Filtration is the removal of contaminants from waters to get waters that is fit for normal domestic consumption or for irrigation of fields and also for industrial uses (eg. For use by establishments for food). With the gradual depletion of natural sources of drinking waters (deep waters), is increasingly resorting to surface waters (seas, rivers, lakes and dams) (survival water purification systems).
Quick filters are identical to those lenses; only varies the thickness of material forming the filter bed and the mattress filtering, in order to make faster the speed of filtration, equal to 5-10 m / hour. In this case the filtration is mechanical. For quick filters as a rule are used leach monolayer (single media) consisting of quartz sand (50-80 cm thick) supported by a mattress filter, or a drainage layer, consisting of coarser material (such as gravel) the thickness.
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.
Indeed, the presence of substances in suspension, for example, can nullify the effect of final disinfection since such particles may protect microorganisms against the action of disinfectants. In treatment of flocculation will exploit the properties of certain substances, called coagulants, which under certain operating conditions, in form of waters insoluble compounds with electric charge of opposite sign (positive charge) than that of colloids constituents as to eliminate the turbidity (negative charge).
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).
Treatments: also divided into several phases, improve the organoleptic characteristics of waters (adsorption on activated carbon) and lower the content of dissolved solids (demineralization). The interventions of this type are provided, when necessary, upstream of treatment processes of filtration 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 '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.
These flocculants, added in small doses, immediately after the coagulant, improve the efficiency of process affecting mainly. The adjuvants used are polyelectrolytes, organic macromolecules obtained through polymerization processes, waters-soluble or dispersible well, characterized by the presence of charged groups or at least polar throughout the chain.
Quick filters are identical to those lenses; only varies the thickness of material forming the filter bed and the mattress filtering, in order to make faster the speed of filtration, equal to 5-10 m / hour. In this case the filtration is mechanical. For quick filters as a rule are used leach monolayer (single media) consisting of quartz sand (50-80 cm thick) supported by a mattress filter, or a drainage layer, consisting of coarser material (such as gravel) the thickness.
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.
Indeed, the presence of substances in suspension, for example, can nullify the effect of final disinfection since such particles may protect microorganisms against the action of disinfectants. In treatment of flocculation will exploit the properties of certain substances, called coagulants, which under certain operating conditions, in form of waters insoluble compounds with electric charge of opposite sign (positive charge) than that of colloids constituents as to eliminate the turbidity (negative charge).
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).
Treatments: also divided into several phases, improve the organoleptic characteristics of waters (adsorption on activated carbon) and lower the content of dissolved solids (demineralization). The interventions of this type are provided, when necessary, upstream of treatment processes of filtration 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 '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.
These flocculants, added in small doses, immediately after the coagulant, improve the efficiency of process affecting mainly. The adjuvants used are polyelectrolytes, organic macromolecules obtained through polymerization processes, waters-soluble or dispersible well, characterized by the presence of charged groups or at least polar throughout the chain.
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