Effluent filtration and sack filter apparatus

Details Effluent filtration and sack filter apparatus Effluent filtration and sack filter apparatus

1993-05-05

1994-02-15

Dawson, Robert A.

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

210791, 210388, 210241, 210107, 210448, 210485, B01D 6100, B01D 2446, B01D 2430

Patent

active

052863875

DESCRIPTION:

BRIEF SUMMARY
This invention relates to effluent filtration, and more particularly to a method and apparatus for filtering liquid effluent.
A problem with treating liquid effluent, particularly from the domestic sector, is to prevent visible pollutants, such as rags, rubber materials, plastics etc, from being discharged with the liquid effluent via sea outfalls and causing visible pollution of the sea and bathing beaches. This problem has not been solved by straightforward filtration, because of difficulties caused by "blinding" of the filters, i.e. blockage of the pores in the filters caused by the solid materials. The problem is a wide one, and is not restricted to sea outfalls or to domestic effluent.
The present invention has surprisingly solved this problem by making use of disposable sack filters in combination with agitation means and/or disposable sack filters of decreasing porosity in a cascade formation. The agitation means or drop from level to level minimise blinding of the sack filters.
In one aspect, the invention provides a method of filtering liquid effluent, comprising causing said effluent to pass through filtration means comprising at least one disposable sack filter, the open end of the sack filter being attached to an outflow conduit, and the opposing closed end of the sack filter being attached to a moving support thereby to cause agitation of the sack filter.
In another aspect, the invention provides a method of filtering liquid effluent, comprising causing said effluent to pass through a plurality of filtration means arranged at successively lower levels, wherein each filtration means comprises at least one disposable sack filter of defined porosity, the respective porosities of the sack filters decreasing successively from the first filtration means to the last filtration means.
The above aspects of the method of the invention may be employed separately or in combination with each other.
The invention also provides apparatus for filtering liquid effluents, comprising, in sequence, inlet means, filtration means, and outlet means, and wherein the filtration means comprise at least one disposable sack filter, the open end of the sack filter being attached to an outflow conduit in communication with the inlet means, and the opposing closed end of the sack filter being attached to a movable support thereby to cause agitation of the sack filter when in use.
The invention further provides apparatus for filtering liquid effluent, comprising, in sequence, inlet means, a plurality of filtration means arranged at successively lower levels, and outlet means, whereby in use effluent is caused to pass successively through each of the filtration means, and wherein each filtration means comprises at least one disposable sack filter of defined porosity, the respective porosities of the sack filters decreasing successively from the first filtration means to the last filtration means.
The above variations on the apparatus of the invention may be employed separately or in combination with each other.
The closed end of the sack filter is preferably supported at about the same horizontal level as the open end. The moving support preferably causes the closed end of the sack filter to rotate and/or reciprocate relative to the open end. The sack filter is preferably accommodated in a filtration chamber having an overflow dam so as to maintain a level of liquid in the chamber, the lowermost side of the sack filter being covered by the liquid. Such a filtration chamber may constitute one of a series of successively lower levels through which the effluent is caused to pass. Filtration means may also be provided at at least one other level.
Preferably, additional means are provided for lengthening the time interval taken for the sack filters to blind. For example, at least some of the sack filters may be agitated by means of a shaking system provided by a cam or other off-centre device. Alternatively, a water jet system may be used to spray some or all of the sack filters either constantly or at irregular or predetermined i

REFERENCES:
patent: 2070201 (1937-09-01), Geary
patent: 2482302 (1949-09-01), Summers et al.
patent: 4842751 (1989-06-01), Dunkers
patent: 4970004 (1990-11-01), Rosaen
patent: 5053141 (1991-10-01), Laiho
patent: 5158672 (1992-10-01), Lagrech

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