A new generation of tech uses heat from the sun to provide clean, salt-free water Solar-thermal technologies could process seawater and groundwater to make it drinkable at less cost. Credit: Warren Keelan In an increasingly hot and crowded world, clean water is becoming a precious commodity. Two thirds of the global population will have problems accessing fresh water by 2025, and removing salt and contaminants from the oceans and groundwater is one way to slake humanity's thirst. Today's large desalination plants, though, cost millions of dollars to build. Most use reverse osmosis, which forces seawater through salt-blocking membranes. The required electricity accounts for up to half of a plant's expenses , and the process leaves behind a supersalty, chemical-laced soup that can harm local ecosystems . Such facilities are typically powered by carbon-emitting fossil fuels; efforts have been made (especially in the Middle East, Asia and Africa) to use solar panels instead, ...
Iron is one of the major secondary contaminant in both domestic and industrial water supply. Iron have caused water industries several billions of dollars . Iron is the second most abundant metal in the earth's crust behind Aluminum(8%), of which iron accounts for about 5%. Elemental iron is rarely found in nature, as the iron ions Fe2+ and Fe3+ readily combine with oxygen- and sulfur-containing compounds to form oxides, hydroxides, carbonates, and sulfides. As rain fall, rain water infiltrates the soil and underlying geologic formations and dissolves iron, causing it to seep into aquifers that serve as sources of groundwater for wells. In surface water, such as rivers and lakes, dissolved iron is hardly ever found, because it readily reacts with oxygen, forms insoluble compounds and sinks out into the bottom of the water body. Iron is seldom found at concentrations greater than 10 milligrams per liter (mg/L) or 10 parts per million. The iron that seep into the sources of g...