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Your search keyword '"Eberhard, A."' showing total 111 results
Start Over Author "Eberhard, A." Language english Journal water research
111 results on '"Eberhard, A."'

5. Pesticides are the dominant stressors for vulnerable insects in lowland streams

Author

Liess, Matthias, Liebmann, Liana, Vormeier, Philipp, Weisner, Oliver, Altenburger, Rolf, Borchardt, Dietrich, Brack, Werner, Chatzinotas, Antonis, Escher, Beate, Foit, Kaarina, Gunold, Roman, Henz, Sebastian, Hitzfeld, Kristina L., Schmitt-Jansen, Mechthild, Kamjunke, Norbert, Kaske, Oliver, Knillmann, Saskia, Krauss, Martin, Küster, Eberhard, Link, Moritz, Lück, Maren, Möder, Monika, Müller, Alexandra, Paschke, Albrecht, Schäfer, Ralf B., Schneeweiss, Anke, Schreiner, Verena C., Schulze, Tobias, Schüürmann, Gerrit, von Tümpling, Wolf, Weitere, Markus, Wogram, Jörn, and Reemtsma, Thorsten

Published
2021
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45. Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration

Author

Eberhard Morgenroth, Mark C.M. van Loosdrecht, Nicolas Derlon, Morez Jafari, Cristian Picioreanu, and Peter Desmond

Subjects
Environmental Engineering, Materials science, Biofouling, Water flow, Poromechanics, Ultrafiltration, Biofilm compression, Hydraulic resistance, Fluid-structural model, Elastic modulus, Poroelasticity, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, Viscoelasticity, Composite material, Waste Management and Disposal, 0105 earth and related environmental sciences, Water Science and Technology, Civil and Structural Engineering, Ecological Modeling, Biofilm, Membranes, Artificial, biochemical phenomena, metabolism, and nutrition, 021001 nanoscience & nanotechnology, Compression (physics), Pollution, Biofilms, Deformation (engineering), 0210 nano-technology, Filtration
Abstract

Biofilm formation in membrane systems negatively impacts the filtration system performances. This study evaluated how biofilm compression driven by permeate flow increases the hydraulic resistance and leads to reduction in permeate flux. We analysed the effect of biofilm compression on hydraulic resistance and permeate flux through computational models supported by experimental data. Biofilms with homogeneous surface structure were subjected to step-wise changes in flux and transmembrane pressure during compression and relaxation tests. Biofilm thickness under applied forces was measured non-invasively in-situ using optical coherence tomography (OCT). A numerical model of poroelasticity, which couples water flow through the biofilm with biofilm mechanics, was developed to correlate the structural deformation with biofilm hydraulics (permeability and resistance). The computational model enabled extracting mechanical and hydrological parameters corresponding to the experimental data. Homogeneous biofilms under elevated compression forces experienced a significant reduction in thickness while only a slight increase in resistance was observed. This shows that hydraulic resistance of homogeneous biofilms was affected more by permeability decrease due to pore closure than by a decrease in thickness. Both viscoelastic and elastoplastic models could describe well the permanent biofilm deformation. However, for biofilms under study, a simpler elastic model could also be used due to the small irreversible deformations. The elastic moduli fitting the measured data were in agreement with other reported values for biofilm under compression. Biofilm stiffening under larger flow-driven compression forces was observed and described numerically by correlating inversely the elastic modulus with biofilm porosity. The importance of this newly developed method lies in estimation of accurate biofilm mechanical parameters to be used in numerical models for both membrane filtration system and biofouling cleaning strategies. Such model can ultimately be used to identify optimal operating conditions for membrane system subjected to biofouling., Water Research, 145, ISSN:0043-1354, ISSN:1879-2448

Published
2018

50. Physical structure determines compression of membrane biofilms during Gravity Driven Membrane (GDM) ultrafiltration.

Author

Desmond, Peter, Morgenroth, Eberhard, and Derlon, Nicolas

Subjects
*BIOFILMS, *ULTRAFILTRATION, *MEMBRANE potential, *HYDRAULICS, *PHOSPHORUS
Abstract

Increasing transmembrane pressure (TMP) can compress and increase the hydraulic resistance of membrane biofilms. The purpose of the present study is to evaluate how compression of membrane biofilms occurs and how structural rearrangement can affect hydraulic resistance. Biofilms with heterogeneous and homogeneous physical structures were grown in membrane fouling simulators (MFS) in dead-end mode for 20 days with either (i) a nutrient enriched condition with a nutrient ratio of 100:30:10 (C: N: P), (ii) a phosphorus limitation (C: N: P ratio: 100:30:0), or (iii) river water (C: N: P ratio: ca. 100:10:1). The structural and hydraulic response of membrane biofilms to (a) changes in transmembrane pressures ( 0.06-0.1-0.5-0.1-0. 06 bar) and (b) changes in permeate flux ( 10-15-20-15- 10 L/m 2 /h) were investigated. Optical coherence tomography (OCT) was used to monitor biofilm structural response, and OCT images were processed to quantify changes in the mean biofilm thickness and relative roughness. Nutrient enriched and river water biofilms had heterogeneous physical structures with greater surface roughness (Ra' > 0.2) than homogeneous P limiting biofilms (Ra' < 0.2). Compression of biofilms with rough heterogeneous structures (Ra' > 0.2) was irreversible, indicated by irreversible decrease in surface roughness, partial relaxation in mean biofilm thickness and irreversible increase in hydraulic resistance. Compression of homogeneous biofilm (Ra' < 0.2) was on the other hand reversible, indicated by full relaxation of the biofilms structure and restoration of initial hydraulic resistance. Hydraulic response (i.e., change in the specific biofilm resistance) did not correspond with the change in physical structure of heterogeneous biofilms. The presented study provides a fundamental understanding of how biofilm physical structure can affect the biofilm's response to a change in TMP, with practical relevance for the operation of GDM filtration systems. [ABSTRACT FROM AUTHOR]

Published
2018
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