Since waste water contaminated with solid material is released at very many locations, for instance in industry, including particularly the food processing industry and cattle farming industry, such methods and devices are generally known. In addition to cleaning waste water flows, methods of this type are also used for drying product flows such as coal slurries.

The basis of the new method and device is a device as known from the international patent application WO 96/04054, which should be deemed as interpolated in the description.

The invention will be further elucidated with reference to the annexed drawings.

Figure 1 shows in highly simplifie manner a device of the prior art.

Figure 2 shows an embodiment of the device according to the invention.

Figure 3 shows a partial cross-section of a further embodiment variant- Figure 4 shows a further developed system in which the method according to the invention is applied.

The known device as shown in figure 1 comprises a drying and separating device 1 comprising a frusto- conical chamber 2 to which air is fed via a conduit 3 which debouches tangentially on a large diameter of chamber 2. The air is supplied using an air pump or air compressor 6 driven by a combustion engine 7.

Protruding into chamber 2 is a tube 4 the open end of which lies very close to the part of chamber 2 of small diameter. As seen in figure 1, the air supplied via conduit 3 flows with an increasing vortex to the left in chamber 2 and enters the end of tube 4 where it will display a very strong vortex.

Close to the inlet of tube 4 a feed conduit 5 for the mixture for separating respectively drying protrudes into device 1. The mixture comes from a storage reservoir 8 and is fed into conduit 5 in dosed manner via a dosing device 9.

The supplied quantity of air is very much larger than the supplied quantity of mixture. At a processing capacity of the aqueous mixture fed via conduit 5 of l m3 per hour, an quantity of air is supplied of 15,000 to 20,000 m3 per hour.

Due to the strong vortex in tube 4 the water of the mixture is taken up into the air and the solid material separated. A quantity of dry substance taken up into an unsaturated water vapour flow thus results. This dry substance is separated in the cyclone 10 connected thereafter and is there released via conduit 11. The air with the water taken up therein leaves the cyclone at 12.

The device according to the invention relates primarily to the vortex device 1., The vortex device known from said international patent application is of complicated structure and at the location of the transition from the conical vortex chamber to tube 4 there occur flow losses which adversely affect the efficiency of the total device.

In the device according to the invention a separating device is used in which no reversal of the flow direction of the air takes place.

In the embodiment of figure 2 the device 15 comprises a vortex chamber 17 to which once again air with a great flow rate is supplied tangentially at a large diameter via a conduit 18. The vortex tube 16 connects onto the small diameter of the conical vortex

chamber 17 so that the supplied air which is strongly vortical close to the small diameter arrives in this vortex tube 16 without flow direction reversa. The mixture feed conduit 19 debouches at the beginning of tube 16. Due to the known venturi action the mixture will be drawn out of conduit 19 into the air flow flowing through vortex tube 16. Instead of conduit 19 extending sideways through a wall of tube 16, it is of course also possible to have conduit 19 protrude into vortex tube 16 from the opposite end of the vortex chamber and co- axially therewith. This has the advantage that the radial part of conduit 19 cannot disturb the air flow.

Figure 3 shows a partial cross-section of a further embodiment variant. A separate conical vortex chamber is not applied here, but the air from the pump or compressor is supplied on one sida 21 of a tube 22 of constant diameter. In the part connecting to supply side 21 are arranged helically extending plates 23 which ensure that the supply of the air is brought into a strong helical vortex.

A constriction 24 which forms a venturi is formed in the part of tube 22 connecting onto the part in which helical plates 23 are arranged. Debouching just beyond the venturi is a mixture feed conduit 25 with which the aqueous mixture is carried into the strongly vortical air flow, wherein in the above described manner the water is taken up into the air and the solid material is released as relatively dry substance into a cyclone to bc connected thereafter.

Figure 4 shows a further developed system in which the method according to the invention is applied.

The central part is once again the vortex devi. ce 31, which is here shown schematically in the embodiment of figure 2, but in which another embodiment can also be used.

Fed to vortex device 31 in the above described manner is air which is provided at a high flow rate by

means of an air pump 32. Pump 32 is driven with a combustion engine, in particular a diesel engine 33.

The air from air pump 32 is guided via a heat exchanger 36, wherein this air, already raised in temperature by the compression, is further heated with cooling water from the cooling-water circuit 34 of engine 33. The hot exhaust gases from exhaust conduit 35 also relinguish their heat to the liquid in the circuit 34 in heat exchanger 46. Instead of directly causing the cooling liquid of engine 33 to circulate, an additional circuit can of course be constructed to which the heat from the cooling water of engine 33 and the exhaust gases is relinquished.

Instead of cooling water heat and exhaust gas heat, it is also possible to use only one of the two sources.

As noted above, the heated air arrives in vortex device 31 where it is mixed with the aqueous mixture. Due to the higher temperature thereof, the supplied air can contain more water, whereby the efficiency of device 30 increases.

The solid material taken up into the air is carried via conduit 38 to cyclone 39, where the solid material is separated at 40 and the air containing the water is further transported via conduit 41.

The air from cyclone 39 may still possess a considerable residual heat which is utilized in the preferred embodiment shown here to supply a biological purification device 42, shown here schematically, with heat and air by means of a bubble conduit 43. The operation of biological purification device 42 becomes more efficient and effective due to the supplied heat.

The waste water fed via conduit 44 is pre-treated in biological cleaner 42 and leaves biological cleaner 42 through conduit 45 which carries the waste water with solid material taken up therein to the vortex device 31.

In conduit 45 is accommodated a further heat exchanger 37 in which the heat originating from engine 33

is likewise supplied to the mixture. Due to the obtained temperature increase of the mixture, the operation of vortex device 31 will improve further.

With the device described here the dry substance content of the (waste) water flow can be increased in the described single process run from 1% to 95%. The dry substance released at 40 can hereby be further processed in very suitable manner. When the solid material is for instance an organic material, they can be usefully employed or for instance be further processed in an incinerator. The released heat can optionally be re- utilized to heat the air and mixture flows.

Because in the shown embodiment the used air released from cyclone 39 is guided through the bath of the biological purification device 42, hazardous substances possibly present in this air are washed out of the air, so that only clean air is discharged into the environment.

As noted, the device shown in figure 4 is a preferred embodiment. When no biological purification device is present in the vicinity, the air can of course be discharged directly from conduit 41. Nevertheless, the device then still has a high efficiency due to the utilization of the heat generated by engine 33.

In this respect it is noted that in a combustion engine roughly two-thirds of the energy content of the fuel supplied thereto is released in the form of heat and only one-third in the form of mechanical energy with which pump 32 is driven.

As well as by washing of the used air, the waste emission can also be minimized by using the air in a closed circuit. After leaving for instance the cyclones for separation of the solid material, the air is then first guided through gas driers which remove the water taken up into the air from this air. The gas driers may in per se known manner comprise a cooling device with which the air i, cooled to such an extent that the water present therein condenses. The dried air is then fed back

to the beginning of the closed circuit where it is compresse and optionally heated. Hazardous substances which may be present in the air will be largely removed therefrom with the condensate.

With the device according to the invention a flow of solid material taken up in water can thus be processed at low cost in an environmentally-friendly manner.