scholarly journals Mathematical modelling and analysis of the flocculation process in low retention time hydraulic flocculators

Water SA ◽  
2019 ◽  
Vol 45 (1 January) ◽  
Author(s):  
Danieli Soares De Oliveira ◽  
Clainer Bravin Donadel
Keyword(s):  
Retention Time ◽  
Rational Design ◽  
Physical Modelling ◽  
Process Efficiency ◽  
Particle Interactions ◽  
Helically Coiled Tube ◽  
Proposed Model ◽  
Recycling Systems ◽  
Flocculation Process ◽  
Flocculation Time

This article aims to advance the understanding of particle interactions in low retention time flocculators and proposes a new flocculation model that appropriately considers the influence of retention time in flocculation processes. This consideration is important for units with flocculation time lower than 1 min, as seen in helically coiled tube flocculators (HCTFs), whose retention time is significantly lower than conventional flocculation units (about 30 min). With this, it was possible to obtain a more adherent model, reducing deviations between results obtained by physical modelling (using HCTFs, 48 tests) and those obtained with the proposed model, when compared with results obtained using the flocculation models commonly used for this purpose. The decreasing-rising behaviour presented by experimental data for process efficiency versus retention time, not verified in the benchmark models, was satisfactorily addressed by the proposed model. Furthermore, maximum and average absolute percentage deviations obtained using the model proposed in this study were less than or equal to the results obtained with the benchmark models and less for experimental uncertainty (10%). The results obtained indicate that this model can be a useful tool to support the rational design of low retention time units, including applications for the water industry and water recycling systems.

scholarly journals Effect of Praestol as a Coagulant-Aid to Improve Coagulation-Flocculation in Dye containing Wastewaters

2015 ◽  
Vol 18 (1) ◽  
pp. 38-46 ◽  
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Removal Efficiency ◽  
Dye Removal ◽  
Settling Time ◽  
Solution Ph ◽  
Polyaluminum Chloride ◽  
Flocculation Process ◽  
Flocculation Time

<div> <p>This study was conducted to investigate the effect of praestol, as a coagulant-aid, to improve coagulation-flocculation process in the removal of disperse red 60 from aqueous solutions. The effect of various parameters including coagulants dose (10-1000 mg l<sup>-1</sup>), praestol dose (0-1000 mg l<sup>-1</sup>), solution pH (3-11), initial dye concentration (100-500 mg l<sup>-1</sup>), flocculation speed (30-60 rpm), flocculation time (15-30 min), settling time (5-60 min) and ionic strength (0-6 mg l<sup>-1</sup>) was evaluated on the dye removal. The dye removal efficiency was substantially increased by using praestol in the concentration of 80 mg l<sup>-1 </sup>and 400 mg l<sup>-1 </sup>for coagulation with alum and polyaluminum chloride (PACl), respectively. The maximum dye removal by alum coupled with praestol (Al-P) and PACl coupled with praestol (PA-P) was found to be 97.8% and 98.7%, respectively that were occurred at pH 7. The results showed that the application of PA-P or Al-P can be effectively used to remove disperse red 60 (DR 60) in aqueous solutions.</p> </div> <p>&nbsp;</p>

scholarly journals Modeling of the process of the extinguishing gas concentration changes in the protected compartment

2018 ◽  
Vol 247 ◽  
pp. 00041
Author(s):  
Przemysław Kubica ◽  
Sylwia Boroń
Keyword(s):  
Fire Safety ◽  
Retention Time ◽  
Gas Flow ◽  
Analytical Models ◽  
Correct Prediction ◽  
Atmospheric Conditions ◽  
Flow Process ◽  
Gas Concentration ◽  
Proposed Model ◽  
Concentration Changes

The article discusses the aspect of the fire safety of rooms protected by Fixed Gaseous Extinguishing System (FGE-system). On the basis of a literature study, including the analysis of design standards, it was claimed that analytical models of gas outflow from the compartment ignore some parameters that can affect the process of extinguishing gas concentration changes in time. Correct prediction of the gas flow process may affect the retention time value, which is an important determinant of the fire safety of rooms protected by FGE-system. The density of extinguishing gas was indicated as a parameter with a large potential for extending the retention time. It was noted that the density of gas depends on atmospheric conditions like temperature, pressure and humidity, which are omitted in the standard models. In the research part, the concentration distribution of nitrogen and nitrogen-argon mixtures were analyzed using three methods. Obtained experimental data were compared with analytical calculations using a standard model (model N) and a new proposed model extended by an impact of the atmospheric conditions (model PK). Model PK showed greater accuracy of determining the process of extinguishing gas concentration changes. The new proposed model might be a valuable tool for further analysis of gas flow through the room.

scholarly journals Optimization of the Design of Pre-Signal System Using Improved Cellular Automaton

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yan Li ◽  
Ke Li ◽  
Siran Tao ◽  
Xia Wan ◽  
Kuanmin Chen
Keyword(s):  
Rational Design ◽  
Influence Factors ◽  
Design Parameters ◽  
Signal Timing ◽  
Signal System ◽  
Lane Changing ◽  
Traffic Demand ◽  
Driving Behaviors ◽  
Proposed Model ◽  
Simulation Results

The pre-signal system can improve the efficiency of intersection approach under rational design. One of the main obstacles in optimizing the design of pre-signal system is that driving behaviors in the sorting area cannot be well evaluated. The NaSch model was modified by considering slow probability, turning-deceleration rules, and lane changing rules. It was calibrated with field observed data to explore the interactions among design parameters. The simulation results of the proposed model indicate that the length of sorting area, traffic demand, signal timing, and lane allocation are the most important influence factors. The recommendations of these design parameters are demonstrated. The findings of this paper can be foundations for the design of pre-signal system and show promising improvement in traffic mobility.

scholarly journals Study of the performance of disinfection with sodium hypochlorite on a full-scale sewage treatment plant

2020 ◽  
Vol 15 (6) ◽  
pp. 1
Author(s):  
Maria Rosaria Boni ◽  
Sabrina Copelli ◽  
Massimo Raboni
Keyword(s):  
Sodium Hypochlorite ◽  
Retention Time ◽  
Contact Time ◽  
Regression Line ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Full Scale ◽  
Process Efficiency ◽  
Residual Chlorine

A full-scale sewage treatment plant was investigated to assess the performance of the disinfection stage. Sodium hypochlorite was used as a disinfectant agent and the process efficiency was evaluated by E.coli removal. The research took place over a period of two years in order to evaluate the effect of retention time (t) and residual chlorine (Cr) under different seasonal conditions. The effectiveness of E.coli removal with sodium hypochlorite proved to be strictly dependent on the factor CR  t (product of residual chlorine with the contact time). The regression line of the experimental points was, on the whole, well comparable with the model proposed by Collins, especially in the field of CRt lower than 30 mg L-1 min.

A Knowledge Based Hybrid Model for Improving Manufacturing System in Rolling Mills

2010 ◽  
Vol 443 ◽  
pp. 3-8 ◽  
Author(s):  
Kazem Abhary ◽  
Keith Garner ◽  
Zlatko Kovacic ◽  
Sead Spuzic ◽  
Faik Uzunovic ◽  
...  
Keyword(s):  
Hybrid Model ◽  
Physical Modelling ◽  
Research Strategy ◽  
Process Efficiency ◽  
Small Scale ◽  
Steel Rolling ◽  
Rolling Mills ◽  
Knowledge Based ◽  
Genetic Modelling ◽  
Modelling Process

Hot steel rolling is amongst the most important industrial techniques because of huge amount of consumed resources, immense environmental impact, and the significance and enormous quantity of long products. Criteria for improving rolling operations include process efficiency, resource consumption, system reliability, product quality and ergo-ecological sustainability. There is an increasing availability of information within and beyond the domain of forming by rolling. With advances in computerised information processing, it becomes apparent that further progress is to be sought in intelligently combining the strategies and theories developed in differing disciplines. The key to optimising rolling systems is to be found in hybrid models. This approach calls for utilising cross-disciplinary knowledge, including a selection amongst methods such as stochastic, fuzzy and genetic modelling, process control and optimisation as well as supply chain and maintenance management. Evidence obtained by experiments using small-scale chemo-physical modelling encourages the use laboratory rolling for preliminary validations. Research strategy is conceptualised on the basis of a knowledge-based hybrid model. The sample space for this model is constituted by the rolling passes translated into the form of vectors. An example of a rolling pass translation into the vector form is presented.

Re-evaluation of the Retention Time Prediction “Polarity” Model in the Context of the Development of a Stationary Phase Variable

2014 ◽  
Vol 97 (4) ◽  
pp. 1213-1219
Author(s):  
Adam Karpiński ◽  
Elżbieta Mikiciuk-Olasik ◽  
Paweł Szymański
Keyword(s):  
Stationary Phase ◽  
Retention Time ◽  
Phase Variable ◽  
Disease Treatment ◽  
Retention Model ◽  
Retention Time Prediction ◽  
Time Prediction ◽  
Proposed Model ◽  
Phase Constant ◽  
New Stationary Phase

Abstract The Abraham–Carr retention time prediction model was reviewed and developed in the context of the introduction of a new stationary phase variable. The new variable consists of a binary mixture dielectric constant and a stationary phase descriptor that was derived from the Snyder–Dolan column descriptors theory. In this work, data reported by Torres–Lapasio were investigated (in-silico) in the context of the linearity behavior of the Abraham–Carr theorem logk = ƒ(PNm). This proposed model has been replaced by several experiments that have shown that the stationary phase constant PNS, which is represented by a variable, does not require laboratory experiments. The new model, which contains stationary and mobile phase variables, shows an improved correlation for the majority of the Torres–Lapasio compounds between logk and ΔPN (mobile and stationary phase variables expression). The discussion regarding the model's behavior in the presence of secondary interactions led to research using a polar column and “bulky” compounds as reported by Szymański. Newly developed tacrine 4-fluorobenzoic acid derivatives, potential drugs in Alzheimer's disease treatment, are homologs and were found problematic to separate using regular C18 sorbent. The obtained results show that in the range of 30–70% acetonitrile, a single retention model using Agilent Zorbax SB-cyano sorbent is present, which is confirmed by two investigated models (R2 &gt; 0.95).

scholarly journals PHYSICAL MODELLING OF BEACH EROSION AND LITTORAL DRIFT

1988 ◽  
Vol 1 (21) ◽  
pp. 134 ◽  
Author(s):  
Otavio J. Sayao ◽  
Robert B. Nairn
Keyword(s):  
Grain Size ◽  
Physical Model ◽  
Scale Effects ◽  
Physical Modelling ◽  
Beach Erosion ◽  
Model Design ◽  
Littoral Drift ◽  
Sedimentary Processes ◽  
Dynamic Similarity ◽  
Proposed Model

A new procedure for physical modelling of beach sedimentary processes is presented. It is shown that the modelling requirements proposed by Dean (1985) are necessary but not sufficient for dynamic similarity. Quantification of scale effects due to slope and relative grain size scaling conditions enables extrapolation of the physical model results to prototype situations. Selected examples of the application of the proposed model design are also given.

scholarly journals Radial basis neural tree model for improving waste recovery process in a paper industry

2018 ◽  
Author(s):  
TANUJIT CHAKRABORTY ◽  
Swarup Chattopadhyay ◽  
Ashis Kumar Chakraborty
Keyword(s):  
Paper Industry ◽  
Cost Effective ◽  
Recovery Process ◽  
Process Efficiency ◽  
Regularity Conditions ◽  
Paper Machine ◽  
Tree Model ◽  
Waste Recovery ◽  
Proposed Model ◽  
Radial Basis

In this article, we propose a novel hybridization of regression trees (RT) and radial basis function networks (RBFN), namely, radial basis neural tree (RBNT) model,for waste recovery process improvement in the paper industry. As a by-product of the paper manufacturing process, a lot of waste along with valuable fibers and fillerscome out from the paper machine. The waste recovery process (WRP) involves separating the unwanted materials from the valuable ones so that the recovered fibersand fillers can be further reused in the production process. This job is done by fiber-filler recovery equipment (FFRE). The efficiency of FFRE depends on severalcrucial process parameters and monitoring them is a difficult proposition. The proposed model can be useful to find the essential parameters from the set of availabledata and perform prediction task to improve waste recovery process efficiency. An idea of parameter optimization along with regularity conditions for the universal consistency of the proposed model are given. The proposed model has the advantages of easy interpretability and excellent performance when applied to the FFREefficiency improvement problem. Improved waste recovery will help the industry to become environmentally friendly with less ecological damage apart from being cost-effective.

Assessing the Potential for Digital Transformation

2021 ◽  
Vol 13 (19) ◽  
pp. 11040
Author(s):  
Tatiana Corejova ◽  
Roman Chinoracky
Keyword(s):  
New Technologies ◽  
National Policy ◽  
Digital Technologies ◽  
Economic Benefits ◽  
Digital Transformation ◽  
Process Efficiency ◽  
Policy Makers ◽  
Know How ◽  
Production Processes ◽  
Proposed Model

Historically, new technologies have always increased the efficiency of production processes. Production process efficiency increases productivity. With the growth of productivity, there is usually an increase in sales and profit. Today’s world is mainly influenced by digital technologies. The digitization of production processes leads to the digital transformation of the business and natural economy sectors. If, like other technologies in the past, the effects of digital technologies are associated with a growth in efficiency, productivity and thus also revenues and profits, the aim of this article is to propose a model to assess the potential of a digital transformation from a macroeconomic perspective. The proposed model, which was based on a composite indicator expressing the potential for digital transformation, was quantified for a certain period and for a selected sample of countries. The potential for digital transformation can occur in any country, regardless of the purchasing power of its population and GDP per capita. We can assume that the economic benefits of digital technologies are obvious. Businesses operating in any country innovate and are driven by digital technologies. This is also reflected in employment. New workers who know how to work with digital technologies are needed. Therefore, the results of the assessments and the proposal itself serve as a basis for national policy makers to create national strategies for digital transformation.

Flocculation morphology: effect of particulate shape and coagulant species on flocculation

2006 ◽  
Vol 53 (7) ◽  
pp. 9-16 ◽  
Author(s):  
Jiang Zhanpeng ◽  
Guan Yuntao
Keyword(s):  
Natural Waters ◽  
Colloidal Particles ◽  
Morphological Characteristics ◽  
Process Efficiency ◽  
Traditional Theory ◽  
Nonspherical Particles ◽  
Morphology Model ◽  
Morphology Effect ◽  
Near Future ◽  
Flocculation Process

Flocculation morphology is a new concept that investigates the morphological characteristics of colloidal particles and coagulants in water during the flocculation process, and the influence that these characteristics have on flocculation process efficiency. This paper is a summary of advances in research on this topic over several years. Morphological characteristics of colloids in natural waters and different kinds of hydrolysed coagulants are investigated, and their effect on colloid stability, flocculation kinetics and efficiency is analysed. It is confirmed that the traditional theory has some deviations in coagulation of nonspherical particles, and these deviations are revised by the flocculation morphology model. Flocculation morphology can not only promote research about flocculation theory, but also instruct the production, application and flocculation control. It can be foreseen that more progress will be made in research and application of flocculation morphology in the near future.

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