Spatial distribution and physiological state of bacteria in a sand column experiment during the biodegradation of toluene

2007 ◽  
Vol 41 (10) ◽  
pp. 2089-2100 ◽  
Author(s):  
Hyun-su Kim ◽  
Peter R. Jaffé
Keyword(s):  
Spatial Distribution ◽  
Physiological State ◽  
Column Experiment ◽  
Sand Column

scholarly journals Methods to Improve nZVI Adsorbance on Silicates Surface for Nitrate Reduction

2021 ◽  
Author(s):  
◽  
Handayani Fraser
Keyword(s):  
Silica Fume ◽  
Western Australia ◽  
Column Experiment ◽  
Exchangeable Cation ◽  
Sand Column ◽  
Silica Surfaces ◽  
Pure Silica ◽  
Acid Washing ◽  
Silicate Surface ◽  
Aluminium Silicate

<p>Efforts to remove excess nitrate in the groundwater typically involves expensive ion-exchange membranes or slow reacting bio-reactors. Nano-sized zero valent iron (nZVI) has been used successfully to reduce nitrate into ammonia in various sites in USA and Europe. However, nZVI has a number of major setbacks associated with it, namely the tendency to agglomerate due to magnetic properties, and the possible toxicity due to the nano-sized material.  To circumvent these two setbacks, nZVI could be adsorbed onto solid support. In this research, geothermal sediment microsilicate 600 (Misi) was utilised as a support. Initial results suggested that Misi has potential as a support for nZVI, however modifications were required to improve the adsorbance of nZVI onto Misi surface. Calcination, activation, acid wash and iron oxyhydroxide coating were used as surface modifications for Misi. It was found that the two most important modifications for nZVI adsorption was calcination at either 400 or 600 °C and acid washing in 5.6 M HCl.  Equipped with this knowledge, other silica and silicates were also used to adsorb nZVI. For pure silica surfaces, 3-APTES and 3-TPTMS ligands and pore enlarging methods of calcination of porogen and salt wash were also used. nZVI was not able to be fully adsorbed on pure silica surfaces. Four other silicates were examined: Rice husk ash, Western Australia silica fume, Mt Piper fly ash, and precipitated aluminium silicate. Of these, only Western Australia silica fume and precipitated aluminium silicate showed potential as nZVI support. Based on the SEM-EDS XRD data of all the silica and silicates, it could be tentatively concluded that nZVI requires an aluminium silicate surface for successful adsorption. Aluminium silicate surfaces typically has an exchangeable cation present, and this cation might play a part in nZVI adsorption.  The nZVI/Misi surface was then utilised to reduce nitrate. It was discovered that even though activation and FeOOH did not play a part in nZVI adsorption onto Misi surface, these two steps were important in reduction of nitrate, as the presence of activation and FeOOH increase the reduction of nitrate significantly within 60 minutes. The Misi-supported nZVI were also shown to be more stable in dispersion, and less agglomerated as shown in a sand column experiment.</p>

scholarly journals Methods to Improve nZVI Adsorbance on Silicates Surface for Nitrate Reduction

2021 ◽  
Author(s):  
◽  
Handayani Fraser
Keyword(s):  
Silica Fume ◽  
Western Australia ◽  
Column Experiment ◽  
Exchangeable Cation ◽  
Sand Column ◽  
Silica Surfaces ◽  
Pure Silica ◽  
Acid Washing ◽  
Silicate Surface ◽  
Aluminium Silicate

<p>Efforts to remove excess nitrate in the groundwater typically involves expensive ion-exchange membranes or slow reacting bio-reactors. Nano-sized zero valent iron (nZVI) has been used successfully to reduce nitrate into ammonia in various sites in USA and Europe. However, nZVI has a number of major setbacks associated with it, namely the tendency to agglomerate due to magnetic properties, and the possible toxicity due to the nano-sized material.  To circumvent these two setbacks, nZVI could be adsorbed onto solid support. In this research, geothermal sediment microsilicate 600 (Misi) was utilised as a support. Initial results suggested that Misi has potential as a support for nZVI, however modifications were required to improve the adsorbance of nZVI onto Misi surface. Calcination, activation, acid wash and iron oxyhydroxide coating were used as surface modifications for Misi. It was found that the two most important modifications for nZVI adsorption was calcination at either 400 or 600 °C and acid washing in 5.6 M HCl.  Equipped with this knowledge, other silica and silicates were also used to adsorb nZVI. For pure silica surfaces, 3-APTES and 3-TPTMS ligands and pore enlarging methods of calcination of porogen and salt wash were also used. nZVI was not able to be fully adsorbed on pure silica surfaces. Four other silicates were examined: Rice husk ash, Western Australia silica fume, Mt Piper fly ash, and precipitated aluminium silicate. Of these, only Western Australia silica fume and precipitated aluminium silicate showed potential as nZVI support. Based on the SEM-EDS XRD data of all the silica and silicates, it could be tentatively concluded that nZVI requires an aluminium silicate surface for successful adsorption. Aluminium silicate surfaces typically has an exchangeable cation present, and this cation might play a part in nZVI adsorption.  The nZVI/Misi surface was then utilised to reduce nitrate. It was discovered that even though activation and FeOOH did not play a part in nZVI adsorption onto Misi surface, these two steps were important in reduction of nitrate, as the presence of activation and FeOOH increase the reduction of nitrate significantly within 60 minutes. The Misi-supported nZVI were also shown to be more stable in dispersion, and less agglomerated as shown in a sand column experiment.</p>

scholarly journals Heavy metals removal from landfill leachate by coagulation/flocculation process combined with continuous adsorption using eggshell waste materials

2021 ◽  
Author(s):  
A. Q. Jaradat ◽  
Dua'a B. Telfah ◽  
Rabah Ismail
Keyword(s):  
Heavy Metals ◽  
Landfill Leachate ◽  
Agricultural Waste ◽  
Column Experiment ◽  
Waste Materials ◽  
Optimum Dose ◽  
Sand Column ◽  
Heavy Metals Removal ◽  
Metals Removal ◽  
Eggshell Waste

Abstract The use of agricultural waste materials to remove heavy metals from wastewater is attractive due to its simplicity and economic efficiency. In this study, the applicability of calcined eggshell waste materials (CES) for heavy metals removal from real wastewater were examined via transport column experiment preceded by coagulation/flocculation process.A column packed with granular activated carbon (GAC) is operated in parallel to CES column to evaluate the adsorptive attributes of CES. The findings are assessed from another set of column experiment consisting of sand followed by CES column to evaluate the effect of particulate matter on CES performance toward heavy metals removal. In coagulation experiment, alum addition at an optimum dose (3.0 g/L) reduced the total suspended solids (TSS) by 80%, whereas the Fe, Pb, Zn, Cu, Ni, and Cr were reduced by 80, 77, 76, 73, 56, and 49% respectively. Under the current applied hydrodynamic conditions, using sand column before CES column improved the removal efficiencies of Fe, Pb, Cu, Zn, Ni, and Cr from 50–92%, 55–93%, 60–87%, 53–76%, 45–65%, and 41–60% respectively. The whole results illustrate that CES can be competitive to GAC for heavy metals removal from landfill leachate, mainly if applied after PM removal by sand filtration.

The degradation of highly concentrated organic wastewater by the sand layer method

1997 ◽  
Vol 35 (8) ◽  
pp. 223-229
Author(s):  
Masatomo Nakayama ◽  
Keijiro Enari
Keyword(s):  
Waste Water ◽  
Organic Waste ◽  
Lower Layer ◽  
Removal Rate ◽  
Column Experiment ◽  
Sand Layer ◽  
Biological Degradation ◽  
Sand Column ◽  
Methanogenic Activity ◽  
Seed Sludge

The osmotic action of highly concentrated organic waste water through soil was investigated by a column experiment. In this experiment, 50cm high sand-filled columns were used. The experiment included to estimate the toxic effects of mercury on the biological degradation of highly concentrated organic waste water. By adding seed sludge to the top of the sand column, 90% of the TOC was removed. The TOC was removed within the first 20-30cm of the sand layer. Though the removal rate of T-N was low, the T-P removal rate was over 86%. The effect of mercury on the removal of TOC, T-N, and T-P was not marked in either case. Both the acidogenic activity and the methanogenic activity were measured, and they showed higher values in the upper layer compared with the lower layer. The values of these activities were low in the column experiment with mercury.

Period biofilter operation for enhanced performance during unsteady-state loading conditions

2001 ◽  
Vol 43 (3) ◽  
pp. 231-239 ◽  
Author(s):  
R. L. Irvine ◽  
W. M. Moe
Keyword(s):  
Wastewater Treatment ◽  
Spatial Distribution ◽  
Microbial Communities ◽  
Gas Phase ◽  
Physiological State ◽  
Microbial Consortia ◽  
Contaminant Removal ◽  
Unsteady State ◽  
Periodic Processes ◽  
Contaminant Load

In conventional biofilter operation, contaminated air is passed continuously through packed beds containing microbial consortia capable of contaminant biotransformation. This paper describes how biofilters can be designed and operated as controlled unsteady-state, periodic processes for the destruction of gas-phase contaminants. Such operation, previously limited to applications in wastewater treatment and soil remediation, increases an operator's ability to control the physiological state, “robustness,” and spatial distribution of the microbial communities established within the biofilter and, thus, minimizes uncertainties that often accompany design and operation of biological systems. Results are presented from toluene degrading biofilters that used polyurethane foam packing medium. These studies demonstrate how controlled periodic operations can enhance contaminant removal during transient periods of elevated contaminant load.

Rhenium migration at the Maqarin natural analogue site (Jordan)

2006 ◽  
Vol 94 (9-11) ◽  
Author(s):  
Laurent Trotignon ◽  
J. Rose ◽  
H. Khoury ◽  
A. Milodowski ◽  
P. Bienvenu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Short Duration ◽  
Preliminary Data ◽  
Source Term ◽  
Column Experiment ◽  
Rock Masses ◽  
Natural Analogue ◽  
Specific Source ◽  
Rock Analysis ◽  
Chemical Analogue

Rock analysis and study of groundwater data was combined with a short duration column experiment in order to better understand the behavior of rhenium (Re) in the site of Maqarin (Jordan). Results show that the combustion metamorphism having affected rock masses in Maqarin (Jordan), and led to the formation of “natural cements”, has strongly modified the spatial distribution of several elements, among which Re, creating a specific source term for this element leached by groundwaters. Unaltered cements are shown to contain up to 1.2 μg/g Re to be compared to 0.15 μg/g in the initial biomicrite. Re is rapidly leached from unaltered cements and can be used as a tracer of recent cement alteration episodes. Preliminary data suggest that Re, a chemical analogue of Tc, could be partially retained in fracture minerals.

Column Experiment on Cr (VI) Reduction with SiO2-Coated Fe Nanocomposites

2013 ◽  
Vol 690-693 ◽  
pp. 1041-1044
Author(s):  
Yong Chao Li ◽  
Ke Jia Liu ◽  
Bo Zhi Ren
Keyword(s):  
Groundwater Remediation ◽  
Open Systems ◽  
Column Experiment ◽  
Deionized Water ◽  
Coupling Agents ◽  
Saturated Sand ◽  
Sand Column ◽  
Reactive Material ◽  
Water Saturated

SiO2-coated Fe nanocomposites (Fe@SiO2) were prepared without using any of surface-coupling agents. The outer SiO2 coating offered new possibilities for the control of Fe core agglomeration. In order to investigate Cr (VI) reduction in open systems that simulated subsurface conditions, sand column experiments were conducted. When 10 mg/L of Cr (VI) was injected into the columns, the removal efficiencies of Cr (VI) by the Fe@SiO2 were 65 mg Cr/g Fe. The transport tests in deionized water-saturated sand columns indicated that 88.03% of Fe@SiO2 was eluted. Nonetheless, the mobility of Fe@SiO2 decreased when encountering 10 mmol/L Na+ and Ca2+. Presumably, 15 mg/L humic acid enhanced the mobility of Fe@SiO2. Overall, the results of this study indicate that Fe@SiO2 has the potential to become an effective reactive material for in situ groundwater remediation.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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