Influence Of Coagulation Research Articles

Influence of coagulants and flocculants dosing sequence on the dewaterability of oil sands mature fine tailings by pressure filtration

Rapid and cost-effective dewatering of wet tailings is crucial for clean and sustainable production in mineral processing. In the process of dewatering oil sands mature fine tailings (MFT) through coagulation-flocculation followed by pressure filtration, we observed that the dosing sequence of coagulants and flocculants had a significant influence on dewatering efficiency. Employing two anionic commercial flocculants (SNF3338 or Kemira PAM) together with an inorganic or a natural coagulant (aluminum sulfate, or chitosan), it was found that the sequence of flocculants followed by coagulants (F-C) gave higher net water release during filtration and lower moisture content in filter cakes than those in reverse sequence (C-F). The capillary suction time measurement showed a faster water release rate from the MFT treated with the F-C sequence. Zeta potential measurements indicated that flocs formed by treatment with the F-C sequence had lower negative potential or more positive potentials, likely contributing to the stronger floc strength and improved inter-floc porosity that favored pressure filtration. The findings in this Technical Note could help optimize the chemical treatment regime and reduce chemical consumption in the filtration of fine wet tailings.

Removal of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by coagulation: Influence of coagulant and dosing conditions

Per- and polyfluoroalkyl substances (PFAS) pose significant risks to the environment and human health. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are two of the most frequently detected PFAS in the environment. In most surface water drinking water treatment works (WTW), coagulation is the first processes exposed to a range of contaminants, including PFAS. While not designed to be a process for removal of micropollutants, it is important to understand the fate of PFAS in coagulation processes, intended or otherwise, to determine whether water treatment sludge can be a significant sink for this group of micropollutants. This work advances understanding of PFAS removal in coagulation processes by comparing the removal of PFOA and PFOS by four metal coagulants (Zr, Zn, Fe, and Al) from real water matrices. The coagulant performance followed the order Al > Fe > Zr > Zn. Al was taken forward for further evaluation, with significant removal of PFAS (>15 % for PFOA and > 30 % for PFOS) being observed when the pH<5.5 and the dose was > 5 mg Al·L-1. The adsorption of PFOA and PFOS onto flocs through hydrophobic interaction was the primary removal route. The impacts of background matrix on the mechanisms of coagulation for PFAS were explored using five organic compounds. Macromolecular organic compounds contributed to an increase in removal due to the sorption of PFAS and subsequent removal of the organic-PFAS aggregate during coagulation. Low molecular weight organic matter inhibited the removal of PFAS due to the ineffective removal of these compounds during coagulation.

A new water treatment technology—Hybrid ozonation-coagulation process: A review

Hybrid ozonation-coagulation (HOC) process is an integrated water treatment process of simultaneous ozone and coagulation processes. This paper introduces the origin, performance, reaction mechanism and influence of coagulant in HOC system. Compared with traditional air flotation and pre-ozone-coagulation, HOC system shows more advantages in removal of organic pollutants. It is attributed to abundant pathways for reactive oxygen species (ROS) generation in HOC process, which not only transfers pollutants to flocs but also synchronously degrades some organic pollutants.

The influence of coagulation on the drying dynamics of blood pools

Little is currently known about the importance of clotting during the drying of blood pools. While this is of little moment for droplets where drying occurs faster than contact-phase-induced clotting, clotting may significantly influence blood pools drying as it transform a liquid into a gel. To investigate this influence, we compare the drying of citrated and unmodified blood pools at constant haematocrit, showing large morphological differences during drying, both in the surface appearance, in the colour lightness, as well as in the generation and location of cracks. Further, we designed a clotting-reactivation protocol which allowed recovering the morphological evolution of pure blood drying while using citrate-sampled blood. This result opens the way to the use of citrated blood in blood pools investigations.

Direct coagulation casting of silicon carbide suspension via polyelectrolyte dispersant crosslink reaction

AbstractA direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5‐6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively.

The influence of coagulants and cooking period on the quality of dali ni horbo

The purpose of this research was to determine the effect of coagulants and cooking period on the quality of dali ni horbo. This research was using group randomized design with two factors, such as: coagulants (G): (pineapple juice, lime juice, lemon juice, belimbing wuluh fruit) and cooking period (M): (40, 50 and 60 minutes). The results showed that the coagulants and cooking period gave a very significantly different effect (P<0.01) on pH, moisture and protein contents of the dali ni horbo, but had no significant different effect (P>0.05) on the ash content. Furthermore, the interaction of factors resulted in a significant different effect (P<0.05) on the ash and protein contents. The coagulants decreased the moisture and protein contents of dali ni horbo and increased the pH and ash contents of the products. Based on parameters protein, moisture, ash contents and pH, it was found that the best treatment was dali ni horbo coagulated with lime juice for 40 min.

Changes in Chara hispida L. morphology in response to phosphate aluminium coagulant application

Abstract Progressing eutrophication of waterbodies requires measures to be undertaken that aim at halting or reversing negative changes in the environment. Chemical restoration is one of the most common methods used for lake treatment, where iron or aluminium phosphate coagulants are applied. However, their chemical qualities pose the risk of acidification and aluminium ion release, which become toxic in acidic conditions. The influence of coagulants on aquatic plants, including charophytes that are very valuable from the ecological perspective, is little recognised. For this reason, the aim of the research was to define changes in the growth pattern of the charophyte Chara hispida under the influence of an aluminium coagulant. The research was carried out in mesocosms (0.8 m3) located in situ in a lake. Polyaluminium chloride was applied once to each chamber in doses of 50.0, 100.0 and 200.0 ml m−3. Coagulant concentrations reflected aggressive restoration aimed at precipitation of phosphates, suspension and water colour at the same time. It was proved that the coagulant had inhibited the growth and slightly reduced the length of branchlets, and simultaneously elongated internode cells. Changes in the total length as well as the length of branchlets were caused by a strong pH decrease of the environment which simultaneously induced higher aluminium solubility and toxicity. Elongation of internode cells was caused by reduced light availability, resulting from high water turbidity in the first stage of coagulant’s application, and then from the charophytes’ thallus being covered by a coagulated suspension precipitated from water.

A Novel Plasma-Based Fluid for Particle Image Velocimetry (PIV): In-Vitro Feasibility Study of Flow Diverter Effects in Aneurysm Model.

Particle image velocimetry (PIV) is a commonly used method for in vitro investigation of fluid dynamics in biomedical devices, such as flow diverters for intracranial aneurysm treatment. Since it is limited to transparent blood substituting fluids like water-glycerol mixture, the influence of coagulation and platelet aggregation is neglected. We aimed at the development and the application of a modified platelet rich plasma as a new PIV fluid with blood-like rheological and coagulation properties. In standardized intracranial aneurysm silicone models, the effect of this new PIV plasma on the fluid dynamics before and after flow diverter implantation was evaluated and compared with water-glycerol measurements. The flow diverting effect was strongly dependent on the used fluid, with considerably lower velocities achieved using PIV plasma, despite the same starting viscosity of both fluids. Moreover, triggering coagulation of PIV plasma allowed for intra-aneurysmal clot formation. We presented the first in vitro PIV investigation using a non-Newtonian, clottable PIV plasma, demonstrating a mismatch to a standard PIV fluid and allowing for thrombus formation.

Influence of coagulation on UF performance in a pilot-scale seawater desalination plant

Influence of coagulation on UF performance in a pilot-scale seawater desalination plant

Modelling the dispersion of particle numbers in five European cities

Abstract. We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam, and Athens, in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We used atmospheric dispersion modelling for PNCs in the five target cities and on a European scale, and evaluated the predicted results against available measured concentrations. In all the target cities, the concentrations of particle numbers (PNs) were mostly influenced by the emissions originating from local vehicular traffic. The influence of shipping and harbours was also significant for Helsinki, Oslo, Rotterdam, and Athens, but not for London. The influence of the aviation emissions in Athens was also notable. The regional background concentrations were clearly lower than the contributions originating from urban sources in Helsinki, Oslo, and Athens. The regional background was also lower than urban contributions in traffic environments in London, but higher or approximately equal to urban contributions in Rotterdam. It was numerically evaluated that the influence of coagulation and dry deposition on the predicted PNCs was substantial for the urban background in Oslo. The predicted and measured annual average PNCs in four cities agreed within approximately ≤ 26 % (measured as fractional biases), except for one traffic station in London. This study indicates that it is feasible to model PNCs in major cities within a reasonable accuracy, although major challenges remain in the evaluation of both the emissions and atmospheric transformation of PNCs.

Influence of Coagulation and Anticoagulant Factors on Global Coagulation Assays in Healthy Adults

It remains unclear how coagulation and anticoagulant factors influence global coagulation assays such as prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation assay (TGA). We measured PT, aPTT, coagulation factor and protein levels, and TGA parameters (lag time, endogenous thrombin potential [ETP], and peak thrombin) in 252 apparently healthy adults. Vitamin K-dependent coagulation and anticoagulant factors were significantly correlated with blood lipids. PT was determined by factor (F) V and FVII; aPTT was dependent on antithrombin, protein C, FVIII, and FXII. Lag time was mainly determined by FVII, FXII, and protein S and peak thrombin by FVIII and FIX. Antithrombin (for ETP and lag time) and protein S (for lag time) contributed significantly to TGA inhibition. This knowledge about determinants of global coagulation assays may help interpret the results of coagulation assays and contribute to the future development of diagnostic tools. The synchronized plasma levels of vitamin K-dependent proteins with opposite functionalities may compensate a propensity to hyper- or hypocoagulability in a normal population.

The Influence of Coagulant on the Membrane System

On the beaker test of Laboratory coagulation sedimentation for low turbidity water, through the relationship of water turbidity, residual metal ion content and type of coagulant dosage, and membrane fouling material component within the system, the cause of coagulant fouling membrane system is coagulant sedimentation occurs once again, and put forward to measures of reduce membrane fouling because of coagulant, these will be benefit for adjustment of coagulation sedimentation treatment.

The influence of coagulation and inflammation research on the improvement of polytrauma care.

Treatment guidelines and management principles of polytrauma patients are largely derived from experience, supplemented by the results of few clinical studies. Their clinical impact on survival outcome is rarely scientifically evaluated. Hence, research algorithms need to be developed which enable a rapid and profound reevaluation of the current treatment strategies in polytrauma care and which provide a solid basis for the assessment of future treatment options. Such new concepts might include a more individualized approach and a better identification of operative windows for early definitive care. Since polytrauma results in a complex physiological and immunological disorder, which is additionally influenced by multiple confounding variables, it is challenging to establish such novel algorithms by clinical research only. In this regard, the well defined parameters in valid basic science models can provide a solid base for evaluating current concepts and investigating future treatment options. Here we have analyzed the contribution of basic science to well-established concepts in polytrauma care, such as the management of trauma induced coagulopathy or the damage control orthopedics concept. Many of these ideas moved from previous basic science activities to clinical studies but in many cases the direct effects of basic science on clinical trials or even clinical management strategies often remain elusive. Nevertheless, the knowledge which is created on a daily basis by basic science studies acts as an invaluable data pool, which can be accessed and combined for the clinical researcher to develop and address clinically relevant questions, providing them with a comprehensive pool of information to carefully plan and conduct their clinical trials. This may then subsequently lead to the development of new management principles for polytrauma patients.

Influence of coagulant and free stabilizer on formation of aggregates in magnetic fluids

The influence of coagulant (isopropanol) and free oleic acid on the formation of quasi-spherical aggregates in a colloidal magnetite solution in kerosene is studied experimentally. It is revealed that the mean sizes of these aggregates fit the 60–90-nm range and are independent of the concentrations of coagulant and free oleic acid provided that these concentrations do not exceed 10–12 vol %. The independence of the mean sizes of aggregates on temperature and disperse composition of particles is considered as a supplementary argument in favor of hypothesis that the main reason for their formation are the defects of protective layers, whereas magnetodipole interactions play a secondary role. It is shown that an excess of oleic acid causes a disproportional decrease in the initial susceptibility of magnetic fluid that is interpreted as a result of the formation of droplet aggregates with characteristic sizes of a few micrometers or more. Apparently, isopropanol leads to an analogous effect, but only at low temperatures.

A new event-driven constant-volume method for solution of the time evolution of particle size distribution

Direct simulation Monte Carlo (DSMC) method is an important approach for numerical solution of the population balance equation, which characterizes the dynamic evolution of particle size distribution in dispersed systems. One sample of the whole system (i.e., subsystem) is taken into account in most DSMC methods. It means that a spatially-isotropic whole system is considered, and simulation particles having same number weight are tracked. A new event-driven constant-volume (EDCV) method for population balance modeling is proposed to describe the dynamic evolution in dispersed systems under influence of coagulation, breakage, nucleation, surface growth/dissolution (condensation/evaporation) and deposition (settling). The method adopts the concept of differentially weighting simulation particles, and several schemes of sample restoration are developed to maintain simulation particle number within prescribed bounds, at the same time the constant-volume computational domain is tracked. By comparing of several popular Monte Carlo methods, it is concluded that the proposed EDCV method exhibits comparatively high precision and efficiency.

Inflammation, endothelium, and coagulation in sepsis

Sepsis is a systemic response to infection, and symptoms are produced by host defense systems rather than by the invading pathogens. Amongst the most prominent features of sepsis, contributing significantly to its outcome, is activation of coagulation with concurrent down-regulation of anticoagulant systems and fibrinolysis. Inflammation-induced coagulation on its turn contributes to inflammation. Another important feature of sepsis, associated with key symptoms such as hypovolemia and hypotension, is endothelial dysfunction. Under normal conditions, the endothelium provides for an anticoagulant surface, a property that is lost in sepsis. In this review, data about the interplay between inflammation and coagulation in sepsis are summarized with a special focus on the influence of the endothelium on inflammation-induced coagulation and vice versa. Possible procoagulant properties of the endothelium are described, such as expression of tissue factor (TF) and von Willebrand factor and interaction with platelets. Possible procoagulant roles of microparticles, circulating endothelial cells and endothelial apoptosis, are also discussed. Moreover, the important roles of the endothelium in down-regulating the anticoagulants TF pathway inhibitor, antithrombin, and the protein C (PC) system and inhibition of fibrinolysis are discussed. The influence of coagulation on its turn on inflammation and the endothelium is described with a special focus on protease-activated receptors (PARs). We conclude that the relationship between endothelium and coagulation in sepsis is tight and that further research is needed, for example, to better understand the role of activated PC signaling via PAR-1, the role of the endothelial PC receptor herein, and the role of the glycocalyx.

Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki – Part I: Modelling results within the LIPIKA project

Abstract. A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17–20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm–10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3–50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm−3 was shown to be in a disagreement with the measured particle size evolution, while the modelling runs with the concentration of condensable organic vapour of 109–1010 molecules cm−3 resulted in particle sizes that were closest to the measured values.

Studies on the interfacial characterization of O/W emulsion for the optimization of its treatment.

Wastewater produced in the form of an o/w emulsion is difficult to treat properly because of its complex behavior. To acquire information for the optimization of emulsion controlling processes, the interfacial features of emulsion systems have been investigated in this work. The surface tension is found to decrease as the oil content is increased, and contact angle is influenced by the hydrophobicity of the substrate. The work of adhesion for substrates with different degrees of hydrophobicity has been estimated from the contact angle and surface tension. Temperature and pH have a significant influence on the turbidity and surface tension, and it is observed that electrophoretic characteristics of oil droplets are closely related with turbidity. Also, effects of inorganic salts and surfactants on the electrokinetic properties of emulsions have been considered, and the influence of coagulant on the stability is discussed through the calculation of potential energy of interaction between oil droplets. Adsorption and electrocoagulation processes have been attempted under various conditions in order to examine the practical treatment efficiencies of emulsion in relation to its interfacial characteristics.

KINETICS OF AEROSOL FORMATION DURING TUNGSTEN HEXACARBONYL PHOTOLYSIS

The kinetics of formation and growth of the nanometer-sized aerosol particles during tungsten hexacarbonyl (W(CO) 6) vapour photolysis in air have been investigated. Special attention has been given to the research on the influence of coagulation during the time interval ( t 1) between the moment the vapours leave the irradiation zone (i.e. generation of condensing products stops) and the moment particle concentration and size distribution are measured. Aerosol formation kinetics within the Smoluchowski coagulation model in the clusters free-molecular collision regime was modelled numerically. The rate of monomer formation F( t) was calculated for different rates of W(CO) 6 photolysis at various t 1 values. Calculated values of F( t) were in good agreement with measured W(CO) 6 photolysis rates W phot. Particles concentration and size were shown to be determined by irradiation dose D= I/ I 0× t 0 ( I/ I 0 is relative irradiation intensity, t 0 is irradiation time), when t 1⪢ t 0.

Influence of coagulation, sedimentation, and grazing by zooplankton on phytoplankton aggregate distributions in aquatic systems

Phytoplankton growing at the surface of lakes and oceans are removed from the water column by gravitational sedimentation and/or zooplankton grazing. Both of these processes are influenced by the aggregation state of the phytoplankton, which, in turn, may be altered through particle‐particle coagulation. In this study, we present a mathematical analysis of these phenomena in an attempt to better understand the physical and biological factors that control phytoplankton concentrations in aquatic systems. During phytoplankton blooms, grazer concentrations are relatively low, the concentration of phytoplankton in the mixed layer is high, and phytoplankton production at the surface is countered by coagulation and sedimentation. In this case, dynamic scaling theory indicates that the concentration of total phytoplankton aggregates N0 and the volume fraction of phytoplankton N1 should decay as power laws of depth z: N0 ≈ z−γ and N1 ≈ z−ε. The values of the power law exponents γ and ε are determined by the physical and chemical processes responsible for coagulation and sedimentation in a given system. Under nonbloom conditions, the concentration of grazers is relatively high, the phytoplankton concentrations are relatively low, and phytoplankton generated at the surface are quickly transferred to higher‐trophic levels by grazing. In this case, N0 and N1 decay with depth in an approximately exponential fashion. These results suggest that the principle mechanism by which phytoplankton are removed from the water column in natural aquatic systems may be differentiated by the depth evolution of N0 and N1.