EP0709529B1 - Waste water filter system and the resulting method for reducing strainable impurities of emergency outlets of mixed systems and mixed water clarification tanks - Google Patents

Description

The invention relates to a relief system of a mixing system or mixed water clarifier with a wastewater filter system to reduce the amount of dirt that can be screened. The reduction of floating and suspended matter in the relief water quantities of mixing systems is achieved on the one hand by fixed baffles and floating baffles (according to DE 3503407) and also by means of screen screens (Deutschland Kommunal 2/1993 p. 42) as well as by a flushing screen system according to DE-A-2 743 580 realized. Here, the aforementioned elements are designed so that they correspond in length to the downstream fixed and movable weir systems.

Floating baffles are a significant improvement when properly installed, when it is important to retain floating substances in the mixed water network to prevent relief in the receiving water. In this respect, however, it should be noted that, particularly in the case of relief control by means of vertically controllable weirs according to DE 2552516, dirt cargo particles that are still in suspension and are located in the area between the lower edge of the floating baffle and weir edge are discharged into the receiving water, and thus ultimately worsen the dirt cargo balance. The use of sieve screens and flushing screens comes very close to this invention, because floating and suspended matter can be retained in a similar way, but limited in size to the existing mesh size. The main drawbacks, however, are that the use of sieve racks and flushing rakes in the inlet area of vertically controllable weir systems is not possible, and that the sieve grate construction significantly reduces the hydraulic power, which also requires machine cleaning.

• Q _vor = Entlastungswassermenge    (m ³)
• # = Filterversetzungsfaktor    (%)
• k° = Filtergewebekonstante    (-)
• L = Länge der benetzten Filterbahn    (m)
• b = Filterbreite ideel    (m)
• g = Erdbeschleunigung    (m/s ²)
• h_max = Statisches Energiegefälle    (m)

The present invention has therefore set itself the task of reducing the discharge of screenable dirt loads in relief systems of mixing systems and mixed water clarifiers in order of size to particle sizes in the millimeter range and thereby optimally support the possibilities of controlling the sewer storage spaces by means of measuring weir systems according to quality and quantity (according to DE 4016378) . This object is achieved according to the invention by one of the features of claim 1. The fabric filter web is then drawn into a defined channel area, the water level curve not touching the aforementioned fabric filter web in dry weather. When there is an increased amount of mixed water and the water level rises accordingly, the fabric filter web is flown from below upwards into the so-called relief chamber, whereby the floating and suspended matter of the incoming mixed water (Qzu) are retained in the lower channel chamber, the particle size of which is the specified one Mesh width of the fabric filter web exceeds. In the aforementioned case, due to the filter resistance and the differential water levels that occur, an upward curvature of the fabric filter web, in particular in the event of relief, can occur until it is completely braced. The shown movement options or flexing effects of the fabric filter web thus allow the fabric filter web to be cleaned automatically, which is ultimately reinforced because the mixed water that has already entered the relief chamber returns when the inlet water level of the mixing system drops. A further continuous cleaning effect of the fabric filter surface on the underside is also achieved by the trailing tension occurring in the flow direction at elevated water level positions; how they are optimally supported, for example, in connection with flushing waves of the flushing weirs according to DE 3616418 in mixing systems. So that the specified amount of relief water (Q vor) can be drained to the receiving water by means of, for example, a vertically controlled weir system, the wetted fabric filter area should be selected so large that at least the following equation is met: $${\mathit{\text{Q}}}_{\mathit{\text{in front}}}\text{= \# ∗ k ° ∗ L ∗ b ∗}\sqrt{\text{2 ∗}{\mathit{\text{g ∗ h}}}_{\text{Max}}}\text{(}{\mathit{\text{m}}}^{\text{3rd}}\text{)}$$

• Q _before = relief water volume ( m ³ )
• # = Filter offset factor (%)
• k ° = filter fabric constant (-)
• L = length of the wetted filter web ( m )
• b = filter width ideel ( m )
• g = gravitational acceleration ( m / s ² )
• h _max = static energy gradient ( m )

Of course, the above formula also applies to mixed water clarifiers with different shapes. However, the product from L ∗ b must correspond to at least part of the surface [F] of the mixed water clarifier, which means that the above formula for determining the amount of relief water (Q before) must be changed as follows: $${\mathit{\text{Q}}}_{\mathit{\text{in front}}}\text{= \# ∗ k ° ∗ F ∗}\sqrt{\text{2 ∗}{\mathit{\text{g ∗ h}}}_{\text{Max}}}\text{(}{\mathit{\text{m}}}^{\text{3rd}}\text{)}$$

A possible embodiment of the invention is explained in more detail with reference to drawings. 1 shows a longitudinal section of a mixed water collector in which the dry weather water level ( 18 ) lies below the fabric filter web ( 1 ) and the weir upper edge ( 26 ) has been raised to the maximum water level position ( 7 ). It can also be seen that a relief system ( 25 ) is arranged between the inlet-side inspection shaft axis "AA" or the outlet-side inspection shaft axis "DD" in the region of an axis "CC" displaced off-center in the direction of flow ( 27 ). It can be seen how the fabric filter web ( 1 ) in the slide rails in the defined channel area ( 3 ) ( 2 ) should be retracted and locked. Furthermore, it can be seen that the entire fabric filter web ( 1 ) consists of several individual surfaces ( 20 ) which are connected to one another by means of point connections ( 21 ) and ultimately in the start area ( 4 ) or in the end area ( 5 ) via a corresponding curve formation ( 6 ) up to the maximum water level ( 7 ), which means that the entire relief space ( 23 ) can only be covered with filtered mixed water in the event of a dam.

Fig. 2 shows a longitudinal section of a mixed water collector in the relief state, in which the maximum water level position ( 7 ) in the constructive initial area ( 4 ) was assumed. The indicated relief activity by lowering the upper weir edge ( 26 ) of the controllable weir ( 24 ) lowers the energy line in the area of the relief system ( 25 ) by the differential pressure ( 28 ), which results from the sum of the pipe friction losses and filter resistances, etc. With this system behavior, depending on the level of the relief activity, the arching of the fabric filter web ( 1 ) shown, which ultimately reveals the flexing effect and the resulting self-cleaning of the fabric filter web ( 1 ).

Fig. 3 shows a cross section of the mixed water collector "CC" in which the sensible arrangement of the fabric filter web ( 1 ) can be seen within the relief system ( 25 ). In the present case, the controllable weir ( 24 ) is lowered and is in the so-called relief case, with excess waste water being drained off towards the receiving water. In such a system state, the wastewater flows through the fabric filter web ( 1 ) due to the differential pressure ( 28 ) occurring from the different absolute water levels in the sewer and relief chamber ( 23 ) and thus creates an upward curvature of the fabric filter web ( 1 ), which ultimately results in the flexing effect becomes recognizable. In this overall system, the floating baffle ( 22 ) has the task of holding back any light material in the mixing system that has passed through the fabric filter web ( 1 ). Furthermore, it can also be seen that in the weir area ( 9 ) of relief systems ( 25 ) at least one slide rail ( 2 ) must always be locked below the fixed weir edge ( 29 ), so that a seamless reduction of sievable dirt loads from mixing systems or mixed water clarifiers can be made possible.

Fig. 4 shows a cross section of the mixed water collector "AA" in the direction of flow ( 27 ), in which the sensible locking of a fabric filter web ( 1 ) by means of tensile sliding elements ( 13 ) located on its lateral edges ( 11 ), which in turn can be seen within the parallel slide rails ( 2 ), here designed like half rails, are drawn in and are subject to a reversible arrangement. Furthermore, it can be seen that the fabric filter web ( 1 ) is pulled up to the maximum water level position ( 7 ) by means of the slide rails ( 2 ) located in the vertical outer wall areas ( 19 ), shown here in broken lines, so that the mixed water quantities flowing to the relief chamber ( 23 ) procedurally differ from those can be exempted from screenable dirt loads. The fabric filter sheet ( 1 ), due to its own weight, has a sag [DH] ( 16 ) in this representation and clarifies the fact of claim 5, according to which the maximum dry weather water level ( 18 ) should normally be below the fabric filter sheet ( 1 ) .

Fig. 5 shows a cross section of the mixed water collector "BB" in which the dry weather water level ( 18 ) is below the then sagging by the weight of the fabric filter web ( 1 ), whereby it must be necessary that the width ( 14 ) of the fabric filter web ( 1 ) is greater than that Pipe profile width ( 15 ). Furthermore, a possible variant for the reversible locking of the fabric filter web ( 1 ) is shown in detail 3.1, wherein it can be seen that the fabric filter web ( 1 ) has reinforcements ( 12 ) on its edges ( 11 ), on which the tensile sliding element ( 13 ) acts as a slide shoe formed is located within the slide rail ( 2 ).

Fig. 6 , however, shows a cross section of the mixed water collector "BB" in which due to a relief by lowering the weir ( 24 ) not shown here or in the case of mixed water accumulation and thus increased inlet water levels, the fabric filter web ( 1 ) is curved upwards. It can be seen here that as a result of the flow through the fabric filter web ( 1 ) from bottom to top, reinforcements ( 12 ) with tension-resistant sliding elements ( 13 ) are necessary at their lateral edges ( 11 ). so that power can be transferred to the slide rails ( 2 ).

Fig. 7 shows a top view "EE" a section through the relief system ( 25 ) in which the arrangement of the individual surfaces ( 20 ) of the fabric filter webs ( 1 ) and the arrangement of the eyelet connections ( 21 ) together with the slide rails ( 2 ) is shown.

Claims (8)

1. Emergency outlet of a mixed system and/or mixed-water clarification tank with waste water filter system for reducing strainable impurities whereby a fibrous filter mat (1) reaching beyond the maximal water level (7) both in the constructional starting section (4) and the constructional end section (5) via a corresponding curve (6) is primarily led in parallel sliding rails (2) within a defined DK length channel section (3) and then secured in a reversible manner, whereby in dry weather the water level hydrograph does not touch the fibrous filter mat (1) and where in case of increased mixed-water loads and correspondingly rising water levels the fibrous filter mat (1) is wetted from bottom to top into the relief area (23).
2. Emergency outlet pursuant to Claim 1, an important characteristic feature being that the defined channel section consists of the length DK (3) of mixed systems from a length ZR (8) pipe system on the inlet side, a length WB (9) weir area, a length AR (10) pipe system on the outlet side and the constructional starting section of length KA (4) and/or the constructional end section of length KE (5), and is therefore governed by the formula listed below: $$\text{DK = KA + ZR + WB + AR + KE}$$

   

   whereby WB (9) is equal to the overflow width of a weir system.
3. Emergency outlet pursuant to Claims 1 or 2, an important characteristic feature being that the fibrous filter mat (1) is strengthened (12) on the lateral edges (11) permitting to attach tension-proof sliding elements (13) designed as sliding rollers and/or sliding blocks or the like in order to achieve that the fibrous filter mat (1) can be introduced into the pertaining sliding rails (2).
4. Emergency outlet pursuant to Claims 1 through 3, an important characteristic feature being that the width (14) of the fibrous filter mat (1) exceeds the channel profile width (15), whereby a fibrous filter mat sagging [DH] (16) occurs over the entire specifically defined channel section (3).
5. Emergency outlet pursuant to one of Claims 1 to 4, an important characteristic feature being that the lowest sagging point (17) of the fibrous filter mat (1) ist above the maximal dry weather water levels (18) of the mixed system and that the positioning of the sliding rails (2) is fixed on or in the vertical external wall area (19) of the defined channel section (3).
6. Emergency outlet pursuant to one of Claims 1 to 5, an important characteristic feature being that the fibrous filter mat (1) eventually consists of several individual surfaces (20) connected to each other by means of corrosion and tension-proof eyebolts (21).
7. Emergency outlet pursuant to one of Claims 1 to 6, an important characteristic feature being that in each case of installation in the weir area (9) of fixed and/or controllable emergency outlet weirs (24,25) at least one sliding rail (2) of the fibrous filter mat (1) must be positioned below the fixed weir edge (29).
8. Emergency outlet pursuant to one of Claims 1 to7, an important characteristic being that analogous to a specifically defined channel section (3) one fibrous filter mat (1) is also introduced and reversibly fixed in mixed-water clarification tanks which are also provided with emergency outlets (25), whereby the sliding rails (2) on or in the vertical external wall area (19) must be fixed in line with the respective shape of the clarification tank.

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