scholarly journals Column Experiments on Sorption Coefficients and Biodegradation Rates of Selected Pharmaceuticals in Three Aquifer Sediments

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 14 ◽  
Author(s):  
Aleksandra Kiecak ◽  
Friederike Breuer ◽  
Christine Stumpp
Keyword(s):  
Environmental Concern ◽  
Sandy Loam ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Transport Processes ◽  
Column Experiments ◽  
Transport Parameters ◽  
Degradation Rates ◽  
The Impact ◽  
Flow Velocities

The presence of pharmaceuticals in the environment, and in groundwater, has been recognized as a great environmental concern. Biodegradation and sorption are the main processes leading to the removal of contamination from the water phase. The aim of this study was to determine the transport processes of selected pharmaceuticals (antipyrine, atenolol, carbamazepine, caffeine, diclofenac, ketoprofen, sulfamethoxazole) in selected sediments (coarse sand, medium sand, sandy loam) in laboratory experiments. Moreover, the impact of flow velocities on the sorption and degradation rates of the selected compounds was studied. Column experiments were performed at three flow velocities, under abiotic and biotic conditions, applying conservative (bromide) and reactive tracers (pharmaceuticals). From the breakthrough curves, retardation factors and degradation rates were determined and the influence of variable flow conditions on transport parameters was evaluated. Low observed concentrations and recoveries of atenolol indicated a strong influence of sorption on its transport. Diclofenac, caffeine, and carbamazepine were also affected by sorption but to a lesser extent. Sulfamethoxazole, ketoprofen, and antipyrine were recovered nearly completely, indicating an almost conservative transport behavior. Biodegradation was small for all the compounds, as the results from biotic and abiotic column experiments were similar. Transport of the tested pharmaceuticals was not influenced by different flow velocities, as similar modelled degradation rates and retardation factors were found for all tested flow velocities.

scholarly journals Preselection of a sorption model based on a column test: the algorithm and an example of its application

2021 ◽  
Author(s):  
Marek Marciniak ◽  
Monika Okońska ◽  
Mariusz Kaczmarek
Keyword(s):  
Mathematical Model ◽  
Breakthrough Curve ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Column Experiments ◽  
Transport Parameters ◽  
Sorption Model ◽  
Advection Dispersion ◽  
Conservative Tracer ◽  
Reactive Tracer

AbstractIn order to describe the contamination of saturated porous media, it is necessary to find an appropriate mathematical model that includes processes occurring in aquifers, such as advection, dispersion, diffusion, and various kinds of sorption. The identification of parameters of those processes is possible through laboratory column experiments, which result in records of breakthrough curves for a conservative tracer and a reactive tracer. An algorithm leading to the preliminary selection of the mathematical model that best describes transport processes of the reactive tracer in the experimental column is proposed in this article. A study published previously presented a sensitivity analysis for an arbitrarily adopted variability of the transport parameters. The analysis involved examining changes in the shape of breakthrough curves caused by the alteration of each parameter value. Specially defined indicators called descriptors were proposed to quantitatively describe the breakthrough curves. Then, formulas were proposed to determine the percentage deviations of descriptors of the breakthrough curve obtained for the reactive tracer in relation to the descriptors of the breakthrough curve of the conservative tracer. In the work described in this article, the deviations are analyzed and an algorithm is proposed that allows the preselection of the most suitable sorption model out of the five discussed simple (one-site) and six hybrid (two-site) models. The algorithm can facilitate and accelerate the interpretation of column experiments of contaminant transport in a porous medium. An example is provided to illustrate the usability of the proposed algorithm.

scholarly journals Use of column experiments to investigate the fate of organic micropollutants – a review

2016 ◽  
Author(s):  
Stefan Banzhaf ◽  
Klaus H. Hebig
Keyword(s):  
Boundary Conditions ◽  
Field Experiments ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Column Experiments ◽  
Organic Micropollutants ◽  
Transport Parameters ◽  
Column Studies ◽  
Set Up ◽  
The Individual

Abstract. Although column experiments are frequently used to investigate the transport of organic micropollutants, little guidance is available on what they can be used for, how they should be set up, and how the experiments should be carried out. This review covers the use of column experiments to investigate the fate of organic micropollutants. Alternative setups are discussed together with their respective advantages and limitations. An overview is presented of published column experiments investigating the transport of organic micropollutants, and suggestions are offered on how to improve the comparability of future results from different experiments. The main purpose of column experiments is to investigate the transport and attenuation of a specific compound within a specific sediment or substrate. The transport of (organic) solutes in groundwater is influenced by the chemical and physical properties of the compounds, the solvent (i.e. the groundwater, including all solutes), and the substrate (the aquifer material). By adjusting these boundary conditions a multitude of different processes and related research questions can be investigated using a variety of experimental setups. Apart from the ability to effectively control the individual boundary conditions, the main advantage of column experiments compared to other experimental setups (such as those used in field experiments, or in batch microcosm experiments) is that conservative and reactive solute breakthrough curves can be derived, which represent the sum of the transport processes. There are well-established methods for analyzing these curves. The effects observed in column studies are often a result of dynamic, non-equilibrium processes. Time (or flow velocity) is an important factor, in contrast to batch experiments where all processes are observed until equilibrium is reached in the substrate-solution system. Slight variations in the boundary conditions of different experiments can have a marked influence on the transport and degradation of organic micropollutants. This is of critical importance when comparing general results from different column experiments investigating the transport behavior of a specific organic compound. Such variations unfortunately mean that the results from most column experiments are not transferable to other hydrogeochemical environments but are only valid for the specific experimental setup used. Column experiments are fast, flexible, and easy to manage; their boundary conditions can be controlled and they are cheap compared to extensive field experiments. They can provide good estimates of all relevant transport parameters. However, the obtained results will almost always be limited to the scale of the experiment and not directly transferrable to field scales as too many parameters are exclusive to the column setup. The challenge for the future is to develop standardized column experiments on organic micropollutants in order to overcome these issues.

scholarly journals Use of column experiments to investigate the fate of organic micropollutants – a review

2016 ◽  
Vol 20 (9) ◽  
pp. 3719-3737 ◽  
Author(s):  
Stefan Banzhaf ◽  
Klaus H. Hebig
Keyword(s):  
Boundary Conditions ◽  
Field Experiments ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Column Experiments ◽  
Organic Micropollutants ◽  
Transport Parameters ◽  
Column Studies ◽  
Set Up ◽  
The Individual

Abstract. Although column experiments are frequently used to investigate the transport of organic micropollutants, little guidance is available on what they can be used for, how they should be set up, and how the experiments should be carried out. This review covers the use of column experiments to investigate the fate of organic micropollutants. Alternative setups are discussed together with their respective advantages and limitations. An overview is presented of published column experiments investigating the transport of organic micropollutants, and suggestions are offered on how to improve the comparability of future results from different experiments. The main purpose of column experiments is to investigate the transport and attenuation of a specific compound within a specific sediment or substrate. The transport of (organic) solutes in groundwater is influenced by the chemical and physical properties of the compounds, the solvent (i.e., the groundwater, including all solutes), and the substrate (the aquifer material). By adjusting these boundary conditions a multitude of different processes and related research questions can be investigated using a variety of experimental setups. Apart from the ability to effectively control the individual boundary conditions, the main advantage of column experiments compared to other experimental setups (such as those used in field experiments, or in batch microcosm experiments) is that conservative and reactive solute breakthrough curves can be derived, which represent the sum of the transport processes. There are well-established methods for analyzing these curves. The effects observed in column studies are often a result of dynamic, non-equilibrium processes. Time (or flow velocity) is an important factor, in contrast to batch experiments where all processes are observed until equilibrium is reached in the substrate-solution system. Slight variations in the boundary conditions of different experiments can have a marked influence on the transport and degradation of organic micropollutants. This is of critical importance when comparing general results from different column experiments investigating the transport behavior of a specific organic compound. Such variations unfortunately mean that the results from most column experiments are not transferable to other hydrogeochemical environments but are only valid for the specific experimental setup used. Column experiments are fast, flexible, and easy to manage; their boundary conditions can be controlled and they are cheap compared to extensive field experiments. They can provide good estimates of all relevant transport parameters. However, the obtained results will almost always be limited to the scale of the experiment and are not directly transferrable to field scales as too many parameters are exclusive to the column setup. The challenge for the future is to develop standardized column experiments on organic micropollutants in order to overcome these issues.

Phosphorus transport in saturated slag columns: experiments and mathematical models

1996 ◽  
Vol 34 (1-2) ◽  
pp. 153-160 ◽  
Author(s):  
S. H. Lee ◽  
S. Vigneswaran ◽  
K. Bajracharya
Keyword(s):  
Mathematical Models ◽  
Sorption Capacity ◽  
Algal Blooms ◽  
Sandy Loam ◽  
Dynamic Condition ◽  
Water Environment ◽  
Breakthrough Curves ◽  
Column Experiments ◽  
Phosphorus Transport ◽  
Waste Products

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.

scholarly journals Determination of the sodium retardation factor using different methods: Analysis of their characteristics and impact on the solute movement prediction in a structured Brazilian soil

2018 ◽  
Vol 22 (4) ◽  
pp. 281-289
Author(s):  
Vanessa Godoy ◽  
Gian Franco Napa-García ◽  
Lázaro Zuquette
Keyword(s):  
Prediction Models ◽  
Breakthrough Curves ◽  
Retardation Factor ◽  
Determination Method ◽  
Transport Parameters ◽  
Undisturbed Soil ◽  
Analytical Analysis ◽  
Initial Concentration ◽  
Preferential Pathways ◽  
The Impact

The retardation factor (Rd) is one of the main important solute transport parameters. Its value can vary significantly depending on the method used for its determination. In this paper, the sodium Rd is experimentally determined using undisturbed sandy columns to compare four methods of Rd determination and assess the impact of the chosen method in the prediction of sodium movement. Column experiments in undisturbed soil columns and analytical analysis were performed. The results showed that the soil has dual-porosity and preferential pathways. The breakthrough curves were in accordance with the soil’s physical characteristics. The Rd values ranged from 1.7 to 7.77 depending on the initial concentration and on the method used. These differences arise from the conceptual model of each Rd determination method. The experimental and analytical analysis indicated that the higher the Rd, the slower the movement. The methods that best reproduced the laboratory sodium movement were Ogata and Banks’ (1961), and Langmuir and Freundlich’s isotherms. The prediction models presented smaller errors with the increase of the initial concentration. In these cases, the predicted concentrations can be overestimated up to 22.5 % when using a not suitable method. Hence these results suggest that the Rd determination method can strongly affect the prediction of the sodium movement. Because of that, it is of vital importance to evaluate each method and how they can be adequate to the soil under investigation when determining Rd.

scholarly journals Comparison of Surface Roughness and Transport Processes of Sawed, Split and Natural Sandstone Fractures

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2530 ◽  
Author(s):  
Sascha Frank ◽  
Thomas Heinze ◽  
Stefan Wohnlich
Keyword(s):  
Surface Roughness ◽  
Tracer Tests ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Natural Fracture ◽  
Transport Parameters ◽  
Fracture Surfaces ◽  
Advection Dispersion ◽  
Hydraulic Aperture ◽  
Surface Morphologies

In single fractures, dispersion is often linked to the roughness of the fracture surfaces and the resulting local aperture distribution. To experimentally investigate the effects of diverse fracture types and surface morphologies in sandstones, three fractures were considered: those generated by sawing and splitting, and a natural sedimentary fracture. The fracture surface morphologies were digitally analyzed and the hydraulic and transport parameters of the fractures were determined from Darcy and the tracer tests using a fit of a continuous time random walk (CTRW) and a classical advection–dispersion equation (ADE). While the sawed specimen with the smoothest surface had the smallest dispersivity, the natural fracture has the largest dispersivity due to strong anisotropy and non-matching fracture surfaces, although its surface roughness is comparable to the split specimen. The parameterization of the CTRW and of the ADE agree well for β > 4 of the truncated power law. For smaller values of β, non-Fickian transport processes are dominant. Channeling effects are observable in the tracer breakthrough curves. The transport behavior in the fractures is controlled by multiple constraints such as several surface roughness parameters and the equivalent hydraulic aperture.

scholarly journals Breakthrough Investigation of Advective and Diffusive Transport in a Porous Matrix with a Crack

Fluids ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 358
Author(s):  
Ekkehard Holzbecher
Keyword(s):  
Flow Direction ◽  
Porous Matrix ◽  
Systematic Investigation ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Free Fluid ◽  
Transport Parameters ◽  
Transport Patterns ◽  
Set Up ◽  
Application Fields

Fluid flow and transport processes in fractured porous media are of particular interest for geologists and in the material sciences. Here a systematic investigation is presented, dealing with a generic geometric set-up of a porous matrix with a crack. In such a combined porous medium/free fluid system flow patterns have been examined frequently, while the resulting transport patterns have attracted less attention. Using numerical modeling with finite elements the problem is approached using a dimensionless formulation. With a reduced number of dimensionless parameter combinations (Darcy-, Peclet- and Reynolds-numbers) solution dependencies are examined in parametric sweeps. Breakthrough curves are fitted in comparison to those of 1D model approaches, yielding effective diffusivities and velocities. The computations reveal highest sensitivity concerning the angle between crack axis and flow direction, followed by the Peclet number and the crack axes ratio. As a dimensionless representation is used the results are scale independent. Thus, they deliver estimations concerning effective heat and solute transport parameters that can be relevant in all application fields.

Analysis of partial breakthrough data by a transfer-function method

Soil Research ◽  
2006 ◽  
Vol 44 (2) ◽  
pp. 175 ◽  
Author(s):  
M. A. Mojid ◽  
D. A. Rose ◽  
G. C. L. Wyseure
Keyword(s):  
Transfer Function ◽  
Solute Transport ◽  
Calcium Chloride ◽  
Unsaturated Soils ◽  
Function Method ◽  
Sandy Loam ◽  
Breakthrough Curves ◽  
Time Domain Reflectometry ◽  
Transport Parameters ◽  
Transfer Function Method

A transfer-function method has been applied to determine solute-transport parameters from earlier sections of complete breakthrough data. Time-domain reflectometry allows the measurement of breakthrough data in unsaturated soil. In fine-textured soils, the flow of water must be kept low to maintain unsaturated conditions, and so experiments for a complete breakthrough of solute may last a very long time. Substantial savings of time and computer memory might be achieved if data could be analysed from an earlier section of breakthrough data. Data at 2 vertical positions (input at upper and response at lower position) from a complete breakthrough of calcium chloride applied as a pulse input to 4 unsaturated soils (coarse sand, sandy loam, clay loam, clay) were divided into 4 sets of increasing duration. Transport parameters of calcium chloride were determined by a transfer function, which results in similar values of the parameters from the last 3 datasets in all 4 soils. In the clay soil, however, because of erroneous breakthrough data the fit between the measured and estimated breakthrough curves (BTCs) was poor, but the transport parameters were consistent among different segments of data. We show that it is possible to determine successfully solute-transport parameters from partial breakthrough data, which include the peak of the response BTC. This transfer-function method is thus a powerful tool to shorten breakthrough experiments.

Modelling E. coli transport in soil columns: simulation of wastewater reuse in agriculture

2008 ◽  
Vol 57 (7) ◽  
pp. 1123-1129 ◽  
Author(s):  
Edward Smith ◽  
Aimen Badawy
Keyword(s):  
Agricultural Soils ◽  
Chemical Properties ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Treated Wastewater ◽  
Reclaimed Wastewater ◽  
Soil Columns ◽  
Local Conditions ◽  
E Coli ◽  
The Impact

Transport of E. coli bacteria was investigated in laboratory soil columns for three Egyptian agricultural soils, with aim toward determining a set of site specific criteria for safe and sustainable use of treated wastewater in irrigation in Egypt. In particular, the impacts of varying soil type and hydraulic loading rate (HLR) on E. coli effluent breakthrough curves were examined in the laboratory and simulated using the CXTFIT package to solve a one-dimensional mass transport equation that included advection, dispersion, adsorption, and straining/filtration. The attempt was made to measure the coefficients associated with each mass transfer process from independent experiments. The HLR used in irrigation was found to exert considerable influence on the impact of transport processes on E. coli breakthrough. At low HLRs, adsorption and straining/filtration are significant in addition to advection and dispersion. However, at high HLRs approaching flood irrigation, E. coli is essentially unaffected by reaction processes, with breakthrough a function of advection and dispersion only. Estimating Kdvia independent batch experiments did not provide a suitable description of adsorption of E. coli in soil columns. To ensure safe and sustainable reuse of reclaimed wastewater in irrigation, guidelines should account for physical and chemical properties of the soil and other local conditions that may impact residual contaminant transport.

Studying the transport and retention of naturally occurring microplastics (MPs) in sandy soils using column experiments

2021 ◽  
Author(s):  
Ahmad Ameen ◽  
Margaret Stevenson ◽  
Alfred Paul Blaschke
Keyword(s):  
Soil Column ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Column Experiments ◽  
Human Society ◽  
Sand Mixture ◽  
Glass Column ◽  
Chemical Factors ◽  
Transport Behaviour ◽  
Physical And Chemical

<p>In the 1950’s, plastics were introduced as a miracle material and since then it has revolutionised human society in almost every domain of our daily life. The benefits of plastics are countless but their inherent resistance to degradation has ultimately led to their accumulation in the environment in the form of micro and nano plastics. In recent years, the presence of microplastics (MP) in fresh water sources has raised questions related to the protection of drinking water. In Austria, the exact status of groundwater contamination by MP is unknown. To understand the behaviour of MP that are present in the environment, a study was conducted to investigate the transport and distribution of MP in groundwater using column experiments.</p><p>Polyethylene MP were produced from 3D fluorescent printing material using a milling technique and in a well-defined size range of 1-200 μm. A borosilicate glass column (1.5 cm diameter and 10 cm long) was used as our experimental setup. The columns were packed with quartz and coarse sand. A layer of homogenized MP-sand mixture (approximately 3 to 5% w/w) was applied at the top of a soil column. The transport behaviour of MP were analysed in terms of various physical and chemical factors like MP-concentration, soil particle size, inflow rate, ionic strength and straining effect. The outflow from the column was collected at different pore volume intervals and analysed for the presence of MP. The breakthrough curves (BTCs) were obtained by measuring the MP concentrations of the effluent.</p>

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