Assessment of biofilm destabilisation and consequent facilitated zinc transport

2005 ◽  
Vol 51 (2) ◽  
pp. 21-28 ◽  
Author(s):  
M. Muris ◽  
C. Delolme ◽  
J.-P. Gaudet ◽  
L. Spadini
Keyword(s):  
Porous Media ◽  
Pseudomonas Putida ◽  
Facilitated Transport ◽  
Small Extent ◽  
Zinc Transport ◽  
Batch Experiments ◽  
Hydraulic Flow ◽  
Great Affinity ◽  
Pollutants Transport ◽  
The Moment

In infiltration basins, such as in any kind of porous media, bacteria may form biofilms. When conditions induce destabilization of this biofilm, resulting colloids are transported by the hydraulic flow. Some studies have focused on the role played by these bacterial colloids in pollutants transport in soil. This study deals with the ability of Pseudomonas putida to retain zinc and investigates the facilitated transport of this metal. Batch and columns experiments have been carried out. Bacteria display a great affinity for zinc in batch experiments and facilitated transport have been highlighted in a small extent, for the moment. A scenario of stabilization/destabilization of the biofilm has been designed and may be employed for further investigations.

Facilitated transport in porous media

1991 ◽  
Vol 46 (2) ◽  
pp. 477-496 ◽  
Author(s):  
J. Alberto Ochoa-Tapia ◽  
Pieter Stroeve ◽  
Stephen Whitaker
Keyword(s):  
Porous Media ◽  
Facilitated Transport ◽  
Transport In Porous Media

scholarly journals Cosmopolitan Civility: understanding power and difference

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Andrew Jakubowicz
Keyword(s):  
Social Inclusion ◽  
Small Extent ◽  
Skilled Workers ◽  
Fiscal Discipline ◽  
Radical Reform ◽  
The Arts ◽  
University Of Technology ◽  
The Government ◽  
The Moment ◽  
The University

The 4 Rs conference at the University of Technology Sydney in October 2008 took place less than a year after the election of the Rudd Labor government. The moment is important to capture – the government had been swept into office on a wave of hostility to the Howard conservatives, but it did not have a mandate for radical reform. Its promises had carefully targeted key constituencies – skilled workers, small business, the urban “chattering” classes, people in education, in health and in the arts (to a small extent). The government was committed to fiscal discipline with a more humane face, its great vision summarised under the rubric of “social inclusion”.

Experimental Investigation of Freeze-Thaw Processes in Soils and Grouting Materials

2021 ◽  
Author(s):  
Jan Christopher Hesse ◽  
Jan-Henrik Kupfernagel ◽  
Markus Schedel ◽  
Bastian Welsch ◽  
Lutz Müller ◽  
...  
Keyword(s):  
Porous Media ◽  
P Wave ◽  
Ice Formation ◽  
Unfrozen Water ◽  
Pure Liquid ◽  
Detailed Knowledge ◽  
Strong Impact ◽  
Hydraulic Flow ◽  
Freeze Thaw ◽  
Grouting Materials

<p>Freezing and thawing in the subsurface is often related to complex technical handling of possible influences on the engineered structures (e.g. permafrost or geothermal heat pumps). Freeze-thaw processes in the vicinity of borehole heat exchangers can significantly impair the system. However, for groundwater protection and thermal efficiency, the hydraulic and thermal integrity of such systems must be permanently ensured for the complete operation time. Detailed knowledge on freeze-thaw processes in porous media, such as soils or geotechnical grouts, and the driven parameters, is still pending. Freezing in porous media does not occur as a sudden transition from pure liquid water to the ice phase, but rather within a freezing interval strongly depending on various boundary conditions such as soil type or pore water chemistry. As the content of frozen and unfrozen water has a strong impact on material properties, it is essential to have suitable information about the different factors influencing freezing processes as well as the thermo-hydraulic-mechanical (THM) effects on porous media due to phase change. Thus, a THM laboratory experiment was developed and built to gain more knowledge on freeze-thaw processes and their effects on soil and grouting materials. The experiment consists of a modified triaxial test, enabling for controlled temperature and hydraulic flow conditions, that is combined with an ultrasonic measurement device to determine the unfrozen water content.</p><p>In this contribution, results of the THM experiment are presented, whereas the following parameters were investigated: The freezing interval using P-wave velocity, freezing pressure as well as axial and radial volume expansion due to ice formation as well as the influence of hydraulic flow on the ice formation. First, benchmark experiments were conducted on well-characterized solid rock samples to avoid any influence of a variable sample pore structure during the experiments. Further experiments focused on the investigation of soil samples of different texture classes. For upscaling to real scale applications, the experimental findings will be implemented in numerical models.</p>

scholarly journals Surface coating with Ca(OH)2 for improvement of the transport of nanoscale zero-valent iron (nZVI) in porous media

2013 ◽  
Vol 68 (10) ◽  
pp. 2287-2293 ◽  
Author(s):  
Cai-jie Wei ◽  
Xiao-yan Li
Keyword(s):  
Porous Media ◽  
Surface Coating ◽  
Coating Layer ◽  
Zero Valent Iron ◽  
Mass Ratio ◽  
Batch Experiments ◽  
Effective Protection ◽  
Transmission Electron ◽  
Nanoscale Zero Valent Iron ◽  
Protection Layer

A novel thermal deposition method was developed to coat Ca(OH)2 on the surface of nanoscale zero-valent iron (nZVI). The nZVI particles with the Ca(OH)2 coating layer, nZVI/Ca(OH)2, had a clear core-shell structure based on the transmission electron microscopy observations, and the Ca(OH)2 shell was identified as an amorphous phase. The Ca(OH)2 coating shell would not only function as an effective protection layer for nZVI but also improve the mobility of nZVI in porous media for its use in environmental decontamination. A 10% Ca/Fe mass ratio was found to result in a proper thickness of the Ca(OH)2 shell on the nZVI surface. Based on the filtration tests in sand columns, the Ca(OH)2-based surface coating could greatly improve the mobility and transport of nZVI particles in porous media. In addition, batch experiments were conducted to evaluate the reactivity of Ca(OH)2-coated nZVI particles for the reduction of Cr(VI) and its removal from water.

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