scholarly journals Removal of chlorinated solvents from carbonate-buffered water by zero-valent iron

2007 ◽  
Vol 5 (1) ◽  
pp. 87-106 ◽  
Author(s):  
Marek Jiricek ◽  
Ondra Sracek ◽  
Vaclav Janda
Keyword(s):  
Chlorinated Solvents ◽  
Ground Level ◽  
Permeable Reactive Barrier ◽  
Input Concentration ◽  
Reactive Cell ◽  
Total Input ◽  
Slow Kinetics ◽  
Dissolved Species ◽  
Concentration Changes ◽  
Inlet Zone

AbstractThe performance of a ground level reactive cell, filled with Fe0, designed for the treatment of water contaminated by chlorinated solvents, having a total input concentration of approximately 2 mg 1−1 of the principal contaminants trichloroethene and perchloroethene, was tested at the Milovice site in the Czech Republic. A residence time of 1.62 days in the box was sufficient to reduce concentrations to a fraction less than 0.015 of the initial concentration. However, incomplete degradation of cis-1,2-DCE was observed. Reactions approximated first-order kinetics. The principal changes of concentrations of inorganic dissolved species in the reactive cell occurred for Ca2+, HCO 3−, NO 3− (decreased) and for Fe (initially increased, then decreased). Changes for Ca2+ and HCO 3− were caused by the precipitation of secondary carbonate mineral phases such as aragonite and siderite with the minor presence of green rust-CO3. Concentration changes were gradual, along the complete length of the cell with a maximum at the inlet zone. The observations were attributed to minor increases of pH and slow kinetics of precipitation in the carbonate-buffered system. The average porosity loss was estimated to be approximately 2.7 % of the initial porosity per year, suggesting the long-term function of the permeable reactive barrier.

Experimental and Computational Study of Vaporization of Volatile Organic Compounds

2007 ◽  
Author(s):  
Ryo S. Amano ◽  
Jose Martinez Lucci ◽  
Krishna S. Guntur
Keyword(s):  
Gas Chromatography ◽  
Heat Source ◽  
Chlorinated Solvents ◽  
Soil Vapor Extraction ◽  
Vapor Extraction ◽  
Soil Matrix ◽  
University Of Wisconsin ◽  
Concentration Changes ◽  
Heated Soil ◽  
The University

Heated Soil Vapor Extraction (HSVE) is a technology that has been used successfully to clean up subsurface soils at sites containing chlorinated solvents and petroleum hydrocarbons. The costs have been extremely high due to the large amount of energy required to volatilize high molecular weight polycyclic aromatic hydrocarbon (PAH) compounds present in the soil matrix. One remediation contractor states that hydrocarbons are oxidized in situ by achieving temperatures in the >1000 F range near the heaters [1]. A critical question is whether the volatile portion of manufactured gas plant (MGP) hydrocarbons (VOCs) can be stripped out at lower temperatures such that the remaining contaminants will be unavailable for transport or subsequent dissolution into the groundwater. Soil remediation by heated soil vapor extraction system is a relatively new technology developed at the University of Wisconsin-Milwaukee [2]. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. The process developed at UWM, consists of a heater/boiler that pump and circulates hot oil through a pipeline that is enclosed in a larger-diameter pipe. This extraction pipe is vertically installed within the contaminated soil up to a certain depth and is welded at the bottom and capped at the top. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. Our previous studies had removed higher boiling compounds such as naphthalene, etc., to non-detectable level. Thus, the current technology is very promising for removing most of the chemicals compounds; and can also remove these high boiling compounds from the saturated zone. Gas chromatography (GC) is utilized in monitoring the relative concentration changes over the extraction period. Gas chromatography-mass spectrometry (GCMS) assists in the identification and separation of extracted components. The experimental research is currently being conducted at the University of Wisconsin-Milwaukee. The objectives of this study are to identify contaminants and time required to remove them through HSVE treatment and provide data for computation fluid dynamics CFD analysis.

scholarly journals Non-uniformity in outdoor CO2 concentration in city of Copenhagen

2019 ◽  
Vol 111 ◽  
pp. 02007
Author(s):  
Hiroki Takahashi ◽  
Mariya Petrova Bivolarova ◽  
Athanasia Keli ◽  
Jürgen Nickel ◽  
Arsen Krikor Melikov
Keyword(s):  
Energy Use ◽  
Working Hours ◽  
Ground Level ◽  
Co2 Concentration ◽  
Ventilation Rate ◽  
Measuring Instruments ◽  
Preliminary Results ◽  
Downtown Area ◽  
Concentration Changes ◽  
One Year

The accurate data of outdoor CO2 concentration are important for the proper design of ventilation and thus for indoor air quality and energy use in buildings. Typical design practice is to assume outdoor CO2 concentration to be 400 ppm. However, the outdoor CO2 concentration may be different in different areas of cities. This paper presents preliminary results of long-term (one year) outdoor CO2 concentration changes in four districts of Copenhagen (Denmark). The districts included downtown area and suburbs with different surroundings. Four buildings were selected for the measurements, one building in each district. Outdoor CO2 concentration measurements were performed at two levels – ground level and top of the buildings. Special attention was paid to use accurate measuring instruments. The instruments were carefully calibrated before the measurements. The calibration of the instruments was checked periodically. In this paper, preliminary results from summer and autumn measurements are presented. The outdoor CO2 concentration varied over the day and from day to day in the range between 340 and 450 ppm. The CO2 concentration at the ground of the buildings was usually 10 to 40 ppm higher than that at the top level in autumn. At the buildings in the suburbs, during the working hours, the outdoor CO2 concentration measured on the top level close to the intake duct was on average 408 ppm. At the building in the downtown area, that was on average 414 ppm. However, the outdoor CO2 concentration varied depending on the building, level and time. During the working hours, the 75 percentiles of outdoor CO2 concentration varied between 384 ppm and 442 ppm, which indicates that the required ventilation rate could be different over 10% depending on the building location site, measurement height and time. In order to ensure the required indoor limits of CO2 concentration, CO2 measurements must be performed close to the location of the outdoor air intake.

Experimental Study of Treating Volatile Organic Compounds

2007 ◽  
Author(s):  
Ryo S. Amano ◽  
Jose Martinez Lucci ◽  
Krishna S. Guntur ◽  
M. Mahmun Hossain ◽  
M. Monzur Morshed ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Heat Source ◽  
Chlorinated Solvents ◽  
Soil Vapor Extraction ◽  
Vapor Extraction ◽  
Soil Matrix ◽  
University Of Wisconsin ◽  
Concentration Changes ◽  
Heated Soil ◽  
The University

Heated Soil Vapor Extraction (HSVE) is a technology that has been used successfully to clean up subsurface soils at sites containing chlorinated solvents and petroleum hydrocarbons. The costs have been extremely high due to the large amount of energy required to volatilize high molecular weight polycyclic aromatic hydrocarbon (PAH) compounds present in the soil matrix. One remediation contractor states that hydrocarbons are oxidized in situ by achieving temperatures in the >1000 F range near the heaters [1]. A critical question is whether the volatile portion of manufactured gas plant (MGP) hydrocarbons (VOCs) can be stripped out at lower temperatures such that the remaining contaminants will be unavailable for transport or subsequent dissolution into the groundwater. Soil remediation by heated soil vapor extraction system is a relatively new technology developed by Jay Jatkar Inc. (JJI) along with the University of Wisconsin-Milwaukee [2]. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. The process developed by JJI, consists of a heater/boiler that pump and circulates hot oil through a pipeline that is enclosed in a larger-diameter pipe. This extraction pipe is vertically installed within the contaminated soil up to a certain depth and is welded at the bottom and capped at the top. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. Our previous studies had removed higher boiling compounds, such as naphthalene, etc., to a non-detectable level. Thus, the current technology is very promising for removing most of the chemical compounds; and can also remove these boiling compounds from the saturated zone. Gas chromatography (GC) is utilized in monitoring the relative concentration changes over the extraction period. Gas chromatography-mass spectrometry (GC-MS) assists in the identification and separation of extracted components. The experimental research is currently being conducted at the University of Wisconsin-Milwaukee. The objectives of this study are to identify contaminants and time required to remove them through HSVE treatment and provide data for computation fluid dynamics CFD analysis.

scholarly journals A Comprehensive Review for Groundwater Contamination and Remediation: Occurrence, Migration and Adsorption Modelling

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5913
Author(s):  
Osamah Al-Hashimi ◽  
Khalid Hashim ◽  
Edward Loffill ◽  
Tina Marolt Čebašek ◽  
Ismini Nakouti ◽  
...  
Keyword(s):  
Groundwater Contamination ◽  
Treatment Process ◽  
Chlorinated Solvents ◽  
Breakthrough Curves ◽  
Permeable Reactive Barriers ◽  
Permeable Reactive Barrier ◽  
Anthropogenic Activity ◽  
Inorganic Contaminants ◽  
Efficient Treatment ◽  
Pump And Treat

The provision of safe water for people is a human right; historically, a major number of people depend on groundwater as a source of water for their needs, such as agricultural, industrial or human activities. Water resources have recently been affected by organic and/or inorganic contaminants as a result of population growth and increased anthropogenic activity, soil leaching and pollution. Water resource remediation has become a serious environmental concern, since it has a direct impact on many aspects of people’s lives. For decades, the pump-and-treat method has been considered the predominant treatment process for the remediation of contaminated groundwater with organic and inorganic contaminants. On the other side, this technique missed sustainability and the new concept of using renewable energy. Permeable reactive barriers (PRBs) have been implemented as an alternative to conventional pump-and-treat systems for remediating polluted groundwater because of their effectiveness and ease of implementation. In this paper, a review of the importance of groundwater, contamination and biological, physical as well as chemical remediation techniques have been discussed. In this review, the principles of the permeable reactive barrier’s use as a remediation technique have been introduced along with commonly used reactive materials and the recent applications of the permeable reactive barrier in the remediation of different contaminants, such as heavy metals, chlorinated solvents and pesticides. This paper also discusses the characteristics of reactive media and contaminants’ uptake mechanisms. Finally, remediation isotherms, the breakthrough curves and kinetic sorption models are also being presented. It has been found that groundwater could be contaminated by different pollutants and must be remediated to fit human, agricultural and industrial needs. The PRB technique is an efficient treatment process that is an inexpensive alternative for the pump-and-treat procedure and represents a promising technique to treat groundwater pollution.

scholarly journals Concentration Changes Of PM10 Under Liquid Precipitation Conditions

2015 ◽  
Vol 22 (3) ◽  
pp. 363-378 ◽  
Author(s):  
Tomasz Olszowski
Keyword(s):  
Large Scale ◽  
Rainfall Intensity ◽  
Reference Method ◽  
Field Research ◽  
Ground Level ◽  
Convective Precipitation ◽  
Pollution Dispersion ◽  
Simple Regression Model ◽  
Concentration Changes ◽  
Scavenging Efficiency

Abstract This study reports the results of field research into variability of the scavenging coefficient (Λ) of suspended dust comprising particles with aerodynamic diameters less than 10 mm. Registration of PM10 over 7 years in conditions of the occurrence of rainfall (convective light showers, large-scale precipitation and storms) was undertaken in an undeveloped rural area. The analysis involved 806 observations taken at constant time intervals of 0.5 hour. The measurements of the concentration of PM10 were performed by means of a reference method accompanied by concurrent registration of basic meteorological parameters. It was found that, for PM10, the scavenging efficiency is considerably influenced by rainfall intensity R and the type of precipitation. In the case of convective precipitation, data on Λ are only partially related to “classical approach” of rain scavenging. Within the range of comparable values of rainfall intensity, the type of wet deposition (except for storms) does not influence the effectiveness of scavenging PM10 from the ground-level zone. The large number of observations conducted in real-time conditions yielded a proposal of simple regression model, which can be deemed suitable for the description of variability Λ (DPM10), but only to a limited extent for large-scale precipitation. The collected results can be applied in air pollution dispersion models and deposition and were found to be generally representative for areas with similar climatic characteristics.

scholarly journals Groundwater flow and storage within an alpine meadow-talus complex

2010 ◽  
Vol 7 (1) ◽  
pp. 1535-1567
Author(s):  
A. F. McClymont ◽  
M. Hayashi ◽  
L. R. Bentley ◽  
D. Muir ◽  
E. Kruschell
Keyword(s):  
Water Table ◽  
Alpine Meadow ◽  
Seismic Refraction ◽  
Seismic Profiles ◽  
Fine Grained ◽  
Rock Formations ◽  
Total Input ◽  
Dissolved Species ◽  
Ground Penetrating ◽  
Alpine Watersheds

Abstract. The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m2) alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that lies under the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m). Combined interpretations from the GPR and ERT data show that the fine-grained sediment, that the meadow basin is comprised of, has a total volume of ca. 3300 m3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14–21 mg/L) within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3–0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10−7 m/s. We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface flow out of the basin and helps to maintain the stable water-table depth.

scholarly journals Groundwater modeling of the withdrawal sustainability of Cannara artesian aquifer (Umbria, Italy)

2018 ◽  
Vol 7 (3) ◽  
pp. 47-60 ◽  
Author(s):  
Giovanni Pietro Beretta ◽  
Monica Avanzini ◽  
Tomaso Marangoni ◽  
Marino Burini ◽  
Giacomo Schirò ◽  
...  
Keyword(s):  
Drinking Water ◽  
Groundwater Modeling ◽  
Chlorinated Solvents ◽  
Ground Level ◽  
Confined Aquifer ◽  
Aquifer Recharge ◽  
Water Supplies ◽  
Umbria Region ◽  
Short Period ◽  
The 1960S

The Cannara aquifer (Umbria, Italy) has been known for more than a century, and is one of the main drinking water supplies in the Umbria Region. In the beginning it was used for irrigation purposes, since this area was mainly agricultural up to the 1960s. The groundwater—exploited by Umbra Acque S.p.A. (a Company supplying drinking water)—is 150 m under ground level and is contained in a porous confined aquifer, which originally had artesian characteristics. Exploitation of 200–300 l/s with nine wells caused a reduction of piezometric level, maintaining the confined aquifer conditions, except for a very short period during which the aquifer was depressurised by drought, and for increase of emergency withdrawals replacing other water supplies (from springs) for drinking purposes. The occasional presence of iron and ammonium ions confirms the confinement of the groundwater and their hydrochemical facies in a redox environment, while in nearby areas and shallow aquifers anthropogenic contaminants (nitrates and chlorinated solvents) are reported. For the protection of this aquifer of strategic interest (the most important well field in Umbria), all hydrological and hydrochemical data available have been reviewed, and the aquifer recharge studied. Sustainable rates of withdrawal, and groundwater protection areas have been identified using a numerical flow model. Further action for monitoring groundwater of both shallow and artesian aquifers, together with well-revamping, have been proposed.

scholarly journals Groundwater flow and storage within an alpine meadow-talus complex

2010 ◽  
Vol 14 (6) ◽  
pp. 859-872 ◽  
Author(s):  
A. F. McClymont ◽  
M. Hayashi ◽  
L. R. Bentley ◽  
D. Muir ◽  
E. Ernst
Keyword(s):  
Water Table ◽  
Alpine Meadow ◽  
Seismic Refraction ◽  
Seismic Profiles ◽  
Fine Grained ◽  
Rock Formations ◽  
Total Input ◽  
Dissolved Species ◽  
Ground Penetrating ◽  
Alpine Watersheds

Abstract. The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m2) alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that underlies the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m). Combined interpretations from the GPR and ERT data show that the fine-grained sediment comprising the meadow basin has a total volume of ca. 3300 m3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14–21 mg/L) within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3–0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10−7 m/s. We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface flow out of the basin and helps to maintain the stable water-table depth.

Estimation of NO2 and SO2 concentration changes in Europe from meteorological data with Neural Network

2020 ◽  
Author(s):  
Andrey Vlasenko ◽  
Volker Mattias ◽  
Ulrich Callies
Keyword(s):  
Neural Network ◽  
Air Quality ◽  
Meteorological Data ◽  
Approximation Error ◽  
Concentration Data ◽  
Input Concentration ◽  
Chemical Substances ◽  
Bounded Continuous Function ◽  
Concentration Changes ◽  
The Difference

&lt;p&gt;Chemical substances of anthropogenic and natural origin released into the atmosphere affect air quality and, as a consequence, the health of the population. As a result, there is a demand for reliable air quality simulations and future scenarios investigating the effects of emission reduction measures. Due to high computational costs, the prediction of concentrations of chemical substances with discretized atmospheric chemistry transport models (CTM) is still a great challenge. An alternative to the cumbersome numerical estimates is a computationally efficient neural network (NN). The design of the NN is much simpler than a CTM and allows approximating any bounded continuous function (i.e., concentration time series) with the desired accuracy. In particular, the NN trained on a set of CTM estimates can produce similar to CTM estimates up to the approximation error. We test the ability of a NN to produce CTM concentration estimates with the example of daily mean summer NO2 and SO2 concentrations. The measures of success in these tests are the difference in the consumption of computational resources and the difference between NN and CTM concentration estimates. Relying on the fact that after spin-up, CTM estimates are independent of the initial concentrations, we show that recurrent NN can also spin-up and predict atmospheric chemical state without having input concentration data. Moreover, we show that if the emission scenario does not change significantly from year to year, the NN can predict daily mean concentrations from meteorological data only.&lt;/p&gt;

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