scholarly journals Arsenic removal from drinking water using low-pressure nanofiltration under various operating conditions

2018 ◽  
Vol 13 (2) ◽  
pp. 295-302 ◽  
Author(s):  
M. Harfoush ◽  
S. A. Mirbagheri ◽  
M. Ehteshami ◽  
S. Nejati
Keyword(s):  
Drinking Water ◽  
Arsenic Removal ◽  
Arsenic Concentration ◽  
Inorganic Arsenic ◽  
Low Pressure ◽  
Operating Conditions ◽  
Polluted Water ◽  
Initial Concentration ◽  
Wide Range ◽  
Arsenite Removal

Abstract Currently, one of the main environmental concerns is the toxicity caused by arsenic. Arsenic-polluted water can cause many human health problems including various cancerous diseases. In natural water, inorganic arsenic can be found in the forms of arsenite and arsenate, which have been found in several Iranian provinces – e.g., East Azerbaijan, Kurdistan, and the city of Bijar – in high concentrations. Modern nanofiltration (NF) technology enables a wide range of water resource pollutants to be controlled efficiently. In this study, in an attempt to enhance arsenic removal (both arsenite and arsenate) from drinking water using low pressure NF, operating conditions like arsenic concentration, the trans-membrane pressure applied, and a range of different temperatures have all been considered. The highest arsenate removal achieved was 94% with an initial concentration of 500 μg/L, at 7 bar pressure, and 28 °C. The highest arsenite removal was 90%, with an initial concentration of 100 μg/L, at 5 bar pressure, and also at 28 °C. Increasing the pressure had a positive effect on the removal of both species, however, increasing the temperature had negative impacts. It was always found that arsenate removal was better than arsenite removal.

Adsorptive Removal of As(III) from Aqueous Solution by Raw Coconut Husk and Iron Impregnated Coconut Husk: Kinetics and Equilibrium Analyses

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Shashi Bala Gautam ◽  
Mohd. Siraj Alam ◽  
Suantak Kamsonlian
Keyword(s):  
Aqueous Solution ◽  
Arsenic Concentration ◽  
Intraparticle Diffusion ◽  
Operating Conditions ◽  
Isotherm Models ◽  
Diffusion Control ◽  
Order Kinetic ◽  
Initial Concentration ◽  
Coconut Husk ◽  
Wide Range

Abstract As(III) removal from aqueous solution was conducted using low-cost adsorbents like unmodified raw coconut husk (RCH) and modified iron impregnated coconut husk (IICH). Prepared both adsorbents was characterisation by using elemental analyses, FTIR, TGA, SEM and EDX. The analysis behaviour indicates, both adsorbents are highly suitability for As(III) removal. The effects of operational parameters, such as pH, adsorbent dose and initial concentration on these adsorbents were investigated and compared with other agriculture based adsorbent. The result reveals that the As(III) removal capacity is effective in the pH range of 6.2–7.8 and the optimum pH and adsorbents dose was found as 7.0 and 40 g l−1, for RCH and IICH, respectively. Kinetic and equilibrium studies over a wide range of operating conditions are tested to evaluate the effectiveness of RCH and IICH to remove As(III) from water. The values of both kf1 and ks2 values are found to be nearly same and same trend was observed at higher 50 mg l−1 and lower arsenic concentration 25 mg l−1 for RCH and IICH. But the kinetic data is fitted better in the pseudo-second-order kinetic model than the pseudo-first order model. The effective intraparticle diffusion coefficient of As(III) ions in RCH and IICH is observed to be 2.145×10−9 cm2 s−1 and 1.838×10−10 cm2 s−1, which indicates that the overall As(III) adsorption on both adsorbents are intraparticle diffusion control. Equilibrium isotherms for the adsorption of As(III) on RCH and IICH were analyzed at different dose and different initial concentration. At different concentration system, Freundlich isotherm and Redlich-Peterson are best fitted followed by Langmuir and Temkin isotherm models and for varying doses, all equilibrium models give almost similar fitness.

scholarly journals First step concerning improvement of arsenic removal by adapted Kanchan filters in the lowlands of Nepal

2020 ◽  
pp. 01-09 ◽  
Author(s):  
Barbara Mueller
Keyword(s):  
Drinking Water ◽  
Ground Water ◽  
Removal Efficiency ◽  
Arsenic Removal ◽  
Arsenic Concentration ◽  
Operating Conditions ◽  
World Health ◽  
Water Composition ◽  
Keywords Arsenic ◽  
Health Organization

In the Terai region of Nepal (the southern lowlands of the country) the arsenic concentration of extracted ground water used as drinking water frequently exceeds the actual World Health Organization (WHO) drinking water guideline concentration of 10 μg/L. Single household filters (so called Kanchan filters) are employed to eliminate as from the well water. Being assembled to remove as utilizing zero-valent (ZVI) media, their efficiency was observed to vary to a high degree depending on design, ground water composition and the current operating conditions. Based on these concerns three field campaigns were organized in order to test ground water composition and filter handling on spot. This report depicts for the first time the results of this screening regarding removal efficiencies and clearly disclose future adaptation of the design and enhancement of the Kanchan filters uniquely used in Nepal. Removal efficiency varied between 5.81 % to 97.1 % depending on material, usage and mode of operation. The measurements of improvement include the replacement of nails and sand regularly; increasing the contact time between ground water and nails; preventing the nails from drying in order to maintain oxidizing settings; proper and regularly repeated instructions of the users. Keywords: Arsenic; Kanchan filters; Removal efficiency

As(III) Removal by Dynamic Adsorption onto Amberlite XAD7 Functionalized with Crown Ether and Doped with Fe(III) Ions

2019 ◽  
Vol 70 (7) ◽  
pp. 2330-2334
Author(s):  
Mihaela Ciopec ◽  
Adina Negrea ◽  
Narcis Duteanu ◽  
Corneliu Mircea Davidescu ◽  
Iosif Hulka ◽  
...  
Keyword(s):  
Adsorption Process ◽  
Arsenic Removal ◽  
Arsenic Concentration ◽  
Fixed Bed ◽  
World Health ◽  
Arsenic Content ◽  
Arsenic Adsorption ◽  
Stage Of Development ◽  
Wide Range ◽  
Health Organization

Arsenic content in groundwater�s present a wide range of concentration, ranging from hundreds of micrograms to thousands of micrograms of arsenic per litter, while the maximum permitted arsenic concentration established by World Health Organization (WHO) is 10 mg L-1. According to the WHO all people, regardless of their stage of development and their social economic condition, have the right to have access to adequate drinking water. The most efficient and economic technique used for arsenic removal is represented by adsorption. In order to make this remediation technique more affordable and environmentally friendly is important to new materials with advance adsorbent properties. Novelty of present paper is represented by the usage of a new adsorbent material obtained by physical - chemical modification of Amberlite XAD polymers using crown ethers followed by iron doping, due to well-known affinity of arsenic for iron ions. Present paper aims to test the obtained modified Amberlite polymer for arsenic removal from real groundwater by using adsorption in a fixed bed column, establishing in this way a mechanism for the adsorption process. During experimental work was studied the influence of competing ions from real water into the arsenic adsorption process.

scholarly journals Nanofiltration for Arsenic Removal: Challenges, Recent Developments, and Perspectives

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1323 ◽  
Author(s):  
TA Siddique ◽  
Naba K. Dutta ◽  
Namita Roy Choudhury
Keyword(s):  
Drinking Water ◽  
Arsenic Removal ◽  
Environmental Concern ◽  
Low Cost ◽  
Inorganic Arsenic ◽  
Water Security ◽  
Polymer Nanocomposite ◽  
Life Forms ◽  
Current Status ◽  
The Status

Arsenic (As) removal is of major significance because inorganic arsenic is highly toxic to all life forms, is a confirmed carcinogen, and is of significant environmental concern. As contamination in drinking water alone threatens more than 150 million people all over the world. Therefore, several conventional methods such as oxidation, coagulation, adsorption, etc., have been implemented for As removal, but due to their cost-maintenance limitations; there is a drive for advanced, low cost nanofiltration membrane-based technology. Thus, in order to address the increasing demand of fresh and drinking water, this review focuses on advanced nanofiltration (NF) strategy for As removal to safeguard water security. The review concentrates on different types of NF membranes, membrane fabrication processes, and their mechanism and efficiency of performance for removing As from contaminated water. The article provides an overview of the current status of polymer-, polymer composite-, and polymer nanocomposite-based NF membranes, to assess the status of nanomaterial-facilitated NF membranes and to incite progress in this area. Finally, future perspectives and future trends are highlighted.

scholarly journals Alginate-based biotechnology: a review on the arsenic removal technologies and future possibilities

2019 ◽  
Vol 68 (6) ◽  
pp. 369-389 ◽  
Author(s):  
Shakhawat Chowdhury ◽  
Imran Rahman Chowdhury ◽  
Fayzul Kabir ◽  
Mohammad Abu Jafar Mazumder ◽  
Md. Hasan Zahir ◽  
...  
Keyword(s):  
Drinking Water ◽  
Arsenic Removal ◽  
Alginate Bead ◽  
Alginate Beads ◽  
Industrial Applications ◽  
Mass Scale ◽  
Future Research ◽  
Large Area ◽  
Arsenic Adsorption ◽  
Wide Range

Abstract The alginate-based adsorption technologies have emerged as potential methods for arsenic removal from drinking water. The adsorbents (iron oxide, hydroxide, nano zero valent iron (nZVI), industrial waste, minerals, magnetite, goethite, zirconium oxide, etc.) are impregnated into alginate beads to produce the media. The biocompatibility, rough surface with large area, and amorphous and high water permeable bead structure improve arsenic adsorption efficiency while the regeneration process is simpler than the conventional adsorbents. In recent years, studies have reported laboratory-scale applications of alginate beads, encapsulated and impregnated with adsorbents, for arsenic removal from drinking water. The arsenic removal efficiencies were reported to be over 95% with a wide range of concentrations (10–1,000 parts per billion) and pH (3.0–7.5). However, commercial- and/or mass-scale applications have not been reported yet, due possibly to overall cost, complexity, reusability, and arsenic waste-laden sludge management. In this paper, research achievement on arsenic removal using alginate-based adsorbents has been reviewed. The review was performed in context to alginate bead development, adsorbent encapsulation and impregnation, application, performance, and regeneration. The advantages and limitations of the methods were analyzed and the scopes of future research were identified for mass scale domestic and industrial applications.

The Off-Design Performance of a Low-Pressure Turbine Cascade

1987 ◽  
Vol 109 (2) ◽  
pp. 201-209 ◽  
Author(s):  
H. P. Hodson ◽  
R. G. Dominy
Keyword(s):  
Reynolds Numbers ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Surface Flow ◽  
Operating Conditions ◽  
Turbine Cascade ◽  
Linear Cascade ◽  
Design Performance ◽  
Low Pressure Turbine ◽  
Wide Range

The ability of a given blade profile to operate over a wide range of conditions is often of the utmost importance. This paper reports the off-design performance of a low-pressure turbine rotor root section in a linear cascade. Data were obtained using pneumatic probes and surface flow visualization. The effects of incidence (+9, 0, −20 deg), Reynolds (1.5, 2.9, 6.0 × 105), pitch-chord ratio (0.46, 0.56, 0.69), and inlet boundary layer thickness (0.011, 0.022 δ*/C) are discussed. Particular attention is paid to the three dimensionality of the flow field. Significant differences in the detail of the flow occur over the range of operating conditions investigated. It is found that the production of new secondary loss is greatest at lower Reynolds numbers, positive incidence, and the higher pitch-chord ratios.

Arsenic Removal from Drinking Water Using Low Pressure Membranes

2013 ◽  
Vol 52 (29) ◽  
pp. 9958-9964 ◽  
Author(s):  
Harun Elcik ◽  
Mehmet Cakmakci ◽  
Erkan Sahinkaya ◽  
Bestamin Ozkaya
Keyword(s):  
Drinking Water ◽  
Arsenic Removal ◽  
Low Pressure

scholarly journals Arsenic Removal from Contaminated Water Using Natural Adsorbents: A Review

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1407
Author(s):  
Kanfolo Franck Herve YEO ◽  
Chaokun Li ◽  
Hui Zhang ◽  
Jin Chen ◽  
Wendong Wang ◽  
...  
Keyword(s):  
Drinking Water ◽  
Ion Exchange ◽  
Flow Rate ◽  
Contact Time ◽  
Arsenic Removal ◽  
Polluted Water ◽  
Contaminated Water ◽  
Natural Materials ◽  
The Past ◽  
Natural Adsorbents

More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions.

Experimental and Numerical Investigation of the Flow in a Low-Pressure Industrial Steam Turbine With Part-Span Connectors

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Markus Häfele ◽  
Christoph Traxinger ◽  
Marius Grübel ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
...  
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Numerical Study ◽  
Three Dimensional ◽  
Low Pressure ◽  
Operating Conditions ◽  
Engineering Practice ◽  
Cfd Model ◽  
Wide Range ◽  
The Impact

An experimental and numerical study on the flow in a three-stage low-pressure (LP) industrial steam turbine is presented and analyzed. The investigated LP section features conical friction bolts in the last and a lacing wire in the penultimate rotor blade row. These part-span connectors (PSC) allow safe turbine operation over an extremely wide range and even in blade resonance condition. However, additional losses are generated which affect the performance of the turbine. In order to capture the impact of PSCs on the flow field, extensive measurements with pneumatic multihole probes in an industrial steam turbine test rig have been carried out. State-of-the-art three-dimensional computational fluid dynamics (CFD) applying a nonequilibrium steam (NES) model is used to examine the aerothermodynamic effects of PSCs on the wet steam flow. The vortex system in coupled LP steam turbine rotor blading is discussed in this paper. In order to validate the CFD model, a detailed comparison between measurement data and steady-state CFD results is performed for several operating conditions. The investigation shows that the applied one-passage CFD model is able to capture the three-dimensional flow field in LP steam turbine blading with PSC and the total pressure reduction due to the PSC with a generally good agreement to measured values and is therefore sufficient for engineering practice.

scholarly journals A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions

2006 ◽  
Vol 129 (3) ◽  
pp. 527-541 ◽  
Author(s):  
Y. B. Suzen ◽  
P. G. Huang ◽  
D. E. Ashpis ◽  
R. J. Volino ◽  
T. C. Corke ◽  
...  
Keyword(s):  
Experimental Data ◽  
Transport Equation ◽  
Low Pressure ◽  
Equation Model ◽  
Operating Conditions ◽  
Computational Results ◽  
Transitional Flows ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Intermittency Factor

A transport equation for the intermittency factor is employed to predict the transitional flows in low-pressure turbines. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, μt, with the intermittency factor, γ. Turbulent quantities are predicted by using Menter’s two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model which can produce both the experimentally observed streamwise variation of intermittency and a realistic profile in the cross stream direction. The model had been previously validated against low-pressure turbine experiments with success. In this paper, the model is applied to predictions of three sets of recent low-pressure turbine experiments on the Pack B blade to further validate its predicting capabilities under various flow conditions. Comparisons of computational results with experimental data are provided. Overall, good agreement between the experimental data and computational results is obtained. The new model has been shown to have the capability of accurately predicting transitional flows under a wide range of low-pressure turbine conditions.

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