2,631 research outputs found
Trace Contaminant Removal using Hybrid Membrane Processes in Water Recycling
Water recycling plays an essential role in integrated water management, especially in an arid country like Australia
but also worldwide [1]. Water recycling, however, has suffered extensive constraints due to "toilet to tap" media
campaigns and "yuck factor" attitudes in the community. The support of the community for water recycling projects
generally decreases as the personal contact with the recycled water increases [2]. Some of the very valid concerns of the
community stem from uncertainties involved in water recycling, such as the issue of persistent organic pollutants (POPs)
potentially present in recycled waters or the ever growing group of endocrine disrupting chemicals have been of
particular concern to sections of the community.
Endocrine disrupters have the potential to interfere with our normal growth, development and reproduction.
Modulation of that system could cause severe adverse health effects. Industrial chemicals, consumer chemicals and
chemicals in the environment can be endocrine disrupters that mimic, enhance or inhibit the action of hormones [3, 4].
Sewage disposal to water sources may be a major exposure pathway for pharmaceuticals, synthetic and natural
hormones, industrial chemicals to humans and wildlife, directly and via the food chain. This concerns disposal of
treated effluents and applications of recycled water.
This paper aims to address some of the uncertainties and risks involved in recycling technology and aims to stress
caution and the need for well designed recycling projects. This risk expands to water treatment in situations where
contaminated waters are treated
The role of proton precipitation in Jovian aurora: Theory and observation
It was proposed that the Jovian auroral emissions observed by Voyager spacecraft could be explained by energetic protons precipitating into the upper atmosphere of Jupiter. Such precipitation of energetic protons results in Doppler-shifted Lyman alpha emission that can be quantitatively analyzed to determine the energy flux and energy distribution of the incoming particle beam. Modeling of the expected emission from a reasonably chosen Voyager energetic proton spectrum can be used in conjunction with International Ultraviolet Explorer (IUE) observations, which show a relative lack of red-shifted Lyman alpha emission, to set upper limits on the amount of proton precipitation taking place in the Jovian aurora. Such calculations indicate that less than 10 percent of the ultraviolet auroral emissions at Jupiter can be explained by proton precipitation
Yosemite Conference on Ionospheric Plasma in the Magnetosphere: Sources, Mechanisms and Consequences, meeting report
The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. Due to the recent changes in our perception of the dynamics of the ionospheric/magnetospheric system, it was deemed timely to bring researchers together to discuss and contrast the relative importance of solar versus terrestrial sources of magnetospheric plasma. Although the solar wind was once thought to dominate the supply of plasma in the Earth's magnetosphere, it is now thought that the Earth's ionosphere is a significant contributor. Polar wind and other large volume outflows of plasma have been seen at relatively high altitudes over the polar cap and are now being correlated with outflows found in the magnetotail. The auroral ion fountain and cleft ion fountain are examples of ionospheric sources of plasma in the magnetosphere, observed by the Dynamics Explorer 1 (DE 1) spacecraft. The conference was organized into six sessions: four consisting of prepared oral presentations, one poster session, and one session for open forum discussion. The first three oral sessions dealt separately with the three major topics of the conference, i.e., the sources, mechanisms, and consequences of ionospheric plasma in the magnetosphere. A special session of invited oral presentations was held to discuss extraterrestrial ionospheric/magnetospheric plasma processes. The poster session was extended over two evenings during which presenters discussed their papers on a one-on-one basis. The last session of the conferences was reserved for open discussions of those topics or ideas considered most interesting or controversial
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Scientific rationale of a Saturn probe mission
We describe the main scientific goals to be addressed by future in situ exploration of Saturn
DE 1 RIMS operational characteristics
The Retarding Ion Mass Spectrometer (RIMS) on the Dynamics Explorer 1 spacecraft observes both the thermal and superthermal (50 eV) ions of the ionosphere and inner magnetosphere. It is capable of measuring the detailed species distribution function of these ions in many cases. It was equipped with an integral electrometer to permit in-flight calibration of the detector sensitivities and variations thereof. A guide to understanding the RIMS data set is given. The reduction process from count rates to physical quantities is discussed in some detail. The procedure used to establish in-flight calibration is described, and results of a comparison with densities from plasma wave measurements are provided. Finally, a discussion is provided of various anomalies in the data set, including changes of channeltron efficiency with time, spin modulation of the axial sensor heads, apparent potential differences between the sensor heads, and failures of the radial head retarding potential sweep and of the -Z axial head aperture plane bias. Studies of the RIMS data set should be conducted only with a thorough awareness of the material presented here, or in collaboration with one of the scientists actively involved with RIMS data analysis
Adsorptive interactions between membranes and trace contaminants
Widespread occurrences of endocrine-disrupting chemicals (EDCs) in waterways have attracted a great attention of the scientific community. While scientific evidence associated with human health is restricted due to the long-term effects, impacts of EDCs on trout at the common concentration encountered in sewage effluent have been confirmed by both in vitro and in vivo studies. The impacts of steroid estrogens such as estrone, estradiol (natural hormones) and ethinylestradiol (a synthetic hormone) are often more serious than other synthetic EDCs as they have far higher endocrine-disrupting potency, despite of their low concentration. This paper investigates retention and adsorptive behavior of the natural hormones estrone by two commercial reverse osmosis membranes TFC-S and X-20, using dead end stirred cell systems. While an adsorptive process that reaches a breakthrough governs the retention of estrone by the TFC-S membrane; a sieving mechanism is responsible for the high removal of estrone using the X-20 membrane
Removal of the Natural Hormone Estrone from Aqueous Solutions using Nanofiltration and Reverse Osmosis
The ability of a variety of nanofiltration and reverse osmosis membranes to retain the natural
hormone estrone are examined here as a function of solution conditions. While size exclusion
dominates retention with the tighter membranes, both size exclusion and adsorptive effects appear
to be instrumental in maintaining high retention on nanofiltration membranes that otherwise exhibit
relatively low ion retentions. These adsorptive effects may be driven by hydrogen bonding between
estrone and the membrane. Electrostatic attraction appears to aid retention with an apparent slight
decrease in retention at high NaCl concentrations. Deprotonation of estrone leads to a significant
decrease in retention, most likely as a result of the effect of strong electrostatic repulsive forces
decreasing the proximity of the negatively charged estrone to the negatively charged membrane
surface and thus lowering the potential for adsorptive retention. This deprotonation effect is absent
for tight RO membranes. The results reported here indicate that while open nanofiltration
membranes may be effective in retaining estrone under some conditions, the extent of retention may
be very susceptible to maintenance of adsorptive capacity at the membrane surface and depend on
solution chemistry
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