DE2220867A1 - PROCESS FOR THE PROCESSING OF WASTE CONTAINING PLASTIC PARTICLES - Google Patents

Description

Annex to the patent application by

Klöckner-Humboldt-Deutz H 72/15

Public company Le / Kr

dated April 27, 1972 2220867

Process for the treatment of waste water containing plastic particles

The invention relates to a method for removing fine particles Plastic particles from waste water from the manufacture of plastics, in particular from the manufacture of PVC.

In the manufacture of plastics, especially in the manufacture When the product is dewatered, raw PVC produces waste water, the finely divided plastic particles lying in the ^ range contain. Because of the small particle size and their hydrophobic properties, removal of these particles, for example, due to sedimentation in settling basins, it is practically impracticable even with the addition of flocculants. The object of the invention is to create a method that enables the removal of these finely divided plastic admixtures.

The object is achieved according to the invention in that the waste water initially with surface-active substances (surfactants) as

309845/0701

ORIGINAL INSPECTED

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Foamer added and then a finely divided gas bubble stream are exposed, with the accumulating on the bath surface, enriched with the plasticbexmengurigen Foam is stripped off. This makes it possible to use such wastewater, whose solids content, for example what is high is that they have a milky appearance, can be practically completely clarified and without further treatment can be diverted into a receiving water. A major advantage of the method according to the invention is can be seen in the fact that, surprisingly, only very small amounts of surface-active substances have to be added, to float the plastic contaminants out of the bath, where it is primarily important that the resulting foam, in which the plastic particles are incorporated are stable. Because of the low consumption of surfactants, preferably biodegradable surfactants such as Pine oils can be used, the treated wastewater can be in the without additional cleaning measures Receiving waters are released.

In an embodiment of the invention it is provided that the stripped Foam is exposed to a gas bubble stream at least one more time. With the help of this measure can achieve a reduction in the foam volume and thus a further enrichment, so that a mechanical drainage becomes possible.

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In an advantageous embodiment of the method according to the invention, it is therefore also provided that the enriched Foam is dewatered by means of a centrifuge.

In another advantageous embodiment of the invention Process is provided that the enriched foam is dewatered by filtration, preferably by means of a drum filter with a pre-filter layer on its filter surface is applied.

The method according to the invention is based on an exemplary embodiment for the treatment of PVC wastewater explained in more detail. The wastewater from the PVC factories becomes initially mixed with a surfactant, for example pine oil, in an amount of approx. 0.01 g / l turbidity and preferably well mixed in a stirring tank.

The turbidity mixed with the surfactant is then depending on the resulting Amount of wastewater supplied to one or more parallel adjacent containers in which the wastewater is exposed to a finely divided stream of bubbles.

The aeration can be carried out, for example, with the aid of conventional flotation cells, with both stirrerless flotation cells as well as flotation cells with

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Stirrers can be used. The foam that collects on the surface of the bath in each container will mechanically stripped, while the solids-free clear water, the solids content of at most 10 to 20 mg of solids per liter, is withdrawn from the cell.

The foam stripped from the bath surface is fed to at least one further container, depending on the degree of enrichment and there again exposed to a stream of bubbles. This results in a further reduction in the volume of the foam by about 9/10 with a corresponding enrichment of the solids in the foam floating in the second cell. If the degree of enrichment in the aftertreatment is not sufficient, one or more aftertreatment cells can be used downstream to enrich the foam.

The foam obtained in this way is so strongly enriched with the finely divided plastic particles that it is mechanically can be drained. A solid bowl centrifuge in which the enriched Foam drained to a residual moisture of approx. 35 - 50% will. The practically solids-free clear water that occurs in the aftertreatment cells and in the centrifuge is now

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abandoned the receiving water. Instead of a full bowl centrifuge it is advisable for very fine plastic admixtures to filter the foam, for example with drum filters, A pre-filter layer is applied to the filter surface.

Claims

Claims (4)

Claims 1. Process for the removal of fine plastic particles from waste water from the production of plastics, in particular from the production of PVC, thereby characterized in that the wastewater is initially mixed with surface-active substances (surfactants) as foaming agents and then be exposed to a finely divided gas bubble stream, with the accumulating on the bath surface, with the plastic foam accumulated in admixtures is stripped off. 2. The method according to claim 1, characterized in that the stripped foam at least one more time Is exposed to gas bubble flow. 3. The method according to claim 1 or 2, characterized in that the enriched foam, preferably by means of a Centrifuge is dewatered. 4. The method according to claim 1 or 2, characterized in that the enriched foam is drained by filtration is, preferably by means of a drum filter, on the filter surface of which a pre-filter layer is applied. 3 0 9 8 ~ S / 0 7 0 1