scholarly journals Application of GETFLOWS Coupled with Chemical Reactions to Arsenic Removal through Ferrihydrite Coprecipitation in an Artificial Wetland of a Japanese Closed Mine

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 475 ◽  
Author(s):  
Tatsuya Kato ◽  
Yohei Kawasaki ◽  
Masakazu Kadokura ◽  
Kohei Suzuki ◽  
Yasuhiro Tawara ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Arsenic Removal ◽  
Mine Drainage ◽  
Cost Effective ◽  
General Purpose ◽  
Uranium Mine ◽  
Ferrous Ions ◽  
Arsenic Adsorption ◽  
Artificial Wetland ◽  
Ferrous Oxidation

Passive systems that utilize a natural power such as a pond, plant, or microorganisms, is expected to be a cost-effective method for acid mine drainage (AMD) treatment. The Ningyo-toge mine, a non-operational uranium mine located in Okayama Prefecture, Japan, generates AMD containing arsenic and iron. To quantitatively study arsenic and iron ion removal in an artificial wetland and pond, chemical reactions were modeled and incorporated into the GETFLOWS (general-purpose terrestrial fluid-flow simulator) software. The chemical reaction models consisted of arsenite and ferrous oxidation equations and arsenic adsorption on ferrihydrite. The X-ray diffraction analysis of sediment samples showed ferrihydrite patterns. These results were consistent with the model for arsenite/ferrous oxidation and arsenic adsorption on ferrihydrite. Geofluid simulation was conducted to simulate mass transfer with the utilized topographic model, inlet flow rate, precipitation, and evaporation. The measured arsenic and iron ions concentrations in solution samples from the wetland and pond, fitted well with the model. This indicated that the main removal mechanism was the oxidation of arsenite/ferrous ions and that arsenic was removed by adsorption rather than dilution.

Arsenic Adsorptive Media Technology Selection Strategies

2006 ◽  
Vol 41 (2) ◽  
pp. 171-184 ◽  
Author(s):  
Paul Westerhoff ◽  
Michelle De Haan ◽  
Alan Martindale ◽  
Mohammad Badruzzaman
Keyword(s):  
Continuous Flow ◽  
Arsenic Removal ◽  
Microscopic Analysis ◽  
Cost Effective ◽  
Pilot Scale ◽  
Breakthrough Curves ◽  
Technology Selection ◽  
Small Scale ◽  
Column Tests ◽  
Arsenic Adsorption

Abstract More stringent arsenic regulations are requiring water utilities of all sizes to install treatment systems on wells which historically only had chlorination. A case study is presented for evaluating arsenic adsorption media at a well site in Mesa, Arizona, but the approach and methodological conclusions are transferable to any arsenic treatment system. The goal of this project is to develop a comprehensive, cost-effective and rapid approach for selecting arsenic adsorptive media. Batch laboratory tests, labscale continuous flow column tests and pilot-scale tests were conducted to evaluate removal efficiency, robustness, operational benefits and cost effectiveness of eight different commercially available adsorbents. Batch tests conducted at multiple pH levels provided limited benefit when compared against continuous flow rapid small-scale column tests (RSSCTs) to evaluate arsenic removal capability by different media. Breakthrough curves of arsenic, vanadium, silica and other trace metals corresponded well between lab-scale RSSCT and field-based pilot scale, suggesting that RSSCTs offer a timesaving approach for adsorptive media selection. Leaching tests on spent media verified that media could be safely disposed and high-resolution microscopic analysis indicated that calcium and silica accumulate on media surfaces and affect the longevity of arsenic removal systems.

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 Evaluation of Fe-Mg Binary Oxide for As (III) Adsorption—Synthesis, Characterization and Kinetic Modelling

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 805
Author(s):  
Saif Ullah Khan ◽  
Rumman Zaidi ◽  
Feroz Shaik ◽  
Izharul Haq Farooqi ◽  
Ameer Azam ◽  
...  
Keyword(s):  
Arsenic Removal ◽  
Kinetic Modelling ◽  
Arsenic Concentration ◽  
Experimental Studies ◽  
Precipitation Method ◽  
Arsenic Adsorption ◽  
Adsorbent Dosage ◽  
X Ray ◽  
Co Precipitation ◽  
Contaminated Waters

Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO3.9H2O and MgNO3.6H2O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX) and ultraviolet–visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1–1 g/L) but trend reversed on increasing initial arsenic concentration attaining qmax of 263.20 mg/g. Adsorption was quite efficient in pH range 4–8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO42−, CO32− and PO43− were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (qmax of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis.

A Practical Method for the Rational Design of Ship Structures

1980 ◽  
Vol 24 (02) ◽  
pp. 101-113 ◽  
Author(s):  
Owen F. Hughes ◽  
Farrokh Mistree ◽  
Vedran Žanic
Keyword(s):  
Optimum Design ◽  
Rational Design ◽  
Cost Effective ◽  
Practical Method ◽  
General Purpose ◽  
Processing Unit ◽  
Ship Structures ◽  
Finite Element Program ◽  
Central Processing ◽  
Element Program

A practical, rationally based method is presented for the automated optimum design of ship structures. The method required the development of (a) a rapid, design-oriented finite-element program for the analysis of ship structures; (b) a comprehensive mathematical model for the evaluation of the capability of the structure; and (c) a cost-effective optimization algorithm for the solution of a large, highly constrained, nonlinear redesign problem. These developments have been incorporated into a program called SHIPOPT. The efficiency and robustness of the method is illustrated by using it to determine the optimum design of a complete cargo hold of a general-purpose cargo ship. The overall dimensions and the design loads are the same as those used in the design of the very successful SD14 series of ships. The redesign problem contains 94 variables, a nonlinear objective function, and over 500 constraints of which approximately half are non-linear. Program SHIPOPT required approximately eight minutes of central processing unit time on a CDC CYBER 171 to determine the optimum design.

Pilot-Scale Performance of Iron and Arsenic Removal from Contaminated Groundwater

2005 ◽  
Vol 40 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Biswaranjan Manna ◽  
Uday Chand Ghosh
Keyword(s):  
Arsenic Removal ◽  
Cost Effective ◽  
Pilot Scale ◽  
Cost Evaluation ◽  
Contaminated Groundwater ◽  
Arsenic Content ◽  
Hand Pump ◽  
Excess Iron ◽  
Tube Wells ◽  
Performance Results

Abstract Pilot-scale performance in reducing excess iron and arsenic from contaminated groundwater has been systematically reported. Here, a double column unit, the first packed with β-MnO2 and the second with crystalline FeOOH (goethite variety), with filters attached to the outlet of hand-pump tube-wells has been used in the field. Results showed that the filters generate 10,000 to 15,000 BV and 19,000 to 35,000 BV water with iron ≤ 0.3 mg/L and arsenic ≤10 µg/L from groundwater having influent iron and arsenic levels of 3.75 to 7.25 mg/L and 70 to 220 µg/L, respectively. The downflow rate of effluent water was 237.6 to 305.5 L/m2-min. The performance results were achieved with a single charging of the iron and arsenic removal media. Toxicity characteristic leaching procedure (TCLP) tests of the waste (arsenic content: 2.4 g/kg) showed that it is not hazardous to the environment and does not pose any risk to users. Cost evaluation showed $US0.50 to 0.70 per 1000 gallons of treated water and, hence, the technology is cost-effective for countries such as India and Bangladesh.

scholarly journals Arsenic Removal from Water by Green Synthesized Magnetic Nanoparticles

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2520
Author(s):  
Jasmina Nikić ◽  
Aleksandra Tubić ◽  
Malcolm Watson ◽  
Snežana Maletić ◽  
Marko Šolić ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Arsenic Removal ◽  
Low Cost ◽  
High Capacity ◽  
Bet Surface Area ◽  
Arsenic Adsorption ◽  
Promising Alternative ◽  
Antioxidant Power ◽  
Corn Silk ◽  
Onion Peel

Magnetite nanoparticles were synthesized by a simple and ecofriendly method using onion peel (MNp-OP) and corn silk extract (MNp-CS), in order to develop new low-cost adsorbents for arsenic removal from groundwater. As a point of comparison, magnetite nanoparticles were also synthesized with a conventional chemical process (MNp-CO). The antioxidant potential of onion peel and corn silk extracts was determined using ferric reducing antioxidant power (FRAP) and free radical (DPPH) scavenging assays, including the total phenolics, flavonoids and tannins contents. The synthesized magnetite nanoparticles were characterised using different techniques (Scanning electron microscope/Energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analyzer). The adsorption capacity of MNp-OP and MNp-CS and the arsenic removal mechanism of these novel adsorbents was investigated through kinetic and equilibrium experiments and their corresponding mathematical models. Characterisation of MNp-OP and MNp-CS shows high BET specific surface areas of 243 m2/g and 261 m2/g, respectively. XRD and FTIR analysis confirmed the formation and presence of magnetite nanoparticles. The arsenic adsorption mechanism on MNp-OP, MNp-CS and MNp-CO involves chemisorption, intraparticle and external diffusion. Maximal adsorption capacities of MNp-OP, MNp-CS and MNp-CO were 1.86, 2.79, and 1.30 mg/g respectively. The green synthesis applied using onion peel and corn silk extracts was cost effective and environmentally friendly, and results in adsorbents with a high capacity for arsenic and magnetic properties, making them a very promising alternative approach in the treatment of arsenic contaminated groundwater.

scholarly journals A deep learning approach to automatic gingivitis screening based on classification and localization in RGB photos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wen Li ◽  
Yuan Liang ◽  
Xuan Zhang ◽  
Chao Liu ◽  
Lei He ◽  
...  
Keyword(s):  
Deep Learning ◽  
Low Income ◽  
Dental Health ◽  
Area Under The Curve ◽  
Cost Effective ◽  
General Purpose ◽  
Dental Calculus ◽  
Task Learning ◽  
Large Populations ◽  
Dental Diseases

AbstractRoutine dental visit is the most common approach to detect the gingivitis. However, such diagnosis can sometimes be unavailable due to the limited medical resources in certain areas and costly for low-income populations. This study proposes to screen the existence of gingivitis and its irritants, i.e., dental calculus and soft deposits, from oral photos with a novel Multi-Task Learning convolutional neural network (CNN) model. The study can be meaningful for promoting the public dental health, since it sheds light on a cost-effective and ubiquitous solution for the early detection of dental issues. With 625 patients included in this study, the classification Area Under the Curve (AUC) for detecting gingivitis, dental calculus and soft deposits were 87.11%, 80.11%, and 78.57%, respectively; Meanwhile, according to our experiments, the model can also localize the three types of findings on oral photos with moderate accuracy, which enables the model to explain the screen results. By comparing to general-purpose CNNs, we showed our model significantly outperformed on both classification and localization tasks, which indicates the effectiveness of Multi-Task Learning on dental disease detection. In all, the study shows the potential of deep learning for enabling the screening of dental diseases among large populations.

scholarly journals New Aerogel Products for Construction Use: Product Specifications, Application Examples, Practical Aspects

2020 ◽  
Vol 172 ◽  
pp. 21005
Author(s):  
Eva Günther ◽  
Marc Fricke ◽  
Wibke Lölsberg ◽  
Arne Klinkebiel ◽  
Dirk Weinrich
Keyword(s):  
High Performance ◽  
Cost Effective ◽  
General Purpose ◽  
Water Repellent ◽  
Knudsen Effect ◽  
Insulation Materials ◽  
Key Characteristics ◽  
Structural Details ◽  
Problem Solvers ◽  
Product Specifications

Two new high-performance insulation materials (HPIM) for the usage in buildings are presented. We show how to use and apply the upcoming aerogel products and give examples for structural details. While both materials achieve very low lambda values due to Knudsen-Effect of aerogels, they differ clearly in other key characteristics. SLENTEX® is a slim, mechanically flexible, non-combustible aerogel mat. It is open for water vapor diffusion but water-repellent. It is suitable for applications with strict fire regulations since it is a purely mineral-based product. SLENTITE® is a homogeneous polyurethane-based aerogel insulation board without lamination or encapsulation layers and also vapor open. Its surface adheres to almost any organic or inorganic binder. It can be processed very much like conventional insulation boards. While their handling and application are very similar to other insulation materials, aerogels are however no general-purpose insulation products: due to their sophisticated production process, and thus higher price compared to conventional insulation products, HPIM are best applied as problem solvers. In well-motivated situations, e.g. where space is limited or particular aesthetic requirements apply, they offer cost effective alternatives to standard solutions.

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