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Walter A.,University of Innsbruck | Knapp B.A.,University of Innsbruck | Farbmacher T.,University of Innsbruck | Ebner C.,Abwasserverband Zirl und Umgebung | And 2 more authors.
Microbial Biotechnology

To find links between the biotic characteristics and abiotic process parameters in anaerobic digestion systems, the microbial communities of nine full-scale biogas plants in South Tyrol (Italy) and Vorarlberg (Austria) were investigated using molecular techniques and the physical and chemical properties were monitored. DNA from sludge samples was subjected to microarray hybridization with the ANAEROCHIP microarray and results indicated that sludge samples grouped into two main clusters, dominated either by Methanosarcina or by Methanosaeta, both aceticlastic methanogens. Hydrogenotrophic methanogens were hardly detected or if detected, gave low hybridization signals. Results obtained using denaturing gradient gel electrophoresis (DGGE) supported the findings of microarray hybridization. Real-time PCR targeting Methanosarcina and Methanosaeta was conducted to provide quantitative data on the dominating methanogens. Correlation analysis to determine any links between the microbial communities found by microarray analysis, and the physicochemical parameters investigated was conducted. It was shown that the sludge samples dominated by the genus Methanosarcina were positively correlated with higher concentrations of acetate, whereas sludge samples dominated by representatives of the genus Methanosaeta had lower acetate concentrations. No other correlations between biotic characteristics and abiotic parameters were found. Methanogenic communities in each reactor were highly stable and resilient over the whole year. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd. Source

Franke-Whittle I.H.,University of Innsbruck | Walter A.,University of Innsbruck | Ebner C.,Abwasserverband Zirl und Umgebung | Insam H.,University of Innsbruck
Waste Management

A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array. © 2014 The Authors. Source

Nowak O.,Nowak Abwasser Beratung e.U. | Ebner C.,Abwasserverband Zirl und Umgebung
Osterreichische Wasser- und Abfallwirtschaft

Meanwhile, the long-term practical experience and the scientific research results about the utilisation of organic residues in heated sludge digesters of municipal wastewater treatment plants are sufficient for an interim résumé about co-digestion and for recommendations for the practical approach. In this paper, effects, backlashes and consequences of the co-digestion of organic substrates are described in detail. Concerning the stability of the digestion process and the expected production of digestion residues, co-digestion has proved to exhibit positive effects. Problems might occur regarding the additional nitrogen loads in the reject water from sludge treatment as well as with regard to the enrichment of impurities in the sludge digesters—in particular in the case of the use of food leftovers from restaurants and so-called bio-waste from households. Additional attention has to be paid to the storage of the co-substrates as well as to the optimal utilisation of the energy produced in excess. © 2016 Springer-Verlag Wien Source

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