Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1997-05-19
1999-03-30
Gorgos, Kathryn
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204240, 204276, 204275, 422255, C25B 1500, C25B 900, B01D 900
Patent
active
058883592
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This application is a 371 application of a U.S. PCT/FI194/00518 International Application published as WO96/15989 May 30, 1996.
The present invention relates to a flock separating apparatus for use in sewage or sludge treatment, comprising an electrolytic cell and a separating tank, into which the flock developed in the electrolytic cell is delivered and in which the flock rises up through the action of a gas produced in electrolysis.
The treatment or purification of sewage and industrial process waters is conventionally (e.g. International Reference WO 89/06161) carried out by using flock separating tanks with air blown therein, so that the rising air bubbles carry the lighter solids to the surface as flock which can be removed. For example, the Patent publications U.S. Pat. Nos. 4,673,494 and 4,294,697 disclose such a combination of an electrolytic cell and a separating tank such that the electrolytically produced flock can be brought up to the surface in the separating tank by means of a gas released in electrolysis. Such a combination does not allow the use of optimal cell and tank structures and dimensions, resulting in a poor separation efficiency. The prior known flock separating tanks are relatively shallow and have been aimed at a relatively large surface area.
SUMMARY OF THE INVENTION
An object of the invention is to provide an improved flock separating apparatus, wherein the flock rising speed and a resulting separation efficiency have been substantially increased when compared to the prior known equipment.
This object is achieved according to the invention in such a manner that the separating tank comprises a substantially vertical pipe, separated from an electrolytic cell and having a length which is at least 10 times, preferably at least 15 times more than its diameter, and that a feed or supply pipe extending from the electrolytic cell to the separating pipe opens below the mid-point of the separating pipe, said separating pipe having its bottom end connected to a treated-water receiving and discharge tank and its top end rising above the surface level of said receiving and discharge tank.
Thus, an important point in the invention is that a hydrogen gas produced in electrolysis is used for carrying the flock up in a narrow pipe with a high hydrostatic pressure and a high flow rate. Because of a high flow rate, the hydrogen gas adhered to flock particles does not have enough time to separate and, thus, the hydrostatic pressure in a high separating space produces a high rising speed for flock particles. On the other hand, the receiving and discharge tank with a sufficiently large surface area makes sure, according to the principle of communicating vessels, that the water contained in the separating pipe does not pursue a high rising speed and comes virtually to a halt at the water level of said receiving and discharge tank. Thus, the discharging flock carries along a minimal amount of water.
Although the bottom end of the separating pipe could open directly within the opening area of the supply pipe, the separating pipe can be extended downwards e.g. for positioning a sand filter in such a manner that typically about 1/2-1/8 of the separating pipe length is located below the supply pipe opening area.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several Figures of which like reference numerals identify like elements, and in which:
The invention will now be described in more detail by way of an exemplary embodiment with reference made to the single Figure, which shows a flock separating apparatus of the invention in a schematic vertical section.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The water or sludge subjected to a purification treatment is delivered throug
REFERENCES:
patent: 1099396 (1914-06-01), Rothwell
patent: 4834872 (1989-05-01), Overath
Patent abstracts of Japan, vol. 9, No.260, C-309, JP A 60-110389, Y. Denki et al., Sludge Concentrating Method, 15 Jun. 1985.
Journal WPCF, vol. 54, No. 12, John R. Bratby, Treatment of Raw Wastewater Overflows by Dissolved-Air Flotation, Dec. 1982, pp. 1558-1565.
Gorgos Kathryn
HLS-Elektroautomatiikka OY
Parsons Thomas H
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