Oxidant Delivery Approaches and Contingency Planning

Simpkin, Thomas J.; Palaia, Tom; Petri, Benjamin G.; Smith, Brant

doi:10.1007/978-1-4419-7826-4_11

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…The effect of the injection solution viscosity will also differ depending on the type of field injection performed. Injection of fluids into the subsurface whether for pump tests or remediation purposes are typically performed in two ways: constant head (CH) or constant flux (CF) injections. , CF injections use a constant volumetric flow rate to inject water (or remediant) into the subsurface, while CH injections specify a constant head or pressure at the well and the fluid is applied to the subsurface via gravity feed. CF injections were used by Bennett et al in this field trial while others have injected nZVI into the subsurface via CH injections. ,,,, …”

Section: Resultsmentioning

confidence: 99%

“…However CF injections will increase the hydraulic head at the well with time (Figure (b). For example, the simulated hydraulic head at the well ( h I ) rose from 1.3 at 10 min to 1.7 m at 20 h. This type of pressure increase can lead to daylighting and cracking in the well seal. , Either of these outcomes will significantly decrease the spread of nZVI and potentially render the injection well unusable for future injections. In addition, it is desirable to inject nZVI quickly into the ground to reduce nZVI oxidation in the synthesis vessel .…”

Section: Resultsmentioning

confidence: 99%

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A Field-Validated Model for In Situ Transport of Polymer-Stabilized nZVI and Implications for Subsurface Injection

Król

Oleniuk

Kocur

et al. 2013

Environ. Sci. Technol.

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Nanoscale zerovalent iron (nZVI) particles have significant potential to remediate contaminated source zones. However, the transport of these particles through porous media is not well understood, especially at the field scale. This paper describes the simulation of a field injection of carboxylmethyl cellulose (CMC) stabilized nZVI using a 3D compositional simulator, modified to include colloidal filtration theory (CFT). The model includes composition dependent viscosity and spatially and temporally variable velocity, appropriate for the simulation of push-pull tests (PPTs) with CMC stabilized nZVI. Using only attachment efficiency as a fitting parameter, model results were in good agreement with field observations when spatially variable viscosity effects on collision efficiency were included in the transport modeling. This implies that CFT-modified transport equations can be used to simulate stabilized nZVI field transport. Model results show that an increase in solution viscosity, resulting from injection of CMC stabilized nZVI suspension, affects nZVI mobility by decreasing attachment as well as changing the hydraulics of the system. This effect is especially noticeable with intermittent pumping during PPTs. Results from this study suggest that careful consideration of nZVI suspension formulation is important for optimal delivery of nZVI which can be facilitated with the use of a compositional simulator.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A Field-Validated Model for In Situ Transport of Polymer-Stabilized nZVI and Implications for Subsurface Injection

Król

Oleniuk

Kocur

et al. 2013

Environ. Sci. Technol.

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“…The inline mixer was used to minimize the contact time between persulfate and the ferrous sulfate/citric acid solution. This would reduce losses of persulfate due to decomposition upstream of the fracture, similar to field applications where persulfate and activator are co‐injected with mixing at the injection point (Huling & Pivetz 2006; Simpkin et al., 2011). Injections 1–13 were intermittent injections whereby the duration of a specific persulfate injection was up to 3 hr, followed by water injection.…”

Section: Methodsmentioning

confidence: 99%

Toluene NAPL Oxidation by Ferrous Activated Persulfate in a Fractured Rock Glass Replica

Kalogerakis

Liu

Furbacher

et al. 2022

Water Resources Research

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Non‐aqueous phase liquids (NAPLs), such as toluene, often contaminate the subsurface. In this study, we focus on the transformation of toluene NAPL trapped in a single glass replica of a rock fracture via in situ chemical oxidation (ISCO) with ferrous activated persulfate. The trapped toluene consisted of a main trapped blob surrounded by smaller blobs. Over 53 days, successive persulfate injections into the fracture were interspersed with periods of water flushing. During persulfate injections, effluent toluene concentrations were below 0.04 mM. The rebound toluene concentrations during intervening water flushing periods decreased from 0.9 to 0.3 mM over the study. The smaller toluene blobs were removed by dissolution and partial oxidation. The main toluene blob was reduced in area by 35.5% and in volume by 37.3% due to dissolution and partial oxidation. The main blob changed in shape with reduction in size and there was also formation of an oxidation by‐product zone around the blob. The reduction in toluene effluent concentrations with time over successive persulfate injections and periods of water flushing was attributed to reductions in the NAPL‐water interfacial area of the blob and the formation of the by‐product zone surrounding the blob, which resulted in limited toluene dissolution. Analysis of by‐products of toluene oxidation by ferrous activated persulfate suggests that oligomers were part of the by‐product zone formed in the fracture. Gas bubbles were also observed in the fracture and may have formed from toluene oxidation and persulfate decomposition.

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“…Therefore, short injection intervals limit the risk in delivering a disproportionate volume of oxidant into higher permeability layers and greater probability of injecting the oxidant into discrete zones within the TTZ (Figure ). Where feasible, the length of a well screen in an injection well should be no more than 10 to 15 ft (3.05 to 4.57 m), particularly in heterogeneous formations and where treating highly contaminated source zones (Simkins et al ). Shorter injection well screens (<10 to 15 ft) (<3.05 to 4.57 m), and direct‐push injection using short injection intervals (2 to 4 ft) (0.61 to 1.22 m) can further limit the role of preferential pathways.…”

Section: Critical Analysis Of Oxidant Volume Estimation Methodsmentioning

confidence: 99%

In Situ Chemical Oxidation: Permanganate Oxidant Volume Design Considerations

Huling¹,

Ross²,

Prestbo

2017

Groundwater Monitoring Rem

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Contaminant rebound and low contaminant removal are reported more frequently with in situ chemical oxidation than other in situ technologies. Although there are multiple causes for these results, a critical analysis indicates that low oxidant volume delivery is a key issue. The volume of oxidant injected is critical and porosity of the aquifer matrix can be used to estimate the pore volume. The total porosity (qT) is the volume of voids relative to the total volume of aquifer material. The mobile porosity (qM) is the fraction of voids that readily contributes to fluid displacement, and is less than qT leading to smaller estimates of oxidant volume. Injecting low‐oxidant volume may result in inadequate oxidant distribution and postinjection dispersal within the radius of influence, insufficient oxidant contact and oxidant loading, and incomplete treatment; whereas, greater oxidant volume achieves a greater oxidant footprint and may involve risk that the injected oxidant may migrate into nontarget areas and displacement of contaminated groundwater. Design guidelines and recommendations are provided that could help achieve more effective technology deployment, reduce the role of heterogeneities in the subsurface, and result in greater probability the oxidant is delivered to the targeted treatment zone.

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Oxidant Delivery Approaches and Contingency Planning

Cited by 7 publications

References 7 publications

A Field-Validated Model for In Situ Transport of Polymer-Stabilized nZVI and Implications for Subsurface Injection

A Field-Validated Model for In Situ Transport of Polymer-Stabilized nZVI and Implications for Subsurface Injection

Toluene NAPL Oxidation by Ferrous Activated Persulfate in a Fractured Rock Glass Replica

In Situ Chemical Oxidation: Permanganate Oxidant Volume Design Considerations

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