Desalination, desalinization, and desalinisation refer to any of several processes that remove some amount of salt and other minerals from saline water. More generally, desalination may also refer to the removal of salts and minerals, as in soil desalination, which also happens to be a major issue for agricultural production. Salt water is desalinated to produce fresh water suitable for human consumption or irrigation. One potential byproduct of desalination is salt. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use. Due to relatively high energy consumption, the costs of desalinating sea water are generally higher than the alternatives (fresh water from rivers or groundwater, water recycling and water conservation), but alternatives are not always available and rapid overdraw and depletion of reserves is a critical problem worldwide.
Multiple-effect distillationMultiple-effect distillation (MED) is a distillation process often used for sea water desalination. It consists of multiple stages or "effects". In each stage the feed water is heated by steam in tubes. The tubes can be submerged in the feed water, but more typically the feed water is sprayed on the top of a bank of horizontal tubes, and then drips from tube to tube until it is collected at the bottom of the stage. Operating principles Schematic of a multiple effect desalination plant. The plant can be seen as a sequence of closed spaces separated by tube walls, with a heat source in one end and a heat sink in the other end. Trade-offs The thinner the metal in the tubes and the thinner the layers of liquid on either side of the tube walls, the more efficient is the energy transport from space to space. The first and last stages need external heating and cooling respectively. External feed water must be supplied to the first stage. Advantages See also
Fresh Water Scarcity And Cost-Effective DesalinationBy Greg Borzo The scarcity of fresh water is an increasingly serious problem around the world due to growing populations and diminishing supplies of fresh water. Desalination could help alleviate these shortages, but it has traditionally been an extremely expensive process. The demand for water is so great that the worldwide desalination market is expected to reach an astonishing $87.8 billion by 2016, even though only about 1 percent of the world’s drinking water is produced by desalination. To help meet this need, the Innovation Fund, the University of Chicago’s venture philanthropic proof-of-concept fund, awarded Heinrich Jaeger, the William J. “In order for desalination to become a real solution to the growing water scarcity problem, new technologies will be required to reduce the major cost components of the process,” says Sean Sheridan, an assistant director at UChicagoTech, which administers the Innovation Fund.
Learning package on Hydrology by the National Institute of Hydrology | India Water PortalA "Learning Package on Hydrology" by the National Institute of Hydrology deals with elements of the hydrologic cycle and explains the processes of rainfall, runoff and evapotranspiration and their interaction. This “Learning Package on Hydrology” by the National Institute of Hydrology deals with the basic scientific concepts underlying hydrology. In a general sense the package deals with elements of the hydrologic cycle and explains the processes of rainfall, runoff and evapotranspiration and their interaction. The topics covered include precipitation, abstraction from precipitation, streamflow measurement, hydrographs, flood routing, flood control, groundwater, runoff and floods. The package deals with the occurrence, circulation and distribution of water of the earth and earth's atmosphere. Various phases of the hydrological cycle, such as rainfall, runoff, evaporation and transpiration are all non-uniformly distributed both in time and space. Download the learning package here:
Engineers develop revolutionary nanotech water desalination membraneResearchers at the UCLA Henry Samueli School of Engineering and Applied Science today announced they have developed a new reverse osmosis (RO) membrane that promises to reduce the cost of seawater desalination and wastewater reclamation. Reverse osmosis desalination uses extremely high pressure to force saline or polluted waters through the pores of a semi-permeable membrane. Water molecules under pressure pass through these pores, but salt ions and other impurities cannot, resulting in highly purified water. The new membrane, developed by civil and environmental engineering assistant professor Eric Hoek and his research team, uses a uniquely cross-linked matrix of polymers and engineered nanoparticles designed to draw in water ions but repel nearly all contaminants. These new membranes are structured at the nanoscale to create molecular tunnels through which water flows more easily than contaminants. With these improvements, less energy is needed to pump water through the membranes.
Water and Conflict in Asia?Water security is emerging as an increasingly important and vital issue for the Asia-Pacific region. Perhaps no other resource—other than oxygen—is so intricately linked to human health and survival. However, as the region’s population growth continues to surge, the demand for water is increasing substantially, without a concomitant increase in water resources. Many Asian countries are beginning to experience moderate to severe water shortages, brought on by the simultaneous effects of agricultural growth, industrialization, and urbanization. To explore this complex issue, the Asia-Pacific Center for Security Studies (APCSS) held a one-day seminar on September 17, 1999 entitled “Water and Conflict in Asia.” The world’s freshwater supply is finite. When analyzing freshwater and its relationship to human consumption, it is useful to delineate two concepts: availability vs. access. The Availability Issue: Is Asia Running Out of Freshwater? India is experiencing similar shortages.
Toxic shock: California allows up to one thousand times more glyphosate in drinking water than needed to cause breast cancer in women(NaturalNews) Late last week, a story broke that revealed glyphosate -- the chemical name of Roundup herbicide -- multiplies the proliferation of breast cancer cells by 500% to 1300%... even at exposures of just a few parts per trillion (ppt). The study, published in Food and Chemical Toxicology, is entitled, "Glyphosate induces human breast cancer cells growth via estrogen receptors." You can read the abstract here. There's a whole lot more to this story, however, but to follow it, you need to understand these terms: ppm = parts per million = 10 (-6) = number of parts out of a million ppb = parts per billion = 10 (-9), which is 1,000 times smaller than ppm ppt = parts per trillion = 10 (-12), which is 1,000 times smaller than ppb and 1,000,000 times smaller than ppm The study found that breast cancer cell proliferation is accelerated by glyphosate in extremely low concentrations: ppt to ppb. This news, all by itself, sent shockwaves across the 'net all weekend. The document openly admits: