scholarly journals In situ oxalic acid injection to accelerate arsenic remediation at a superfund site in New Jersey

2014 ◽  
Vol 11 (5) ◽  
pp. 525 ◽  
Author(s):  
Karen Wovkulich ◽  
Martin Stute ◽  
Brian J. Mailloux ◽  
Alison R. Keimowitz ◽  
James Ross ◽  
...  
Keyword(s):  
New Jersey ◽  
Oxalic Acid ◽  
Solid Phase ◽  
Sediment Cores ◽  
Pilot Scale ◽  
Contaminated Site ◽  
Superfund Site ◽  
Superfund Sites ◽  
Pump And Treat

Environmental context Arsenic is one of the most common contaminants at US Superfund sites; therefore, establishing techniques to accelerate As remediation could benefit many sites. In a pilot scale study, we determined that addition of oxalic acid to the subsurface has the potential to increase arsenic release from sediments and possibly improve remediation efficiency by pump and treat techniques. Because pump and treat remediation can require many decades to sufficiently decrease contaminant levels, methods for improving remediation could lead to substantial savings in time and resources. Abstract Arsenic is a prevalent contaminant at a large number of US Superfund sites; establishing techniques that accelerate As remediation could benefit many sites. Hundreds of tonnes of As were released into the environment by the Vineland Chemical Co. in southern New Jersey during its manufacturing lifetime (1949–1994), resulting in extensive contamination of surface and subsurface soils and sediments, groundwater, and the downstream watershed. Despite substantial intervention at this Superfund site, sufficient aquifer clean up could require many decades if based on traditional pump and treat technologies only. Laboratory column experiments have suggested that oxalic acid addition to contaminated aquifer solids could promote significant As release from the solid phase. To evaluate the potential of chemical additions to increase As release in situ and boost treatment efficiency, a forced gradient pilot scale study was conducted on the Vineland site. During spring and summer 2009, oxalic acid and bromide tracer were injected into a small portion (~50m2) of the site for 3 months. Groundwater samples indicate that introduction of oxalic acid led to increased As release. Between 2.9 and 3.6kg of As were removed from the sampled wells as a result of the oxalic acid treatment during the 3-month injection. A comparison of As concentrations on sediment cores collected before and after treatment and analysed using X-ray fluorescence spectroscopy suggested reduction in As concentrations of ~36% (median difference) to 48% (mean difference). Although further study is necessary, the addition of oxalic acid shows potential for accelerating treatment of a highly contaminated site and decreasing the As remediation time-scale.

scholarly journals Phosphate Induced Arsenic Mobilization as a Potentially Effective In-Situ Remediation Technique—Preliminary Column Tests

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2364
Author(s):  
Martin V. Maier ◽  
Yvonne Wolter ◽  
Daniel Zentler ◽  
Christian Scholz ◽  
Charlotte N. Stirn ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Ph Value ◽  
Surface Complexation ◽  
Contaminated Sites ◽  
Contaminated Site ◽  
Anoxic Conditions ◽  
Arsenic Mobility ◽  
Pump And Treat ◽  
Reducing Conditions

Arsenic (As) contamination of groundwater is commonly remediated by pump and treat. However, this technique is difficult to apply or maintain efficiently because the mobility of arsenic varies depending on the geochemical aquifer conditions. Arsenic interacting with the sediment can cause strong retardation, which is counteracted by ions competing for sedimentary sorption sites like silica, bicarbonate and phosphate. Phosphate competes most effectively with arsenic for sorption sites due to its chemical similarity. To accelerate an ongoing but ineffective pump and treat remediation, we examined the competitive effect of increasing phosphate doses on contaminated aquifer material of different depths and thus under distinct geochemical conditions. In the columns with phosphate addition, significant amounts of arsenic were released rapidly under oxic and anoxic conditions. In all tests, the grade of leaching was higher under anoxic conditions than under oxic conditions. As(III) was the dominant species, in particular during the first release peaks and the anoxic tests. Higher amounts of phosphate did not trigger the arsenic release further and led to a shift of arsenic species. We suggest that the competitive surface complexation is the major process of arsenic release especially when higher amounts of phosphate are used. Commonly arsenic release is described at iron reducing conditions. In contrast, we observed that a change in prevailing redox potential towards manganese reducing conditions in the oxic tests and iron reducing conditions in the anoxic column took place later and thus independently of arsenic release. The reduction of As(V) to As(III) under both redox conditions is presumed to be an effect of microbial detoxification. A loss of sulphate in all columns with phosphate indicates an increased microbial activity, which might play a significant role in the process of arsenic release. Preliminary tests with sediment material from a contaminated site showed that phosphate additions did not change the pH value significantly. Therefore, a release of other metals is not likely. Our results indicate that in-situ application of phosphate amendments to arsenic-contaminated sites could accelerate and enhance arsenic mobility to improve the efficiency of pump and treat remediation without negative side effects. The novelty of this approach is the use of only small amounts of phosphate in order to stimulate microbial activity in addition to surface complexation. Therefore, this method might become an innovative and cost-effective remediation for arsenic contaminated sites.

Pilot-scale injection of colloidal activated carbon for PFAS immobilization at a contaminated field site

2020 ◽  
Author(s):  
Fritjof Fagerlund ◽  
Georgios Niarchos ◽  
Lutz Ahrens ◽  
Dan Berggren Kleja ◽  
Jonny Bergman ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Seasonal Changes ◽  
Preferential Flow ◽  
Pilot Scale ◽  
Contaminated Site ◽  
Flow Paths ◽  
Groundwater Levels ◽  
Geological Setting ◽  
Scale Test

<p>Per- and polyfluorinated alkyl substances (PFASs) are extremely recalcitrant contaminants that pose a challenge for remediation in soil and groundwater due to their chemical stability and resistance to degradation. They are used in numerous consumer products and their use in firefighting aqueous-film-forming foams has led to worldwide contamination of groundwater resources associated with airports and firefighting training areas. One of the currently most promising in-situ treatment techniques is stabilization using activated carbon (AC) sorbents that can immobilize PFASs in the soil and prevent further spreading from a contaminated site. However, few documented field studies exist.</p><p>In this study we investigated in-situ stabilization of PFASs by injection of colloidal activated carbon (CAC, PlumeStop®) at a PFAS contaminated site in Arboga, Sweden. Prior to the design of the pilot-scale test and CAC injection, the geology and state of contamination were carefully characterized and PFAS concentrations and groundwater levels were monitored continuously for almost one year. CAC was injected to create a defined zone of PFAS-sorption where PFASs from the contaminant plume would be sorbed to CAC and removed from the flowing groundwater, similar to a permeable reactive barrier. The effect of the injected CAC was studied by monitoring PFAS concentrations in the groundwater up- and down-gradient as well as within the CAC barrier both before and after injection. General water chemistry and groundwater levels were also monitored.</p><p>The site characterization showed that there are two distinct source zones of PFAS contamination with different contamination signatures. Continuous baseline monitoring prior to CAC injection did not show any major changes in PFAS concentrations, but revealed seasonal variations in the groundwater levels and flow patterns, leading to seasonal changes also in the direction of contaminant transport. The CAC injection pilot-scale test was therefore designed to shield the down-gradient evaluation wells in small part of the plume accounting for seasonal changes. The geological setting of the site mainly is clayey till soil of relatively low hydraulic conductivity on top of crystalline bedrock, but there are also high permeability flow paths. The low-pressure CAC injections were hence designed and adapted to avoid excessive preferential flow of CAC and achieve a good distribution of CAC in the intended treatment zone (barrier).</p><p>Preliminary results from the monitoring showed strong reduction of all measured PFASs within and directly down-gradient of the CAC barrier. These results indicate that the installation of the CAC barrier was successful despite a relatively complex geological setting where fast preferential flow paths exist. The continuing monitoring will show how the CAC performs over time.</p>

scholarly journals Treatability Study of In Situ Technologies for Remediation of Hexavalent Chromium in Groundwater at the Puchack Well Field Superfund Site, New Jersey

2006 ◽  
Author(s):  
Vince R. Vermeul ◽  
Jim E. Szecsody ◽  
Michael J. Truex ◽  
Carolyn A. Burns ◽  
Donald C. Girvin ◽  
...  
Keyword(s):  
New Jersey ◽  
Hexavalent Chromium ◽  
Superfund Site ◽  
Well Field

Dynamic studies of silicide-mediated crystallization of amorphous silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1352-1353
Author(s):  
C. Hayzelden ◽  
J. L. Batstone
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Metallic Phase ◽  
Single Crystal Substrate ◽  
Free Electrons ◽  
Melt Temperature ◽  
Transmission Electron ◽  
Crystal Substrate ◽  
High Resolution Tem

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.

Gowanus Canal Superfund Site. III: Leaching of In Situ Stabilization/Solidification Mix Designs

2020 ◽  
Vol 24 (4) ◽  
pp. 04020045
Author(s):  
Dennis G. Grubb ◽  
Theresa M. Himmer ◽  
Jeff L. Gentry ◽  
Alexandra J. Salter-Blanc ◽  
Christos D. Tsiamis
Keyword(s):  
Superfund Site ◽  
In Situ Stabilization

Solid Phase Excitation-Emission Matrix Spectroscopy for In-Situ Chemical Analysis of Combustion Aerosols

2020 ◽  
Author(s):  
Gaurav Mahamuni ◽  
Jiayang He ◽  
Jay Rutherford ◽  
Byron Ockerman ◽  
Edmund Seto ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Cigarette Smoke ◽  
Forest Fires ◽  
Solid Phase ◽  
Incident Angle ◽  
Personal Exposure ◽  
Traffic Emission ◽  
Excitation Emission Matrix ◽  
Internal Excitation

<p>Exposure to combustion generated aerosols such as PM from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. It is important to assess the chemical composition of PM to examine personal exposure. Excitation-emission matrix (EEM) spectroscopy has been shown as a sensitive and cost-effective technique for evaluation of combustion PM composition and as a source apportionment tool. However, EEM measurements are hindered by a solvent extraction step and a need for benchtop instrumentation. Here, we present a methodology that eliminates this labor-intensive sample preparation and allows to automate and miniaturize the detection platform. A miniature electrostatic collector deposits PM sample onto transparent polydimethylsiloxane (PDMS) coated substrate, where PAH components are extracted into solid-phase (SP) solvent and analyzed using EEM spectroscopy in-situ. We evaluated external and internal excitation schemes to optimized signal to noise ratio. Analysis of woodsmoke and cigarette smoke samples showed good agreement with liquid extraction EEM spectra. Internal excitation is hindered by fluorescent interference from PDMS at λ<250nm. The external excitation EEM spectra are dependent on the incident angle; ranges of 30-40⁰ and 55-65⁰ showed the best results. The proposed SP-EEM technique can be used for development of miniaturized sensors for chemical analysis of combustion generated PM. </p>

On-site and in situ bioremediation of wood-preservative contaminated groundwater

2000 ◽  
Vol 42 (5-6) ◽  
pp. 371-376 ◽  
Author(s):  
J.A. Puhakka ◽  
K.T. Järvinen ◽  
J.H. Langwaldt ◽  
E.S. Melin ◽  
M.K. Männistö ◽  
...  
Keyword(s):  
Iron Oxidation ◽  
Wood Preservative ◽  
Pilot Scale ◽  
High Rate ◽  
Contaminated Groundwater ◽  
Groundwater Temperature ◽  
In Situ Bioremediation ◽  
Contaminated Aquifer ◽  
Fluidized Bed Process

This paper reviews ten years of research on on-site and in situ bioremediation of chlorophenol contaminated groundwater. Laboratory experiments on the development of a high-rate, fluidized-bed process resulted in a full-scale, pump-and-treat application which has operated for several years. The system operates at ambient groundwater temperature of 7 to 9°C at 2.7 d hydraulic retention time and chlorophenol removal efficiencies of 98.5 to 99.9%. The microbial ecology studies of the contaminated aquifer revealed a diverse chlorophenol-degrading community. In situ biodegradation of chlorophenols is controlled by oxygen availability, only. Laboratory and pilot-scale experiments showed the potential for in situ aquifer bioremediation with iron oxidation and precipitation as a potential problem.

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