A cargo de: Josep M.Soler
Fecha: Jueves 21 de Junio a las 12:15
Lugar: Departamento de Ingeniería Civil y Ambienta, Modulo D2-Aula CIHS, Planta Baja
A first in situ diffusion experiment in non-fractured granite (monopole 1) was already performed at the Grimsel Test Site. Several tracers (3H as HTO, 22Na+, 134Cs+, 131I- with stable I- as carrier) were continuously circulated through a packed-off borehole and the decrease in tracer concentrations in the liquid phase was monitored for a period of 789 days (June 2007 – August 2009). Subsequently, the borehole section was overcored and the tracer profiles in the rock analyzed. From the modeling of the experiment it was evident that a Borehole Disturbed Zone (BDZ) had to be taken into account. HTO seemed to display large rock capacity values in the BDZ. Also, modeling of out-leaching experiments (3H, I-) using overcored rock samples from monopole 1 gave apparent diffusion coefficients one order of magnitude larger than those obtained from the modeling of the in situ experiment. Given these results, it was decided to perform a second experiment (monopole 2), which includes a second observation borehole close to the new injection borehole.
Tracer circulation in the new monopole 2 experiment started in March 5th 2014 and ended in August 22nd 2017 (1266 days). The selected tracers were 3H, 22Na+, 134Cs+, 133Ba2+ and 36Cl-. A first predictive modeling exercise (1D-radial model) was performed early in the experiment using transport and sorption parameters from monopole 1, together with laboratory results for 133Ba2+ and 36Cl-. Those predictive calculations were compared with initial monitoring data from the in situ experiment (activities in the circulation system of the injection borehole). No apparent effect from a possible Borehole Disturbed Zone (BDZ) was observed from the experimental data. The very initial drop in activities for HTO, 22Na+ and 36Cl- (non- and weakly-sorbing tracers) during the first day of tracer circulation were clearly due to initial mixing in the circulation system. The initial drop in activities for 134Cs+ and 133Ba2+ showed clearly the effect of sorption. Bulk rock parameters for 134Cs+ from monopole 1 seemed to be applicable to monopole 2. However, 133Ba2+ seemed to sorb more strongly than expected (or to diffuse faster into the rock).
The final measurements are now compared with results from the existing calculations and also from new calculations using parameters from laboratory experiments for HTO and 36Cl-. Additionally, 2D calculations have been performed to check the possible effect of advection through the rock matrix.
a cargo de: Lurdes Martinez Landa. Investigadora UPC
Fecha: Jueves 28 de Junio a las 12:15 h
Lugar: Departamento de Ingeniería Civil y Ambienta, Modulo D2-Aula CIHS, Planta Baja
Water is essential for life, pure drinking water is a limited resource and its demand to supply ratio is increasing globally due to population growth, climate change… Development of efficient, sustainable and cost-effective techniques for water purification and reuse is therefore urgent.
Artificial Recharge is an often used technique to replenish exploited aquifers. Water of insufficient quality for drinking is infiltrated via basins or surface spreading through soils and aquifer sediments thereby improving its quality. Although managed recharge has been used for decades, the techniques is often operated as a black box without knowledge of the micro-organisms and the metabolic processes and pathways involved.
ACWAPUR project aims at developing innovative techniques to prevent leaching of pathogens, inorganic nutrients and organic pollutants to underlying aquifers during artificial recharge processes. This will be achieved by the use of advanced treatment permeable barriers, with a porosity that prevent leaching of pathogens and at the same time provide optimal conditions for microbial degradation processes. These barriers are constructed using organic layers to promote sorption of organic pollutants and facilitate the creation of different redox conditions to accelerate aerobic and anaerobic degradation processes.
In this context, we have constructed a group of 6 small recharge basins, combining different plants and barriers compositions to compare the behavior on the contaminants degradation. This seminar it would be formed by two parts: experiment design and first recharge period (lessons learned or not), and first chemical results. Waiting for the analytical results, we left the second part for summer comeback.
Lectura de Tesis Doctoral
Mechanisms and stochastic dynamics of transport in Darcy-scale heterogeneous porous media
Thesis advisors: Dr. Marco Dentz / Dr. Daniel Fernández García (UPC)
The defense will take place:
thursday, june 14th 2018, 11:00
UPC, Campus Nord
Building C1. Classroom: 002
C/Jordi Girona, 1-3
a cargo de: Arash Massoudieh (Catholic University of America)
Fecha: Martes 12 de Junio a las 12:15 h Lugar: Departamento de Ingeniería Civil y Ambienta, Modulo D2-Aula CIHS, Planta Baja
In this presentation GIFMOD, a new flexible and user-friendly modeling tool for forward and inverse modeling of environmental processes in the surface, subsurface, and the vadose zone will be introduced. GIFMOD can be used to model flow, particle transport and reactive transport in systems composed of streams, ponds, soil, groundwater, catchments, and plants. Transport of multiple classes of particles undergoing settling, resuspension, filtration, and remobilization can also be modeled. The model also allows prediction of transport and reaction of user defined water quality constituents in the system based on user-provided reaction networks and biokinetics rate expressions. Plants can be considered as individual blocks uptaking water and chemicals through their root system. The modeling framework allows users to represent the system they intend to model with the desired level of complexity and only include the processes they deem essential in the processes. GIFMOD also has a built-in parameter estimation capability both for doing point estimates using a hybrid genetic algorithm and probabilistic parameter estimation using Markov chain Monte Carlo algorithm. The flexibility of the tool allows it to be applied to a wide range of systems ranging from stream networks, stream-catchment systems, surface water-groundwater interaction, batch and column experiments, best management practices, and groundwater flow and reactive transport among others. I will demonstrate the utility of GIFMOD to simulate flow and transport in a stream, bioretention, infiltration basin and permeable pavement GI systems.
a cargo de: Tomás Aquino (IDAEA-CSIC)
Fecha: Jueves 31 de Mayo a las 12:15 h
Lugar: Departamento de Ingeniería Civil y Ambiental, Modulo D2-Aula CIHS, Planta Baja
Accurately simulating reactive transport through heterogeneous media requires resolving the spatial scales at which mixing takes place. This typically requires a fine spatial discretization (Eulerian methods) or large numbers of particles (Lagrangian methods), leading to prohibitively expensive simulations for large-scale transport. We explore a different approach and consider the question: In heterogeneous chemically reactive systems, is it possible to describe the evolution of macroscopic reactant concentrations without explicitly resolving the spatial transport? Traditional Kinetic Monte Carlo methods, such as the Gillespie algorithm , model chemical reactions as random walks in particle number space, without the introduction of spatial coordinates. The inter-reaction times are exponentially distributed under the assumption that the system is well mixed. In real systems, transport limitations lead to incomplete mixing and decreased reaction efficiency. We introduce an arbitrary inter-reaction time distribution, which may account for the impact of incomplete mixing. The resulting process defines an inhomogeneous continuous time random walk in particle number space, from which we derive a generalized chemical master equation and formulate a generalized Gillespie algorithm . We then determine the modified chemical rate laws for different inter-reaction time distributions, which describe the macroscopic reaction kinetics. We trace Michaelis–Menten-type kinetics back to finite-mean delay times, and predict time-nonlocal macroscopic reaction kinetics as a consequence of broadly distributed delays. Non-Markovian kinetics exhibit weak ergodicity breaking and show key features of reactions under local non-equilibrium.