Partial Clogging Research Articles

Influence of Hydrogen Peroxide Catalyst Grain Size on Performance and Ageing

Two different diameters of Pt/Al2O3 spherical catalysts (1 mm and 2 mm) for HTP 98% decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.

Flood Disaster in Erbil City: Problems and Solutions

Several floods occurred in Erbil City in 2021 and 2022, which caused disaster in the city. 12 people died, thousands of houses and vehicles were destroyed, and numerous public projects such as electric stations and roads were damaged as well. Specifying reasons and providing suitable solutions are essential for minimizing damages. Thus, this research aimed to identify causes and offer scientific solutions for minimizing flood damage in the future. Several site visits for the locations of floods were carried out. Quantitative and qualitative data collection was conducted. Based on the catchment properties and maximum probable rainfall, the peak flood is 250, 200, 90, and 70 m3/s for Roshnbiri Bridge, Roshnbiri-Daratu Culvert, Korean Drainage Valley, and Daratu Natural Valley, respectively. Heavy rainfall, partial or full clogging of some inlets, sewers, and culverts, obstructions in watersheds, altering the direction of normal flow, technical and design problems, and disposal of waste in watersheds are the main factors contributing to the flood. Cleaning watersheds, maintaining storm sewers, providing new diversion channels, proper design of storm sewers, culverts, and bridges, eliminating barriers on the usual streams, and studying the master plans of the new projects and cities are the main solutions for minimizing flood disasters in Erbil City.

Black zeolite coatings for stray light reduction and in-orbit molecular decontamination

Black zeolite coatings were developed for two major contaminations encountered by actors of the space field: in-orbit molecular contamination and stray light contamination. They both affect the performance of on-board equipment of satellites and especially optical devices. A silicone binder and FAU-type zeolite were combined together with different amounts of black pigment (bone char or carbon black) in order to develop various coatings. Binder content was fixed at 20 wt % for all black zeolite coatings after the drying procedure whereas zeolite contents varied from 50 to 75 wt % and from 60 to 79 wt % for coatings developed with bone char and carbon black, respectively. Amounts involved of bone char and carbon black ranged from 5 to 30 wt % and from 1 to 20 wt %, respectively. The aim of increasing black pigment amount was to improve light absorption properties of the coatings. Despite the addition of black pigment, interesting adhesion and cohesion properties were obtained. Total reflection measurements showed a clear improvement of light absorption properties by black coatings. Small amounts of black pigment especially with carbon black (1–5 wt %) were sufficient to increase light absorption compared to white zeolite coating. Nitrogen adsorption-desorption experiments showed a partial clogging of black zeolite coatings porosity from 20 to 25 wt %. Nevertheless, interesting results regarding n-hexane adsorption capacities where values varying from 100 to 130 mg/ganhydrous zeolite were determined. Black zeolite coatings developed in this study show a way to deal with the above-mentioned issues.

Influence of coarse aggregate granulometry on clogging in pervious concrete

The phenomenon of clogging in pervious concrete (PC) has been one of the main causes of the hydraulic useful life reduction. This phenomenon begins with the partial or total clogging of the pore network and consequently the reduction of the permeability coefficient. Considering that the porous network of the PC is directly related to the aggregate used, the present work aims to evaluate the influence of granulometry on the clogging of the PC. The results showed that the largest aggregate size (D_max=19 mm) favors the hydraulic properties of the material. However, the variation of the granulometry grading distribution (poorly graded and single-sized) does not generate a significant difference in such results. In terms of clogging, there was a marked effect on the type of the granulometry grading distribution, the use of poorly graded aggregates led to a lower permeability reduction due to clogging when compared to PCs with single-sized aggregates.

Recent developments in design criteria for granular and geotextile filters

Granular and geotextile filters are commonly provided in several hydrological infrastructures to limit soil erosion and allow unimpeded water seepage. The success of a filter depends on forming a bridging structure, which is governed by the grain size distribution of soil and the constriction size distribution of filter. Currently, the retention requirement is satisfied considering representative grain and opening size, whereas the hydraulic conductivity requirement is satisfied considering empirical factors for avoiding excessive clogging. In this paper, the design criteria for granular and geotextile filters are reviewed, and improved design criteria are presented. A probabilistic retention criterion is developed, considering the grain size and constriction size as random variables. The influence of filter thickness is incorporated into the criterion by considering the number of constrictions in a filtration path. A hydraulic conductivity criterion is developed theoretically based on governing flow equations and the expected partial clogging of geotextiles. The limit states for the developed criteria are evaluated based on the wide range of experimental data. The developed design criteria are applicable to granular and nonwoven geotextiles, which offers an improvement in design compared to the existing criteria in practice.

Integration of laser structuring into the electrode manufacturing process chain for lithium-ion batteries

Despite the electrochemical benefits of laser electrode structuring, the process is not yet implemented in state-of-the-art industrial battery production due to a limited knowledge regarding its implementation into the manufacturing process chain. In this study, three process integration positions for laser structuring of graphite anodes, which are either after coating, after drying or after calendering, were experimentally evaluated. The obtained electrodes were analyzed regarding geometrical, mechanical and electrochemical characteristics. The results indicate that the material ablation process is governed by the evaporation of solvent and binder for wet and dry electrodes, respectively. As a consequence, electrodes structured in wet condition exhibited fewer particle residues on the electrode surfaces and a high coating adhesion strength. In contrast, laser structuring of dry electrodes significantly reduced the pull-off strengths of the electrode coatings. A tortuosity reduction and an increased discharge capacity at high C-rates by laser structuring were observed for all structured electrodes, but with higher performance improvements for electrodes structured in dry state. Although a partial clogging of the structures was observed in electrodes structured before calendering, laser structuring yielded a comparable electrochemical performance of electrodes which were structured in dry condition before and after calendering.

Biocementation of coral sand under seawater environment and an improved three-stage biogrouting approach

The Sporosarcina pasteurii (S. pasteurii)-DSM 33 was acclimated to grow and secrete urease under different salinity level conditions via direct evolution method, and ultimately the new acclimated species, S. pasteurii-DSM 33-ASW100, was of higher cell growth rate and ureolysis activity under seawater environment. Meanwhile, this study further revealed a fact that high concentration of calcium chloride (>0.25 mol/L) would inhibit the existing urease activity but hardly affect the urease secretion function of S. pasteurii-DSM 33-ASW100. The rising of urea concentration would not mitigate the inhibitory effect of calcium chloride on urease activity; by contrast, it could stimulate S. pasteurii-DSM 33-ASW100 to secrete more urease, ultimately conducting the microbially induced carbonate precipitation (MICP) reaction under a higher pH level (∼8.0). In the seawater environment, the optimal coral sand particle size for MICP reaction was about 0.5–1.0 mm. Moreover, the new designed three-stage biogrouting method significantly mitigate the issue of non-uniform distribution of cells and crystals in the column, thereby greatly increasing the unconfined compressive strength of MICP-treated coral sand column (>9.0 MPa) with a relatively high CaCO3 content (∼32 % by weight) as well as calcium ion utilization rate (∼85 %). Results also indicated that excessive input of CaCl2 (>0.5 mol/L) may result in less uniformity of crystallization and thus lead to a relative lower unconfined compressive strength (∼4.0 MPa). Excessive addition of urea (>1.0 mol/L) may lead to partial clogging issues due to too fast reaction of MICP, consequently column strength dropping down to around 2.0 MPa.

Assessment of emitter clogging with multiple fouling and root intrusion in sub-surface drip irrigation during 5-year sugarcane growth

Emitter clogging is a primary barrier constraining the widespread and efficient application of subsurface drip irrigation (SDI). The increasing risk of SDI buried emitter’s clogging due to physical, chemical, biological and root intrusion, possess considerable technical and economical challenges. Thus, a five-year sugarcane field experiment was conducted to experimentally examine the SDI emitter clogging. X-ray diffraction (XRD), high-throughput sequencing (16 S rRNA) and multi-level statistics were used to characterize the sugarcane SDI emitter multi-type clogging. Roots intrusion mainly found in severe and complete clogging accounted for less than 5.0% of total clogging. Conversely, the slight clogging (70.1%±8.41%) and partial clogging (20.0% ± 6.99%) caused by chemical, physical and biological fouling, showed positive linear correlations with SDI Dra and CU. The binary interactions of precipitates - particulates contributed 26.6%, and ternary interactions of precipitates - particulates - biofouling contributed 46.1% to sugarcane SDI emitter clogging. Sugarcane SDI could be successfully meet the irrigation and fertilizer demands for more than five years.

Improved design criteria for nonwoven geotextile filters with internally stable and unstable soils

In geotextile filtration, the soil fines are either accumulated near the interface, clogged, or washed out, which primarily depends on the grain size distribution (GSD) of soil and the constriction size distribution (CSD) of geotextile. Also, the movement of fines significantly affects the flow capacity of geotextile. Currently, the retention requirement is satisfied based on representative grain and opening sizes, whereas the hydraulic conductivity and clogging requirements are satisfied considering the properties of virgin geotextile. This paper presents a probabilistic retention criterion considering the grain and constriction sizes as random variables. The influence of geotextile thickness is incorporated into the criterion by considering the number of geotextile constrictions in a filtration path. A theoretical approach to predict CSD is presented if the measured data is unavailable. For hydraulic conductivity and clogging requirements, a criterion is presented considering the expected partial clogging of geotextile, which is predicted based on the semi-analytical approach. The limit states for the developed criteria are evaluated based on the wide range of experimental data from the current study and published literature. The developed design criteria are applicable to internally stable and unstable soils, which offers an improvement in design compared to the existing criteria in practice.

Determination of particle-bound nutrients and micropollutants concentrations and loads in small rivers – A novel sampling method

Pollutants and excessive nutrient inputs into rivers pose a problem for aquatic ecosystems. Humans are also at risk when these substances enter the food chain via drinking water supplies and food. Water quality monitoring and research on pollutant transport are important components for protecting humans and endangered species. Since there are few ready and easy-to-use suspended sediment samplers for small streams and usually low pollutant concentrations, there is little information on pollutant transport in such small streams. However, research is essential to protect highly endangered species such as the freshwater pearl mussel “Margaritifera margaritifera”. This publication, therefore, aims to present a new method for collecting suspended sediments even in small rivers. The sampler presented corresponds to an adapted bed load trap, with a considerably reduced mesh size of the sampler, so that sediments smaller than 2 mm can be collected. After hydraulic pre-tests, sediment samples were collected at six sampling points with the new sampler over a time period of two weeks. In addition, sediments were taken from the river bed for a comparison between mobile sediments and deposits. The sediments were analysed for selected chemical micropollutants and phosphorus availability was checked by phosphorus fractionation. The observed mechanical-biological clogging of the mesh occurs in the first 72 h, depending on the river stretch. This effect can also be observed at other samplers and usually prevents the collection of suspended sediment. However, with this new sampler concept, clogging is advantageous. Due to the partial clogging of the mesh, water can continue to flow through, but finer sediment particles are retained in the sampler. Results show that the sampler collects sufficient sample volumes even in small rivers with low bed gradients and low flow velocities. The samplers also ensure sediment sampling over a defined time period (2 weeks in this study). The presented suspended sediment sampler method can help to understand nutrient and pollutant transport better, even in small streams. These findings can improve the knowledge on underlying processes, which will help to protect endangered species such as the freshwater pearl mussel.

Modeling Asymmetric Flow in the Thin‐Slab Casting Mold Under Electromagnetic Brake

Continuous casting (CC) is nowadays the world‐leading technology for steel production. The thin slab casting (TSC) is featured by a slab shape close to the final products and a high casting speed. The quality of the thin slabs strongly depends on the uniformity of the turbulent flow and the superheat distribution, defining the solid shell growth against a funnel‐shaped mold. In most studies, it is commonly assumed that the submerged entry nozzle (SEN) is properly arranged, and the melt inflow is symmetric. However, the misalignment or clogging of the nozzle can lead to an asymmetric flow pattern. Herein, the asymmetry is imposed via a partial SEN clogging: a) a local porous zone inside the nozzle reflects the presence of the clog material; b) the resistance of the clog is varied from low to high values. The solidification during TSC is modeled, including the effects of the turbulent flow. The variation of the flow pattern and the solidified shell thickness are studied for different permeability values of the SEN clogging. These effects are considered with and without the applied electromagnetic brake (EMBr) using an in‐house magnetohydrodynamics (MHD) and solidification solver developed within the open‐source package OpenFOAM.

A zero-valent iron and zeolite filter for nitrate recycling from agricultural drainage water

Nitrate reduction to ammonium followed by ammonium capture and reuse, represent a new pathway to recycle nitrogen, prevent eutrophication, and to save energy used for industrial ammonium production. The present study investigates the principle of nitrogen recycling to agricultural drainage water using a coupled zero-valent iron (ZVI) and zeolite-based filter column system tested in laboratory and field continuous-flow experiments. A 40-day laboratory test showed 82% nitrate removal, of which 70% was converted to ammonium. In the following pilot scale field test, a total of 59.2 m3 (1700 pore volumes) drainage water with a nitrate concentration of 2–8 mg L−1 NO3−-N was filtrated. An oxidizing unit inserted after the ZVI unit removed iron(II) and optimized ammonium retention in the zeolite unit. Nitrate removal efficiency was 94% for the entire 56-day period with a slight pH increase (pH 8.9). All ammonium produced was retained by the zeolite unit. Formation of green rust carbonate (layered FeII–FeIII-hydroxide) was observed on ZVI particle surfaces, which may increase the redox capacity of the filter system by up to 50% and contribute to its cost-efficiency. Moreover, all phosphate in the influent waters with concentrations between 0.1 and 0.5 mg L−1 was retained due to sorption by iron oxides in the system. Corrosion products formed cause partial filter clogging and should be removed by regular cleaning and backflushing. In conclusion, the ZVI – zeolite coupled filter system serves as a promising and cost-effective technology for nutrient removal and ammonium retention from agricultural drainage water.

Factors affecting geotextile filter long-term behaviour and their relevance in design

Geotextile and granular filters are widely used in civil (e.g. earth dams, embankments, drainage trenches, etc.) and environmental (e.g. landfills, permeable reactive barriers, etc.) engineering works. Geotextile filters are considered to be an effective alternative to conventional granular filters whose function is to prevent the movement of fine particles from the base soil allowing the liquid to flow as freely as possible. The design of a geotextile filter requires the knowledge of the base soil–filter interaction that is a very complex process due to the large number of factors involved. In this paper, the complex cases of geotextile filter design in contact with internally unstable cohesionless soils and in critical/severe applications are analysed based on recent research also developed by the authors. Moreover, the influence of the main factors affecting geotextile/filter long-term behaviour which are generally neglected in current design criteria, such as vertical effective stress, partial clogging, flow conditions, type of contact at the interface and type of permeant, are examined. Furthermore, various performance tests to evaluate the long-term soil–geotextile filter behaviour and the reliability and limits of different design criteria for cohesionless soils are discussed.

Investigation of flux stability and fouling mechanism during simultaneous treatment of different produced water streams using forward osmosis and membrane distillation

Forward osmosis-membrane distillation (FO-MD) hybrids were recently found suitable for produced water treatment. Exclusion of synthetic chemical draw solutions, typically used for FO, can reduce FO-MD operational costs and ease its onsite application. This study experimentally validates a novel concept for the simultaneous treatment of different produced water streams available at the same industrial site using an FO-MD hybrid system. The water oil separator outlet (WO) stream was selected as FO draw solution and it generated average fluxes ranging between 8.30 LMH and 26.78 LMH with four different feed streams. FO fluxes were found to be governed by the complex composition of the feed streams. On the other hand, with WO stream as MD feed, an average flux of 14.41 LMH was achieved. Calcium ions were found as a main reason for MD flux decline in the form of CaSO4 scaling and stimulating the interaction between the membrane and humic acid molecules to form scale layer causing reduction in heat transfer and decline in MD flux (6%). Emulsified oil solution was responsible for partial pore clogging resulting in further 2% flux decline. Ethylenediaminetetraaceticacid (EDTA) was able to mask a portion of calcium ions and resulted in a complete recovery of the original MD flux. Under hybrid FO-MD experiments MD fluxes between 5.62 LMH and 11.12 LMH were achieved. Therefore, the novel concept is validated to produce fairly stable FO and MD fluxes, with few streams, without severe fouling and producing excellent product water quality.

DEM-CFD Simulation and Experiments on the Flow Characteristics of Particles in Vortex Pumps

Due to their outstanding anti-clogging ability, vortex pumps have been gradually promoted and applied in recent years. However, when transporting sewage containing solids, they will still encounter problems such as partial clogging, overwork wear, etc., therefore, it is particularly important to master the flow characteristics of solid particles in the vortex pump. In this paper, the Discrete Element Model-Computational Fluid Dynamics (DEM-CFD) coupled calculation method is introduced into the numerical simulation of vortex pumps and particles with diameters of 1, 2 and 3 mm and concentrations of 1% and 5%, were subjected to numerical simulation and study of the flow characteristics of the particles, then rapeseed was used to represent solid particles in tests. It was obvious that the CFD results were in good agreement with the experimental results, whereby the high speed photography experimental results of the pump inlet section show that the experimental results are consistent with the numerical simulation results. The results show that there are three typical movement tracks of solid particles in the vortex pump: in Track A particles flow through the impeller and enter the volute by the through flow, in Track B particles go directly into the volute through the lateral cavity under the influence of circulation flow and in Track C the particles enter the impeller from the front cover end area of the impeller blade inlet and then into the volute through the back half area of blade. It can be found that the particles are mainly distributed at the back of the volute.

Evaluation of Different Methods to Assess the Hydraulic Behavior in Horizontal Treatment Wetlands

While there have been numerous studies on the rate and development of clogging in horizontal subsurface treatment wetlands (HSTWs) and, consequently, the effects on its hydraulic characteristics, research has not shown a clear understanding of the processes. The existing methods for measuring the impact of clogging provide limited information on the extension and degree of the phenomenon. This study aimed to evaluate the capacity of various measurement techniques to assess the degree and variation in space and time of clogging in HSTWs. Hydraulic conductivity at saturation (Ks) measurements were conducted using a newly implemented scheme, the drainage equation method, and traditional tracer tests, which were carried out in a full-scale HSTW system, located in Sicily, Italy, during 2019. After five years of operation, the results highlighted a severe decrease in Ks (<1000 m day−1) in the inlet zone (despite the fact that the filter gravel was replaced in 2017), a very high reduction of Ks along the central path inside the bed, a nonuniform flow through the HSTW, the presence of stagnant zones, and a reduction of the porosity of the bed gravel. Nonetheless, the mean values of the physical–chemical and bacteriological parameters at the hybrid treatment wetland (hybrid TW) outlet indicated that the partial clogging had no significant effect on the quality of the discharged water. Moreover, the results obtained using the different measurement techniques (in terms of both the Ks values and the flow distribution inside the bed) were consistent with each other and with results obtained previously for the same system. Finally, the most efficient combination of methods to assess clogging in HSTWs was identified.

Study some optical properties of different total suspended solids in media filters by using He–Ne laser

The drip irrigation emitter is a small mechanical device which is designed to dissipate pressure and constantly discharge a small, uniform flow of water. Partial and total clogging of emitters is closely related to the quality of the irrigation water. Physical factors for water quality include all inorganic materials such as sand, silt and clay; the filtration of the irrigation water is essential in order to avoid blockages damage of the small passage emitters, drippers, sprayers and sprinklers. This is a mechanical water treatment and it is achieved by the installation of main filtering devices (filters) at the control head of the irrigation systems. Sand–gravel media filters are particularly suitable for water with high suspended solid content. The precision agriculture database generally includes irrigation facilities, water availability and planning of other inputs. The science of remote sensing RS is usually restricted to methods that detect and measure electromagnetic energy including visible and non-visible radiations that interact with surface materials and the atmosphere. A new multispectral optical sensor system has been designed and developed for measuring total suspended solid (TSS) concentration in polluted water. In this study, the optical sensing system has been designed for measuring scattered radiation from water samples from media filters at the irrigation systems. This study aims to measure the peak of optical properties at transmission and absorption intensities of irrigation water samples. Three different concentration levels of TSS are 286.8, 270 and 290 mg/l. It was noticed that high values were 4240 and 3880 for absorption intensities to Zaffaran media and Misr bank media at wavelength 632.8 nm.

Exopolysaccharides may increase biocrust rigidity and induce runoff generation

The potential of biocrusts (biological soil crusts) to generate runoff is a matter of great controversy, especially in arid and semiarid regions. Most authors maintain that runoff in the presence of biocrusts is generated as a result of hydrophobicity, crust structure, texture or surface roughness. Hypothesizing that runoff over biocrusts may result from partial pore clogging, brought on by extracellular polymeric substances (EPS), we compare two crust types from Nizzana in the northwestern Negev, Israel (NIZID, NIZPON) that readily generate runoff under natural field conditions to a crust type from Nizzanim in the southern coast of Israel (NIMID) that fails to generate runoff. We hypothesize that biocrust-induced EPS of the NIZ crusts will have different biochemical and viscoelastic properties than that of NIM. We conducted sprinkling experiments on the crusts, measured the biochemical properties (thickness, water repellency, compressive strength, water-holding capacity, silt and clay content, roughness) and the adhesion and viscoelastic properties of the crust EPS using quartz crystal microbalance with dissipation monitoring (QCM-D). Both crusts were not water repellent and were characterized by a relatively smooth surface. The NIZ crusts were however characterized by higher water-holding capacity and compressive strength. As far as the EPS is concerned, higher shear viscosity and shear modulus characterized the NIZ crusts, indicating higher crust integrity and rigidity and the formation of durable mineral grain-EPS matrix of the NIZ crusts. The findings point to a possible link between crust rigidity and runoff coefficients providing supporting evident for the role played by EPS in crust formation and runoff generation. Knowledge regarding the potentiality of runoff and hence water redistribution may assist in ecosystem management and agroforestry practices.

High-rate carboxylate production in dry fermentation of food waste at room temperature

Dry fermentation of food waste was optimized to achieve the maximum solid loading rate for carboxylate production without clogging events in a dry fermenter run at neutral pH. High inoculum-to-substrate ratio improved food waste solubilization and carboxylate yield, but the ratio 15% completely clogged the dry fermenter. Higher leachate circulate rate tended to enhance food waste fermentation, but partial clogging was observed at 13.2 L/h of leachate circulation rate. The dry fermenter achieved carboxylate yield of 428.5 g/kg food waste and volatile solid reduction of 79% at the solid loading rate 4.82 kg volatile solids/m3-d. This study first tracks chemical oxygen demand (COD) in food waste dry fermentation, showing maximum soluble COD <60% of food waste COD with residual food waste 13.6–16.3%. The operating cost was as low as $1.7/ton FW, implying that food waste treatment will be cost-neutral if recovered carboxylate can create economic benefit over the operating cost.

Emitters and Filters Performance under Treated Sewage Water Reuse with Drip Irrigation

An experiment was carried out under open field conditions on black cotton soil at Agriculture College, Nagpur to study the performance of different types of emitters and filters while using irrigation water of different qualities for different periods of operation. Eight treatments comprising of irrigation water quality as main treatment [domestic treated sewage water (DTSW) from a phytorid sewage treatment plant and deep open well water (WW)], sub-treatments comprising of emitter type (inline and online) and time of operation (60 h and 120 h) of drip system were planned. Gravel filter, followed by disk filter, was used to filter water of different quality. Partial clogging percentage of gravel filter was higher in case of DTSW. Emission uniformity coefficient decreased rapidly in DTSW compared to WW. Mean discharge reduction percentage was 13.23 % in gravel filter, and 18.72 % in disk filter. Emitter’s emission uniformity percentage in WW was better than in DTSW. The manual operation time (i.e. time interval between two consecutive maintenance events) for disk filter was shorter than gravel filter in both treatments. Domestic treated sewage water could be used for crop production with proper maintenance of filter, lateral and emitters.