DE8915904U1 - Device for wastewater treatment by flocculation and flotation - Google Patents

Description

Dipl.-Ing. LUDWIG MUNK

PATENT ATTORNEY

EUROPEAN PATENT ATTORNEY Representative at the European Patent Office 8900 AUGSBURG Prinzregentenstraße 1

Telephone 0821-519622 Fax 0821-514242 Telex 533761 (Distribution: for PA Munk)

[P] Parking garage Schaezlerstrasse.

Dipl.-Ing. Ludwig Munk · Prinzregentenstrasse 1, 8900 Augsburg

German Patent Office Zweibrückenstr. 12

8000 Munich 2 Bank details: Deutsche Bank Augsburg (bank code 720 70001) Account no. 4156790

Dresdner Bank Augsburg (bank code 72080101) Account No. 107001000

Post Office Checking Office Munich (bank code 70010080) Account number 488 20-808

VNR: 106 21.10.91 - mu/ju

Applicant: Müller Rehm Wassertechnik GmbH,
8901 Koenigsbrunn

Device for wastewater treatment by flocculation and flotation

The invention relates to a device for wastewater purification by flocculation and flotation.

All state-of-the-art devices and/or processes for the combination of flocculation

and flotation have the disadvantage that either the flocculation takes place in the agitator tanks upstream of the flotation and therefore the flotation-effective gas bubbles attach themselves to the already formed floc and thus only to the outer floc shell (e.g. company brochures Sepaflot, Lurgi, Possibilities of flotation, Environment No. 5, 1975, Flotation, Cleaner + Scrubber, Issue 4/82) or the flocculation takes place in pipes of relaxation flotation systems without optimizable energy input for the flocculation (e.g. company brochure TOSS, Kleindienst).

In the case of flocculation in pipelines (cf. Meins, Flocculation in Pipelines, GWF Water/Wastewater 121, H 2) of relaxation flotation systems, with optimized flocculation, flotation-capable flocs are formed which even with high shear forces or long residence times due to the inclusion of air bubbles do not lose their buoyancy, but if flocculation is not carried out optimally, as a result of long flocculation times and the coalescence of the small air bubbles required for flotation into those with a larger diameter, an inclusion or even an attachment of the air bubble to the floc, and thus a flotation effect, does not occur.

The object of the present invention is to optimize the floc formation in combination with the relaxed air flotation, taking into account the optimal energy ratios in the flocculation sub-steps flocculation and/or adsorption coagulation and agglomeration.

This object is achieved by the characterizing measures of claim 1.

The device according to the invention combines the advantages of precisely adjustable energy input ratios of stirred tank flocculation in pipes of flotation plants in the presence of air released by pressure relief, which leads to the inclusion of air bubbles in the floc being formed.

According to Bernhard (The technical conception of the measures to prevent the progressive eutrophication of the Wahnbachtalsperre, Limnologica Vol. 10, 1976 p.) it is known that the flocculation step is time and energy dependent.

On the one hand, there must be a rapid and complete homogenization of the flocculants with the wastewater to be spread, which requires high turbulence in the flowing medium, and on the other hand, after the formation of polyneclear hydroxo complexes and the destabilization of colloids after the addition of the flocculant, excessive shear forces in the flowing medium must not prevent or hinder the agglomeration of the microflocs into macroflocs.

This can be avoided with the device according to the invention.

-A-

Advantageous embodiments of the overarching measures are specified in the subclaims.

The embodiment shown schematically in the drawing is described below.

In the drawing show:

Figure 1 is a view of the device according to the invention partially in section and

Figure 2 A-E various perforated plates for the floccu-

lation cell of the arrangement according to Figure 1.

According to Figure 1, a partial flow of already purified water is enriched with a defined amount of air via the air throttle 4 via the nozzle 1 via the valve 2, which extends into the suction line of the booster pump 3.

This air dissolves in the water flow in the precisely dimensioned pipe section 6 downstream of the pressure booster pump 5, which is filled with packing, as a result of the overpressure created by the pipe constriction 7. The pipe constriction extends into the expansion and flocculation cell 8, into which the waste water to be spread is fed by means of the feed pump 9 via the pipe 10 and inlet opening 11, directly to the inlet opening of the pipe constriction 7 of the expanded air/water mixture.

The dosing connections 12, 13 for the flocculant and flocculant aid solutions protrude into this turbulence zone of the expansion and flocculation cell 8.

The relaxation and flocculation cell 8 is limited, as seen in the flow direction of the aqueous medium, by the perforated plate 14 according to Figure 2.

At a certain distance, determined by the spacers 15, further perforated plates 16, 17, 18, 19 follow in the direction of flow according to Figure 2 in the order A, B, C, D, E.

The energy input generated by this arrangement of perforated plates 14, 16, 17, 18, 19 causes the optimized agglomeration of the micro flakes formed in the relaxation and flocculation cell 8 to form separable macro flakes, which, during their flake growth, enclose the microfine air bubbles released during the pressure relaxation. This agglomeration section 20 equipped with the perforated plates 14, 16, 17, 18, 19, as seen in the flow direction, merges into the flotation pipe 21, which protrudes into the separation area of the flotation cell 22.

In this flotation cell 22, the aqueous medium is separated into floating dirt flakes, which are drawn off from the upper area of the cell 23, and clear water, which is drawn off from the lower area of the cell 24.

Claims (6)

Expectations 1. Device for waste water purification by flocculation and flotation , characterized in that a partial flow of purified water or fresh water is enriched with air via a valve (2) attached to the suction side in front of a pressure booster pump (5), that, viewed in the direction of flow, a pipe (6) equipped with packing elements is connected after the pressure booster pump, that the pipe (6) opens into the cell (8) via a constriction (7), that this cell has further lateral inlet connections (11, 12, 13) for waste water to be treated (11), flocculant (12) and flocculation aid (13), that, viewed further in the direction of flow, a floc agglomeration section, divided into a high or low turbulence area, designed as a succession of perforated plates (14, 16, 17, 18, 19) and spacers (15) between the perforated plates and that, further in the flow direction, the agglomeration section (20) ends in a flotation pipe (21) which projects into the separation area of a flotation cell (22). 2. Device according to claim 1, characterized in that Raschig rings and/or Berl saddles are preferably used as filling bodies in the air release section (6). 3. Device according to claim 1 and 2, characterized in that the pipe constriction (7) at the end of the air release section (6) can be designed as a slide. 4. Device according to claims 1 to 3, characterized in that the air release section (6) is divided into segments with different filling materials. 5. Device according to claims 1 to 4, characterized in that the relaxation and flocculation cell (8), the individual segments of the agglomeration section (20) and the flotation pipe (21) are connected to one another by means of flanges. 6. Device according to claims 1 to 5, characterized in that the flotation cell (22) can be designed both as a round and as a rectangular flotation cell.