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).
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).
Forms special surface filtration membrane processes are divided according to size of pores in: microfiltration, ultrafiltration, nanofiltration and hyperfiltration or reverse osmosis. Filtration membranes can be used for example as an alternative to or flocculation processes adsorption.
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 waters containing sediments that can create several problems during the cycle of filtration. This law is valid for strictly spherical particles immersed in a liquid at rest and at constant temperature where the downward motion is not influenced neither by the presence of other particles or from the container walls.
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.
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).
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).
Forms special surface filtration membrane processes are divided according to size of pores in: microfiltration, ultrafiltration, nanofiltration and hyperfiltration or reverse osmosis. Filtration membranes can be used for example as an alternative to or flocculation processes adsorption.
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 waters containing sediments that can create several problems during the cycle of filtration. This law is valid for strictly spherical particles immersed in a liquid at rest and at constant temperature where the downward motion is not influenced neither by the presence of other particles or from the container walls.
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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