Exponential clogging time for a one dimensional DLA

When considering DLA on a cylinder it is natural to ask how many particles it takes to clog the cylinder, e.g. modeling clogging of arteries. In this note we formulate a very simple DLA clogging model and establish an exponential lower bound on the number of particles arriving before clogging appears

Clogging and Jamming of Colloidal Monolayers Driven Across a Disordered Landscape

We experimentally investigate the clogging and jamming of interacting paramagnetic colloids driven through a quenched disordered landscape of fixed obstacles. When the particles are forced to cross a single aperture between two obstacles, we find an intermittent dynamics characterized by an exponential distribution of burst size. At the collective level, we observe that quenched disorder decreases the particle ow, but it also greatly enhances the "faster is slower" effect, that occurs when increasing the particle speed. Further, we show that clogging events may be controlled by tuning the pair interactions between the particles during transport, such that the colloidal ow decreases for repulsive interactions, but increases for anisotropic attraction. We provide an experimental test-bed to investigate the crucial role of disorder on clogging and jamming in driven microscale matter

Methodology to quantify clogging coefficients for grated inlets: application to SANT MARTI catchment (Barcelona)

This is the accepted version of the following article: Gómez, M, Parés, J, Russo, B, Martínez‐Gomariz, E. Methodology to quantify clogging coefficients for grated inlets. Application to SANT MARTI catchment (Barcelona). J Flood Risk Management. 2019; 12:e12479. https://doi.org/10.1111/jfr3.12479, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1111/jfr3.12479.Within the drainage system of a city, the set of inlets is in charge of taking the runoff produced by local storms to the stormwater/sewer. In the drainage system design the selection of appropriate inlet models and their location is one of the fundamental aspects. The hydraulics of these inlets has received great attention within the last years; however, few inlet makers provide the hydraulic capacity of their products. In addition, these data usually consider clean water, while in reality, numerous inlets can be either totally or partially clogged. This aspect should be kept in mind within the design process. In this paper, a methodology to consider the hydraulic effects of clogging phenomena is presented. The work started from a visual inspection of the grated inlets throughout the urban catchment of Sant Martí, Barcelona, as a means of identifying clogging patterns, their repetitive forms and their associated frequency. After that, clogged patterns were reproduced in laboratory testing of typical inlets types, thereby obtaining the real quantity of water that could be captured by each of them. It was shown that the same expression employed to describe the efficiency of clean inlets can be used to assess the efficiency of those clogged. A reduction factor in terms of hydraulic capacity and related to each clogging pattern has been defined for use in hydraulic studies of runoff along streets. Finally, the paper compares the obtained results in terms of clogging coefficient with another experimental campaign carried out in other catchment of the city.Peer ReviewedPostprint (author's final draft

Development of the technology for the fabrication of reliable laminar flow control panels

Various configurations of porous, perforated and slotted materials were flow tested to determine if they would meet the LFC surface smoothness and flow requirements. The candidate materials were then tested for susceptibility to clogging and for resistance to corrosion. Of the materials tested, perforated titanium, porous polyimide, and slotted assemblies demonstrated a much greater resistance to clogging than other porous materials

Experimental investigation of pore clogging by microparticles: Evidence for a critical flux density of particle yielding arches and deposits

Prediction of pore fouling by microparticles is still challenging and remains a difficult step to optimize membrane and filtration processes. The scientific issue consists in determining the relevant operation parameters controlling the capture of particles and the clogging of the filter. In this study, we have developed for a dead-end and cross-flow filtration a poly-dimethylsiloxane (PDMS) device which allows direct observation of the clogging dynamics of microchannels (20 lm wide) by micrometric particles (5 lm diameter). The experiments highlight the formation of different 3D clogging patterns according to the filtration conditions (particle concentration, flowrate, particle flux density and physical–chemical conditions of suspension). Besides, we have determined under which specific conditions of filtration, the latex microparticles are captured and form arches, clusters or dendrites. For each type of structure, the temporal dynamics of the particle deposition are analyzed by means of the average thickness of deposit. The critical conditions for the formation of arches leading to deposit formation have been identified in term of a combination of operating conditions: the particle oncentration and the particle velocity. A critical particle flux density yielding pore clogging is then observed and characterized. Studying these experimental results helps to identify pore clogging mechanisms: deposition, interception and bridging

Electrochemically induced precipitation enables fresh urine stabilization and facilitates source separation

Source separation of urine can enable nutrient recycling, facilitate wastewater management, and conserve water. Without stabilization of the urine, urea is quickly hydrolyzed into ammonia and (bi)carbonate, causing nutrient loss, clogging of collection systems, ammonia volatilization, and odor nuisance. In this study, electrochemically induced precipitation and stabilization of fresh urine was successfully demonstrated. By recirculating the urine over the cathodic compartment of an electrochemical cell, the pH was increased due to the production of hydroxyl ions at the cathode. The pH increased to 11-12, decreasing calcium and magnesium concentrations by >80%, and minimizing scaling and clogging during downstream processing. At pH 11, urine could be stabilized for one week, while an increase to pH 12 allowed urine storage without urea hydrolysis for >18 months. By a smart selection of membranes [anion exchange membrane (AEM) with a cation exchange membrane (CEM) or a bipolar membrane (BPM)], no chemical input was required in the electrochemical cell and an acidic stream was produced that can be used to periodically rinse the electrochemical cell and toilet. On-site electrochemical treatment, close to the toilet, is a promising new concept to minimize clogging in collection systems by forcing controlled precipitation and to inhibit urea hydrolysis during storage until further treatment in more centralized nutrient recovery plants