Abcs Of Survival Water Purification Systems

By Stacey Burt


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).

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.

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).

The flocculation basins have a rectangular shape and can be: Staged: where to achieve greater efficiency, the tank is divided into several zones in series in which the agitation is gradually decreasing. Channels: are horizontal flow, where the pool is subdivided by transverse partitions to form a channel whose width is gradually increased so as to obtain a flow velocity gradually decreasing.

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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