SOURCES AND MECHANISMS OF GROUNDWATER CONTAMINATION DUE TO ARSENIC : A CASE STUDY IN HANOI CITY

Joint Research on Environmental Science and Technology for the Eart

Effects of Activated Carbon and Cationic Exchange Resin Pretreatments on Groundwater Defluoridation by Reverse Osmosis Process

The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25 °C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 × 10-5 compared 9.6 × 10-6 m3/m2•s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved. It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux.The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25°C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 x 10-5 compared 9.6 x10-6 m3/m2·s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved.  It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux

GROUNDWATER CONTAMINATION IN HANOI CITY DUE TO AMMONIA, ARSENIC, IRON AND ORGANIC MATTER

Joint Research on Environmental Science and Technology for the Eart

GROUNDWATER CONTAMINATION IN HANOI CITY DUE TO AMMONIA, ARSENIC, IRON AND ORGANIC MATTER

Joint Research on Environmental Science and Technology for the Eart

Endothelin system in intestinal villi: A possible role of endothelin-2/vasoactive intestinal contractor in the maintenance of intestinal architecture

The endothelin system consists of three ligands (ET-1, ET-2 and ET-3) and at least two receptors (ETA and ETB). In mice ET-2 counterpart is a peptide originally called " vasoactive intestinal contractor" (VIC) for this reason, this peptide is frequently named ET-2/VIC. In intestinal villi, fibroblasts-like cells express endothelin's receptors and response to ET-1 and ET-3 peptides, changing their cellular shape. Several functions have been attributed to these peptides in the " architecture" maintenance of intestinal villi acting over sub-epithelial fibroblasts. Despite this, ET-2/VIC has not been analyzed in depth. In this work we show the intestine gene expression and immunolocalization of ET-1, ET-2 and the ETA and ETB receptors from duodenum to rectus and in the villus-crypt axis in mice, allowing a complete analysis of their functions. While ET-1 is expressed uniformly, ET-2 had a particular distribution, being higher at the bottom of the villi of duodenum, ileum and jejunum and reverting this pattern in the crypts of colon and rectus, where the higher expression was at the top. We postulated that ET-2 would act in a cooperative manner with ET-1, giving to the villus the straight enough to withstand mechanical stress.Fil: Bianchi, Mariana. Universidad Nacional de Entre Ríos. Facultad de Ingeniería. Departamento de Biología. Laboratorio de Microscopía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Adur, Javier Fernando. Universidad Nacional de Entre Ríos. Facultad de Ingeniería. Departamento de Biología. Laboratorio de Microscopía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Takizawa, Satoshi. Institute for Biological Resources and Functions; JapónFil: Saida, Kaname. Soka University; Japón. Institute for Biological Resources and Functions; JapónFil: Casco, Victor Hugo. Universidad Nacional de Entre Ríos. Facultad de Ingeniería. Departamento de Biología. Laboratorio de Microscopía; Argentin

Application of nanofiltration processes to fluoride removal from groundwaters in the Chiang Mai Basin

The highly concentrated fluoride in groundwater has been observed in the confined aquifers of the alluvial sediments in the Chiang Mai Basin. Nanofiltration process was applied to the control of fluoride exposure to the local residents, who have suffered from serious dental and osteal fluorosis. The membrane plants used polyamide nanofilters, which were found to have different fluoride removal rates depending on pH of feed waters. Although fluoride removal rates were high at neutral to basic pH, calcium carbonate scale on the membrane surface was estimated to be the major problem in membrane fouling. Optimum combination of pretreatment in the membrane plant was evaluated through the investigation on the groundwater quality and the operational conditions

CoSix contact resistance after etching and ashing plasma exposure

K. Katahira et al., Journal of Vacuum Science & Technology A 27, 844 (2009) https://doi.org/10.1116/1.313014

PRELIMINARY SURVEY OF WATER ENVIRONMENT PROBLEMS IN HCMC

Joint Research on Environmental Science and Technology for the Eart

Suzaku Observation of Abell 1689: Anisotropic Temperature and Entropy Distributions Associated with the Large-Scale Structure

(Abridged) We present results of Suzaku observations of the intracluster medium (ICM) in Abell 1689, combined with complementary analysis of the SDSS data and weak and strong lensing analysis of Subaru/Suprime-Cam and HST/ACS observations. Faint X-ray emission from the ICM around the virial radius is detected at 4.0 sigma significance. We find anisotropic gas temperature and entropy distributions in cluster outskirts correlated with large-scale structure of galaxies. The high temperature and entropy region in the northeastern (NE) outskirts is connected to an overdense filamentary structure. The outskirt regions in contact with low density void environments have low gas temperatures and entropies, deviating from hydrostatic equilibrium. These results suggest that thermalization of the ICM occurs faster along the filamentary structures than the void regions. A joint X-ray and lensing analysis shows that the hydrostatic mass is $\sim60-90$ of spherical lensing one but comparable to a triaxial halo mass within errors in 0.6r_{2500} \simlt r \simlt 0.8r_{500}, and that it is significantly biased as low as \simlt60% within $0.4r_{2500}$, irrespective of mass models. The thermal gas pressure within $r_{500}$ is, at most, $\sim50$--60% of the total pressure to balance fully the gravity of the spherical lensing mass, and $\sim30$--40% around the virial radius. Although these constitute lower limits when one considers the possible halo triaxiality, these small relative contributions of thermal pressure would require additional sources of pressure, such as bulk and/or turbulent motions.Comment: 24 pages, 15 figures, 9 tables. Accepted for publication in Ap