Kinetics, mass transfer, and mass re-equilibrium for arsenate adsorption on iron oxide-based carbons

2018 ◽  
Author(s):  
◽  
Zhengyang Wang
Keyword(s):  
Mass Transfer ◽  
Water Treatment ◽  
Large Scale ◽  
Freundlich Isotherm ◽  
Small Scale ◽  
Crossover Point ◽  
Hydraulic Residence Time ◽  
In Situ Extraction ◽  
Small Water ◽  
Batch Tests

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Removal of arsenic (As) from drinking water sources is much needed worldwide, and small water treatment systems, such as point-of-use (POU) treatment, could be an effective solution for residential applications. Adopting existing removal technologies that are successful in large-scale treatment to small-scale units, however, is rather ineffective due to the short hydraulic residence time in small water treatment systems. … The Freundlich isotherm can fit experimental data well: a crossover point for the two fitted Freundlich isotherms was observed and nano-FeAC had higher adsorption plateau. Furthermore, we demonstrated that due to the MRE process, a pseudo-equilibrium of FeMC was altered to another steady state by an in situ extraction with nano-FeAC in both batch and column systems. The overall inter-medium mass transfer resulted in both improved adsorption densities obtained by batch tests and a large bed volume prior to the 10 [mu]g As/L breakthrough at a short empty bed contact time (0.85 min).

Small water and wastewater systems: pathways to sustainable development?

2004 ◽  
Vol 48 (11-12) ◽  
pp. 7-14 ◽  
Author(s):  
G. Ho
Keyword(s):  
Sustainable Development ◽  
Large Scale ◽  
Small Scale ◽  
Technology Choice ◽  
Large Scale Systems ◽  
Environmentally Sustainable ◽  
Small Water ◽  
Developing Communities ◽  
Wastewater Systems ◽  
Water And Wastewater

Globally we are faced with billions of people without access to safe water and adequate sanitation. These are generally located in developing communities. Even in developed communities the current large scale systems for supplying water, collecting wastewater and treating it are not environmentally sustainable, because it is difficult to close the cycle of water and nutrients. This paper discusses the advantages of small scale water and wastewater systems in overcoming the difficulties in providing water and wastewater systems in developing communities and in achieving sustainability in both developed and developing communities. Particular attention is given to technology and technology choice, even though technology alone does not provide the complete answer. Disadvantages of small scale systems and how they may be overcome are discussed.

scholarly journals Heat and mass transfer enhancement strategies by impinging jets: A literature review

2020 ◽  
pp. 227-227
Author(s):  
Florin Bode ◽  
Claudiu Patrascu ◽  
Ilinca Nastase
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Large Scale ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Nozzle Geometry ◽  
Small Scale ◽  
Mixing Enhancement ◽  
Transfer Enhancement

Heat and mass transfer can be greatly increased when using impinging jets, regardless the application. The reason behind this is the complex behavior of the impinging jet flow which is leading to the generation of a multitude of flow phenomena, like: large-scale structures, small scale turbulent mixing, large curvature involving strong normal stresses and strong shear, stagnation, separation and re-attachment of the wall boundary layers, increased heat transfer at the impinged plate. All these phenomena listed above have highly unsteady nature and even though a lot of scientific studies have approached this subject, the impinging jet is not fully understood due to the difficulties of carrying out detailed experimental and numerically investigations. Nevertheless, for heat transfer enhancement in impinging jet applications, both passive and active strategies are employed. The effect of nozzle geometry and the impinging surface macrostructure modification are some of the most prominent passive strategies. On the other side, the most used active strategies utilize acoustical and mechanical oscillations in the exit plane of the flow, which in certain situations favors mixing enhancement. This is favored by the intensification of some instabilities and by the onset of large scale vortices with important levels of energy.

scholarly journals Relating force balances and flow length scales in geodynamo simulations

2020 ◽  
Vol 224 (3) ◽  
pp. 1890-1904
Author(s):  
T Schwaiger ◽  
T Gastine ◽  
J Aubert
Keyword(s):  
Kinetic Energy ◽  
Large Scale ◽  
Magnetic Energy ◽  
Force Balance ◽  
Small Scale ◽  
Scaling Analysis ◽  
Length Scale ◽  
Crossover Point ◽  
Length Scales ◽  
Flow Length

SUMMARY In fluid dynamics, the scaling behaviour of flow length scales is commonly used to infer the governing force balance of a system. The key to a successful approach is to measure length scales that are simultaneously representative of the energy contained in the solution (energetically relevant) and also indicative of the established force balance (dynamically relevant). In the case of numerical simulations of rotating convection and magnetohydrodynamic dynamos in spherical shells, it has remained difficult to measure length scales that are both energetically and dynamically relevant, a situation that has led to conflicting interpretations, and sometimes misrepresentations of the underlying force balance. By analysing an extensive set of magnetic and non-magnetic models, we focus on two length scales that achieve both energetic and dynamical relevance. The first one is the peak of the poloidal kinetic energy spectrum, which we successfully compare to crossover points on spectral representations of the force balance. In most dynamo models, this result confirms that the dominant length scale of the system is controlled by a previously proposed quasi-geostrophic (QG-) MAC (Magneto-Archimedean-Coriolis) balance. In non-magnetic convection models, the analysis generally favours a QG-CIA (Coriolis-Inertia-Archimedean) balance. Viscosity, which is typically a minor contributor to the force balance, does not control the dominant length scale at high convective supercriticalities in the non-magnetic case, and in the dynamo case, once the generated magnetic energy largely exceeds the kinetic energy. In dynamo models, we introduce a second energetically relevant length scale associated with the loss of axial invariance in the flow. We again relate this length scale to another crossover point in scale-dependent force balance diagrams, which marks the transition between large-scale geostrophy (the equilibrium of Coriolis and pressure forces) and small-scale magnetostrophy, where the Lorentz force overtakes the Coriolis force. Scaling analysis of these two energetically and dynamically relevant length scales suggests that the Earth’s dynamo is controlled by a QG-MAC balance at a dominant scale of about $200 \, \mathrm{km}$, while magnetostrophic effects are deferred to scales smaller than $50 \, \mathrm{km}$.

An Overview on Pulp and Paper Manufacturing Process and its Waste Treatment

2020 ◽  
Vol 11 (10) ◽  
pp. 1060-1064
Author(s):  
C. Arshiya ◽  
G. Aravind ◽  
S.Sangeetha Gandhi ◽  
A.Ajay Arokiyaraj ◽  
T.A. Saufishan ◽  
...  
Keyword(s):  
Waste Water ◽  
Water Treatment ◽  
Manufacturing Process ◽  
Large Scale ◽  
Manufacturing Industry ◽  
Waste Water Treatment ◽  
Pulp And Paper ◽  
Small Scale ◽  
Treatment Methods ◽  
Paper Manufacturing

The pulp and paper industry has a great impact in the world. It has been manufactured for ages and ages, it is still booming up as industry in small scale and large scale levels. Despite the fact that they produce printing and writing papers, paper rolls, packaging material etc. they also produce large amount of waste materials from their Industry by Manufacturing. This when left untreated leads to environmental pollution, harsh contamination and so on. As every industry has its own waste water treatment methods to recycle, reuse and reduce pollution. This Industry also has its own criteria to carry out the process of waste water treatment, yet it lags in being efficient in it. By the sources collected and compared with other kinds of industries it is listed that pulp and paper manufacturing industry is one of the top most industries to produce large volumes of waste water which has degradable organics at higher level. Hence this paper aims to study the manufacturing process, waste water components released and its effect on environment, the treatment methods carried out and how it can be improvised efficiently in forthcoming days

Study on self-purification capacity for organic pollutants in stagnant water

2002 ◽  
Vol 46 (9) ◽  
pp. 137-146 ◽  
Author(s):  
M. Saito ◽  
Y. Magara ◽  
Wisjnuprapto
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Large Scale ◽  
Oxygen Supply ◽  
Mass Transfer Rate ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Polluted Water ◽  
Small Water

Polluted water is abandoned or stored untreated in many places. Especially, small water bodies such as ditches, ponds, wastewater tanks, etc. have not yet well been considered. The self-purification stabilizes the wastewater, but oxygen supply limits the biodegradation process. In the natural environment, approximately 3 g oxygen can be dissolved per m2 per day if the water is completely deprived from dissolved oxygen; this is the magnitude of self-purification capacity. To improve the quality of polluted water with higher oxygen demand than natural reaeration capacity, enhanced aeration is required. The laboratory experiment disclosed that water trickling onto the water surface or shallow stirring of water less than 10 mm in depth increased the mass transfer rate significantly. At the same time, the methods were found more efficient than bubbling aeration of large-scale treatment plant in terms of energy input against oxygen supply. Though it is an efficient method, elaborate application will be necessary since the mass transfer rate is not as high as bubbling aeration.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

Planetary gentrification and urban (re)development

2019 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Loretta Lees
Keyword(s):  
Low Income ◽  
Policy Making ◽  
Large Scale ◽  
Urban Redevelopment ◽  
Urban Transformation ◽  
Small Scale ◽  
Income Groups ◽  
Low Income Groups

Abstract Gentrification is no-longer, if it ever was, a small scale process of urban transformation. Gentrification globally is more often practised as large scale urban redevelopment. It is state-led or state-induced. The results are clear – the displacement and disenfranchisement of low income groups in favour of wealthier in-movers. So, why has gentrification come to dominate policy making worldwide and what can be done about it?

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