Traditional colloid filtration theory predicts exponential colloid retention profiles (RPs) based on a constant fractional removal per grain passed. However, under unfavorable conditions, where repulsive barriers inhibit colloid attachment, observed transport exhibits non-exponential RPs. These anomalies are observed across diverse colloid types, including pathogens, engineered nanomaterials,...
Microplastic (MP, < 5 mm) pollution is widespread in soils, where particles can persist, migrate with groundwater, and carry harmful chemicals and microorganisms 1-2. Understanding how MPs are transported and retained in porous media is therefore essential for assessing their environmental impacts 3. However, standardized methods to investigate MP transport in soils are still limited 4-5. Most...
Groundwater contamination remains a significant environmental challenge, necessitating the development of advanced remediation strategies. One promising approach involves the injection of nanomaterials, such as nano-sized zero-valent iron (nZVI) or colloidal activated carbon, to degrade or immobilize contaminants in situ. The success of nanoremediation hinges on quantitative understanding of...
Clogging from particle-laden flows in confined porous environments spans multiple scales and is ubiquitous across biological, environmental, and engineered systems. It results from the obstruction of narrow pathways, causing permeability loss, reduced injectivity, and, in severe cases, complete blockage. Mitigation is therefore essential to sustain performance and extend the lifetime of porous...
Evaporation of soil is a key hydrological process which returns $20 \%$ of terrestrial precipitation directly to the atmosphere. This large-scale phenomenon is governed at the microscale by capillary flows along water films. Indeed, continuity of these films between the top of the soil and the evaporative front deep inside the soil is essential for efficient drying. Since the fate of these...
In civil engineering, it is common practice to support the walls of an open excavation, such as a borehole or trench, by filling it with fluid. The traditional and most widely used support fluids are slurries of bentonite clay in water. Semi-dilute aqueous solutions of high-molecular-weight polymer ("polymer fluids") are known to have a variety of advantages over traditional bentonite...
Understanding the fate of colloids in porous media, such as rocks and soils, is crucial for environmental applications including groundwater remediation. Colloids spanning nanometre to micrometre length scales can deposit within pore spaces, obstruct flow pathways, and significantly alter permeability. Colloid deposition in porous media may occur through sieving, hydrodynamic bridging, or...
The remediation of contaminated soils and groundwater is a major challenge. A promising approach exploits colloid movement under the effect of solute concentration gradients generated in situ by the contaminant [1]. This phenomenon, called diffusiophoresis, offers considerable potential to direct colloids toward areas of the porous microstructure that would otherwise be inaccessible (e.g....
Diffusiophoresis refers to the out-of-equilibrium phenomenon that triggers colloid migration along gradients of local salt concentration in its ambient. First discovered in the 1950s [1], later developed theoretically in the 1980s [2], this phenomenon has recently caught the attention of scientists across disciplines. Due to the logarithmic dependence of the diffusiophoretic drift velocity on...
In the context of climate change, many key environmental engineering applications rely on transport and reactive processes in porous media, including CO2 storage in geological formations and the remediation of contaminated soils and aquifers. Ensuring the integrity of geological containment barriers and improving groundwater quality requires the development of effective engineering strategies,...
Aging and fragmentation processes of plastic debris favor the formation of reactive micro- and nano-plastic (NPs) particles, which behave as vectors of pollutants in porous media. One of the most common types of NPs is made of polystyrene polymer (PS) that has shown selective adsorption towards metals, e.g., lead (Pb$^{2+}$) and arsenic, under typical fresh-water and shallow aquifer...
Dynamics and interactions of particles and particle-like matter in porous media are crucial to diverse contexts from natural and industrial processes to biological phenomena. Yet, attempts to understand particle transport have largely focused on idealized colloidal dynamics considering otherwise pure colloid–fluid–surface interactions. Meanwhile, transport of particle-like matter in complex...
Biofilms alter the hydraulic properties of porous media, impacting processes from groundwater remediation to industrial filtration. While biomass accumulation is known to reduce permeability, a quantitative link between its spatial organization and system- scale hydraulics remains missing. Here, using microfluidics, time-lapse microscopy, and a novel mechanistic model we demonstrate that...
Soil compaction is a primary driver of agricultural soil degradation, significantly altering hydraulic properties such as water retention, infiltration, and root penetrability. While external factors like machinery traffic and livestock trampling are well-documented, the role of Root-Induced Soil Compaction (RISC) remains relatively underexplored. RISC, driven by root elongation and radial...
We investigate coupled feedbacks between pore-scale hydrodynamics, nutrient transport, and bacterial behavior in heterogeneous pore spaces by relying on statistically robust metrics rooted in Information Theory. Bacterial motility and chemotaxis are main drivers of a variety of bacteria-mediated processes taking place in natural and engineered porous systems, including, e.g., bioremediation of...
Bacteria are well-recognised as having a beneficial effect on the structure of soil in that they favour soil aggregation and increase soil pore connectivity1,2. Soil opacity renders its dynamic imaging at the microscale difficult, so our knowledge on bacterial activity in soil largely results from end-point measurements. Microfluidic chambers enable the dynamic observation of bacteria in model...
Groundwater remediation places strong demands on treatment technologies, which must achieve effective removal of contaminants such as Bisphenol-A at trace concentrations while operating under site-specific hydrogeological and regulatory constraints. Circulation-based remediation concepts, such as groundwater circulation wells (GCWs), create controlled subsurface flow fields through extraction...
Keywords: Hydrodynamic dispersion, Porous media, Quorum sensing, S. aureus, Transport Phenomena
Bacterial environments are inherently dynamic, with fluid flow constantly shaping their physicochemical landscape in non-trivial ways. Quorum sensing (QS) is a key mechanism by which bacteria communicate through the diffusion of QS molecules, termed autoinducers, to cope with these dynamic...
Accurate representation of root water uptake is critical for simulating soil–plant water dynamics, yet commonly applied root density distributions are empirical and may not reflect functionally active roots. In this study, we propose a drying-rate-based root distribution derived directly from field-measured soil water content (θ) dynamics, and we use actual transpiration derived from sap flow...
Mine tailings generated by artisanal gold mining constitute a major source of soil and water contamination in Sahelian regions, where agricultural land and water resources are particularly vulnerable. These tailings behave as environmental porous media in which water circulation, redox conditions and soil–plant interactions control the mobility, bioavailability and transfer of trace metals. In...
Soil macropores left by the soil fauna or decayed roots act as preferential pathways where gravity-driven flow bypasses most of the soil matrix. These fast, out-of-equilibrium, water transfers co-exist with slower capillary-driven flow in the soil matrix. Some water and the contaminants it contains can transfer from the macropores to the matrix.
These lateral exchanges are considered in...
Chlorinated organic compounds (COCs) are widely used industrial chemicals that pose significant environmental risks due to their toxicity, volatility, instability, and limited solubility in groundwater, often leading to persistent secondary contamination [1, 2]. Recent studies have highlighted the potential of Pickering emulsion injection as an innovative strategy for soil and groundwater...
Lignocellulosic biomass is an abundant source of low-carbon energy that remains largely untapped, with 181 billion tonnes of waste per year [1] mainly coming from cereal agriculture. The architecture of this type of biomass is highly complex and varies with species: it can be defined as a continuum of spatial scales, from the scale of polymeric molecules making up plant cell walls to the scale...
Capacitive deionization (CDI) is widely implemented as an electrosorptive desalination technology that is typically designed and operated to maximize overall salt removal rather than to achieve ion-specific selectivity. However, ion electrosorption in porous carbons is inherently governed by pore size, surface chemistry, ion hydration, and transport kinetics, so that selective behavior can be...
One of the dominant classes of subsurface pollutants in soils and aquifers is that of non-aqueous phase liquids (NAPL), and in particular petroleum products, which arise from leaks during petroleum production and storage. In situ bioremediation has emerged as a preferred strategy for treating such hydrocarbon contamination, owing to its sustainability and cost-effectiveness[1]. Compared with...
Emerging contaminants, including microplastics (MPs), nanoplastics (NPs), heavy metals, boron, and per- and polyfluoroalkyl substances (PFAS), are increasingly detected in water and soil systems and pose significant risks to ecosystems and public health. Their widespread occurrence and persistence place growing pressure on conventional treatment technologies. Carbonaceous porous materials,...
Non-aqueous phase liquid (NAPL) contamination is among the most persistent and challenging forms of subsurface pollution, posing long-term risks to groundwater resources and ecosystem health. In particular, Dense Non-Aqueous Phase Liquids (DNAPLs) are difficult to detect and monitor due to their low mobility, strong capillary trapping, and density greater than water, which promotes downward...
The 3D characterization of a porous medium is fundamental for understanding the pore-scale mechanisms that control matrix-fluid interactions in flow-through systems. For instance, nanoparticle mobility in porous media is a key challenge within the nanoremediation technology, as the reactive nanoparticles are to target specific areas of the contaminated aquifer. Over the past two and a half...
