WO1995007125A1

WO1995007125A1 - Process for separating lightweight minerals from waste water and separator therefor

Info

Publication number: WO1995007125A1
Application number: PCT/EP1994/003029
Authority: WO
Inventors: Ulrich Bachon; Hans-Georg Loseries; Axel Middelhaufe
Original assignee: Passavant-Werke Ag
Priority date: 1993-09-09
Filing date: 1994-09-09
Publication date: 1995-03-16
Also published as: DE4330552C2; DE4330552A1

Abstract

Before entering into the sewerage system, waste water contaminated with light, predominantly mineral fluids is passed through a DIN-standard separator, which constitues a smoothing run wherein the light fluids can rise to the surface due to their different density from that of water. To improve the degree of separation and to facilitate a water-free extraction of separated materials, the waste water in the smoothing run is circulated a number of times in a spiral stream whereby the upwardly separating light fluid passes into a no-flow zone where two-dimensional constriction compresses it to an extraction point. There the compressed light fluid is periodically extracted through the difference in density from water. The extraction is initiated when a scanning sensor indicates a sufficient layer.

Description

Process for separating mineral light materials from waste water and separator therefor

The invention relates to a method for separating mineral light substances from waste water contaminated with these light substances, such as oil, gasoline, benzene, and to a separating container.

The separation technique by gravity due to the difference in density has due to the more stringent discharge conditions (Appendix 49 to the Rahinen-Abwasser-Verwaltungsvcrschrift § 7a Water Budget Act) has undergone constant further development.

Until now it was common to use a calming pool and to carry out the hydraulic design according to DIN 1999. To improve the degree of separation of finely dispersed light liquids, so-called coalescence separators have been developed which use the principle of combining the drops to form aggregates capable of rising (DIN 1999, parts 4 to 6). With both types of separator, the problem of removing the floating light liquid is not satisfactorily solved. The separators designed according to DIN 1999 part 1 to 3 have a storage space for the floating light liquid. When the storage limit is reached, a probe arranged in the storage layer reports that the separator must be disposed of. If the disposal is then refrained from, a float closure arranged in front of the pure water outlet ensures that the pure water outlet is closed before the light liquid floating on the permissible amount of storage can get into the outlet.

Another possibility are light liquid separators, which enable the floating light liquid to drain off automatically. These separators take advantage of the phenomenon that the light liquid stratifies above the water according to its density difference to water. The corresponding separators contain a conical lid on the liquid level that absorbs the floating liquid. whose funnel tip contains the overflow for the light liquid (DE-C 29 51 205). The light liquid is collected and stored in a special container and can be removed later.

A disadvantage of this type of separator are two facts: the conical cover only covers part of the cross-sectional area available for swimming, and the inflow of the wastewater to be treated comes through the cover vertically from above. The reduced floating surface means that there is also outside the funnel cover

Can collect light liquids that do not run off. The inflow of waste water through the light liquid layer causes a deterioration in the separator result.

The one known from DE-A-35 14 157

Light liquid separators of a similar design no longer have these disadvantages: the wastewater to be cleaned is fed in from the side via a calming wall. The funnel cover now covers the entire separating ascent area. The degree of separation of this type of separator is unsatisfactory, however, because the settling time for the waste water flowing from the inlet to the opposite outlet through the separator tank is far too short.

The object of achieving an improvement in the separation effect is achieved according to the invention in that the wastewater in the calming section is forced to rotate several times in a spiral flow that the the lower area and in the upper area of the calming section are directed into flowless zones of the calming section and are compressed there by a two-dimensional contraction to a drainage point and that the substances are then allowed to run off due to the difference in density to water. This new process results in an excellent separation of the contaminants and a largely automatic removal of the previously water-free compressed substances.

The floating mineral light substances are preferably drawn off automatically via a raised overflow edge. The overflow edge lies below the layer of light material which is layered on the resting water level due to the difference in density. The overflow edge is set higher than the rise so that water cannot get into the light material overflow when the dividing line rises due to the maximum inflow.

Another advantageous possibility of preventing water from flowing out of the light material overflow is to control the light material discharge by means of a closure valve arranged in front of the overflow and actuated by a float. Its float is tared in such a way that it floats on water, but goes under in the light material. The float thus ensures that the

Light material overflow opens when a certain amount of light materials has accumulated. The increase in the dividing line caused by high wastewater inflow can initially lead to the closing of the float valve so that neither light materials nor water can run off. So that Open the float valve again at the end of the inlet and drain the floating light substances, the valve seat is placed according to the invention so deeply below the overflow edge that the resulting hydrostatic force exerted on the valve plate from the float's residual buoyancy force and from the clean water side from below is less than the closing force counterforce exerted by the column of light materials on the valve disk from above.

A third option for controlling the light material discharge is a control valve in the light material outlet and sensors in the zone in front of the light material overflow. The valve is controlled in such a way that the valve is opened in the presence of light substances and closed in the presence of water.

Finally, it is also conceivable to switch the sensor provided in the light material collection zone to a pump which either sucks the light materials directly or conveys a pressure medium into the calming section which presses the light materials from the light material discharge with closed inlets and outlets.

A separating basin or container for carrying out the separating process is characterized in particular in that a guide wall which is spiraled from the tangential waste water inlet into the upright cylindrical or polyhedral vessel to the central clean water outlet is provided for a more than simple circulation of the waste water. Also the reverse flow direction from the inside to the outside is conceivable.

In both cases the flow path is extended in such a way that even the smallest light liquid particles are separated and can rise into the upper flow-free zone under the cone cover. The spiral guide wall, e.g. can consist of an outer straight section, a middle three-quarter circle section and an inner radial section, only needs to reach up to this flow-free zone.

The floating light liquid preferably always extends into the funnel opening of the cone cover. The separator is therefore preferably always operated without a clear surface. This mode of operation is e.g. achieved in that the inlet and outlet pipes are inflated, i.e. the drain is much higher than the funnel tip. It is conceivable then to pull the overflow line for the light liquid through the pure water drain line so much that the light liquid continuously drains off automatically. However, this means that the light liquid to be separated always has the same density. Since this is rarely the case, it is proposed in an embodiment of the invention to provide the overflow for the floating light liquid with a closure member and one in the area of the floating light liquid

Arrange conductivity probe, which is connected to the control of the closure member in such a way that it opens in the presence of light liquid and at Presence of water is closed. In this way, regardless of the density of the light liquid, it is always drawn off automatically, so that there is only a little light liquid in the separating container. In order to prevent the closure member from being opened at too short intervals, two conductivity probes of different heights can be provided in an embodiment of the invention, which are connected to the control of the closure member such that when the lower probe senses the presence of light liquid, the closure member opened and, when the upper probe senses the presence of water, the closure member is shut off again. In both cases, the hydrostatic pressure prevailing in the inlet and outlet lines can be used to draw off the light liquid. Additional pressure generation is then not necessary.

In an effort to further improve the degree of separation in this new type of separator, it is proposed according to the invention to arrange coalescence elements which extend transversely in the spiral flow path. These coalescence elements, which freely end at the top in the flowless zone, can be designed in a known manner as a bar or wire mesh, perforated plate, screen surface, random fiber mat or reticulated foam sheet. It is important about these elements that they refer to the

Apply light shear forces when flowing around them, which allow them to flow together by reducing the surface tension. Since the wastewater that is cleaned in the separators according to the application often also contains sediments, for example sand, starch and the like, it is mandatory to precede the light material separator with a sludge trap. This sludge trap can be omitted if, in a further embodiment of the invention, the separator tank has a bottom which is curved or funnel-shaped and in which the sediments collect during the spiral flow. The drain opening for the sediments receives a closure element, and the hydrostatic pressure of the water columns can also be used to remove the sediments. With the aim of thickening the sediment before discharge and preventing it from clinging to the cone wall, a circumferential broaching and thickening crusher can be provided in the cone bottom. Such crows are known in sewage treatment plants.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the figures. Show it:

Fig. 1 shows a first embodiment in

Vertical section according to I - I of Fig. 2,

Fig. 2 shows the embodiment of Fig. 1 in

Transverse axis section according to II - IT of Fig. 1,

Fig. 3 shows a second embodiment in

Vertical axis section,

4 shows the cross section to FIG. 3, 5 shows a third embodiment variant only in vertical section,

Fig. 6 shows another embodiment.

The separator housing 1 shown in FIGS. 1 and 2 consists of a cylindrical or polyhedral middle part 2 and a conical cover 3 or bottom 4. At the cone tips there are extraction openings 5, 6 with closures 7, 8. The waste water inlet 9 contains a tangential one the middle part circumference opens, slightly conically expanded inlet connection 10, to which a guide wall 11 connects in the interior of the separator housing 1. The guide wall 11 consists of an outer surface section 11 ', a three-quarter circle central section 11' 'and an inner radial section 11' ''. This closes at the inner end of the radial section 11 '' '

Pure water drain pipe 12, which is first led down here and then out through two pipe angles and finally upwards. As shown in FIG. 2 in particular, in the cross section through which wastewater flows in a spiral form, there is a coalescence insert 13 at the end of the three-quarter circle, which here has the form of a vertical bar grid. However, any other shape is also conceivable, for example a perforated or screen grid, a packing made of flow bodies or a layer of reticulated plastic foam. Under the conical cover 3 there are two conductivity measuring probes 14, 15 at different heights, which are connected to the upper closure 7 via a logic control 16. During operation, the wastewater to be cleaned enters the separator housing largely calmly and without vortexes. During the essentially laminar spiral flow along the guide wall 11, both light and sinking materials have the opportunity to float or sediment and thus pass out of the flowless and the flowless zone. The light substances 17 collect under the cone cover 3 and can be pulled off by opening the closure 7 and collected in a disposal container (not shown). The two probes 14, 15 automate the removal in such a way that the lower probe 14 opens the closure 7 in the presence of light substances 17 and the upper probe 15 closes it again in the presence of water. With this control it is achieved that only a small amount of light materials collect in the separator and that the discharge takes place without water. The sediments can be removed at regular intervals or when the need is ascertained through a sight glass.

The direction of flow through the separator housing 20 according to FIGS. 3 and 4 is from the inside to the outside. The separator shown here differs from that shown in Fig. 1/2 in that only light materials can be separated. If the wastewater also contains sediment, a conventional sludge trap must be installed upstream of this separator. The bottom 21 of the light material separator is flat and carries the guide wall 22, which is essentially a mirror image of FIGS. 1/2. The inlet pipe 24 which dips through the conical cover 23 from above is half open in the section covering the guide wall 22. The wastewater entering is thereby spread over the entire height of the guide wall 22 and slowed down accordingly. It initially flows along the radial section of the guide wall and is deflected at the end thereof into the circulation which ends in the weakly conical outlet connection 25. The outlet 26 for the floating light substances is again arranged exactly at the tip of the conical cover 23.

The separator 20 shown in FIG. 5, on the other hand, is only suitable for separating suspended matter. He can e.g. 3 and 4 upstream of a light material separator and then ensures a complete separation of even difficult to separate sediments. The peculiarity of this embodiment is that the conical base 31 consists of a flatter upper (31 ') and a steeper lower truncated cone 31' '. In the area of sedimenting sediments 32, a clearing mechanism 33 rotates, which is driven from above (geared motor 34). A certain thickening effect is also achieved with this broaching device, which increases the solids content of the sludge. The guide wall 35 has the course shown in Fig. 1/2. Because of the drive shaft 36 lying in the container axis, the pure water outlet 37 has moved somewhat out of the center.

6 again shows a separation vessel 40 for separating light and sinking substances. The cone cover 43 has a weaker inclination than the cone bottom. The wastewater inlet 49 is here attached to the outside of the separating vessel and opens with a slot 50 tangentially on the circumference. The baffle 45 is the continuation of the inner edge of the inlet slot. A valve plate 42 connected to a float 41 is used to control the removal of the light materials 47, which lies against the valve seat 48 provided at the light material outlet 46 from below. The upright stable floating position of the valve body is brought about by a weight 51 attached to the float. A plurality of rods 52, which are arranged around the valve seat, serve for vertical guidance.

The float valve is closed when the separating vessel is filled with * water in accordance with the standards. If mineral light materials 47 are brought in with the waste water, they float to the top of the cone cover and form a growing layer of floating material there. When the layer of floating material has reached a certain thickness, the residual buoyancy of the swimmer decreases because he is increasingly surrounded by a medium with a lower density than water. If the inflow stops, then the dividing line 53 drops to water to the level specified by the pure water discharge level 54. This means that the float valve 41, 42 can sink and release the outlet 46 for the escape of the floating substances. As the floating substances run out, the dividing line rises again and closes the float valve again. Above the closed float valve there is now a column made of floating materials, which ensures that the float valve can open for the next outlet of floating materials. The column is dimensioned in relation to the residual buoyancy of the float so that it opens the valve plate in the idle state. The advantage of the new design can be seen above all in the fact that the guide wall forces a long and essentially laminar flow without a short circuit, which results in a high-level separation of the wastewater contents.

Claims

claims

1.Procedure for separating mineral light substances and possibly heavy substances from waste water contaminated with these substances by calming flow through a calming section operated without a free-flowing mirror, the light substances floating due to the lower density compared to water, collecting in the upper area of the calming section and being withdrawn from there , characterized in that the wastewater in the calming section is forced into a spiral flow that circulates several times, that the substances collecting in the upper area and in the lower area are directed into flowless zones and are compressed there by a two-dimensional contraction to a drainage point, and that the substances subsequently pass through the density difference existing in water are allowed to run off.

2. The method according to claim 1, with an overflow edge arranged in the upper region of the calming section for the floating light substances and a raised trailing edge for the pure water at the end of the calming section, characterized in that the overflow edge is placed so high above the trailing edge for the cleaned waste water that the at the maximum inflow, the increase in the dividing line light materials / water is smaller than the height difference.

3. The method according to claim 1, characterized in that in front of an overflow edge having upper deduction for the floated light materials an actuated by an internal float closure valve is provided, the float is tared so that it floats on water and goes under in the light materials, and that the valve seat for the closure valve is placed so deeply below the overflow edge that the closing force exerted by the float's residual buoyancy and from the pure water side is less than the counterforce exerted on the float of the closure valve by the column of light materials from the outside.

The method of claim 1, with a controllable shutoff valve in the floating of the Light materials, characterized in that the closure valve is controlled in the manner of sensors sensing the layer of the floating light substances, that the valve is opened in the presence of floating light substances and closed in the presence of water.

Method according to claims 1 to 3, so that the layer of the floating light substances is sensed and pumped out when a certain layer thickness is reached or discharged by introducing a pressure medium into the otherwise closed calming section.

6. The method of claim 1 to 5, d a d u r c h g e k e n e z e i c h n e t that the water content in the light-free zone of the calming section is sensed and an alarm is triggered when light substances are sensed.

Separation basin or container for carrying out the method described in claims 1 to 6, consisting of a vertical cylindrical or polyhedral separation container through which the waste water flows, horizontally, deεεen air-free lid and, if applicable, arched or 17

conical and equipped at the narrowest point with a discharge opening for the substances separated by floating or sinking, characterized by a guide wall (11.) running from the inlet (9, 24, 49) to the pure water outlet (12, 25, 62) , 22, 35, 45) for a more than simple circulation of the waste water.

8. separation basin according to claim 7, characterized in that the guide wall (11, 22, 35, 45) extends at most to the beginning of the conical or curved cover (2, 23, 43) or bottom (4, 31, 44) .

Separator basin according to claim 7 or 8 with an external tangential inlet for the waste water, characterized in that the guide wall (11) consists of a surface section (11 ') connected to the tangential inlet (10), an approximately concentric three-quarter circle (II -'-' ) and an inner, approximately radially extending deflection section (II ^,, ').

10. separating basin according to claim 9, d a d u r c h g e k e n n e e c h n e t that in the conical or curved bottom (31) and / or lid a clearing and / or

Thickening counter (33) rotates.

11. Separation basin according to claim 10, that the bottom consists of two truncated cones with different cone angles, and that the clearing device (33) is accommodated in the lower truncated cone (31 ') with a smaller cone angle.

12. Separation basin according to one or more of claims 7 to 11, in which the discharge opening for the floating light substances is equipped with a closure member, characterized by a measuring probe (14, 15) arranged in the region of the floating light substances, which is connected to the control (16). the closure member (7) is connected such that it is opened in the presence of light liquid and closed in the absence of water.

13. Separation basin according to claim 12, characterized by two measuring probes (14, 15) arranged at different heights under the cover (3), of which the lower (14) opens the closure member (7) in the presence of light liquid and the upper (15) in the presence of water, the closure member (7) closes.

14. Separation basin according to one or more of the claims

7 to 13, characterized by coalescence elements (13) inserted transversely in the flow path.

15. separation basin according to one or more of claims 7 to 14, characterized by a valve seat (48) arranged upstream of the discharge opening (46) and a valve plate (42) which acts on the valve seat (48) from below and is actuated by a float (41), the float is tared in such a way to the light substances accumulating there that it floats on water and is immersed in the light substances.

16. Separation basin according to claim 15, characterized in that the valve seat (48) lies at such a distance below the overflow edge for the floating light materials that the column of light materials exerted on the valve plate (42) resting on the closed valve plate exerts a lifting force is greater than the closing force exerted by the float and the water column standing in front of the pure water outlet on the valve plate from below.

17. Separation basin according to claim 7 biε 16, d a d u r c h g e k e n n z e i c h n e t that the closure valve (8) in the discharge opening (6) of the sediments is designed as a pinch valve.