1,720,976 research outputs found
Factors shaping microbial communities in field-scale thermophilic and mesophilic anaerobic digesters treating food wastewater
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Microbial communities underpinning anaerobic mono- and co-digestion of sewage sludge and food waste: a full-scale study
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Magnetite as an enhancer in methanogenic degradation of volatile fatty acids under ammonia-stressed conditions
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Development of an interspecies interaction model: An experiment on Clostridium cadaveris and Clostridium sporogenes under anaerobic condition
No full textThe specific primer and probe sets for quantifying Clostridiwn cadaveris and Clostridium sporogenes using a quantitative real-time PCR were designed. Each primer and probe set detected only the target species very specifically. The two species were cultivated in pure and mixed culture in batch mode with glucose as the only carbon source. The designed QPCR sets were used successfully to estimate the biokinetic parameters of each species in pure culture: i.e., maximum specific growth rate mu(max), half saturation concentration K-s, growth yield Y, and decay coefficient K-d. of C. cadaveris and C. sporogenes were 0.311 +/- 0.020 and 0.360 +/- 0.019 h(-1), 4.241 +/- 1.653 and 5.171 +/- 1.097 g/L, 0.301 +/- 0.065 and 0.199 +/- 0.037 10(11) copies/g, 0.005 0.043 and 0.009 +/- 0.025 h(-1), respectively. The effect of interspecific interaction of on substrate consumption rate and microbial growth was evaluated using mixed culture; curve fitting and comparison of coefficients detected increase in substrate consumption rate but decrease in microbial growth rate; these results imply interspecific interaction effect. A new model was of the interspecific interaction was developed, with focus on accuracy, realism, simplicity and biological significance. This interspecific interaction model may be extended to more complex bioprocesses such as biological wastewater treatment systems and anaerobic digestion.11Nsciescopu
Temporal variation in bacterial and methanogenic communities of three full-scale anaerobic digesters treating swine wastewater
No full textTo investigate the effects of temporal variations of process parameters on microbial community structures in the two types of full-scale anaerobic digester treating swine wastewater, three full-scale anaerobic digesters were monitored. An anaerobic filter (AF)-type digester located in Gong-Ju (GJ) showed the highest COD removal among three digesters and maintained stable efficiency. A digester in Hong-Seong (HS) was of the same type as it GJ and showed improved efficiency over the sampling period. A continuously stirred tank reactor (CSTR)-type digester in Soon-Cheon (SC) showed decreasing efficiency due to a high residual concentration of VFAs and NH4+. These process efficiencies were closely correlated to the Simpson indices of the methanogenic communities. Genera Bacillus, Methanosaeta, and Methanospirillum that have filamentous morphology were dominant in both AF-type digesters, but genera Acholeplasma, Methanosarcina, and Methanoculleus that have spherical or coccoid morphology were dominantly abundant in the CSTR-type digester. Correlation between populations suggests a possible syntrophic relationship between genera Desulfobulbus and Methanosaeta in digesters GJ and HS.11Nsciescopu
A comparative study on the process efficiencies and microbial community structures of six full-scale wet and semi-dry anaerobic digesters treating food wastes
No full textThe purpose of this study was to investigate the effect of different types of food wastes on the process efficiencyand microbial community structures in full-scale anaerobic digesters and to identify parameters that affect thesecriteria. Six full-scale anaerobic digesters were investigated; three were operated under “wet” condition (totalsolids TS ≤10%), and three were run under “semi-dry” condition (10% ≤TS ≤20%). Removal efficiency ofvolatile solids was much higher in the wet digesters (75.2 ± 3.8%) than in the semi-dry digesters(42.6 ± 5.5%). The bacterial and archaeal communities were distinctly characterized by familiesPorphyromonadaceae, Sphingobacteriaceae, Syntrophomonadaceae, and Methanobacteriaceae in the wet digesters;and of Clostridiaceae, Patulibacteraceae, Pseudonocardiaceae, Lachnospiraceae, Rikenellaceae, andMethanomicrobiaceae in the semi-dry digesters. The discriminant parameters identified were TS content ofinfluent, concentration of total ammonia nitrogen and the ratio of soluble chemical oxygen demand (COD) toCOD in the digester.The purpose of this study was to investigate the effect of different types of food wastes on the process efficiencyand microbial community structures in full-scale anaerobic digesters and to identify parameters that affect thesecriteria. Six full-scale anaerobic digesters were investigated; three were operated under “wet” condition (totalsolids TS ≤10%), and three were run under “semi-dry” condition (10% ≤TS ≤20%). Removal efficiency ofvolatile solids was much higher in the wet digesters (75.2 ± 3.8%) than in the semi-dry digesters(42.6 ± 5.5%). The bacterial and archaeal communities were distinctly characterized by familiesPorphyromonadaceae, Sphingobacteriaceae, Syntrophomonadaceae, and Methanobacteriaceae in the wet digesters;and of Clostridiaceae, Patulibacteraceae, Pseudonocardiaceae, Lachnospiraceae, Rikenellaceae, andMethanomicrobiaceae in the semi-dry digesters. The discriminant parameters identified were TS content ofinfluent, concentration of total ammonia nitrogen and the ratio of soluble chemical oxygen demand (COD) toCOD in the digester.1
Bacteria and archaea communities in full-scale thermophilic and mesophilic anaerobic digesters treating food Wastewater: Key process parameters andmicrobial indicators of process instability
No full textIn this study, four different mesophilic and thermophilic full-scale anaerobic digesters treating food wastewater(FWW) were monitored for 1–2 years in order to investigate: 1) microbial communities underpinning anaerobicdigestion of FWW, 2) significant factors shaping microbial community structures, and 3) potential microbialindicators of process instability. Twenty-seven bacterial genera were identified as abundant bacteria underpinningthe anaerobic digestion of FWW. Methanosaeta harundinacea, M. concilii, Methanoculleus bourgensis, M.thermophilus, and Methanobacterium beijingense were revealed as dominant methanogens. Bacterial communitystructures were clearly differentiated by digesters; archaeal community structures of each digester were dominatedby one or two methanogen species. Temperature, ammonia, propionate, Na+, and acetate in the digesterwere significant factors shaping microbial community structures. The total microbial populations, microbialdiversity, and specific bacteria genera showed potential as indicators of process instability in the anaerobicdigestion of FWW.1
Identifying methanogen community structures and their correlations with performance parameters in four full-scale anaerobic sludge digesters
No full textFour full-scale mesophilic anaerobic digesters treating waste sludge were monitored to characterize methanogen communities and their relationship with process parameters. The performance of the four digesters were dissimilar with the average chemical oxygen demand removal efficiencies between 24 and 45% and differing pH. Real-time quantitative PCR showed that archaeal 16S rRNA gene concentration ([ARC]) and, more pronouncedly, its ratio to bacterial counterpart ([ARC]/[BAC]) correlated positively with the performance parameters, including the lipid removal efficiency. Pyrosequencing identified 12 methanogen genera, of which Methanolinea, Methansaeta, and Methanospirillum collectively accounted for 79.2% of total archaeal reads. However, Methanoculleus, a numerically minor (1.9 ± 2.6%) taxa, was the most promising biomarker for positive performance, while Methanoregula was abundant in samples with poor performance. These results could be useful for the control and management of anaerobic sludge digestion.1112Nsciescopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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