Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Patent
1996-09-26
1998-09-29
Lithgow, Thomas M.
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
210712, 210194, 2102212, 2105121, C02F 124
Patent
active
058142290
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method and apparatus for treating water. More specifically, the invention is a further development of the method and apparatus described in EP patent publication No. 0 448 597.
As explained in the latter publication the water treatment takes place mainly by flotation and physical adsorption based on air bubbles of varying sizes produced from a diffusor at the bottom of a water basin. Thus, the flotation process is carried out by means of air bubbles of a size ranging from about 0.03 mm up to about 0.12 mm attaching to particles thus increasing their buoyancy. The particles as a consequence from a slurry at the surface. The adsorption process occurs via air bubbles of a size about 0.8 mm combining with colloidal or dissolved polarized substances and forming therewith a voluminous bubble foam at the water surface.
According to the above patent the diffusor is located in a chamber which is partly separated from the remaining part of the basin by a partition wall and has a substantially smaller volume than that of the latter part. The adsorption process then takes place substantially within this chamber while the flotation process takes place substantially within the basin itself, and the water, owing to the pumping effect from the diffusor bubbles, circulates up through the chamber and out into the basin at the opposite side of the partition wall. The bubble foam is continuously removed as it forms at the water surface in the chamber, while the slurry that is formed way out in the basin is removed at the rim of the basin opposite the chamber. At either place the removal is carried out by allowing the foam and slurry respectively to flow over a weir together with a top water layer.
While the technique according to the above EP patent represents a substantial improvement compared to prior water treatment methods, it also suffers from certain defects and disadvantages. Thus, it is a problem to get the bubble foam at the chamber water surface removed sufficiently rapidly by the weir technique that is used. As noted in the patent it is important to have this foam removed before it disintegrates to drop the impurities back into the water. Another disadvantage is the fact that by the above weir technique a relatively large water flow will accompany the foam and slurry out of the basin.
SUMMARY OF INVENTION
According to the present invention it has now been found that these defects and disadvantages of the process disclosed in the EP patent can be avoided in a particularly simple manner.
Thus, surprisingly it has been found that if the wall that partly separates the chamber from the remaining part of the prior basin is removed, then important advantages may be achieved if, in addition to the laterally directed water circulation that takes place in the basin owing to the diffusor pumping effect, also a longitudinally circulating flow is established in the basin water. Practically all of the foam and slurry on the water surface will then gradually gather in a peripheral flow path in the basin and may easily be removed from one or more places therealong. The foam is viscous and the slurry will intermix with the foam and attach to it thus forming a stabile foam-slurry mixture. According to a preferred embodiment of the invention the foam-slurry mixture is effectively removed from the flow path by means of a suction means communicating with a vacuum source.
The fact that the system according to the invention, contrary to that described in the above EP patent No. 0 448 597, does not include any chamber-forming partition wall in the water basin results in a reduced residence time of the foam before it is removed. Furthermore the foam is quickly removed from the turbulent zone above the air diffusers where the foam tends to disintegrate. This results in a lower resuspension of impurities, leading to an enhanced cleaning effect. Additionally, removal of the chamber partition wall allows the foam from the adsorption process, together with the floating slurry from the f
REFERENCES:
patent: 2418950 (1947-04-01), Montgomery
patent: 3428175 (1969-02-01), Hukki
patent: 4663046 (1987-05-01), Feldkirchner
patent: 4696740 (1987-09-01), Mochizuki
patent: 4721562 (1988-01-01), Barnscheidt
patent: 4834872 (1989-05-01), Overath
patent: 5108586 (1992-04-01), Iwashige
patent: 5139662 (1992-08-01), Ozawa
patent: 5160620 (1992-11-01), Lygren
patent: 5509535 (1996-04-01), Schneider
Lithgow Thomas M.
Puraq AS
LandOfFree
Water treatment method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water treatment method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water treatment method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-683491