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Water pollution is mainly caused by chemicals, bacteria and other microorganisms present in natural waters in increasing numbers. Organic chemicals and inorganic (mineral) occur in the form of solutions, colloidal solutions and suspensions. The chemical composition of pollutants is shaped by natural factors, such as disassemble substances from soils and rocks, development and death of aquatic organisms and anthropogenic factors. The most common anthropogenic pollution of surface water include pesticides, surfactants, petroleum hydrocarbons, phenols, chlorinated derivatives of biphenyl and heavy metals: lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), mercury (Hg) and zinc (Zn), and heated water (thermal pollution), which are particularly dangerous for surface water with low flow or stagnant water. Most of the anthropogenic pollution is toxic to aquatic organisms. Impurities are very persistent in the aquatic environment and very difficult to undergoing chemical and biochemical processes are called refractive substances.