Arsenic removal by a membrane hybrid filtration system

Arsenic is a toxic semi-metallic element that can be fatal to human health. Membrane filtration can remove a number of contaminants from water, including arsenic. Removal of arsenic by membrane filtration is highly dependent on the species of arsenic and the properties of the membrane. The performance of the nanofilter is better for removing As(V) than As(III). About 57% of As(III) and 81% of As(V) was removed from 500 mg/L arsenic solutions by nanofiltration (NTR729HF, Nitto Denko Corp., Japan) of 700 molecular weight (MW) cutoff. The removal efficiency of microfiltration (MF) was much lower than that of nanofiltration (NF) due to its larger pore size. By comparison only 37% of As(III) and 40% of As(V) were removed by microfiltration (PVA membrane, Pure-Envitech, Korea). However, the removal efficiency of microfiltration was increased dramatically when a small amount of nanoscale zero valent iron (nZVI) was added. The removal efficiency by MF increased up to 90% with As(V) and 84% with As(III) when an amount of 0.1 g/L of nZVI was added into the arsenic solution. © 2008 Elsevier B.V. All rights reserved

Serially connected forward osmosis membrane elements of pressure-assisted forward osmosis-reverse osmosis hybrid system: Process performance and economic analysis

© 2018 Elsevier B.V. Due to the improved dilution of draw streams, employing pressure-assisted forward osmosis (PAFO) to the hybrid system of forward osmosis (FO) followed by reverse osmosis (RO) for seawater desalination has been expected to reduce the overall economics. However, replacing FO with PAFO causes an additional energy cost in the seawater dilution step which inevitably leads to a question that PAFO-RO hybrid is truly an economically beneficial option. More importantly, though serial connection of FO elements improves the dilution of initial draw water, this economic benefit is also compensated with the additional membrane. To rationalize its overall performance and economic benefit, thorough performance and economic evaluations were conducted based on actual pilot-scale PAFO operations for serial connection of up to three 8040 FO elements. The results showed the FO-RO hybrid is not an economically feasible option unless a significant unit FO element cost cut-down is guaranteed. Meanwhile, PAFO-RO showed benefits with regards to target RO recovery and unit FO element cost, particularly when two FO elements are serially connected (SE2). It was found that PAFO-RO, indeed, has higher economic potential than FO-RO. A graphical overlapping method suggested in this work can help determine optimal serial configuration and operating conditions of PAFO-RO

Graphene Schottky diodes: an experimental review of the rectifying graphene/semiconductor heterojunction

In the past decade graphene has been one of the most studied material for several unique and excellent properties. Due to its two dimensional nature, physical and chemical properties and ease of manipulation, graphene offers the possibility of integration with the exiting semiconductor technology for next-generation electronic and sensing devices. In this context, the understanding of the graphene/semiconductor interface is of great importance since it can constitute a versatile standalone device as well as the building-block of more advanced electronic systems. Since graphene was brought to the attention of the scientific community in 2004, the device research has been focused on the more complex graphene transistors, while the graphene/semiconductor junction, despite its importance, has started to be the subject of systematic investigation only recently. As a result, a thorough understanding of the physics and the potentialities of this device is still missing. The studies of the past few years have demonstrated that graphene can form junctions with 3D or 2D semiconducting materials which have rectifying characteristics and behave as excellent Schottky diodes. The main novelty of these devices is the tunable Schottky barrier height, a feature which makes the graphene/semiconductor junction a great platform for the study of interface transport mechanisms as well as for applications in photo-detection, high-speed communications, solar cells, chemical and biological sensing, etc. In this paper, we review the state-of-the art of the research on graphene/semiconductor junctions, the attempts towards a modeling and the most promising applications.Comment: 85 pages. Review articl

Early Diagnosis of HIV Infection in Infants - One Caribbean and Six Sub-Saharan African Countries, 2011-2015.

Pediatric human immunodeficiency virus (HIV) infection remains an important public health issue in resource-limited settings. In 2015, 1.4 million children aged 50% decline. The most common challenges for access to testing for early infant diagnosis included difficulties in specimen transport, long turnaround time between specimen collection and receipt of results, and limitations in supply chain management. Further reductions in HIV mortality in children can be achieved through continued expansion and improvement of services for early infant diagnosis in PEPFAR-supported countries, including initiatives targeted to reach HIV-exposed infants, ensure access to programs for early infant diagnosis of HIV, and facilitate prompt linkage to treatment for children diagnosed with HIV infection

SUBSTANTION AND STUDY OF ALGORITHNS OF ANALYTICAL PHOTOTRIANGULATION WITH ADDED DATA

There the determination procedure of requirements for accuracy of phototriangulation has been grounded; the mathematical simulators of variants of analytical phototriangulation with added data have been developed. The developed program set allows to use effectively the added data in the phototriangulation procerss in creation of large-scale topographic maps for the territory of Socialist Republic of Vietnam. The variants of analitical phototriangulation process with added data in the large-scale map-making have beem introduced. The bodies of aerophotography, of laboratory and field works in creation of large-scale topographic maps have been decreasedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

DEP GIS Mapping Effectiveness

Abstract Water and sewer utilities across the country are struggling with aging infrastructure. Simultaneously, climate change is causing more extremes in temperature as well as increasing frequency and strength of storms. As a result, water and sewer systems are increasingly susceptible to damage. The use of a Geographic Information System (GIS) has become an important tool for both water and sewer utilities to manage their systems and increase preparedness for climate change. Our project sponsored by The Massachusetts Department of Environmental Protection evaluated the work done through the Water Utility Resilience Program. This program provided water utilities with Geographic Information System data and training done by Tighe & Bond. We found water utilities need assistance training GIS staff

The performance of contact flocculation-filtration as pretreatment of seawater reverse osmosis

Deep bed filtration has traditionally been used as a pretreatment in seawater desalination. The performance of contact flocculation-filtration (CFF) as pretreatment of seawater reverse osmosis (SWRO) was evaluated in terms of pressure drop through the filter and removal of organics and turbidity. The average turbidity, total suspended solids, and dissolved organic carbon (DOC) of raw seawater were 0.92 NTU, 3.6, and 1.12mg/L, respectively. The performances of CFF were experimentally evaluated with different flocculant doses (0.5-3.0mg Fe3+/L) and rapid mixing times (1.7-14.4 s). Here rapid mixing was performed in a spiral flocculation unit which consisted of a PVC tube of length 0.5m and internal diameters of 0.16 and 0.40 cm. The experimental results show that the filtration rate of 10.0m/h led to an extensive increase in both head loss (pressure drop) and turbidity as compared to those at filtration rates of 5.0 and 7.5 m/h. The head loss also significantly decreased when the flocculant dose was reduced from 3 to 0.5mg Fe3+/L. However, the organic matter (26% of DOC) removal was lower at a lower dose of ferric chloride (1.0 mg/L as Fe3+). The removal efficiency of DOC at low concentration of ferric was improved considerably through the improvement of rapid mixing. The application of CFF process also led to a significant decrease in ultrafiltermodified fouling index (UF-MFI). © 2012 Desalination Publications. All rights reserved

The odd voigt effect under a strong electric field in semiconductors

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Ti-salt flocculation for dissolved organic matter removal in seawater

In this study, the removal of different fractions of organic matter in seawater was investigated using titanium tetrachloride (TiCl4) flocculation and compared with ferric chloride (FeCl3) flocculation. The organic matter fractions were characterised using liquid chromatography-organic carbon detector (LC-OCD). Results showed the hydrophobic compounds removal was dominant by both flocculants. However, the removal of hydrophilic organic compounds, such as humics and low-molecular weight neutral compounds of seawater, was superior by TiCl4 flocculation compared to FeCl3 flocculation and this removal increased considerably with the increase of TiCl4 doses. The flocculated sludge after TiCl4 flocculation was incinerated to produce titanium dioxide (TiO2) nanoparticle. TiO2 from seawater sludge characterised by X-ray diffraction (XRD) and scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS) showed predominant anatase phase with Si as a main dopant. © 2013 Copyright Balaban Desalination Publications