Eutrophi: Due to the erosive power of rivers carry salt, organic matter and suspended solids. To all this, human action adds waste from domestic and industrial activities (solids and metals mining), agriculture and livestock (nitrates, phosphates, pesticides, etc.) That the self-purification capacity of the rivers have can not assume , which are triggered by pollution processes whose effects are: Restriction on the use of water. Alteration in wildlife and / or aquatic flora. Appearance and odor. However, better defended rivers of pollution dynamics, which allows them to dilute the pollutants. In contrast, lakes tend to store waste. One of the main problems affecting the lakes is the eutrophication process. Eutrophication occurs when large amounts of organic matter reach a small reservoir of water, such as a lake. Microbial decomposition of organic matter consumes oxygen and releases a series of compounds. Both are vital nutrients for plants, which reproduce explosively. In cold weather, the algae die and sink to the bottom, where they release nutrients into the water utilized in the following favorable season and also produce an acidification of the fund. Thus, the eutrophication of the lake continues regardless of new external inputs of organic matter in what some authors call biofísicoquímica chain reaction, which is equivalent to that in living is a death by overeating. Measures to minimize, limit or prohibit domestic and agricultural discharges. Treating waste water. Reduce polyphosphate detergents. Injecting pure O2. Add N.

The self-purification is a system that occurs in natural waters, and consists of a series of mechanisms of sedimentation of particles in them and of chemical and biological processes that cause degradation of the organic matter to be converted into inorganic matter, will serve as a nutrient for algae, increasing their photosynthetic activity and O2 enriched water. With them removed extraneous matter from the water and restores the natural balance.