Klinglmair M.,Technical University of Denmark |
Vadenbo C.,Institute of Environmental Engineering |
Astrup T.F.,Technical University of Denmark |
Scheutz C.,Technical University of Denmark
Resources, Conservation and Recycling | Year: 2017
Phosphorus (P) is present in large amounts in agricultural residues and organic wastes from human consumption, from which it can be recovered as fertiliser, reducing dependence on primary P. Crucial for a secondary resource is its ability to fulfil the functions of the resource intended to be substituted. This quality of secondary resources is not captured well by material flow analysis (MFA). A static MFA of the Danish anthropogenic P cycle was adapted for optimization via linear programming to minimize primary P imports. The MFA system was adapted to reflect typical nutrient availability from various secondary-P fertilisers, to allow for exchange of secondary-P fertilisers between regions (sewage sludge incineration ash and composted organic household waste), and to reflect the system's development over 3 annual time steps. Since P accumulating in agricultural soil gradually becomes available for plants over time, the outcome showed both a gradual decline of mineral P fertiliser inputs and net additions to soil P stocks stabilising at distinctly lower levels than evident from the static MFA. The optimization model's outcome, accounting for the dynamic aspects of transport and P availability to crops over time, suggests a substitution potential of over 80% (9.8 Gg primary P) by P recovered from sewage sludge and household biowaste, compared to 35% in the static MFA. © 2017 Elsevier B.V.
Wang S.-Y.,Institute of Environmental Engineering |
Kuo Y.-C.,Formosa Petrochemical |
Hong A.,University of Utah |
Chang Y.-M.,National Taipei University of Technology |
Kao C.-M.,Institute of Environmental Engineering
Chemosphere | Year: 2016
Lubricant and diesel oil-polluted sites are difficult to remediate because they have less volatile and biodegradable characteristics. The goal of this research was to evaluate the potential of applying an enhanced landfarming to bioremediate soils polluted by lubricant and diesel. Microcosm study was performed to evaluate the optimal treatment conditions with the addition of different additives (nutrients, addition of activated sludge from oil-refining wastewater facility, compost, TPH-degrading bacteria, and fern chips) to enhance total petroleum hydrocarbon (TPH) removal. To simulate the aerobic landfarming biosystem, air in the microcosm headspace was replaced once a week. Results demonstrate that the additives of activated sludge and compost could result in the increase in soil microbial populations and raise TPH degradation efficiency (up to 83% of TPH removal with 175 days of incubation) with initial (TPH = 4100 mg/kg). The first-order TPH degradation rate reached 0.01 1/d in microcosms with additive of activated sludge (mass ratio of soil to inocula = 50:1). The soil microbial communities were determined by nucleotide sequence analyses and 16S rRNA-based denatured gradient gel electrophoresis. Thirty-four specific TPH-degrading bacteria were detected in microcosm soils. Chromatograph analyses demonstrate that resolved peaks were more biodegradable than unresolved complex mixture. Results indicate that more aggressive remedial measures are required to enhance the TPH biodegradation, which included the increase of (1) microbial population or TPH-degrading bacteria, (2) biodegradable carbon sources, (3) nutrient content, and (4) soil permeability. © 2016 Elsevier Ltd
PubMed | National Taipei University of Technology, University of Utah, Formosa Petrochemical and Institute of Environmental Engineering
Type: | Journal: Chemosphere | Year: 2016
Lubricant and diesel oil-polluted sites are difficult to remediate because they have less volatile and biodegradable characteristics. The goal of this research was to evaluate the potential of applying an enhanced landfarming to bioremediate soils polluted by lubricant and diesel. Microcosm study was performed to evaluate the optimal treatment conditions with the addition of different additives (nutrients, addition of activated sludge from oil-refining wastewater facility, compost, TPH-degrading bacteria, and fern chips) to enhance total petroleum hydrocarbon (TPH) removal. To simulate the aerobic landfarming biosystem, air in the microcosm headspace was replaced once a week. Results demonstrate that the additives of activated sludge and compost could result in the increase in soil microbial populations and raise TPH degradation efficiency (up to 83% of TPH removal with 175 days of incubation) with initial (TPH=4100mg/kg). The first-order TPH degradation rate reached 0.011/d in microcosms with additive of activated sludge (mass ratio of soil to inocula=50:1). The soil microbial communities were determined by nucleotide sequence analyses and 16S rRNA-based denatured gradient gel electrophoresis. Thirty-four specific TPH-degrading bacteria were detected in microcosm soils. Chromatograph analyses demonstrate that resolved peaks were more biodegradable than unresolved complex mixture. Results indicate that more aggressive remedial measures are required to enhance the TPH biodegradation, which included the increase of (1) microbial population or TPH-degrading bacteria, (2) biodegradable carbon sources, (3) nutrient content, and (4) soil permeability.
Krolikowska J.,Cracow University of Technology |
Debowska B.,Cracow University of Technology |
Krolikowski A.,Institute of Environmental Engineering
Environmental Engineering IV - Proceedings of the Conference on Environmental Engineering IV | Year: 2013
This work is devoted to the problems of operating a vacuum sewer system. The presented results are based on the authors' own research and data from scientific sources. The analysis included in this work relates to the failure of vacuum sewer system components and the operating costs of such systems, which are governed primarily by the electricity consumption. © 2013 Taylor & Francis Group.
Fatichi S.,University of Florence |
Fatichi S.,University of Michigan |
Fatichi S.,Institute of Environmental Engineering |
Ivanov V.Y.,University of Michigan |
Caporali E.,University of Florence
Journal of Advances in Modeling Earth Systems | Year: 2012
Numerous studies have explored the role of vegetation in controlling and mediating hydrological states and fluxes at the level of individual processes, which has led to improvements in our understanding of plot-scale dynamics. Relatively less effort has been directed toward spatially-explicit studies of vegetation-hydrology interactions at larger scales of a landscape. Only few continuous, process-oriented ecohydrological models had been proposed with structures of varying complexity. This study contributes to their further evolution and presents a novel ecohydrological model, Tethys-Chloris. The model synthesizes the state-of-the-art knowledge on individual processes and coupling mechanisms drawn from the disciplines of hydrology, plant physiology, and ecology. Specifically, the model reproduces all essential components of the hydrological cycle: it resolves the mass and energy budgets in the atmospheric surface layer at the hourly scale, while representing up to two layers of vegetation; it includes a module of snowpack evolution; it describes the saturated and unsaturated soil water dynamics, processes of runoff generation and flow routing. The component of vegetation dynamics parameterizes life cycle processes of different plant functional types, including photosynthesis, phenology, carbon allocation, and tissue turnover. This study presents a confirmation of the long-term, plot-scale model performance by simulating two types of ecosystems corresponding to different climate conditions. A consistent and highly satisfactory model skill in reproducing the energy and water budgets as well as physiological cycles of plants with minimum calibration overhead is demonstrated. Furthermore, these applications demonstrate that the model permits the identification of data types and observation frequencies crucial for appropriate evaluation of modeled dynamics. More importantly, through a synthesis of a wide array of process representations, the model ensures that climate, soil, vegetation, and topography collectively identify essential modes controlling ecohydrological systems, i.e., that satisfactory performance is a result of appropriate mimicking of internal processes. Copyright © 2012 by the American Geophysical Union.
News Article | November 11, 2015
Imagine a species that is only one millimetre long and has only a limited swimming ability. Yet, its mobility is sufficient for moving, feeding and reproducing in freshwater and seawater. That's exactly what a type of zooplankton of the crustaceans family - namely the calanoid copepods - does. In a study published in EPJ E, physicists shed new light on how these zooplankton steer large-scale collective motion under strong turbulence. To do so, the authors study the zooplankton's small-scale motion mechanisms when subjected to background flow motion. These findings are the work of François-Gaël Michalec from the Institute of Environmental Engineering, ETH Zurich, Switzerland, and European colleagues. Ecological applications in the field of zooplankton behaviour ecology include, for example, modelling the feeding efficiency of their predator, fish larvae. Michalec and colleagues previously showed the ability of certain calanoid copepods to adjust their swimming efforts according to the background water flow. In this study, the idea was first to quantify to which extent copepods' self-induced motion - which consists of a succession of intermittent periods of slow swimming with strong relocation jumps - results in alternately low and high swimming speeds in calm water. To do so, the authors reconstructed the trajectories of a large number of copepods swimming freely by video tracking their motion in 3D. Then, the authors focused on elucidating the relative contribution of relocation jumps and turbulence, which is also intermittent, to the substantial fluctuations in speed that are observed in copepods swimming under background flow motion. By using an original statistical analysis method, they precisely identified the contribution of both small and large time scales to these animals' speed fluctuations. They found that at short time scales, due to the copepods' frequent relocation jumps, the intermittent nature of their self-induced motion amplifies the intermittent properties of the underlying flow. Reference: Characterization of intermittency in zooplankton behaviour in turbulence. F-G. Michalec, F.G. Schmitt, S. Souissi, and Markus Holzner (2015), Eur. Phys. J. E 38: 108, DOI: 10.1140/epje/i2015-15108-2 More information: François-Gaël Michalec et al. Characterization of intermittency in zooplankton behaviour in turbulence, The European Physical Journal E (2015). DOI: 10.1140/epje/i2015-15108-2
Gulan U.,Institute of Environmental Engineering |
Turkoglu H.,Gazi University
Strojarstvo | Year: 2010
In this study, fluid flow and concentration distribution on the cathode side of a Proton Exchange Membrane Fuel Cell were numerically analyzed. The problem domain consists of a cathode gas flow channel, cathode gas diffusion layer and cathode catalyst layer. The governing equations, continuity, momentum and concentration equations were discritized by the control volume method and solved using a computer program based on SIMPLE algorithm. Simulations were made for different values of gas diffusion layer porosity, catalyst layer porosity and the ratio of the cathode gas diffusion layer thickness to the gas flow channel height. Using the results of these simulations, the effects of these parameters on flow, oxygen concentration and current density distribution were analyzed. It is observed that increasing the porosities of the gas diffusion layer and catalyst layer increases the current and power densities. The increase in the porosity of the gas diffusion layer also increases the oxygen concentration in both gas diffusion and catalyst layers but decreases the oxygen concentration in gas flow channel. Simulations also showed that increasing porosity of the catalyst layer increases the oxygen concentration in a catalyst layer but decreases the oxygen concentration in a gas flow channel and gas diffusion layer. It is also seen that the effect of the gas diffusion layer porosity is more dominant on cell performance compared to the catalyst layer porosity. The analysis of the effect of the ratio of the cathode gas diffusion layer thickness to the gas flow channel height on the cell performance showed that the increasing ratio of the cathode gas diffusion layer thickness to the gas flow channel height decreases the current and power densities. An analysis of the data obtained from simulations also shows that increasing the ratio of the cathode gas diffusion layer thickness to the gas flow channel height increases the oxygen concentration in the gas flow channel but decreases the oxygen concentration in both gas diffusion and catalyst layers.
Anagnostopoulos G.G.,CUBUS AG |
Fatichi S.,Institute of Environmental Engineering |
Burlando P.,Institute of Environmental Engineering
Water Resources Research | Year: 2015
Extreme rainfall events are the major driver of shallow landslide occurrences in mountainous and steep terrain regions around the world. Subsurface hydrology has a dominant role on the initiation of rainfall-induced shallow landslides, since changes in the soil water content affect significantly the soil shear strength. Rainfall infiltration produces an increase of soil water potential, which is followed by a rapid drop in apparent cohesion. Especially on steep slopes of shallow soils, this loss of shear strength can lead to failure even in unsaturated conditions before positive water pressures are developed. We present HYDROlisthisis, a process-based model, fully distributed in space with fine time resolution, in order to investigate the interactions between surface and subsurface hydrology and shallow landslides initiation. Fundamental elements of the approach are the dependence of shear strength on the three-dimensional (3-D) field of soil water potential, as well as the temporal evolution of soil water potential during the wetting and drying phases. Specifically, 3-D variably saturated flow conditions, including soil hydraulic hysteresis and preferential flow phenomena, are simulated for the subsurface flow, coupled with a surface runoff routine based on the kinematic wave approximation. The geotechnical component of the model is based on a multidimensional limit equilibrium analysis, which takes into account the basic principles of unsaturated soil mechanics. A series of numerical simulations were carried out with various boundary conditions and using different hydrological and geotechnical components. Boundary conditions in terms of distributed soil depth were generated using both empirical and process-based models. The effect of including preferential flow and soil hydraulic hysteresis was tested together with the replacement of the infinite slope assumption with the multidimensional limit equilibrium analysis. The results show that boundary conditions play a crucial role in the model performance and that the introduced hydrological (preferential flow and soil hydraulic hysteresis) and geotechnical components (multidimensional limit equilibrium analysis) significantly improve predictive capabilities in the presented case study. © 2015. American Geophysical Union. All Rights Reserved.
Barenbold F.,Institute of Environmental Engineering |
Crouzy B.,Institute of Environmental Engineering |
Perona P.,University of Edinburgh
Water Resources Research | Year: 2016
In order to shed light on the influence of riverbed vegetation on river morphodynamics, we perform a linear stability analysis on a minimal model of vegetation dynamics coupled with classical one- and two-dimensional Saint-Venant-Exner equations of morphodynamics. Vegetation is modeled as a density field of rigid, nonsubmerged cylinders and affects flow via a roughness change. Furthermore, vegetation is assumed to develop following a logistic dependence and may be uprooted by flow. First, we perform the stability analysis of the reduced one-dimensional framework. As a result of the competitive interaction between vegetation growth and removal through uprooting, we find a domain in the parameter space where originally straight rivers are unstable toward periodic longitudinal patterns. For realistic values of the sediment transport parameter, the dominant longitudinal wavelength is determined by the parameters of the vegetation model. Bed topography is found to adjust to the spatial pattern fixed by vegetation. Subsequently, the stability analysis is repeated for the two-dimensional framework, where the system may evolve toward alternate or multiple bars. On a fixed bed, we find instability toward alternate bars due to flow-vegetation interaction, but no multiple bars. Both alternate and multiple bars are present on a movable, vegetated bed. Finally, we find that the addition of vegetation to a previously unvegetated riverbed favors instability toward alternate bars and thus the development of a single course rather than braiding. © 2016. American Geophysical Union.
Vaclavik V.,Institute of Environmental Engineering |
Dirner V.,Institute of Environmental Engineering |
Dvorsky T.,VSB - Technical University of Ostrava |
Daxner J.,D and Daxner Technology Ltd
Metalurgija | Year: 2012
The paper presents the results of experimental research that dealt with the substitution of finely ground blast furnace slag for Portland cement in the course of simple concrete manufacturing. Physical and mechanical properties of experimental concrete mixtures based on finely ground blast furnace slag were observed.