Water is collected from a channel and transported to next treatment. Along this path, all the particles of type that have a grainy sedimentation rate greater than the rate of climb of current are held in tub. In practice, the sedimentation depends on surface of tub and not by its volume (survival water purification systems). In fact the same flow rate of upward flow (Qa), the greater the surface (S) of tub, the lower the speed of upward flow (Va = Qa / S), the greater the proportion of particles sedimenting.
These sources of supply, due to specific characteristics of waters and / or the degree of pollution, must be subjected to cycles of treatments of filtration necessary to modify the characteristics and improve its quality. Often, this happens even for the deep waters with a high content of organic substances and a high microbial contamination, especially if they are present faecal bacteria (eg. Coliforms).
Filtration is a treatment used to remove suspended solids from the waters not sediment. Treatment consists in passing the raw waters through a filter medium (bed / filter layer or filter cloth). In case of filter layer, the filter material can be made from quartz sand, anthracite or activated charcoal. During filtration the filtered solids gradually begin to clog the filtering layer resulting in an increase of load losses, which is increased to overcome the supply pressure. Exceeded the maximum value of said pressure must be made to interruption of flow and to cleaning of filter medium.
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).
Physical and chemical treatments normal and driven: they are divided into several phases and eliminate non-settleable suspended solids (flocculation) and correct the chemical characteristics of waters by eliminating the dissolved substances that are incompatible with the use to which the waters is bound (softening, stabilization, removal of iron, manganese, desilication, fluoridation and defluoration, aeration).
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.
The sedimentation is carried out in special tanks, called decanters, within which the waters moves in a laminar flow as possible for a time sufficient to allow the sedimentation of heavier particles. Decanters flow or vertical upward flow are generally circular section. Inse tanks the entrance of waters can be centrally from above; in this case waters, to be able to escape from the tank itself is forced along a tortuous path; in fact must first move vertically downwards in order to pass beneath a baffle concentric, said fireplace, subsequently, passed over the obstacle fireplace, must rise and exceed a weir located along the perimeter of tub.
These sources of supply, due to specific characteristics of waters and / or the degree of pollution, must be subjected to cycles of treatments of filtration necessary to modify the characteristics and improve its quality. Often, this happens even for the deep waters with a high content of organic substances and a high microbial contamination, especially if they are present faecal bacteria (eg. Coliforms).
Filtration is a treatment used to remove suspended solids from the waters not sediment. Treatment consists in passing the raw waters through a filter medium (bed / filter layer or filter cloth). In case of filter layer, the filter material can be made from quartz sand, anthracite or activated charcoal. During filtration the filtered solids gradually begin to clog the filtering layer resulting in an increase of load losses, which is increased to overcome the supply pressure. Exceeded the maximum value of said pressure must be made to interruption of flow and to cleaning of filter medium.
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).
Physical and chemical treatments normal and driven: they are divided into several phases and eliminate non-settleable suspended solids (flocculation) and correct the chemical characteristics of waters by eliminating the dissolved substances that are incompatible with the use to which the waters is bound (softening, stabilization, removal of iron, manganese, desilication, fluoridation and defluoration, aeration).
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.
The sedimentation is carried out in special tanks, called decanters, within which the waters moves in a laminar flow as possible for a time sufficient to allow the sedimentation of heavier particles. Decanters flow or vertical upward flow are generally circular section. Inse tanks the entrance of waters can be centrally from above; in this case waters, to be able to escape from the tank itself is forced along a tortuous path; in fact must first move vertically downwards in order to pass beneath a baffle concentric, said fireplace, subsequently, passed over the obstacle fireplace, must rise and exceed a weir located along the perimeter of tub.
0 comments:
Post a Comment