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Journal of Chemistry
Volume 2017 (2017), Article ID 8764510, 19 pages
Research Article

Rheology and Microbiology of Sludge from a Thermophilic Aerobic Membrane Reactor

1Department of Civil and Architectural Engineering, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
2Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
3University Research Center “Integrated Models for Prevention and Protection in Environmental and Occupational Health” (MISTRAL), Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
4Department of Civil, Environmental, Architectural Engineering and Mathematics, University of Brescia, Via Branze 43, 25123 Brescia, Italy

Correspondence should be addressed to Giorgio Bertanza; ti.sbinu@aznatreb.oigroig

Received 13 April 2017; Revised 21 June 2017; Accepted 27 June 2017; Published 28 August 2017

Academic Editor: Nicolas Roche

Copyright © 2017 Alessandro Abbà et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A thermophilic aerobic membrane reactor (TAMR) treating high-strength COD liquid wastes was submitted to an integrated investigation, with the aim of characterizing the biomass and its rheological behaviour. These processes are still scarcely adopted, also because the knowledge of their biology as well as of the physical-chemical properties of the sludge needs to be improved. In this paper, samples of mixed liquor were taken from a TAMR and submitted to fluorescent in situ hybridization for the identification and quantification of main bacterial groups. Measurements were also targeted at flocs features, filamentous bacteria, and microfauna, in order to characterize the sludge. The studied rheological properties were selected as they influence significantly the performances of membrane bioreactors (MBR) and, in particular, of the TAMR systems that operate under thermophilic conditions (i.e., around 50°C) with high MLSS concentrations (up to 200 gTS L−1). The proper description of the rheological behaviour of sludge represents a useful and fundamental aspect that allows characterizing the hydrodynamics of sludge suspension devoted to the optimization of the related processes. Therefore, in this study, the effects on the sludge rheology produced by the biomass concentration, pH, temperature, and aeration were analysed.