FI60186B - ANORDNING FOER BEHANDLING AV AVLOPPSVATTEN - Google Patents

Description

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(32) (33) (31) Fyrietty «« lolkeu * —Begird priority 25.06.73

Sweden-Sweden (SE) 7308851 ^ 0 (71) ITT Industries, Inc., 320 Park Avenue, New York, N.Y. 10022, USA (72) Giuliano Gatti, Milan, Italy-Italy (lT),

Hjalmar Pries, Sp & nga, Sweden-Sverige (SE) (7L) Oy Kolster Ab (5L) Apparatus for wastewater treatment - Anordning för behandling av avloppsvatten This invention relates generally to apparatus for treating wastewater and more particularly to aeration of sewage.

The construction of relatively large drainage systems for collecting sewage in communities is limited by the fact that sewage is likely to rot in the systems. Sewage rot is the result of the evolution of hydrogen sulfide and other toxic gases into the water. This putrefaction occurs in water 3-6 hours after the water has left the household, unless sufficient oxygen is added to it so that natural biological reactions can occur.

Toxic gases that develop when sewage is rotting make it difficult to purify water efficiently in treatment plants and cause odor problems at large pumping stations. Hydrogen sulfide is also a health hazard.

Therefore, it is important that the decay of sewage in piping systems is kept to a minimum by adding oxygen to it. R.D. Pomeroy and J.D. Studies by Parkhursf show that oxygen consumption in sewage can be as high as 20 mg / l per hour in pipelines and pumping stations due to the biological coating on the walls of the pipelines and the growth of activated sludge in the sewage. By adding oxygen to the water as it is passed through the piping system, it is possible to significantly reduce the organic load of the treatment plants and make higher capacity possible.

The best place to add oxygen to sewage is at the point where the water has left 6,686 smaller, local systems and has begun to accumulate at the first pumping stations. The water has then usually been in contact with the smaller pipes in the system for about 30 minutes. The oxygen reaction rate according to Pomeroy and Parkhurst indicates that there is a risk of lack of oxygen (rot), which means that the addition of oxygen is the most efficient at this point. Farther in the piping system, water passes through other pump stations, usually between 30 stations. minutes.

The present invention relates to an apparatus for aerating sewage in pumping stations.

DE patent publication 2256874 discloses a wastewater treatment device. In this device, the water is aerated so that it is directed to pass diagonally over the installed level. However, this device does not achieve an efficient enough addition of oxygen to the wastewater. In addition, the device has a complex structure, as it uses e.g. several pumps and aeration towers.

The device disclosed in DE patent publication 9149 is generally known in the field of pump technology. This device can be considered as an indication of the general state of the art, which, however, is not directly related to the devices defined in the requirements.

The object of the device according to the invention is to provide a device which performs efficient aeration of wastewater with apparently complex aeration devices. The inventive idea is generally formed by the fact that one pump is used to provide aeration, so that the water to be pumped out is periodically injected back, whereby the aeration becomes very efficient.

The device according to the invention can be implemented within the framework of the above-mentioned basic idea in that it has a pump immersed in a pump well and used for oxidizing and conveying wastewater, a nozzle a nozzle, a control motor for turning the flap and a waste water level indicator, the valve flap being adapted to turn automatically between its two positions according to the water level in the pump sump. The device can also be implemented according to the invention with a pump immersed in a pump sump with an outlet pipe, a nozzle with an air intake and a nozzle adjustment device, which can be infinitely adjusted between two extreme positions, whereby all pumped and aerated water is adapted to return to the pump sump, and in its other extreme position, the pumped and aerated water is adapted to flow out of the pump well.

3 601 86

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a schematic view of oxygen consumption according to Pomeroy and Parkhurst; Fig. 2 shows a schematic view of an embodiment of a sewage aeration device of the present invention; and Figure 3 shows a schematic view of another embodiment of the device of the present invention.

Figure 1 two-curves show the rate of oxygen reaction or oxygen consumption of sewage over time at two temperatures, namely 22 ° C and 26 ° C, according to Pomeroy and Parkhurst studies. These curves show that the time of maximum oxygen consumption is about 30 minutes. Typical sewer-water systems have an interval of about 30 minutes between pumping stations.

Thus, according to the invention, the aeration of the water takes place in the pumping stations. This is usually accomplished by aerating the sewage at the pumping stations with the standard sewage pumps at these stations when these pumps are not used to transfer water in the piping systems. Aeration is done by re-pumping a smaller or larger part of the water so that air is added.

Figure 2 shows a device with which the method of the present invention is implemented, e.g. the device indicated by the general number 10. The device shown in Figure 2 represents a pump station with a tank 12 with an inlet pipe 14 and an outlet pipe 16. The tank is closed by a lid 17. The pump 18 is mounted in the lower part of the tank 12 so that its inlet 20 is immersed in the tank drain 21. Pump outlet 22 is connected by a line 24 to a tank outlet pipe 16. A second line 26 is connected to a line 24. This line extends downwardly at an angle and terminates as a discharge head 28. A valve flap 30 is mounted in line 24 at its junction with line 26. The control device 32 adjusts the position of the valve flap 30. The control device 32 responds to output signals. developed by two liquid surface sensors 34 and 36 having a vertical clearance. The sensors can be photometric or electrolytic. For example, each sensor could form a conductivity measuring cell. Conductors 38 and 40 supply sensor outputs to control device 32. This device includes a suitable control circuit. which normally includes relays and which controls a solenoid which moves the valve flap 30 between the two positions shown in broken lines in Figure 1 at 30a and 30b. Those skilled in the art will understand the details of the sensors 34 and 36 and the control device 32 and will therefore not be described herein. The control device is designed so that when the surface of the water 21 reaches the sensor 34, the valve flap 30 is in position 30b. As the water level drops to the height of the sensor 4 60186 member, the control device moves the flap 30 to position 30a.

Line 26 has aeration means. These include a spray nozzle 42 and an air intake pipe 44 connected to a conduit 26 on the downstream side of the nozzle 22. The air intake pipe 44 extends through the lid 17 and has an inlet end 46 outside the container 12.

Device 10 operates as follows. When the sewage water rises to the height of the sensor 34, the flap 30 is automatically moved to position 30b. In this position of the flap, sewage is pumped directly from the bottom of the tank 12 through line 24 to outlet 16. During this time, the flap prevents flow communication to vent vent 42. When the sewage reaches lower sensor 36 height, through the discharge pipe 16. The water discharged from the nozzle 42 causes air to be absorbed into the line 26 through the pipe 44 and the mixture of water and air is injected through the discharge end 28 of the line 26 back into the tank 12. Thus, the sewage is aerated during this period. This aeration continues until the surface of the sewage water again reaches the level of the sensor 34. Of course, it is possible that the control device 32 is designed so that the flap 30 is in an intermediate position, shown in solid lines in Figure 1, so that part of the water is led to the tank outlet pipe 16 and another part through the nozzle 42 for aeration and returned to the tank.

Thus, the present invention uses a single pump both to transfer sewage from one pumping station to another and also to aerate the water at the station to reduce or prevent water rot.

Figure 3 shows another form of the device according to the present invention. In this embodiment, the basic structure is the same as described above and the same numbers are provided with a comma to indicate the same or similar parts. The device 10 'shown in Figure 3 is similar to that shown in Figure 2, except that the line 26' containing the spray nozzle 42 'is connected to the end of the line 24'. The device 10 'does not have a valve flap 30. The line 26' is connected to the line 24 'by a flexible switch 50. The line 26' is thus pivotally mounted so that its discharge end 28 'can be moved vertically. The discharge head 28 'is spaced from the container outlet pipe 16' and is normally in the position shown in solid lines in Figure 3 aligned with the outlet pipe. The device 52 adjusts the vertical position of the discharge end 28 'of the line 26'. This device may comprise a shaft 54 screwed into the cylinder 56 and rotatable by a wheel 58, whereby rotation of the wheel manually moves the shaft 54 vertically. The wire 26 'would be connected to the shaft by a suitable means, not shown, so that rotation of the shaft changes the vertical position of the wire discharge opening 28'. As in the first embodiment, an electric control device 32 'can be used, which automatically adjusts the position of the discharge opening 28' and which responds to output signals generated by the liquid level indicators 34 'and 36'. The control device 32 * may include a motor, not shown, connected to the shaft 54 by a suitable mechanism. Here, too, those skilled in the art will understand the details of the control device 32 'and the control means of the discharge opening 28' of the line 26 '. Of course, other arrangements could be used. The manually operated adjusting wheel 58 or the automatically responsive fluid level control device 32 'operate to move the line 26' discharge opening 28 'to the position shown by the dashed line in Figure 3 where the drain leaving the discharge contact with the control device 60 connected to the bottom of the discharge pipe 16' so that water enters directed to the bottom of the container 12 '. The control device 32 'is designed so that when the water is at the height of the sensor 34', the discharge nozzle 28 'is in line with the outlet pipe 16', and when the water surface reaches the lower sensor 36 'moves the motor shaft 54 of the control device 32' downwards. to a position where it is directed towards the guide 60 below the discharge pipe 16 ', as shown by the broken lines in Figure 3. The control device 32' may also be designed to place the discharge opening 28 'in an intermediate position where part of the water flows out through the discharge pipe 16' and part downwards into the tank 12 ' .

With the device 10 'in operation and the discharge opening 28' in the position shown in solid lines in Figure 3, the water transferred by the pump 18 'passes through the line 24' through the spray nozzle 42 'and outwards from the discharge opening 28' through the tank discharge pipe 16 '. Thus, the entire amount of water discharged through the discharge pipe 16 'becomes aerated in this device. When the discharge opening 28 'is in its lowest position, the aerated water is directed back to the tank 12 *.

The position of the discharge opening 28 'could, of course, be adjusted by other means, e.g. a simple, mechanical float control device, in which case the float would be connected directly to the line 26'. This solution would be more advantageous because it is an electrical control system of simple ^) !. However, the shape shown in Figure 2 has the advantage that the entire pressure of the pump can be used to pump water out through the discharge pipe 16 and not just the dynamic pressure from the spray nozzle, as in the embodiment of Figure 3. In both forms, the control device can be made such that the pumping and aeration are both continuous and adjustable or take place separately, so that the water is first aerated and then pumped out of the tank. An obvious advantage of the invention is that only one pump is used to perform both aeration and pumping.

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