There are two major factors involved when comparing prices among the three modes of water purification. First, one must consider the energy needed to clean and filter water. Reverse osmosis, with its dependence upon high pressure to subvert the normal flow of water, requires an energy source and is fairly costly. Distillation, with its dependence upon heat to vaporize ground and surface water, also requires an energy source.

Though solar power remains an option for the required heat of distillation, it is still fairly inefficient and impractical. Carbon and multimedia water filters, whether installed at the point of water’s entry in a house or at a tap, do not require any added energy source. Water flows just as it normally would; it is merely diverted through the filter. The higher electricity costs of reverse osmosis and distillation systems double the total cost of the purified water product which carbon and multimedia filters produce. Read more

Single media filters, typically constituting carbon or sand, absorb impurities from water, through both physical and chemical processes, as the water passes through the filter cartridge.

Single media filters will generally remove undesirable tastes, colors, and odors from water as well as such chemicals as hydrogen sulfide, radon, chlorine, volatile organic compounds (VOCs), pesticides, and benzene (Ramstorp, 2003). Drinking water filters will also remove lead and other chemicals transferred from plumbing systems to water. Read more

Reverse osmosis will generally remove any molecular compounds smaller in size than water molecules. Such compounds include salt, manganese, iron, fluoride, lead, and calcium (Binnie et al, 2002). Reverse osmosis is extremely efficient at stripping minerals from water, and it is highly valued as a water purification process in the printing industry, in which mineral-free water must be used.

Although reverse osmosis supplies useful, mineral-free water for printing purposes, it does not provide the healthiest drinking water. Reverse osmosis will remove several mineral and chemical materials from water, including salt, fluoride, lead, manganese, iron, and calcium. Reverse osmosis, because it removes minerals according to physical size, is non-selective in its removal of dangerous and beneficial minerals. Read more

Kaindy Lake (Kazakh: Қайыңды көлі, Qayındı köli) is a 400 metre long lake in Kazakhstan that reaches depths near 30 metres in some areas. It is located 129 km ESE of the city of Almaty and is 2,000 metres above sea level.

It was created by the result of an enormous limestone landslide, triggered by the 1911 Kebin earthquake. The track to Kaindy lake has many scenic views to the Saty Gorge, the Chilik River valley and the Kaindy Gorge. Dried-out trunks of submerged Picea schrenkiana trees rise above the surface. Read more

More than 700 underwater images were submitted for the 2012 Annual Underwater Photography Contest, hosted by the University of Miami’s Rosenstiel School of Marine & Atmospheric Science. These 14 pictures were judged the best of the bunch. Ximena Olds shot this “Best Overall” photograph in the U.S. Virgin Islands, and entered it in the Macro category. The photo depicts a vibrant orange headshield sea slug on a brilliant background of green seagrass. (Photo by Ximena Olds) Read more