Potential Clogging Research Articles

EPIGONE: the argus on the daily operation of throttle structures

This study presents the development of an Early Warning System (EWS) called EPIGONE focusing on the detection of dry weather overflows in the vicinity of throttle structures in sewer systems. Throttle structures are considered as vital parts of a sewer system as they are control sections limiting flow rates to a designed operational value. Because these structures are by definition prone to potential clogging or blockages, a close follow-up of the daily operation by an EWS facilitates increased vigilance or even alarm. Primary goal of EPIGONE is to alert operators and thus allow fast intervention in case of suspected failures of these structures within a settled timeframe. EPIGONE combines overflow water level measurements with rainfall radar information to determine Combined Sewer Overflow (CSO) activity during dry weather as this dual condition will indicate malfunctioning. This combination of measurements was found to be the most cost effective set-up to deploy on a large scale. Water level data are recorded and logged on-site and sent to a central controller via GSM/GPRS, where an algorithm determines dry weather overflow conditions. Rainfall radar data are used as criterion to decide on dry weather conditions. From there on alarms are sent out to multiple recipients via e-mail and/or text messages (SMS). Next to this, it is obvious that this system can also be used for ‘regular’ wet weather CSO monitoring.

Potential Clogging and Dissolution Effects During Artificial Recharge of Groundwater Using Potable Water

To avoid the water quality deterioration that are caused by artificial recharge (AR) of groundwater, potable drinking water has been used as one of the source water for AR to control the side effects caused by the over-exploitation of groundwater. Chemical clogging problems can still be caused by certain chemical components, especially Fe and Al, and a lower concentration of these elements can cause a notable decrease in hydraulic conductivity at the top layer of the infiltration medium. Some components in AR source water can be obstructed by the clogging layer, leading to a change in water quality. The accumulation of total suspended solids (TSS) at the clogging layer can cause physical clogging and worsen the degree of chemical clogging. Although clogging and the related change in water quality were the dominant issues that affect the infiltration rate and health risks during the AR process, the dissolution of the aquifer matrix should also be taken into account. This dissolution contributed to not only the hydraulic conductivity of the infiltration medium but also the potential change in water quality during the aquifer recharge, storage and recovery processes.

Assessment of pathogen survival potential during managed aquifer recharge with diffusion chambers

To evaluate the efficacy of using in situ diffusion chambers for pathogen decay studies in the aquifer. A comparative microbial inactivation study was carried out in groundwater by seeding selected pathogens and indicators in laboratory microcosms and Teflon diffusion chambers (in situ) fitted with 0.010- and 0.025-μm pore-size membranes. The results have shown that there is a difference in the decay rates obtained from the laboratory microcosms and in situ diffusion chambers for several pathogens. The results suggest that the use of laboratory microcosms to determine pathogen decay during the Managed Aquifer Recharge (MAR) may lead to underestimation of decay of adenovirus and Cryptosporidium and subsequent inaccurate assessment of the required residence time in the aquifer for pathogens to be removed from the recharged water. The decay rate of two indicator bacteria, Salmonella enterica and adenovirus, was found to be significantly slower (t-test, P < 0.05) in the in situ studies when 0.010-μm pore-size membranes were used. The assessment of potential clogging of the diffusion cell membranes showed no clogging of the membranes within the 50-day duration of the study as very little difference in the diffusion rates between new and old membranes was observed. Laboratory microcosms-based inactivation studies can significantly underestimate the survival potential of enteric viruses in the groundwater. Consequently, in situ studies should be carried out for accurate assessment of potential enteric virus survival in aquifers. Reliable assessment of potential public health risks from the presence of pathogens in groundwater is essential for proper management of the MAR schemes. The results of this study suggest that in situ assessment of pathogen survival potential in diffusion chambers provided more reliable data for pathogen risk assessment and subsequent risk mitigation plans for MAR schemes.

Monitoring of clogging evolution in the stormwater infiltration system and determinant factors

Infiltration is widely used to manage stormwater in cities and their suburbs. Despite its advantages, questions remain about its long-term performance, in particular the potential for clogging. To address this problem, a field study was undertaken to assess the evolution of clogging over time by means of hydraulic resistance (R) measurements. The experiment was carried out on an infiltration basin continuously monitored for 7 years from 2004 to 2010. The work shows that clogging takes place progressively and can be slowed down by the growth of vegetation. It also showed that the variation from one event to another presented high variability. The variation of successive R-values per time unit has been statistically explained by the variation per time unit of two groups of factors: one linked to physical aspects (water volume and particle load), and more interestingly one linked to biological clogging (solar energy and air temperature), which is generally not considered for these systems. L’infiltration est aujourd’hui largement utilisée dans la gestion des eaux pluviales en milieu urbain. Malgré ses avantages, son efficacité sur le long terme pose encore problème en particulier leur aptitude au colmatage. Pour traiter ce problème, des observations de terrain ont été menées de manière à évaluer l’évolution du colmatage au cours du temps à l’aide de mesures de résistance hydraulique (R). L’observation a été menée sur un bassin d’infiltration suivi en continu sur 7 ans de 2004 à 2010. Le travail montre que le colmatage est très progressif est peut être ralenti par la croissance de végétation. Il montre également une grande variabilité d’un évènement à l’autre. La variation entre deux valeurs de R par unité de temps a pu être expliquée statistiquement par les variations par unité de temps de deux groupes de facteurs : l’un lié à des aspects physiques (volume d’eau et charge particulaire) et de manière plus intéressante à des facteurs biologiques (énergie solaire et température d’air) non considérés habituellement.

The Active Tube Clearance System a Novel Bedside Chest-Tube Clearance Device

: Chest-tube clogging can lead to complications after heart and lung surgery. Surgeons often choose large-diameter chest tubes or place more than one chest tube when concerned about the potential for clogging. The purpose of this report is to describe the design and function of a proprietary active tube clearance system, a novel device that clears clots and debris from chest tubes. DEVICE DESCRIPTION:: The active tube clearance system is a novel chest tube clearance apparatus developed to maintain chest tube patency. Chest tube clearance is achieved by advancing the specially designed clearance member back and forth within the chest tube under sterile conditions, breaking down and pulling clots back toward the drainage receptacle, thereby leaving the inner portion of the chest tube clear of any obstructing material. : By maintaining chest tube patency, chest tube drainage can be performed more safely, and this apparatus may possibly lead to the use of smaller chest tubes and less invasive insertion techniques.

Propagating Fronts in Thin Tubes: Concentration, Electric, and pH Effects in a Two-Dimensional Precipitation Pulse System

In this paper, we studied the dynamics of a CaCO3 precipitate deposition pulse in a thin, long tube connecting two reservoir sinks of coprecipitates. The pulse profile, as well as the time t(c) and distance x(c) of the first appearance of precipitate, is studied as a function of the initial concentration of CO(3)(2-) in the right reservoir, [CO(3)(2-)](0), and later as a function of an applied external electric field at different voltages. The time variations of the pulse location and the pH at the center of the tube are determined. The distance from the calcium chloride sink (x) at any fixed time decreases as [CO(3)(2-)](0) increases. The time evolution of the front location exhibits a crossover between an early time regime and a late time regime. The pH-time curve shows a marked resemblance with a sigmoid shape. At any time, the pH consistently increases with [CO(3)(2-)](0). In the presence of a constant electric field applied across the tube (fixed voltage), t(c) decreased with the field strength, whereas x(c) exhibited a correlated increase. Irregularities in the variation of distance with the applied voltage (at a fixed time) were noted. The pH experiences a slight increase with the applied voltage. The pulse width exhibits a nonlinear time dependence, of the form w = a + bt(1/6). The shape of the deposition pulse deviates from a Gaussian distribution. This study is of special interest in the experimental simulation and modeling of precipitate deposition and potential clogging in microcapillary channels.

Numerical investigation of the clogging mechanism in labyrinth channel of the emitter

AbstractEmitter clogging is a main factor affecting the performance of drip irrigation products. Considering the small size and intricacy of emitters, numerical methods are introduced to study the clogging mechanism of labyrinth channel in the emitter. A three‐dimensional numerical model of clogging analysis is addressed, where Reynolds stress model with wall function is used to simulate the fluid flow in the Eulerian frame, and stochastic trajectory model is adopted to track the motion of the particles in a Lagrangian co‐ordinate system without taking into account the agglomerating behaviour of particles. The analytical results show that in the labyrinth channel, low‐velocity region is developed ahead of each sawtooth and large vortex is shaped just behind it. Small particles are apt to deposit in those regions due to their better following behaviours than those of large ones. The potential clogging regions predicted by simulation are reasonably consistent with the experimental results. Further, it is also found that the particles ranging from 30 to 50 µm behave best when passing through the labyrinth channel, and particle densities have a remarkable effect on the penetration only when their diameters are large than 50 µm. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Estimating the Hydraulic Conductivity of Landfilled Municipal Solid Waste Using the Borehole Permeameter Test

This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity (Ks) was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the Ks of unsaturated soil. The Ks of the landfilled waste was found to range from 5.4×10−6 to 6.1×10−5cm∕s. The Ks was found to be on the lower end of the range of Ks reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values (kw) of the landfilled waste calculated based on Ks were compared with permeability values estimated using air as the fluid (air permeability, ka). Values of ka were found to be approximately three orders of magnitude greater than those of kw. The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in ka and kw.

Particle deposition from aerosol flow inside a T-shaped micro-mixer

A T-shaped micro-reactor was used to mix a particle laden gas stream (an ‘aerosol’) and a clean gas stream, here with the objective of determining particle losses to the inside walls of the reactor (and hence the potential for clogging) as a function of operating conditions. Losses were determined with established on-line concentration measurement techniques, using monodisperse sodium chloride particles and vitamin-E-acetate droplets of variable size range between 10 and 700 nm. Measured losses range between 10 and 95%, depending on flow rate and particle size, and can be modeled with the particle Stokes number. CFD and particle trajectory modeling confirm that particle impact on the walls of the inlet and the mixing zones is the predominant particle deposition mechanism, induced by the local, sharp curvature of streamlines. The modeling points to ways of optimizing the inlet geometry of the mixer to reduce impaction losses significantly.

Printing of protein microarrays via a capillary-free fluid jetting mechanism

Current proteomics experiments rely upon printing techniques such as ink jet, pin, or quill arrayers that were developed for the creation of cDNA microarrays. These techniques often do not meet the requirements needed for successful spotting of proteins to perform high-throughput, array-based proteomic profiling. Biological laser printing (BioLP) is a spotting technology that does not rely on solid pins, quill pins, or capillary-based fluidics. The non-contact mechanism of BioLP utilizes a focused laser pulse to transfer protein solutions, thereby eliminating the potential for orifice clogging, air bubbles, and unnecessary volume loss potentially encountered in commercially available spotting technologies. The speed and spot-to-spot reproducibility of BioLP is comparable to other techniques, while the minimum spot diameter and volume per printed droplet is significantly less at 30 microm and approximately 500 fL, respectively. The transfer of fluid by BioLP occurs through a fluid jetting mechanism, as observed by high-speed images of the printing process. Arraying a solution of BSA with subsequent immunodetection demonstrates the reproducible spotting of protein in an array format with CVs of <3%. Printing of the enzyme alkaline phosphatase followed by a positive reaction with a colorimetric substrate demonstrates that functional protein can be spotted using this laser-based printer.

Biological laser printing of genetically modified Escherichia coli for biosensor applications

One of the primary requirements of cell- or tissue-based sensors is the placement of cells and cellular material at or near the sensing elements of the device. The ability to achieve precise, reproducible and rapid placement of cells is the focus of this study. We have developed a technique, biological laser printing or BioLP™, which satisfies these requirements and has advantages over current technologies. BioLP™ is capable of rapidly depositing patterns of active biomolecules and living cells onto a variety of material surfaces. Unlike ink jet or manual spotting techniques, this process delivers small volume (nl to fl) aliquots of biomaterials without the use of an orifice, thus eliminating potential clogging issues and enabling diverse classes of biomaterials to be deposited. This report describes the use of this laser-based printing method to transfer genetically-modified bacteria capable of responding to various chemical stressors onto agar-coated slides and into microtiter plates. The BioLP™ technology enables smaller spot sizes, increased resolution, and improved reproducibility compared to related technologies.

Minimisation of calcium additions to low carbon steel grades

This investigation aimed to determine the in plant feasibility of decreasing, to an amount close to the minimum literature value, the calcium addition to liquid steel for prevention of alumina buildup during continuous casting. Six plant trials were carried out at calcium additions of 0·14 kg/t of steel (reduced from the original 0·19 kg/t), added to the second ladle of a two or three ladle sequence. Total oxygen samples were taken at the ladle furnace and tundish to determine total oxygen and nitrogen contents of the steel. The total oxygen content at the ladle furnace varied between 19 and 26 ppm, with a slight degree of reoxidation between the ladle furnace and the caster. Alumina clogging was successfully prevented by the addition of 0·14 kg calcium/t of steel during the first five trials. During the sixth trial the submerged entry nozzle (SEN) failed and, although the stopper behaved as if clogging occurred, this behaviour was caused by the poor perfomance of the SEN rather than actual clogging. Microanalysis of inclusions in steel samples revealed a distribution in degrees of modification between different inclusions, and the formation of a substantial amount of CaS (which is taken to indicate overmodification, based on equilibrium calculations). However, the CaS is mostly associated with at least partly liquefied oxide inclusions, which is likely to reduce the potential clogging effect of solid CaS.

Structural settings of hydrothermal outflow: Fracture permeability maintained by fault propagation and interaction

Hydrothermal outflow occurs most commonly at the terminations of individual faults and where multiple faults interact. These areas of fault propagation and interaction are sites of elevated stress termed breakdown regions. Here, stress concentrations cause active fracturing and continual re-opening of fluid-flow conduits, permitting long-lived hydrothermal flow despite potential clogging of fractures due to mineral precipitation. As fault systems evolve, propagation, interaction, and linkage of fault segments result in the migration and eventual localization of breakdown regions in kinematically favorable sites such as fault bends or fault intersections. Concurrent migration of hydrothermal outflow sites along with these areas of elevated permeability leads to predictable patterns of hydrothermal deposition along fault zones. Thus, the distribution of active outflow sites and preserved deposits along fault zones can potentially provide a tool for studying fault-zone evolution.

Solubilities of solids in supercritical fluids—I. New quasistatic experimental method for polycyclic aromatic hydrocarbons (PAHs) + pure fluids

A new quasistatic technique is presented to measure the solubilities of polycyclic aromatic hydrocarbons (PAHs) and other solids in supercritical fluids (SCFs). This technique eliminates potential clogging during expansion of the SCF solutions, a problem inherent with most dynamic SFE units. The pressure inside the equilibrium cell is dropped very slowly in a quasistatic mode by sampling the saturated SCF solutions at low flow rates (1–5 standard ml min −1). The technique is shown to be accurate and extensive data can be obtained in a relatively quick manner. In addition, this technique may be readily used in conjunction with basically any analytical method. After proving the accuracy of the new method, solubility measurements of anthracene, phenanthrene, pyrene, and perylene in supercritical carbon dioxide and ethane have been made at 313, 323 and 333K and pressure range of 100–350 bar. The simulateneous solubilities of anthracene, phenanthrene and pyrene in mixtures were also measured at the above three temperatures and over the same pressure range.

Effect of Khirbet As-Samra treated effluent on the quality of irrigation water in the Central Jordan Valley

Khirbet As-Samra (KA) treated wastewater is being used in irrigation in the Central Jordan Valley. The treated water is collected in King Talal Dam (KTD) and then mixed with King Abdullah Canal (KAC) water, which is diverted from the Yarmouk River for further use in agriculture. The treated water has adversely affected the water quality of Yarmouk River. Comparison of the results of water quality tests with guidelines for water to be used for irrigation, salt tolerance of agricultural crops and the influence of water quality on the potential clogging of drip irrigation systems reveals that treated effluent from KA can be used for irrigation with restrictions. Moreover, concentrations of all trace elements were found to be low and within guidelines for irrigation water. Clogging of drip emitters is expected due to high calcium and magnesium contents, besides the high bacterial counts and nutrients that promote algal growth.

Determination of Metal-Chelate Complex Solubilities in Supercritical Carbon Dioxide

With new interest in the processing of heavy metals by chelation incorporated with supercritical fluid extraction, an accurate metal-chelate complex solubility database has become increasingly important. To measure these solubilities, a dynamic measurement technique was developed to determine organometallic complex solubility as well as chelate agent or ligand solubility in supercritical carbon dioxide. This technique utilizes a mixed-solvent stream to eliminate potential clogging and pressure increases during expansion, problems inherent with most dynamic techniques used to measure solubilities in supercritical fluids. In addition, the technique may be readily used in conjunction with basically any analytical chemical method. After proving the accuracy of the new method by measuring phenanthrene solubility in supercritical carbon dioxide, solubility measurements of two commercially available chelate complexes, cupric acetylacetonate and diethyldithiocarbomate copper salt, were made at near ambient temperatures. A thermodynamic model was then incorporated to predict solubility in supercritical carbon dioxide at varying operational conditions. The model uses Peng−Robinson equation of state and van der Waals-1 mixing rules.

PULSED TRICKLING EFFECTS ON SOIL MOISTURE DISTRIBUTION1

ABSTRACT Laboratory experiments were conducted to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty‐clay loam soil. Both pulsed and continuous irrigation treatments were studied. A simulation model was used to evaluate the results obtained in the laboratory. The agreement between the predicted and measured soil moisture distribution patterns was quite good. For both pulsed and continuous applications, increasing trickle discharge rate resulted in a decrease in the horizontal component and an increase in the vertical component of the wetted soil profile. Compared to the continuous treatments, pulsed applications resulted in significant reduction in water loss below the root zone. Pulsed applications rates can replace continuous small discharge rates to reduce irrigation water runoff problems on heavy soils and with restricted infiltration allow the use of larger emitter orifices to decrease potential clogging of the trickle system.