Effect of pH on Four Defluoridation Adsorbents under Natural High Fluoride Groundwater

2014 ◽  
Vol 643 ◽  
pp. 335-341
Author(s):  
Lian Xiang Li ◽  
Di Xu ◽  
Xian Jun Cheng ◽  
Rui Gang Sun ◽  
Xiao Qin Li
Keyword(s):  
Drinking Water ◽  
Field Performance ◽  
Activated Alumina ◽  
Adsorption Method ◽  
Adsorption Effect ◽  
Application Systems ◽  
High Fluoride ◽  
Actual Field ◽  
Ph Range ◽  
Filed Application

Appropriate drinking water defluoridation technology is urgently needed in china, which has a wide fluoride-rich area. The adsorption defluoridation method in the industrial high fluoride wastewater treatment is generally considered to be efficient and economic. However, the practical application of the method is not ideal in obtaining drinking water defluoridation. Four representative adsorbents activated alumina, activated zeolite, hydroxyapatite and hydrous zirconium oxide have been tested in terms of defluoridation efficiency under natural high fluoride groundwater and compared to clarify existing problems of adsorption methods. Results show that pH significantly affected adsorption efficiency. The adsorbents have low adsorption capacity under natural high fluoride groundwater and can achieve good adsorption effect under acidic conditions. However, in adjusting the water to the appropriate pH range, the adsorption method loses its advantages of convenience and affordability. Therefore, any adsorbent should be tested with actual field waters before designing filed application systems. Further research is also warranted in evaluating the field performance and the economic acceptance of the proposed method.

PTSA (pressure and thermal swing adsorption) method to remove trihalomethanes from drinking water

1997 ◽  
Vol 35 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Shigekazu Nakano ◽  
Tomoko Fukuhara ◽  
Masami Hiasa
Keyword(s):  
Drinking Water ◽  
Residual Chlorine ◽  
Remarkable Difference ◽  
Adsorption Method ◽  
Heating And Cooling ◽  
Point Of Use ◽  
Thermal Swing Adsorption ◽  
Long Time ◽  
Musty Odor ◽  
Vacuum Heating

It has been widely recognized that trihalomethanes (THMs) in drinking water pose a risk to human health. THMs can be removed to a certain extent by the conventional point-of-use (POU) unit which is composed of activated carbon (AC) and microfilter. But it's life on THMs is relatively shorter than on residual chlorine or musty odor. To extent the life of AC adsorber, pressure and thermal swing adsorption (PTSA) was applied by preferential regeneration of chloroform. PTSA was effective to remove THMs, especially chloroform. Adsorption isotherms of chloroform at 25 and 70°C showed a remarkable difference so that thermal swing was considered effective. Chloroform was also desorbed by reducing pressure. By vacuum heating at 70°C, chloroform was almost desorbed from AC and reversible adsorption was considered possible. A prototype of POU unit with PTSA was proposed. Regeneration mode would consist of dewatering, vacuum heating and cooling (backwashing). The unit was maintained in bacteriostatic condition and could be used for a long time without changing an AC cartridge.

scholarly journals Hydrochemical Characterisation of High-Fluoride Groundwater and Development of a Conceptual Groundwater Flow Model Using a Combined Hydrogeological and Hydrochemical Approach on an Active Volcano: Mount Meru, Northern Tanzania

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2159
Author(s):  
George Bennett ◽  
Jill Van Reybrouck ◽  
Ceven Shemsanga ◽  
Mary Kisaka ◽  
Ines Tomašek ◽  
...  
Keyword(s):  
Drinking Water ◽  
Large Scale ◽  
Active Volcano ◽  
Aquifer System ◽  
Groundwater Samples ◽  
Northern Tanzania ◽  
Different Seasons ◽  
High Fluoride ◽  
Arusha National Park ◽  
The Impact

This study characterises high-fluoride groundwater in the aquifer system on the flanks of Mount Meru, focusing on parts of the flanks that were only partially or not at all covered by previous research. Additionally, we analyse the impact of rainwater recharge on groundwater chemistry by monitoring spring discharges during water sampling. The results show that the main groundwater type in the study area is NaHCO3 alkaline groundwater (average pH = 7.8). High F− values were recorded: in 175 groundwater samples, the concentrations range from 0.15 to 301 mg/L (mean: 21.89 mg/L, median: 9.67 mg/L), with 91% of the samples containing F− values above the WHO health-based guideline for drinking water (1.5 mg/L), whereas 39% of the samples have Na+ concentrations above the WHO taste-based guideline of 200 mg/L. The temporal variability in F− concentrations between different seasons is due to the impact of the local groundwater recharge. We recommend that a detailed ecohydrological study should be carried out for the low-fluoride springs from the high-altitude recharge areas on the eastern and northwestern flanks of Mount Meru inside Arusha National Park. These springs are extracted for drinking purposes. An ecohydrological study is required for the management of these springs and their potential enhanced exploitation to ensure the sustainability of this water extraction practice. Another strategy for obtaining safe drinking water could be to use a large-scale filtering system to remove F− from the groundwater.

A Comprehensive Treatise of the High Temperature Specification Parameter |G*|/(1-(1/tanδsinδ)) for Performance Grading of Asphalts

2004 ◽  
Vol 14 (6) ◽  
pp. 303-314 ◽  
Author(s):  
Aroon Shenoy
Keyword(s):  
High Temperature ◽  
Field Performance ◽  
Performance Data ◽  
Asphalt Binders ◽  
Theoretical Derivation ◽  
Comprehensive Treatise ◽  
Actual Field ◽  
Rutting Behavior ◽  
Performance Grading ◽  
Unrecovered Strain

Abstract The term |G*|/(1-(1/tanδ sinδ)) has been suggested as one of the best candidates for the replacement of the Super-pave specification parameter |G*|/sinδ, which has been found to be inadequate in rating polymer-modified binders for high temperature performance grading. This refinement of the Superpave specification parameter evolved through a theoretical derivation based on fundamental concepts. It was shown to be more sensitive to the variations in the phase angle δ than the original Superpave specification parameter. It thus described the unrecovered strain in the asphalt binders more accurately, and hence related to actual field performance data. This article provides a comprehensive treatise of the parameter |G*|/(1-(1/tanδ sinδ)) giving details of its derivation, salient features that are attributed to its success, comparison with actual field performance data for validation and a one-on-one comparison with the existing parameter |G*|/sinδ. It is shown that for all available field data, the parameter |G*|/(1-(1/tanδ sinδ)) does a better job in correlating with the rutting behavior than the parameter |G*|/sinδ for unmodified as well as modified asphalts. Since it is obtained in the same manner as the parameter |G*|/sinδ through the determination of |G*| and δ from a stress-controlled or strain-controlled dynamic shear rheometer, it means that no retraining of technicians and staff is required and implementation for the use of this parameter is immediate, thereby saving enormous amount of time and money. This parameter has the further advantage of being in a form easily adaptable to modeling, and thereby directly applicable for pavement design purposes.

scholarly journals Solid phase selective separation and green preconcentration of Cu, Zn, Pb and Cd in drinking water by using novel functionalized resin

2009 ◽  
Vol 7 (4) ◽  
pp. 945-954 ◽  
Author(s):  
Nagwa Burham ◽  
Sami Azeem ◽  
Mohamed El-Shahat
Keyword(s):  
Drinking Water ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Exchange Capacity ◽  
Coupling Reactions ◽  
Lead And Cadmium ◽  
Sample Flow Rate ◽  
Relative Standard ◽  
Copper Zinc ◽  
Ph Range

AbstractA new solid — phase extraction sorbent was developed based on stepwise anchoring of two ligand molecules for the determination of copper, zinc, lead and cadmium in drinking water by flame AAS. Amberlite XAD-2 functionalized with 4′-(2-hydroxyphenylazo)-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one (HPAPyr) was utilized for preconcentration/separation of these elements. The sorbent was prepared by two successive azo coupling reactions. First, 2-aminophenol was anchored to the amino groups in the resin resulted from nitration followed by reduction. Then, the resulted 2-aminophenol functionalized resin was further diazotized and coupled to the pyrazolone compound and the final product HPAPyr-XAD-2 was characterized by IR and elemental analysis. The optimum pH range for sorption, shaking time, exchange capacity, sample flow rate, preconcentration factor and interference from co-existing ions were investigated. All metal ions were quantitatively desorbed from the resin by 4.5 mol L−1 nitric acid solution. The sorbent provides limit of detection within the range 0.9–3.3 µg L−1 and concentration factor up to 250. The procedure was validated by analysis of certified material NIST-SRM 1577b. Application to drinking water showed satisfactory results with relative standard deviation RSD ≤ 8.5%.

Chronic Lead Exposure of Rats: Open-Field Performance

1982 ◽  
Vol 55 (2) ◽  
pp. 487-490 ◽  
Author(s):  
Charles R. Geist ◽  
Jeffrey E. Praed
Keyword(s):  
Drinking Water ◽  
Weight Gain ◽  
Open Field ◽  
Lead Exposure ◽  
Lead Acetate ◽  
Field Performance ◽  
Postnatal Exposure ◽  
Chronic Lead Exposure ◽  
Prenatal Lead Exposure ◽  
Acetate Form

Three groups of male hooded rats were chronically exposed to lead in the acetate form prenatally, as well as postnatally via the dam's milk and in the drinking water, at concentrations of 0 ppm, 19 ppm, and 38 ppm for 35 days. No significant differences were found in weight gain, although significant increases in food consumption were noted in animals receiving 19 ppm lead acetate and increased ingestion of lead acetate in animals receiving 19 ppm and 38 ppm. When subjects were tested in an open-field task, no significant differences were found in emotionality, the number of squares traversed, frequency and duration of rearing, or in frequency of grooming. However, subjects receiving 38 ppm lead displayed a significant reduction in duration of grooming when compared to animals receiving either 19 ppm or 0 ppm. The results suggest that prenatal lead exposure, followed by postnatal exposure, may affect some elements of activity, while having little effect on others.

Arsenic in drinking water-problems and solutions

1999 ◽  
Vol 40 (2) ◽  
pp. 69-76 ◽  
Author(s):  
T. Viraraghavan ◽  
K. S. Subramanian ◽  
J. A. Aruldoss
Keyword(s):  
United States ◽  
Drinking Water ◽  
Ion Exchange ◽  
Environmental Protection Agency ◽  
The United States ◽  
Activated Alumina ◽  
Column Studies ◽  
Maximum Contaminant Level ◽  
Aluminum Salts ◽  
Contaminant Level

The current United States maximum contaminant level for arsenic in drinking water is set at 50 μg/l. Because of the cancer risks involved, Canada has already lowered the maximum contaminant level to 25 μg/l; the United States Environmental Protection Agency is reviewing the current allowable level for arsenic with a view of lowering it significantly. Various treatment methods have been adopted to remove arsenic from drinking water. These methods include 1) adsorption-coprecipitation using iron and aluminum salts, 2) adsorption on activated alumina, activated carbon, and activated bauxite, 3) reverse osmosis, 4) ion exchange and 5) oxidation followed by filtration. Because of the promise of oxidation-filtration systems, column studies were conducted at the University of Regina to examine oxidation with KMnO4 followed by filtration using manganese greensand and iron-oxide coated sand to examine the removal of arsenic from drinking water; these results were compared with the data from ion exchange studies. These studies demonstrated that As (III) could be reduced from 200 μg/l to below 25 μg/l by the manganese greensand system. In the case of manganese greensand filtration, addition of iron in the ratio of 20:1 was found necessary to achieve this removal.

Study of a New Adsorbent for Fluoride Removal from Waters

1995 ◽  
Vol 30 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Wang Rongshu ◽  
Li Haiming ◽  
Na Ping ◽  
Wang Ying
Keyword(s):  
High Temperature ◽  
High Selectivity ◽  
Adsorption Process ◽  
Field Tests ◽  
Neutral Medium ◽  
Fluoride Removal ◽  
Removal Mechanism ◽  
Activated Alumina ◽  
High Fluoride ◽  
The One

Abstract A new adsorbent for fluoride removal is reported in this study. The process and mechanism of removing fluoride are also reported. The adsorbent was characterized as having high selectivity for fluoride, large adsorption capacity, applicability to neutral medium and much better adsorption at high temperature. The floride removal mechanism is a typical chemisorption which is different from the one used for activated alumina. Adsorption rate was considerably faster at the beginning of the adsorption process, followed by a much slower porous diffusion process. Results of field tests showed that the adsorbent was much more suitable for treating high temperature geothermal water with high fluoride content. It also had the advantages of reducing turbidity, decolorizing, dealkalizing, and removing iron from drinking water.

Actual field performance of a standalone PV mobile-charging station in Serdang, Malaysia

2019 ◽  
Author(s):  
N. I. Ismail ◽  
A. N. Iskandar ◽  
M. N. Mohtar ◽  
M. E. Ya’acob
Keyword(s):  
Field Performance ◽  
Charging Station ◽  
Actual Field

scholarly journals Enhanced virus filtration in hybrid membranes with MWCNT nanocomposite

2019 ◽  
Vol 6 (1) ◽  
pp. 181294 ◽  
Author(s):  
Zoltán Németh ◽  
Gergő Péter Szekeres ◽  
Mateusz Schabikowski ◽  
Krisztina Schrantz ◽  
Jacqueline Traber ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drinking Water ◽  
Electrostatic Interactions ◽  
Membrane Separation ◽  
Area Measurement ◽  
Hybrid Membranes ◽  
Potential Measurement ◽  
Virus Removal ◽  
Multi Walled Carbon Nanotubes ◽  
Ph Range

Membrane separation is proved to be a powerful tool for several applications such as wastewater treatment or the elimination of various microorganisms from drinking water. In this study, the efficiency of inorganic composite-based multi-walled carbon nanotube (MWCNT) hybrid membranes was investigated in the removal of MS2 bacteriophages from contaminated water. With this object, multi-walled carbon nanotubes were coated with copper(I) oxide, titanium(IV) oxide and iron(III) oxide nanoparticles, respectively, and their virus removal capability was tested in both batch and flow experiments. Considering the possible pH range of drinking water, the filtration tests were carried out at pH 5.0, 7.5 and 9.0 as well. The extent of MS2 removal strongly depended on the pH values for each composite, which can be due to electrostatic interactions between the membrane and the virus. The most efficient removal (greater than or equal to 99.99%) was obtained with the Cu 2 O-coated MWCNT membrane in the whole pH range. The fabricated nanocomposites were characterized by X-ray diffraction, specific surface area measurement, dynamic light scattering, zeta potential measurement, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. This study presents a simple route to design novel and effective nanocomposite-based hybrid membranes for virus removal.

Sign in / Sign up

Export Citation Format

Share Document