The basis of the physical methods of water purification based on different physical phenomena, which are used for exposure to water or dirt contained therein. When large amounts of water purification, these methods are mainly used to remove large enough solids and act as a coarse preliminary stage, designed to reduce the load on subsequent fine purification. At the same time there are a number of physical methods that can perform a deep cleaning of the water, but as a rule, the performance of such methods is low.
Straining is a process of passing water to be treated through various grids and screens on which there is apprehension major pollutants. This method relates to a coarse cleaning and often acts as a preliminary step. Its purpose - to remove from the treated water can be easily separated pollutants to reduce the load on the wastewater treatment plants and to ensure the efficiency of subsequent fine purification systems that can be damaged due to contact with the major mechanical impurities.
Defending is part of the department of mechanical impurities from water under the action of gravitational forces cause the particles to sink to the bottom, forming a precipitate. Settling can act both as a preliminary purification step which most large contaminants are separated, and as intermediate steps. This process is performed in settling tanks , equipped with devices for removing the sludge, the residence time of water in which is calculated from the condition of complete precipitation of contaminants which must be separated.
Filtering is based on passing the water to be treated through a porous bed of filter material on which the detention of certain size particles. According to its principle is similar to the filtration straining, but it can be used to carry out both coarse and fine cleaning. Filtering allows you to remove pollutants such as silt, sand, slag, and various solids of a few microns in size. Furthermore, by filtering water can be improved organoleptic qualities. Mechanical filtration is widespread, both in large water treatment plants, as well as in household filters with low productivity.
UV disinfection of water, though not directly produce clean, but is actively used in the process of water treatment and the treatment is already treated water ultraviolet part of the spectrum of light (particularly used with long-wave range of 200-400 nm) is invisible to the human eye, for the purpose of disinfection water. Death of living organisms under this radiation occurs primarily due to damage DNA and RNA molecules, which is caused by the photochemical reactions that occur in their structure. The advantages of this method of disinfection is the independence of the process of composition of water and the preservation of the composition after UV treatment. However, it must consider the presence of solids in water, capable of providing a shielding effect against radiation.
Distillation is the most effective and reliable method of obtaining pure water. At boiling water turns into steam intensively. Those. Only water molecules evaporate and impurities (salts, metals, sand particles, microorganisms) remain in liquid water-in evaporator flask. Then, this steam goes through the pipe, where it is cooled and condensed, ie again turns to water, but clean - no impurities. The condensed water droplets flow in the receiver. This process is called distillation. This "pure water" purity of approximately 99.5% relative salts, organic materials, microorganisms, pyrogens and bacteria