"Who can paint a river out of turn in a river"
Every second, hundreds thousands cubic meters of fresh water move on our planet, already ten most flowing rivers occupy more than 2,500 million hectares. These are the arteries of our world; nourishing the land, renewing seas and oceans, and feeding peoples and environments since immemorial time. Ancient civilizations and major cities have settled along rivers since millennia by communications facilities (main roads) and livelihoods (water and food). At present the great flows of watercourses feed human trade flourishing next to its wadies.
Rivers are fundamental for ecosystem, also harbor the cradle of cultures and development streams. But water pollution is one of the most serious global problems; acid rain, wastewater discharges, agricultural chemicals, heavy metals ... are incorporated into the flow of rivers. The problem is acute worldwide by the quantity and diversity of polluting agents, and / or the impossibility of purification and regeneration of wastewater. However, contemporary societies depends on the chemical products (food industry, pharmaceutical or daily life facilities). Many of these products are toxic (especially processing byproducts). Discharge into surface water may cause irreversible consequences.