DE2900276A1 - Activated sludge basin circulation device - using impeller and raking plough independent of oxygen intake - Google Patents

Abstract

A travelling mechanism to maintain a circulation of a sewage-activated sludge mixt. in aeration basins of biological sewage treatment plant has >=1 impellers which are suspended from a revolving bridge. A raking plough moves along the basin floor and pushes the activated sludge into the circulation caused by the impeller. Circulation is thus clearly sepd. from the aeration function and the latter can be designed independent of the circulation requirements. Power is saved because the circulation is only local and does not involve the whole basin.

Description

Movable circulation device for aeration tanks

The invention relates to a movable circulation device for aeration tanks, with the pool contents (activated sludge-wastewater mixture) only in the area of the respective Bäumer bridge standpoint without simultaneous oxygen introduction directly with a mechanical circulation device (e.g. propeller, pipe pump, etc.) is circulated, this circulating device with a ground clearance shield that sweeps over the bottom of the basin can be combined and thus a compulsory mixing of the pool contents and evacuation of the activated sludge deposited on the bottom of the tank in the clearing intervals takes place at the respective clearing position.

Area of application: Aeration basins in biological sewage treatment plants of technology: In the aeration basins of biological sewage treatment plants, it is essential for the purification performance of the activated sludge is important that the Sdllamll with the discharged and in the basin existing wastewater is intimately mixed. The circulating energy entered must be like this be great that sludge deposits on the bottom of the pool are avoided, as this serious malfunctions can be caused.

Usually the circulation is combined with the oxygen input, d. H. the process of introducing oxygen with surface aerators and with # compressed air creates water currents and turbulences in the basin, which cause the activated sludge to sink to prevent the bottom of the pelvis. For aeration tanks with low loads leads this to the fact that for the energy expenditure not only the amount of oxygen required in each case is decisive, but partly the required circulating energy. I. E. the circulating energy is the minimum factor, in most cases more oxygen is introduced than the activated sludge needed.

Newer systems try this deficiency among other achieved effects to be eliminated by a) the ventilation device was designed to be movable and so in addition to low total pool circulation, there are also zones with increased circulation develop. (e.g. Schreiber countercurrent pool, Vedewa round pool) or b) The oxygen input and the circulation were separated, making both systems more energy-efficient can be. (e.g. Roto-Plot system, Pa. Menzel; oxidation trenches with compressed air ventilation and circulation propellers, Lippeverband Essen, etc.) At the same time, both under a) and b) said devices have the advantage that atmospheric oxygen in the aeration tank Undersupplied zones arise, according to recent findings, a basic requirement for the required denitrification processes, in a) by punctiform air entry, at b) through the now possible intermittent ventilation.

Another prerequisite for denitrification processes to run Secondly, however, in the aeration tank there is a concentration of dirt in the areas that are undersupplied with atmospheric oxygen Zones.

All previously known facilities meet these two basic requirements not or only very imperfectly, because of the classification made under a) and b) inevitably the entire pool content is circulated and thus zones with increased Concentration of dirt cannot or only insufficiently develop.

The present invention is therefore based on the object to reduce the energy input required and at the same time that for the expiry of Denitrification processes required conditions (dirt concentration and Undersupply of atmospheric oxygen in the denitrification zone).

Description: System sketch shown in Figure 1 The task is solved according to the invention in that on one of the activated sludge tank (1) can be moved Scraper bridge (6) one or more mechanical circulation units (7, 8) (e.g. propeller, Pumps) are attached with which the activated sludge - waste water mixture (4) in the area of the respective bridge standpoint is circulated. Which is during the driving intervals Activated sludge (5) deposited on the bottom of the tank (3) can be carried over the bottom of the tank with a (3) brushing blade (9) the circulating unit (7, 8) or the forming Circulating flows (10) supplied and mixed again with the rest of the basin contents (4) will. The latter can also be done in that the generated with the unit (7, 8) Circulating flow (10) is directed against the bottom of the pool (3).

The following effects can be achieved simultaneously with the present arrangement achieve: The circulation is separated from the oxygen input.

Effect: The oxygen input can be adjusted exactly according to the oxygen demand be made.

The circulation takes place only at the respective clearing position.

Effect: Saving of circulating energy, since not the entire pool contents must be circulated.

A basin with different load areas can be maintained because the basin contents mainly due to the arrangement according to the invention is mixed in the vertical direction.

Effect: The desired concentration of dirt occurs in the area of the Wastewater discharge, a prerequisite for the denitrification process, as the longitudinal flow depends on the inflow volume in the pool - depending on the pool construction.

The circulation in the denitrification area takes place directly via a mechanical one Aggregate.

Effect: In the denitrification zone, the disruptive entry of atmospheric oxygen omitted.

In FIG. 1: 1 aeration basin 2 water level 3 basin bottom 4 activated sludge - waste water mixture 5 settled activated sludge 6 scraper bridge 7 tubular propeller 8 Propeller drive 9 Bottom sludge scraper 10 Circulating flow Blank page

Claims (2)

Claims: 1. Movable circulation device (6, 7, 8, 9) for Activation tank (1), characterized in that at one over the activation tank (1) or one or more movable devices (6) next to the aeration tank (1) Circulation units (7, 8) for mechanical circulation of the pool contents (4) on the respective Location of the facility (6, 7, 8) are installed without simultaneous oxygen entry. 2. Movable circulation device (6, 7, 8, 9) for aeration tanks (1) according to itnspruch 1, characterized in that an additional over the basin sole (3) stroking Eodenräumschild (9) is attached.