haiyan; An, Ran; Zhao, Lingzhou; Liu, Bin; Zhang, Yumei

    2015-01-01

    Biofunctionalization with siRNA targeting the key negative modulators of bone turnover involved in the molecular mechanism of osteoporosis, such as casein kinase-2 interacting protein-1 (Ckip-1), may lead to enhanced Ti osseointegration in the osteoporotic condition. In this study, even siRNA loading was accomplished by the thermal alkali (TA) treatment to make the Ti ultrahydrophilic and negatively charged to facilitate the physical adsorption of the positively charged CS/siR complex, designated as TA-CS/siR. The intracellular uptake of the CS/siR complex and the gene knockdown efficiency were assessed with bone marrow mesenchymal stem cells (MSCs) as well as the green fluorescent protein (GFP) expressing H1299 cells. In vitro osteogenic activity of TA-CS/siCkip-1 targeting Ckip-1 was assessed with MSCs. In vivo osseointegration of TA-CS/siCkip-1 was assessed in the osteoporotic rat model. TA-CS/siR showed excellent siRNA delivery efficiency and gene silencing effect. TA-CS/siCkip-1 significantly improved the in vitro osteogenic differentiation of MSCs in terms of the enhanced alkaline phosphatase and collagen product and extracellular matrix mineralization, and led to dramatically enhanced in vivo osseointegration in the osteoporostic rat model, showing promising clinical potential for the osteoporotic condition application. TA-CS/siR may constitute a general approach for developing the advanced Ti implants targeting specific molecular mechanism. PMID:26040545

  6. [The main ways of improvement of medical support of the Air Forces in modern conditions].

    PubMed

    Blaginin, A A; Grebeniuk, A N; Lizogub, I N

    2014-02-01

    Blaginin A.A., Grebenyuk A.N., Lizogub LN. - The main ways of improvement of medical support of the Air Forces in modern conditions. Aircrew conducting active hostilities suffers from the whole spectrum of factors and conditions of the combat situation. The main task for the medical service of the Air Force is to carry out preventive and curative action for aviation specialists who are responsible for the combat capability of aircraft formations. The medical service of the Air Force must have forces and facilities for planning, organization and implementation of the treatment of lightly wounded and sick aviation professionals with short periods of recovery, medical rehabilitation of aircrew qfter suffering injuries, diseases, sanatorium therapy of aircrew with partial failure of health, outpatient and inpatient medical examination aircrew - flight commissions, preventive rest of aviation specialists with symptoms of chronic fatigue. Should be trained aviation physicians, including both basic military medical education and in-depth study of the medical aspects of various fields of personnel of the Air Force. PMID:25046924

  7. New anaerobic process of nitrogen removal.

    PubMed

    Kalyuzhnyi, S; Gladchenko, M; Mulder, A; Versprille, B

    2006-01-01

    This paper reports on successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for the treatment of strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered ANAMMOX (ANaerobic AMMonium OXidation) reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite within an anaerobic biofilm. The achieved results with a nitrogen loading rate of higher than 1,000 mg/L/d and nitrogen removal of around 90% look very promising because they exceed (by 9-18 times) the corresponding nitrogen removal rates of conventional activated sludge systems. The paper describes also some characteristics of DEAMOX sludge, as well as the preliminary results of its microbiological characterization. PMID:17163025

  8. Diversity of anaerobic halophilic microorganisms

    NASA Astrophysics Data System (ADS)

    Oren, Aharon; Oremland, Roland S.

    2000-12-01

    Life in the presence of high salt concentrations is compatible with life in the absence of oxygen. Halophilic and halotolerant anaerobic prokaryotes are found both in the archaeal and in the bacterial domain, and they display a great metabolic diversity. Many of the representatives of the Halobacteriales (Archaea), which are generally considered aerobes, have the potential of anaerobic growth. Some can use alternative electron acceptors such as nitrate, fumarate, dimethylsulfoxide or trimethylamine-N-oxide Halobacterium salinarum can also grow fermentatively on L-arginine, and bacteriorhodopsin-containing cells may even grow anaerobically, energized by light. Obligatory anaerobic halophilic methanogenic Archaea also exist. The bacterial domain contains many anaerobic halophiles, including sulfate reducers. There is also a group of specialized obligatory anaerobic Bacteria, phylogenetically clustering in the low G + C branch of the Firmicutes. Most representatives of this group (order Haloanaerobiales, families Haloanaerobiaceae and Halobacteroidaceae) are fermentative, using a variety of carbohydrates and amino acids. One species combines the potential for anaerobic growth at high salt concentrations with a preference for high temperatures. Others are homoacetogens; Acetohalobium arabaticum can grow anaerobically as a chemolithotroph, producing acetate from hydrogen and CO2. The Haloanaerobiales accumulate high concentrations of K+ and Cl- in their cytoplasm, thereby showing a strategy of salt adaptation similar to that used by the Halobacteriales. Recently a new representative of the Haloanaerobiales was isolated from bottom sediments of the Dead Sea (strain DSSe1), which grows anaerobically by oxidation of glycerol to acetate and CO2 while reducing selenate to selenite and elementary selenium. Other electron acceptors supporting anaerobic growth of this strain are nitrate and trimethylamine-N-oxide. The versatility of life at high salt concentrations with respect

  9. Anaerobic degradation of aircraft deicing fluid (ADF) in upflow anaerobic sludge blanket (UASB) reactors and the fate of ADF additives

    NASA Astrophysics Data System (ADS)

    Pham, Thi Tham

    2002-11-01

    A central composite design was employed to methodically investigate anaerobic treatment of aircraft deicing fluid (ADF) in bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactors. A total of 23 runs at 17 different operating conditions were conducted in continuous mode. The development of four empirical models describing process responses (i.e., chemical oxygen demand (COD) removal efficiency, biomass specific acetoclastic activity, methane production rate, and methane production potential) as functions of ADF concentration, hydraulic retention time (HRT), and biomass concentration is presented. Model verification indicated that predicted responses (COD removal efficiencies, biomass specific acetoclastic activity, and methane production rates and potential) were in good agreement with experimental results. Biomass specific acetoclastic activity was improved by almost two-fold during ADF treatment in UASB reactors. For the design window, COD removal efficiencies were higher than 90%. Predicted methane production potentials were close to theoretical values, and methane production rates increased as the organic loading rate (OLR) was increased. ADF toxicity effects were evident for 1.6% ADF at medium specific organic loadings (SOLR above 0.5 g COD/g VSS/d). In contrast, good reactor stability and excellent removal efficiencies were achieved at 1.2% ADF for reactor loadings approaching that of highly loaded systems (0.73 g COD/g VSS/d). Acclimation to ADF resulted in an initial reduction in the biomass settling velocity. The fate of ADF additives was also investigated. There was minimal sorption of benzotriazole (BT), 5-methyl-1 H-benzotriazole (MeBT), and 5,6-dimethyl-1 H-benzotriazole (DiMeBT) to anaerobic granules. A higher sorption capacity was measured for NP. Active transport may be one of the mechanisms for NP sorption. Ethylene glycol degradation experiments indicated that BT, MeBT, DiMeBT, and the nonionic surfactant Tergitol NP-4 had no significant

  10. Anaerobic Metabolism of Indoleacetate

    PubMed Central

    Ebenau-Jehle, Christa; Thomas, Markus; Scharf, Gernot; Kockelkorn, Daniel; Knapp, Bettina; Schühle, Karola; Heider, Johann

    2012-01-01

    The anaerobic metabolism of indoleacetate (indole-3-acetic acid [IAA]) in the denitrifying betaproteobacterium Azoarcus evansii was studied. The strain oxidized IAA completely and grew with a generation time of 10 h. Enzyme activities that transformed IAA were present in the soluble cell fraction of IAA-grown cells but were 10-fold downregulated in cells grown on 2-aminobenzoate or benzoate. The transformation of IAA did not require molecular oxygen but required electron acceptors like NAD+ or artificial dyes. The first products identified were the enol and keto forms of 2-oxo-IAA. Later, polar products were observed, which could not yet be identified. The first steps likely consist of the anaerobic hydroxylation of the N-heterocyclic pyrrole ring to the enol form of 2-oxo-IAA, which is catalyzed by a molybdenum cofactor-containing dehydrogenase. This step is probably followed by the hydrolytic ring opening of the keto form, which is catalyzed by a hydantoinase-like enzyme. A comparison of the proteome of IAA- and benzoate-grown cells identified IAA-induced proteins. Owing to the high similarity of A. evansii with strain EbN1, whose genome is known, we identified a cluster of 14 genes that code for IAA-induced proteins involved in the early steps of IAA metabolism. These genes include a molybdenum cofactor-dependent dehydrogenase of the xanthine oxidase/aldehyde dehydrogenase family, a hydantoinase, a coenzyme A (CoA) ligase, a CoA transferase, a coenzyme B12-dependent mutase, an acyl-CoA dehydrogenase, a fusion protein of an enoyl-CoA hydratase and a 3-hydroxyacyl-CoA dehydrogenase, a beta-ketothiolase, and a periplasmic substrate binding protein for ABC transport as well as a transcriptional regulator of the GntR family. Five predicted enzymes form or act on CoA thioesters, indicating that soon after the initial oxidation of IAA and possibly ring opening, CoA thioesters are formed, and the carbon skeleton is rearranged, followed by a CoA-dependent thiolytic

  11. Identification of a conserved protein involved in anaerobic unsaturated fatty acid synthesis in Neiserria gonorrhoeae: implications for facultative and obligate anaerobes that lack FabA.

    PubMed

    Isabella, Vincent M; Clark, Virginia L

    2011-10-01

    Transcriptome analysis of the facultative anaerobe, Neisseria gonorrhoeae, revealed that many genes of unknown function were induced under anaerobic conditions. Mutation of one such gene, NGO1024, encoding a protein belonging to the 2-nitropropane dioxygenase-like superfamily of proteins, was found to result in an inability of gonococci to grow anaerobically. Anaerobic growth of an NG1024 mutant was restored upon supplementation with unsaturated fatty acids (UFA), but not with the saturated fatty acid palmitate. Gonococcal fatty acid profiles confirmed that NGO1024 was involved in UFA synthesis anaerobically, but not aerobically, demonstrating that gonococci contain two distinct pathways for the production of UFAs, with a yet unidentified aerobic mechanism, and an anaerobic mechanism involving NGO1024. Expression of genes involved in classical anaerobic UFA synthesis, fabA, fabM and fabB, was toxic in gonococci and unable to complement a NGO1024 mutation, suggesting that the chemistry involved in gonococcal anaerobic UFA synthesis is distinct from that of the classical pathway. NGO1024 homologues, which we suggest naming UfaA, form a distinct lineage within the 2-nitropropane dioxygenase-like superfamily, and are found in many facultative and obligate anaerobes that produce UFAs but lack fabA, suggesting that UfaA is part of a widespread pathway involved in UFA synthesis. PMID:21895795

  12. The metagenome of an anaerobic microbial community decomposing poplar wood chips

    SciTech Connect

    van der Lelie D.; Taghavi, S.; McCorkle, S. M.; Li, L.-L.; Malfatti, S. A.; Monteleone, D.; Donohoe, B. S.; Ding, S.-Y.; Adney, W. S.; Himmel, M. E.; Tringe, S. G.

    2012-05-01

    This study describes the composition and metabolic potential of a lignocellulosic biomass degrading community that decays poplar wood chips under anaerobic conditions. We examined the community that developed on poplar biomass in a non-aerated bioreactor over the course of a year, with no microbial inoculation other than the naturally occurring organisms on the woody material. The composition of this community contrasts in important ways with biomass-degrading communities associated with higher organisms, which have evolved over millions of years into a symbiotic relationship. Both mammalian and insect hosts provide partial size reduction, chemical treatments (low or high pH environments), and complex enzymatic 'secretomes' that improve microbial access to cell wall polymers. We hypothesized that in order to efficiently degrade coarse untreated biomass, a spontaneously assembled free-living community must both employ alternative strategies, such as enzymatic lignin depolymerization, for accessing hemicellulose and cellulose and have a much broader metabolic potential than host-associated communities. This would suggest that such a community would make a valuable resource for finding new catalytic functions involved in biomass decomposition and gaining new insight into the poorly understood process of anaerobic lignin depolymerization. Therefore, in addition to determining the major players in this community, our work specifically aimed at identifying functions potentially involved in the depolymerization of cellulose, hemicelluloses, and lignin, and to assign specific roles to the prevalent community members in the collaborative process of biomass decomposition. A bacterium similar to Magnetospirillum was identified among the dominant community members, which could play a key role in the anaerobic breakdown of aromatic compounds. We suggest that these compounds are released from the lignin fraction in poplar hardwood during the decay process, which would point to

  13. The Metagenome of an Anaerobic Microbial Community Decomposing Poplar Wood Chips

    PubMed Central

    van der Lelie, Daniel; Taghavi, Safiyh; McCorkle, Sean M.; Li, Luen-Luen; Malfatti, Stephanie A.; Monteleone, Denise; Donohoe, Bryon S.; Ding, Shi-You; Adney, William S.; Himmel, Michael E.; Tringe, Susannah G.

    2012-01-01

    This study describes the composition and metabolic potential of a lignocellulosic biomass degrading community that decays poplar wood chips under anaerobic conditions. We examined the community that developed on poplar biomass in a non-aerated bioreactor over the course of a year, with no microbial inoculation other than the naturally occurring organisms on the woody material. The composition of this community contrasts in important ways with biomass-degrading communities associated with higher organisms, which have evolved over millions of years into a symbiotic relationship. Both mammalian and insect hosts provide partial size reduction, chemical treatments (low or high pH environments), and complex enzymatic ‘secretomes’ that improve microbial access to cell wall polymers. We hypothesized that in order to efficiently degrade coarse untreated biomass, a spontaneously assembled free-living community must both employ alternative strategies, such as enzymatic lignin depolymerization, for accessing hemicellulose and cellulose and have a much broader metabolic potential than host-associated communities. This would suggest that such a community would make a valuable resource for finding new catalytic functions involved in biomass decomposition and gaining new insight into the poorly understood process of anaerobic lignin depolymerization. Therefore, in addition to determining the major players in this community, our work specifically aimed at identifying functions potentially involved in the depolymerization of cellulose, hemicelluloses, and lignin, and to assign specific roles to the prevalent community members in the collaborative process of biomass decomposition. A bacterium similar to Magnetospirillum was identified among the dominant community members, which could play a key role in the anaerobic breakdown of aromatic compounds. We suggest that these compounds are released from the lignin fraction in poplar hardwood during the decay process, which would point

  14. Versatile transformations of hydrocarbons in anaerobic bacteria: substrate ranges and regio- and stereo-chemistry of activation reactions†

    PubMed Central

    Jarling, René; Kühner, Simon; Basílio Janke, Eline; Gruner, Andrea; Drozdowska, Marta; Golding, Bernard T.; Rabus, Ralf; Wilkes, Heinz

    2015-01-01

    Anaerobic metabolism of hydrocarbons proceeds either via addition to fumarate or by hydroxylation in various microorganisms, e.g., sulfate-reducing or denitrifying bacteria, which are specialized in utilizing n-alkanes or alkylbenzenes as growth substrates. General pathways for carbon assimilation and energy gain have been elucidated for a limited number of possible substrates. In this work the metabolic activity of 11 bacterial strains during anaerobic growth with crude oil was investigated and compared with the metabolite patterns appearing during anaerobic growth with more than 40 different hydrocarbons supplied as binary mixtures. We show that the range of co-metabolically formed alkyl- and arylalkyl-succinates is much broader in n-alkane than in alkylbenzene utilizers. The structures and stereochemistry of these products are resolved. Furthermore, we demonstrate that anaerobic hydroxylation of alkylbenzenes does not only occur in denitrifiers but also in sulfate reducers. We propose that these processes play a role in detoxification under conditions of solvent stress. The thermophilic sulfate-reducing strain TD3 is shown to produce n-alkylsuccinates, which are suggested not to derive fr