EP0777630B1 - Sewage clarification plant - Google Patents

Abstract

A sewage clarification plant is disclosed, in particular a sewage clarification plant with a collecting and overflow basin for collecting solid-enriched liquids and a separator (2) for separating solids from liquids. The separator has a substantially circular cylindrical drum (5) and a solid-enriched liquid inlet-duct (4) inclined into the inside of the drum (5). The drum (5) is mounted to rotate around a vertical axis of rotation (8) and is driven by an engine (7). The drum (5) has a liquid-permeable screening envelope (9).

Description

The invention relates to a wastewater treatment plant, especially with a collection and overflow basin for collecting of liquids enriched with solids, and one Separation device for separating the solids from the Liquid.

Such a wastewater treatment plant is often used Separation of solids, colloids or the like Waste water, activated sludge / waste water mixtures and the like Screening or filtration made.

Typical areas of application are rainwater treatment, as sand trap in wastewater treatment plants and for solid / liquid separation in aeration plants.

A particularly common area of application is in Mixed water treatment, whereby the mixed water is made up of Dirty water and rainwater, which together are channeled to a sewage treatment plant. At quantitative overload of the sewer network after strong Precipitation can be part of the inflows in Rainwater overflow basins can be cached. But it is also If their capacity is exceeded, the rest of the Basin overflow into the waters. The Chipped liquid must be cleaned beforehand, however no pollutants or other substances in the water initiate. Legal regulations often apply here about the required purity of the chipped water.

According to the state of the art, the water to be cut off by letting the solids settle and / or filters, including fixed filters or slowly rotating ones Drum filters were used in which the solids fortified liquid essentially radially from the Outside of the drum were introduced into the drum and from the inside of the drum as cleaned wastewater were brought out. Such a "rainwater relief structure" is for example from DE-OS 41 01 456 known.

From WO93 / 07539 is a wastewater treatment plant that for the purification of waste water from a manufacturing process of printing plates is used with a separator known that a circular cylindrical drum and one in the Has interior of the drum directed inlet, the Drum rotatable about a vertical axis of rotation by a motor is driven and a permeable to liquids Screen surface, which serves to support a filter bag.

The use of sieve or Computer systems for the separation of solids proposed.

A type of stripping device is known from DE-C-766260, a centrifugal drum with a screw for scraping the mass stuck to the drum wall is provided.

However, this was conventional solid separation devices together that they have a large space requirement and nevertheless with regard to the strength of the possible throughput mass flow are unsatisfactory. this lead to either disproportionately large filters or the Rain overflow basin had to be oversized.

The same applies to sand traps, which for reasons of Operational safety in many wastewater treatment units or Wastewater treatment plants mostly separate the ones in the wastewater washed sand or other mineral substances from the enabled organic substances. For this purpose traditionally the sand separation through the settling effect of sands and mineral substances due to the effect of Gravity reached, or the water flow with the therein contained particles was on a circular path around the Longitudinal axis of the sand trap moves, depending on the basin design a different roll flow was induced, which too a different separation of inorganic material and organic material. The sand or that inorganic material conventionally accumulated the bottom of the pelvis, where it is by suction or flushing devices was subtracted.

Here, too, there was a large space requirement for the sand trap required, at the same time the separation effect was unsatisfactory, or the strength of the possible throughput mass flow remained unsatisfactory at the same time.

The same applies to a solid / liquid separation in aeration plants, using biologically active sludge (the so-called animated sludge) separated from liquid must be and must be returned to the aeration tank. Traditionally, this separation was done in one Clarification basin, which is also a large dimension in one had relatively unsatisfactory throughput mass flow.

Other solids / liquid separation solutions Wastewater treatment plants included at aeration plants Aeration tank and secondary clarifier the steps of screening or flotation in the partial flow. However, this solution is uneconomical, because too large screen areas are required or the plants had to be dimensioned too large.

The object is achieved by the invention, a wastewater treatment plant with regard to the space required significantly reduce, an improved separation effect achieve and at the same time for a high throughput mass flow to interpret.

This is achieved according to the invention in that the Separating device is an essentially circular cylindrical drum and an inlet for the inside of the drum Has liquid enriched with solids, the about a vertical axis of rotation of a drum Motor is driven and the drum is one for liquid permeable sieve surface.

The solids accumulate as the drum rotates the inner wall of the drum. It becomes a high throughput mass flow and realizes an improved separation effect, while at the same time the known collection and Overflow basin, sand separation basin or secondary clarification basin can be made much smaller or under certain circumstances can even be left out entirely.

To prevent the spout from splashing out while the drum is rotating Preventing water can be beneficial in the upper range Drum a collar-like cover may be provided almost the entire top of the drum occupies about the axis of rotation.

The outer surface of the screen advantageously has one of these low flow resistance on that essentially the all liquid radially through the surface of the sieve is thrown outside, the drum advantageous from a shaft structure that collects the liquid is surrounded. This then collects on the walls of the shaft structure cleaned liquid, flows down and becomes finally led out through a first outlet. On the The solids collect inside the drum and can be removed by means of a cleaning device.

The liquid can be fed into the drum from below or done above. In a preferred embodiment the inlet directed into the interior of the drum coaxial to the axis of rotation of the drum. More preferred is at this embodiment that the inside of the drum directional inlet concentric to the axis of rotation of the drum is arranged. In the latter two embodiments the wastewater is fed in such a way that it flows into the rotating Drum enters above the lower face and as a result the acting centrifugal force towards the outside Sieve / outer surface is thrown. At the concentric The arrangement of the inlet is the supply of the liquid particularly advantageously possible from below.

In another embodiment, the separating device an essentially circular cylindrical drum with an im essential tangential inlet for those with solid Enriched liquid to the inside surface of the drum Area of their first face. Through the tangential Inlet into the drum causes the natural energy of the liquid enriched with solids during deposition is helpful and the one required to turn the drum Engine power is reduced.

According to a further advantageous development, a Spray device can be provided on the outside of the drum, which separates the solids deposited on the drum wall through the wall with liquid or compressed air, for example hosed or sprayed. This spraying can be carried out continuously or discontinuously, wherein Spray nozzles on the cylindrical outer surface of the drum are directed.

According to the invention, a cleaning device is provided, by means of which the inner wall of the drum is cleaning is subjected. The cleaning device includes at least one arranged inside the drum and from the inside the drum wall cleaning device with brushes, scrapers and / or spray nozzles for exposure to water, and / or a kind of spraying device, which from the outside of the drum can support cleaning from the inside. This cleaning can also be independent of spraying water from the outside on the inside by brushing, spraying or wiping be made. When cleaning by spraying outside and / or inside, can be done with the spray water mixed solids fraction through a separate outlet be brought out.

Spraying can be continuous, or even if none Cleaning device is arranged fixed in the drum, be carried out discontinuously, i.e. the supply of the with Solids-enriched liquid can be interrupted for this be, and the collection and discharge device can be axially in the drum can be driven in while the drum is with rotates at slow speed so that the entire circumferential surface can be cleaned by the spray nozzles can. In this case, the filtered one Solid fraction by one in the bottom area of the drum located lockable flap removed or omitted be caught by a suitable collecting device as well as be led out of the separation device. If the viscous filter sludge can be pumped, this can also if necessary without spraying the drum wall from the outside, from the collecting and discharging device by means of a pump pumped out a discharge line and, if necessary, at least to be partially returned to a stronger one To allow thickening.

For procedural reasons, the is continuous Operation of the plant preferred, in which the collecting and Diverter is fixed inside the drum and optionally through the spray nozzles liquid or Compressed air on the cylindrical outer surface of the drum is judged.

The various advantageous developments can achieved that the separation process due to the Centrifugal force and through the filtration (with a sieve surface with low flow resistance), whereby the different forms of separation depending on desired throughput mass flow of the to be treated with Solids-enriched liquids or the desired Separation unit can be selected. The drum can only slightly with that enriched with the solids Be filled with liquid, for example on its inner wall only have a liquid film or be completely filled.

The position of the axis of rotation of the drum is essentially vertical. The diameter of the sieve drum can vary Inlet water quantity or cleaning target at least 0.2-0.5m and maximum 3-5m, the diameter / length ratio at 10: 1 to 1:10, preferably 3: 1 to 1: 3 can lie. The rotation speed of the drum is generally up to a few hundred revolutions per minute, preferably about 10 to 600 rpm.

The mesh size of the outer surface of the sieve is preferably 0.5 µm to about 5 mm, preferably 50µm-1mm. In the event of one Slotted screen, the slit width can be up to 5 mm. At A suitable choice of mesh size can be used for the separation process thereby additionally influenced and the filter effect be supported that a filter cake at the Built up inside the drum and in a layer thickness there too is left.

Before the liquid enriched with solids the Cleaning is subject to precipitation and / or flocculation with or without a subsequent sedimentation stage be what the usual in wastewater technology Precipitation chemicals iron and / or aluminum salts or Flocculants such as anionic and cationic polyelectrolytes and caustic soda, lime, acid can be used.

Figur 1 eine Seitenansicht einer ersten Ausführungsform einer erfindungsgemäßen Trenneinrichtung;

Figur 2 eine Seitenansicht einer zweiten Ausführungsform einer erfindungsgemäßen Trenneinrichtung;

Figur 3 eine Draufsicht auf die in Figur 2 gezeigte Trenneinrichtung;

Figur 4 verschiedene Trommeln mit unterschiedlichen Formen.

The invention is explained below using two preferred exemplary embodiments with reference to the drawings. The drawing shows:

Figure 1 is a side view of a first embodiment of a separation device according to the invention;

FIG. 2 shows a side view of a second embodiment of a separating device according to the invention;

Figure 3 is a plan view of the separator shown in Figure 2;

Figure 4 different drums with different shapes.

The separating device 1 shown in Figure 1 is in one Shaft structure 2 installed, the concrete walls 3 in the Drawing are shown. Enriched with solids Liquid is through the inlet 4 about the axis of rotation Drum 5 initiated. The rotatably mounted drum 5 can rotate according to arrow 6 and is driven by a motor 7, preferably an electric motor, using a drive shaft 8 rotated.

According to the illustrated embodiment, the drum 5 a screen surface 9, which is permeable to liquid is. Part of the liquid is preferably through the Sieve outer surface 9 flung and from the wall 3 of the Shaft structure 2 caught and collects due to the Gravity at the bottom 10 of the shaft structure 2. From the Shaft structure 2 opens into outlet 11 in the area of floor 10 for the cleaned liquid.

In addition, the separation device with a collecting and Diverter 12 for cleaning the inside wall of the drum 5 provided, one in viscous form Filter sludge using the pump 13 via line 14 can be dissipated. Liquefaction of the sludge can can also be facilitated by the fact that spray nozzles from the Outer wall of the outer surface of the sieve with a relatively high pressure of Pumped liquid through the surface of the sieve 9 is sprayed. Instead of spraying with a liquid the cleaning of the screen surface is equally effective 9 via compressed air blown out of the spray nozzles.

According to the embodiment shown in Figure 2 the drum 5 has a screen surface 9, which is permeable to liquid. It is preferably a part the liquid is thrown through the screen surface 9 and caught by the wall 3 of the shaft structure 2 and collects gravity on the bottom 10 of the Shaft structure 2. The shaft structure 2 opens into the area the bottom 10 from an outlet 11 for the cleaned liquid. Part of the liquid can also flow vertically down from the Exit drum 5 at its second end face 15. A Catch channel 16 is around the lower edge on the second End face 12 of the drum 5 extending radially and axially arranged overlapping the drum edge to a part of the to collect separated solids. The rest of the separated solids collect on the surface of the sieve, that is, on the inner surface of the drum 5.

In addition, the separation device with a Spray device 17 for cleaning the inner wall of the drum 5 provided, spray nozzles 18 from the outer wall of the screen outer surface forth with relatively high pressure from the pump 19th Spray the liquid conveyed through the surface of the sieve 9, and on the inside of the drum 5 the spray nozzles 15 opposite a collecting device 20 for collecting the solids fraction detached from the spray nozzles which is at its lower end in a discharge pipe 21st opens, which finally in a second outlet 22 for the Drain the solid fraction together with the spray water flows. Instead of spraying with a liquid it is the cleaning of the outer surface of the screen 9 has the same effect Compressed air blown out of the spray nozzles 15.

The collecting / stripping device 20 can also during the normal operation in the axial direction from the screening drum be pulled out and only for the cleaning process in the Drum 5 must have moved in. The inlet 4 is on its Sieve drum 5 facing away, preferably with one in the Drawing not shown collection and overflow basin connected, the overflowing from this basin, with Solids-enriched liquid in the separation device 1 can be cleaned.

FIG. 4 shows various possible shapes for the drum 5, depending on the one to be cleaned, enriched with solids Liquid, depending on the desired throughput mass flow or concerned consistency of the liquid / solid mixture.

With the provision of the wastewater treatment plant according to the invention becomes a simple and economical solution proposed large amounts of water enriched with solids quickly and efficiently from the solids it contains to free. Therefore, it is possible to use the previously used Shrink "cache" pool, and is accordingly the embodiment of the invention Wastewater treatment plant in connection with the opposite reduced size known in the prior art Rain overflow basin, in extreme cases directly at the rain overflow connected to a sewer pipe, sand separator basin or Clarifiers particularly preferred.

Claims (5)

1. A waste water treatment plant, in particular comprising a collection and overflow basin for collecting liquids enriched with solids and a separation device for separating the solids from the liquid, wherein the separation device (1) has an essentially circular cylindrical drum (5) and an inlet (4) for the liquid enriched with solids directed to the inside of the drum, wherein the drum (5), which is pivotally supported about a vertical axis of rotation, is driven by a motor (7), and the drum (5) has a screen jacket (9) permeable to liquid,
   characterized in that a cleaning device, for stripping off solids deposited on the wall of the drum, is provided which is fixedly arranged in the drum (5) or movable into the drum (5) in axial direction.
2. A waste water treatment plant according to claim 1, characterized in that the inlet (4) directed to the inside of the drum (5) is arranged coaxially with respect to the axis of rotation of the drum (5).
3. A waste water treatment plant according to claim 2, characterized in that the inlet (4) directed to the inside of the drum (5) is arranged concentrically with respect to the axis of rotation of the drum (5).
4. A waste water treatment plant according to claim 1, characterized in that the separation device (1) has an inlet (4) which is directed essentially tangentially with respect to the inner surface of the drum (5) in the region of the first end face thereof, for the liquid enriched with solids.
5. A waste water treatment plant according to one of the preceding claims, characterized in that the screen jacket (9) has such a low flow resistance that substantially the entire liquid is flung radially outwards through the screen jacket (9), and that the drum (5) is surrounded by a shaft structure (2) catching the liquid.

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