When the filtering layer begins to clog need cleaning it, which happens every 4 to 6 weeks. The cleaning is manual and involves removing the first layer of sand, sand washing in separate tubs and in reconstruction of filter bed. Quick filters are the most used, particularly in combination with other treatments such as clarification (surface waters) and the removal of iron and manganese (deep waters), and can deal with an input flow rate 40 times higher than that of lens filters (survival water purification systems).
The sedimented material is conveyed towards a hopper formed on bottom of tank, by means of mechanical pickers that sweep the bottom of same, and from here pumped to sludge treatment line. The size of tanks depends on detention time which is a function of characteristics of solid sediments present in raw waters and the type of decanter chosen.
We can also make filters consist of two filter layers of materials with different specific weight (dual media). As a rule, in this case the top layer is made from anthracite, lighter, and the lower one is in quartz sand. The layer of asphalt, being formed by the coarser particles of sand, preserves the rapid occlusion of first layers of sand. After a certain time, the retained particles begin to clog the bed draining decreasing the permeability, and determining, at a constant flow rate of inflow, an increase in waters level in tanks filtering. Exceeded the limit level, the layer drained must be subjected to countercurrent washing to restore its efficiency.
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 entered into a tank head from which it originated the system of waters supply - drinking. The waters containing different types of organic substances and inorganic, hereinafter classified, that must be removed during the purifying treatment. Physical treatments simple: they are articulated in a single step, eliminating the suspended solids and sediments those not coarse sediments (screening and sedimentation) and non-settleable (sieving and filtration).
ants: the most used today are the polyelectrolytes. The agitation speed should be neither too low to prevent sedimentation of flakes, or too high to avoid breakage of flake. The slow agitation is achieved by use of mechanical mixers (dynamic system) or by placing a series of baffles in tank (static system).
Filter volume: the filtration takes place by means of a three-dimensional porous matrix said filter bed consisting of discrete materials of small dimensions (eg. Sand); in this case the particles are retained within filter medium. The effectiveness of a filter material depends on certain properties of particles such as size, shape and surface chemistry. The filters lenses are the first filtration system used in filtration, but they are currently little used. The slow filtration can be used in case of turbidity 10 ppm.
The 'sodium aluminate is very expensive and is also used in treatment of lime-soda softening species in case of high hardness and magnesium. In some waters, even with a strong dose of coagulant, are unable to develop a staple of suitable density. Inse cases, adjuvants are added to waters coagulation to promote the densification of micro-flakes.
What lens filters the filtering action is exerted by the biological film that develops on the surface of filter in 10-15 days (aging time of filter). The film filter is very sensitive to mechanical disturbances and organic contaminants. During the period of maturation of film the filtered waters is not considered potable. The inflow of waters into filter takes place from above while runoff occurs from the bottom; the filtration rate.
The sedimented material is conveyed towards a hopper formed on bottom of tank, by means of mechanical pickers that sweep the bottom of same, and from here pumped to sludge treatment line. The size of tanks depends on detention time which is a function of characteristics of solid sediments present in raw waters and the type of decanter chosen.
We can also make filters consist of two filter layers of materials with different specific weight (dual media). As a rule, in this case the top layer is made from anthracite, lighter, and the lower one is in quartz sand. The layer of asphalt, being formed by the coarser particles of sand, preserves the rapid occlusion of first layers of sand. After a certain time, the retained particles begin to clog the bed draining decreasing the permeability, and determining, at a constant flow rate of inflow, an increase in waters level in tanks filtering. Exceeded the limit level, the layer drained must be subjected to countercurrent washing to restore its efficiency.
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 entered into a tank head from which it originated the system of waters supply - drinking. The waters containing different types of organic substances and inorganic, hereinafter classified, that must be removed during the purifying treatment. Physical treatments simple: they are articulated in a single step, eliminating the suspended solids and sediments those not coarse sediments (screening and sedimentation) and non-settleable (sieving and filtration).
ants: the most used today are the polyelectrolytes. The agitation speed should be neither too low to prevent sedimentation of flakes, or too high to avoid breakage of flake. The slow agitation is achieved by use of mechanical mixers (dynamic system) or by placing a series of baffles in tank (static system).
Filter volume: the filtration takes place by means of a three-dimensional porous matrix said filter bed consisting of discrete materials of small dimensions (eg. Sand); in this case the particles are retained within filter medium. The effectiveness of a filter material depends on certain properties of particles such as size, shape and surface chemistry. The filters lenses are the first filtration system used in filtration, but they are currently little used. The slow filtration can be used in case of turbidity 10 ppm.
The 'sodium aluminate is very expensive and is also used in treatment of lime-soda softening species in case of high hardness and magnesium. In some waters, even with a strong dose of coagulant, are unable to develop a staple of suitable density. Inse cases, adjuvants are added to waters coagulation to promote the densification of micro-flakes.
What lens filters the filtering action is exerted by the biological film that develops on the surface of filter in 10-15 days (aging time of filter). The film filter is very sensitive to mechanical disturbances and organic contaminants. During the period of maturation of film the filtered waters is not considered potable. The inflow of waters into filter takes place from above while runoff occurs from the bottom; the filtration rate.
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