The three most used materials are: sand, used in filtration, is a natural material, silica, from rivers, natural deposits, dunes or obtained from marine pebbles. Its actual density is from about 2.5 to 2.7. Sharp sand is obtained by a career flint grinding or sea pebbles, followed by washing, drying and sieving. It presents angular grains, favor the retention of particles during the filtration (portable water purifiers for survival).
Rolled sand is a natural sand, sifted after washing and drying. Unlike the sharp sand, it has rounded grains, and exists in a grain size range, that is to say of dimension sand, smaller. Anthracite, carbon-based material obtained by calcination of plant material such as wood or peat. It is in form of hard and angular grains. Its actual density is of order of 1.45 to 1.75;
The waters seeps through the network inside the cylinder and is sent to subsequent treatments, while the material is retained on its surface.
After gathering the different small particles of much larger, we must now settle this. In a still body of waters, the heavier suspended particles than waters are subject to their apparent weight (actual weight less buoyancy). They are falling slowly to build up on the bottom: the settling. Their fall velocity obeys Stokes' law:
Besides the possibility to retain materials particularly small, as sieving has the advantage, compared to grilling, to retain all the material that has at least one dimension greater than the measurement step of network. The main drawback of sieving however, is the ease with which occur clogging and the need for frequent maintenance and cleaning. The sieving can applied only in case of waters with a low concentration of suspended solids.
However, the fact that the waters is by nature a solvent makes it somewhat problematic the effective elimination of many unwanted substances. The waters is put into a tank head from which it originated the system of waters supply - drinking. The interventions of this type are provided, when necessary, upstream of treatment processes of waters purification real, and allow the removal of materials and substances which by their nature and size are likely to damage the equipment and compromise the efficiency of subsequent treatment stages.
The screening aims to retain coarse solids non settleable (branches, leaves, rags, plastic, etc.) And solid coarse sediment (gravel, etc.). Among these materials Coarse including the possible fauna of waters body (fish). The grilling is adopted in all the patterns of surface waters treatment, and in this case is placed upstream of other treatments.
For waters of Category A1, may be the only physical treatment in addition to disinfection. The grid consists of series of metal bars placed at a distance such as to create obstacles to coarse bodies carried by the current. The grid is installed internally to channel coming to system, inclined with a slope generally equal to 1: 3.
Rolled sand is a natural sand, sifted after washing and drying. Unlike the sharp sand, it has rounded grains, and exists in a grain size range, that is to say of dimension sand, smaller. Anthracite, carbon-based material obtained by calcination of plant material such as wood or peat. It is in form of hard and angular grains. Its actual density is of order of 1.45 to 1.75;
The waters seeps through the network inside the cylinder and is sent to subsequent treatments, while the material is retained on its surface.
After gathering the different small particles of much larger, we must now settle this. In a still body of waters, the heavier suspended particles than waters are subject to their apparent weight (actual weight less buoyancy). They are falling slowly to build up on the bottom: the settling. Their fall velocity obeys Stokes' law:
Besides the possibility to retain materials particularly small, as sieving has the advantage, compared to grilling, to retain all the material that has at least one dimension greater than the measurement step of network. The main drawback of sieving however, is the ease with which occur clogging and the need for frequent maintenance and cleaning. The sieving can applied only in case of waters with a low concentration of suspended solids.
However, the fact that the waters is by nature a solvent makes it somewhat problematic the effective elimination of many unwanted substances. The waters is put into a tank head from which it originated the system of waters supply - drinking. The interventions of this type are provided, when necessary, upstream of treatment processes of waters purification real, and allow the removal of materials and substances which by their nature and size are likely to damage the equipment and compromise the efficiency of subsequent treatment stages.
The screening aims to retain coarse solids non settleable (branches, leaves, rags, plastic, etc.) And solid coarse sediment (gravel, etc.). Among these materials Coarse including the possible fauna of waters body (fish). The grilling is adopted in all the patterns of surface waters treatment, and in this case is placed upstream of other treatments.
For waters of Category A1, may be the only physical treatment in addition to disinfection. The grid consists of series of metal bars placed at a distance such as to create obstacles to coarse bodies carried by the current. The grid is installed internally to channel coming to system, inclined with a slope generally equal to 1: 3.
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