A new method for the analysis of combined operation of electro-osmotic dewatering and mechanical expression

Electro-osmosis is especially effective in removing liquid from sludge of colloidal particles for which conventional mechanical dewatering is not very successful. This work presents results of experimental work carried out to study and analyze the combined operation of electro-osmotic dewatering (EOD) and mechanical expression (ME) by use of the Terzaghi-Voigt combined model for considering creep deformation of the material. The EOD-ME process combines the advantage of electro-osmosis and mechanical dewatering and consequently results in reduced void ratio compared to individual operation

constant pressure expression of power law non-newtonian fluid/solid mixture

Expression is the separation of liquid from a two-phase solid/liquid system by compression due to movement of the retaining wall. Expression of non-Newtonian fluid/solid mixture is often encountered in the fields of polymer and food industries. However, a reliable method for the design of the expression process has not been established. In this study, we conducted expression experiments of non-Newtonian fluid/solid mixture under a constant pressure condition. As a model suspended particle, cellulose or kieselguhr powder was used. The powder was mixed with an aqueous solution of sodium carboxymethyl cellulose or sodium polyacrylate. The mixture was first preconsolidated in the compression-permeability cell that consisted of a cell cylinder and a piston of 6 cm diameter and then expressed under constant pressure. As the expression advanced, the time course of the thickness of the sample was measured by a dial gauge fitted on the cylinder. The basic consolidation equation was derived by combining the fundamental equation for power law non-Newtonian flow in the cake with the equation of continuity, and was solved numerically using the Runge-Kutta method. The progress of the expression is represented by an average consolidation ratio Uc. The agreement between calculated and experimental Uc was satisfactory when the creep deformation of the material was taken into consideration. It was elucidated that the consolidation time required for attaining a certain degree of primary consolidation depends on the (N+1)/N-th power of the total volume of the solid material , where N is the flow behavior index of the squeezed liquid. On the other hand, the creep constants B, the ratio of creep deformation to the total deformation, and , a measure of the rate of creep deformation, both were found to be -independent parameters, supporting the validity of the assumption made in the theoretical derivation

Constant pressure expression of power law non-Newtonian fluid/solid mixture

Expression of non-Newtonian fluid/solid mixture is often encountered in the fields of polymer and food industries. However, a reliable method for the design of the expression process has not been established. In this study, we conducted expression experiments of power law non-Newtonian fluid/solid mixture under constant pressure condition. The basic consolidation equation was derived by combining the fundamental equation for power law non-Newtonian flow through the cake with the equation of continuity and solved numerically using the Runge-Kutta method. The progress of the expression is represented by an average consolidation ratio Uc. The agreement between calculated and experimental Uc was satisfactory when the creep deformation of the material was taken into consideration. It was also elucidated that the consolidation time required for attaining a certain degree of primary consolidation depends on the (N+1)/N-th power of the total volume of the solid material omega_0, where N is the flow behavior index of the squeezed liquid. On the other hand, the creep constants B, the ratio of creep deformation to the total deformation, and eta, a measure of the rate of creep deformation, both were found to be omega_0-independent parameters, supporting the validity of the assumption made in the theoretical derivation

Dewatering of slurry with poor filterability in basket centrifuge: discharge of supernatant using bypass filter medium

When centrifugal dewatering in basket centrifuge involves the sedimentation of particles in feed slurry, the slurry separates into two phases: supernatant and cake. The dewatering proceeds as the supernatant permeates through the cake. However, if the cake formed has poor permeability, it takes longer time to reach the desired moisture content. In this study , a new method is proposed to dewater slurry which forms cake with poor permeability and a comparison was made with the conventional design. In the proposed design, the filter media is placed not only on the circuit, but also at the bottom of the filter chamber. Thus, even though the cake formed has a high hydrodynamic resistance, the supernatant could be discharged because the filter medium at the bottom has less hydrodynamic resistance than the cake and therefore works as a bypass. It is known from the previous study that when the supernatant is totally discharged, the cake will undergo a consolidation process, which will make the cake more compact. Therefore, it is postulated that the bypass filter medium would improve the dewatering efficiency drastically. The results obtained is that the supernatant still remained in the filter chamber even after 300 s of dewatering when the conventional design was used, while the supernatant was completely discharged within 150 s when the new design was used. Thus, it can be concluded that the filter medium at the bottom of the filter chamber worked as a bypass and improved the dewatering performance

Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions

Analysis of stepwise expression of sake fermentation broth

In the sake brewing, expression is used for the separation of liquid from the fermentation broth. Although the period of expression has to be as short as possible in order to prevent the sake from losing flavour, practically it takes much time to complete expression because of the highly compressible materials (e.g. proteins and starch) in the broth. For the expression of highly compressible materials, it is known empirically that the applied pressure should be low at the beginning of the expression and increased stepwise as the expression proceeds. In this study, we propose a method for the analysis of stepwise expression of highly compressible materials. The fermentation broth of sake was used as the experimental material. The experimental apparatus of constant pressure expression utilised in this study essentially consists of a vertical cylinder with a movable piston. The change in thickness of the material in the cylinder with the time was measured by a dial gauge. The mechanism of liquid removal is filtration at the beginning of expression, followed by consolidation. The filtration rate can be obtained by applying Ruth’s constant pressure filtration theory. In the consolidation period (i.e. after the end of the filtration), the deliquoring rate is calculated by the numerical analysis of the basic consolidation equation. However, because the formula expressing the distribution of solid compressive pressure pS of a filter cake with highly compressible materials has not been established well, the consolidation equation cannot be solved analytically. We therefore propose a new empirical equation representing the pS-distribution of a filter cake with highly compressible materials. The equation proposed in this study makes it possible to analyse the stepwise expression of highly compressible materials

Simplified flocculation model for inorganic and polymer flocculants

Simulation of the flocculation process using both inorganic and polymer flocculants is very difficult because there are many factors that influence the process. In this study, a model that enables the visual understanding of the qualitative trends of the flocculation system using both inorganic and polymer flocculants is proposed. It is a simplified one-dimensional model that expresses flocculation under various additive manners of the flocculant. Various kinds of thought experiments as well as experimental runs with model flocculants were carried out based on the model; the results demonstrate that the model can express many empirical qualitative trends of flocculation

Effect of intermittent addition on turbidity removal by polymer flocculant: computer simulation of simplified flocculation model

Since there are many factors which influence the process of flocculation by polymer flocculant, the scientific understanding of the flocculation mechanism is still under discussion. We have proposed a simple bridging model which expresses flocculation under various additive manners of the flocculant and enables the understanding of qualitative trends of the flocculation system. In this study, from the simulated results based on the model and experimental data, we obtained the following knowledge. 1) The intermittent addition of polymer flocculant gives better and reproducible turbidity removal. 2) The optimum dosage, which results in maximum turbidity removal in a given manner of addition, increases as the number of doses under the intermittent addition increases. 3) At a given amount of primary particles, the reproducibility at the optimum dosage of the 1-time dose is the worst among all results, irrespective of the additive manner. It could, therefore, be concluded that all these findings are originated from the difference of probability of bridging formation among particles under various additive manners

Improvement of immobilization of fat, oil and grease (FOG) by calcium alginate

Current wastewater pre-treatment plant system handling FOG consumes high energy and time. This study aims to introduce a new FOG wastewater pre-treatment by immobilizing the FOG in a calcium alginate gel beads. Using Design-Expert software, Response surface methodology (RSM) based on face centred central composite design (FCCCD) was used to optimize two important variables; pH of FOG and concentration of sodium alginate whereas the oil entrapment efficiency (OEE) was used as a response. The mixtures of synthetic FOG wastewater and sodium alginate were dropped in calcium chloride solution in droplets form to produce gel beads. The optimum combination for having highest OEE percentage at 87.27% was found to be at pH 4.7 and 10000 ppm concentration of sodium alginate. Moreover, coating the gel beads with chitosan has reduced the FOG loss during mechanical expression from 23.73 % to 12.58 %. The gel beads were dissolved completely in phosphate buffer solution of pH 5, 8 and 9. This technique can be applied for easier FOG removal, for it has high OEE percentage and the final gel is also biodegradable

Oseltamivir (Tamiflu®)-induced pneumonia

SummaryWe report the first case of oseltamivir-induced pneumonia. A 50-year-old man was diagnosed with influenza and prescribed oseltamivir. He had a persistent high fever, and developed a productive cough with peripheral blood eosinophilia and his chest radiograph showed ground glass opacity. Bronchoalveolar lavage fluid and histological findings obtained from transbronchial lung biopsy suggested eosinophilic pneumonia with component of cryptogenic organizing pneumonia. Drug lymphocyte stimulation test against oseltamivir was positive. In spite of discontinuation of oseltamivir, his condition did not ameliorate. He was treated with prednisolone for oseltamivir-induced lung injury and the symptoms improved immediately. We should recognize oseltamivir-induced pneumonia as a differential diagnosis in the case of developing pneumonia following treatment with oseltamivir