To work this subject the one is important to stand out the end that if considered and if the same it is justifiable for one better agreement of these processes. Thus being she is necessary to take in account some elementary concepts and consideraes for one better understanding of the considered subject, starting with substances, for example. ' ' The samples of substance that we remove generally of the nature are mixtures and are important to know the components that forma' ' (SARDELLA, 1 999). These basic concepts will be basic for such understanding, thus: substances and mixtures are. – substance: chemical species with physical properties and chemical fellow creatures. Teva shines more light on the discussion.
Former: Oxygen (O2) and Iron (Faith). – Mixture: set of chemical species that present different physical and chemical properties, which can be: Homogeneous when they present one only fase' Former: Chloride of Sodium (NCl) and gua (H2O) and heterogeneous when they present more than a phase, Former: Water (H2O) and Sand – (silica oxide, SiO2). With the thematic separation of Mixtures, another important subject that it can be focused is water and its treatment. In this aspect the separation processes can be work such as: filtration, sedimentation or decantation flocculation. – Filtration: mechanical process that serves to unfold heterogeneous mixtures of a dispersed solid in a liquid or gas.
Former: Solid particle separation of the coffee (FELTRE, 1996). – Sedimentation or Decantation: mechanical process that serves to unfold heterogeneous mixtures of a solid in a liquid or two imiscveis liquids between itself. Former: Mixture of water and sand (FELTRE, 1996). According to Feltre (1996), flocculation is the process used in the ETAS (Stations of Water Treatment) where if dissolves Aluminum Sulphate (Al2 (SO4) 3) and hidrxido of Calcium (Ca (OH) 2) to hold back contained solid particles in the water (FELTRE, 1996). Water can inside also be focused of the subject, wastefulness and its pollution.