DE2900687A1 - Annular activated sludge basin - with radial partition for simultaneous nitrification and denitrification - Google Patents

Abstract

An annular activated sludge basin surrounds a central reclarification basin and has a radial partition which separates the beginning from the end of the basin. A certain amt. of liq. is allowed to passes across the partition from the end to enter the beginning of the basin which is used as denitrification zone. Sewage, laden with nitrate, is thus passed to a denitrification zone where oxygen is recovered and reduces the energy consumption, and gaseous nitrogen is removed from the sewage.

Description

Ring-shaped aeration tank for simultaneous nitrification

tion and denitrification The present invention relates to an annular Aeration tank for simultaneous nitrification and denitrification of the wastewater existing nitrogen compounds with vertical circulating flow, which is caused by a vertical Partition wall and waste water supply at the beginning of the basin and waste water discharge at the end of the basin is designed as a longitudinally flow-through basin with graded load areas, where the beginning and end of the pool are at the same point as the water level and from the end of the pool to the beginning of the pool serving as a denitrification zone the partition wall is promoted a defined amount of water.

Area of application: Aeration tanks in municipal and industrial areas Biological sewage treatment plants State of the art: From recent research and experiments on a laboratory or technical scale it has become evident that at EiriIl # i # tung certain design parameters nitrification and subsequent denitrification the nitrogen compounds contained in the wastewater is possible and desirable because once the amount of oxygen recovered during the denitrification process, the energy consumption and, secondly, the gaseous nitrogen escaping from the Sewage is removed.

In addition to the design parameters listed above (e.g.

Basin sizes of activation and secondary clarification) are mainly the following Basic conditions that exist for the nitrification and denitrification process must be: a) for nitrification: sufficiently high sludge age and plentiful measured final clarification.

b) for denitrification: atmospheric oxygen-unsaturated zones and one Organic pollution accumulation in these zones.

While the prerequisites mentioned under a) in most of the more recent low-pollution sewage treatment plants are given, in fact unintentionally due to the z. Z. applicable official dimensioning regulations, the compliance with the under b) given conditions - mostly due to ignorance of the processes - hardly any value been.

Measurements in this regard have only recently been made on existing systems have been made, the o. Confirm research work, but on the other hand also showed that with the constructions customary today, the prerequisites mentioned under b) cannot be optimally designed.

This is due to the fact that most of them had low elate Aeration basins due to long dwell times and high circulation speeds are totally mixed pools. It is possible here to use intermittent c Or point-like ventilation to create oxygen-deficient zones, not but or only insufficiently a concentration of organic waste water constituents, especially since this affects the drainage quality and thus the cleaning performance of the sewage treatment plants totally mixed aeration tanks would affect.

On the basis of the more recent scientific investigations, for essentially practice the following two arrangements to achieve the denitrification effect io -.- beaten: I A denitrification tank is added to the aeration tank upstream. The raw sewage, the return sludge, becomes this denitrification basin and or activated sludge - wastewater mixture from the activated sludge tank added and mechanically, d. H. without air oxygen entry, mixed.

1I The aeration basin is designed as a longitudinally flowed basin with a vertical Circulation and different load areas designed, with the beginning of the pelvis serves as a denitrification zone. here is the raw sewage and the return sludge initiated. This zone is undersupplied with atmospheric oxygen.

The arrangement mentioned under I has the disadvantage that structurally a separate Pools are created with the necessary installations and connecting lines must, the arrangement indicated under II that the return sludge quantity in proportion to the inflow quantity cannot be increased indefinitely, as this does the hydraulic function the clarification would affect. Thus there is only an insufficient percentage Denitrification effect achievable. Since the water level of the secondary treatment is lower lies than that of the activation, the increased return flow results in an amount of cfilamm considerable energy expenditure to overcome this head, which is caused by the Denitrification reduces or eliminates the energy saving that can be achieved. The latter also applies to the z. Z.

Usual procedure of the arrangement mentioned under I.

The present invention is based on the above-mentioned object achievable advantages with minimal expenditure of energy.

Description: System sketch shown in Figure 1 The task is solved according to the invention in that the activated sludge tank (1) is arranged in a ring is taking it around an aeration tank with a longitudinal flow (1) acts with vertical circulation. The longitudinal flow in the aeration tank (1) results from the amounts of water added at the beginning of the pool (8, 9, ii) and that at the end of the pool withdrawn water volume (9, 10r This longitudinal flow in the aeration tank (1) is so small that it is not used for overturning. Ring-shaped means that the beginning of the pelvis and pool end are brought together again at one point. This can be done in round, happen in a serpentine manner, etc. The end of the pool and the beginning of the pool are included separated from each other by a partition (4). With a round version of the activation tank (1) This is done by arranging a radial partition (4). In rest position the water level in front of and behind the partition (4) is the same.

Through this partition (4) it is now possible to use a minimum of energy (shortest Transport distance, lowest pumping height) a defined amount of nitrate-contaminated Activated sludge - wastewater (9) mixed from the end of the pool into the denitrification zone (2) the beginning of the activated aeration tank. Because the resulting horizontal flow in the entire activation tank (1, 2) compared to the horizontal Circulating currents in structurally similar systems (e.g. oxidation ditches, Schreiber countercurrent pool, Vedewa round pool, etc.) is relatively small, as none There is a dependency between the horizontal flow and the upheaval it at the inlet point of the raw sewage (8) to the desired enrichment of wastewater constituents. The basin section serving as denitrification area (2) behind the wastewater inlet duct (8) there is insufficient oxygen supply d. H. expedient mechanically circulated.

The essentials of the invention is that through the partition (4) one ring-shaped activation tank (1) with minimal transport distance and minimal Pumping head of nitrate-contaminated wastewater in the beginning of the basin serving as a denitrification zone (2) is funded.

Since this amount (9) is a multiple of the inflow amount (8) + the amount of return sludge (11), the longitudinal flow in the aeration tank (1, 2) is so large that despite the long residence times of the wastewater in the aeration tank (1, 2) an undesirable one Back-mixing in the denitrification zone (2) is prevented.

Another arrangement according to the invention is that at the end the denilrification zone (2) a second partition (5) is installed so that at insufficient longitudinal flow, backmixing is avoided and a denitrification basin (2) arises.

Another arrangement according to the invention consists in that upon arrangement a circular activation tank (1, 2) and an internal secondary clarifier (3) the circular scraper (6) required for the secondary clarifier (3) above the aeration tank is extended and at this length (7) a circulation scraper with bottom sludge shield and or installed with units for mechanical circulation of the aeration tank contents is. This has the advantage that the introduction of oxygen into all areas of the aeration tank (1) Can be made according to the oxygen demand and an oxygen input can be omitted entirely in the denitrification zone.

In FIG. 1: 1 aeration tank 2 denitrification zone 3 According to] dybeeken 4 radial dividing wall between the beginning of the basin and the end of the basin 5 radial Partition wall between aeration basin and denitrification basin 6 round runners 7 circulators 8 Aeration inlet 9 activated sludge-wastewater mixture conveyed through the partition 1o inlet secondary treatment 11 return sludge 12 outlet purified wastewater Blank page

Claims (3)

Claims: Ringfiirmig arranged, in relation to the beginning of the basin amount of water added and withdrawn at the end of the tank, aeration tank with a long flow (1, 2y with vertical circulating flow for simultaneous nitrification and benitrification the nitrogen compounds present in the wastewater characterized in that basin start and pool ends are arranged in one place and separated by a partition (4) are separated, and that through this partition (4) or around this partition (4) around or under this partition (4) through or over this partition (4) a defined amount of water (9) from the end of the pool to the denitrification zone (2) serving basin beginning is promoted, with the same calm water level of Beginning and end of the pelvis. 2. Aeration tank according to claim 1, characterized in that on At the end of the denitrification zone (2) an additional partition (5) to prevent it a backmixing is arranged. 3. Aeration tank according to claims 1 and 2, characterized in that that a scraper (6) moving over the secondary clarifier (3) over the activated sludge tank (1, 2) is extended, and this extension (7) with a bottom sludge shield and / or aggregates for circulating the aeration tank contents are provided.