Investigation of gas production and entrapment in granular iron medium

Kamolpornwijit, Wiwat; Liang, Liyuan

doi:10.1016/j.jconhyd.2005.10.009

Cited by 23 publications

(21 citation statements)

References 31 publications

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“…The increased gas generation led to an increased gas entrapment by influencing the balance of gas bubble formation in and release from the reactive filling. In the results presented here the pore volume fraction that is occupied by gas is much higher than 1.3% that was measured in the presence of nitrate as competitive oxidant (Kamolpornwijit and Liang, 2006) and 13.8% that were reported for columns operated under elevated volume flows (Zhang and Gillham, 2005). Comparing maximum gas saturations of columns S6 and S6H or S7 and S7H, lower values were measured in columns S6H and S7H with higher flow velocities.…”

Section: Gas Entrapmentcontrasting

confidence: 64%

“…Corrosion rates obtained from both static (Reardon, 1995(Reardon, , 2005 and continuous column experiments (Kamolpornwijit and Liang, 2006;Parbs et al, 2007) can therefore not be used for comparison between different experimental setups with different iron amounts. Filter dimensions have an effect on corrosion rate: The longer a column the lower are averaged corrosion rates.…”

Section: Estimated Corrosion Ratesmentioning

confidence: 99%

“…Jeen et al (2008) revealed similar results comparing two feed solutions. Kamolpornwijit and Liang (2006) investigated gas generation in continuous column experiments with complex solutions. Van Nooten et al (2008) investigated hydrogen formation while Gu et al (1999) analyzed dissolved hydrogen concentrations in Fe 0 column experiments with concomitant hydrogen consumption by hydrogenotrophic bacteria.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of dissolved inorganic carbon and calcium on gas formation and accumulation in iron permeable reactive barriers

Ruhl

Weber

Jekel

2012

Journal of Contaminant Hydrology

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Section: Gas Entrapmentcontrasting

confidence: 64%

Section: Estimated Corrosion Ratesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of dissolved inorganic carbon and calcium on gas formation and accumulation in iron permeable reactive barriers

Ruhl

Weber

Jekel

2012

Journal of Contaminant Hydrology

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“…Despite their wide diffusion, there is a great uncertainty about the long‐term performance of iron‐based PRBs. Various studies have confirmed that the longevity of an iron barrier mostly depends on hydrogeochemical processes taking place within the barrier itself; build‐up of mineral precipitates (Mackenzie et al, 1999; Puls et al, 1999; Phillips et al, 2000; Kamolpornwijit et al, 2003; Jeen et al, 2008), gas accumulation (Wilkin et al, 2002; Vikesland et al, 2003; Kamolpornwijit and Liang, 2006), and biomass growth (Blowes et al, 1997; O'Hannesin and Gillham, 1998; Liang et al, 2000) are known as the main mechanisms that can compromise the long‐term efficiency of Fe 0 reactive barriers.…”

mentioning

confidence: 99%

Hydrogeochemical and Biological Processes Affecting the Long‐term Performance of an Iron‐Based Permeable Reactive Barrier

et al. 2009

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Despite the wide diffusion of zero-valent iron (Fe(0)) permeable reactive barriers (PRBs), there is still a great uncertainty about their longevity and long-term performance. The aim of this study is to investigate the biological and the hydrogeochemical processes that take place at a Fe(0) installation located in Avigliana, Italy, and to derive some general considerations about long-term performance of PRBs.The examined PRB was installed in November 2004 to remediate a chlorinated solvents plume (mainly trichloroethene and 1,2-dichloroethene). The investigation was performed during the third year of operation and included: (1) groundwater sampling and analysis for chlorinated solvents, dissolved CH(4), dissolved H(2) and major inorganic constituents; (2) Fe(0) core sampling and analysis by SEM-EDS, XRD, and FTIR spectroscopy for the organic fraction; (3) in situ permeability tests and flow field monitoring by water level measurements.The study revealed that iron passivation is negligible, as the PRB is still able to effectively treat the contaminants and to reduce their concentrations below target values. Precipitation of several inorganic compounds inside the PRB was evidenced by SEM-EDS and XRD analysis conducted on iron samples. Groundwater sampling evidenced heavy sulfate depletion and the highest reported CH(4) concentration (>5,000 microg/L) at zero-valent iron PRB sites. These are due to the intense microbial activity of sulfate-reducers and methanogens, whose proliferation was most likely stimulated by the use of a biopolymer (i.e. guar gum) as shoring fluid during the excavation of the barrier. Slug tests within the barrier evidenced an apparent hydraulic conductivity two orders of magnitude lower than the predicted value. This occurrence can be ascribed to biofouling and/or accumulation of CH(4)(g) inside the iron filings.This experience suggests that when biopolymer shoring is planned to be used, long-term column tests should be performed beforehand with initial bacterial inoculation and organic substrate dosing, in order to predict the effects of bacterial overgrowth and gas generation. During construction particular care should be taken in order to minimize the amount of used biopolymer so that complete breakdown can be achieved.

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“…There is always a discrepancy between the observed and the predicted porosity loss; the actual porosity loss being higher than that predicted [75]. Two examples for illustration: (i) Mackenzie et al [82] measured a 5 to 10% porosity loss using tracer tests, while calculations based on mineral precipitation predicted only 1 %; and (ii) Kamolpornwijit and Liang [97] measured porosity losses of 25 to 30% based on tracer tests and attributed 1.3% to trapped gas. Mackenzie et al [82] attributed the remaining porosity loss (up to 9%) to H 2 gas production.…”

Section: The Shortcomings Of Current Modeling Effortsmentioning

confidence: 98%

Predicting the Hydraulic Conductivity of Metallic Iron Filters: Modeling Gone Astray

Noubactep

2016

Water

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Abstract:Since its introduction about 25 years ago, metallic iron (Fe 0 ) has shown its potential as the key component of reactive filtration systems for contaminant removal in polluted waters. Technical applications of such systems can be enhanced by numerical simulation of a filter design to improve, e.g., the service time or the minimum permeability of a prospected system to warrant the required output water quality. This communication discusses the relevant input quantities into such a simulation model, illustrates the possible simplifications and identifies the lack of relevant thermodynamic and kinetic data. As a result, necessary steps are outlined that may improve the numerical simulation and, consequently, the technical design of Fe 0 filters. Following a general overview on the key reactions in a Fe 0 system, the importance of iron corrosion kinetics is illustrated. Iron corrosion kinetics, expressed as a rate constant k iron , determines both the removal rate of contaminants and the average permeability loss of the filter system. While the relevance of a reasonable estimate of k iron is thus obvious, information is scarce. As a conclusion, systematic experiments for the determination of k iron values are suggested to improve the database of this key input parameter to Fe 0 filters.

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Investigation of gas production and entrapment in granular iron medium

Cited by 23 publications

References 31 publications

Influence of dissolved inorganic carbon and calcium on gas formation and accumulation in iron permeable reactive barriers

Influence of dissolved inorganic carbon and calcium on gas formation and accumulation in iron permeable reactive barriers

Hydrogeochemical and Biological Processes Affecting the Long‐term Performance of an Iron‐Based Permeable Reactive Barrier

Predicting the Hydraulic Conductivity of Metallic Iron Filters: Modeling Gone Astray

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