DE4140358C2 - Method and device for generating exact mixing ratios, especially in the dilution of activated sludge with clear water - Google Patents

Description

The invention relates to a method and a Vorrich tion to produce exact mixing ratios zwi at least 2 samples, especially the diluent of activated sludge with clear water. An important Operating parameters for aeration tanks of sewage treatment plants is the sludge volume of the activated sludge, d. H. the Volume fraction of after a certain residence time in related to a graduated cylinder sludge particles on the total volume of the inserted into the measuring cylinder teten activated sludge. To this mud volume on a to be able to adjust optimal value is its perio dische control required. This is in a certain measuring cycle activated sludge from the aeration removed basin in a measuring cylinder, where then after a certain residence time the amount of the settled Read mud on a measuring scale or by means of a optical detector is detected.

With an expected sludge volume larger than 250 ml / l must according to DEV / standard the so-called dil be applied, d. H. those from the revival basin sample is washed with treated wastewater from the secondary clarifier in a predetermined ratio diluted. In order to achieve comparable measurement results, is over one measuring cycle at each sampling an exact same mixture ratio between animated  mud and clear water required. An exact Wed The relationship with today's methods is only in the laboratory realizable. Other methods used in the field Dosing of the delivery volume of activated sludge and clear water via dosing valves or via pumps with adjustment barer speed deliver no useful, reproduzier good result.

One known from DE-OS 31 32 706 known metering used for mixing a water and a syrup component Beverages on the one hand a Wasserabmeßbehälter and the other a syrup dosing tank. The dosing ratio is by the pre-selected via a level controller filling volume of the Wasserabmeßbehälters and by the volume of the Syrupabmeßbehälters certainly. While the Wasserabmeßbehälter only until filled to the level specified by the level controller In contrast, the Syrupabmeßbehälter is completely filled by the syrup component from a reservoir from below in the container is pumped, and that until the liquid exits at the top of the container via a line again.

After the syrup component by completely filling the Syrupabmeßbehälters unchangeable with given filling volume is set, is a dosage of the mixing ratio only possible by filling the capacity of the Wasserabmeßbehälters in any way, e.g. B. by means of the level controller set becomes. The dosage can also be done in other ways, z. B. gravimetric or by determining the inflow with Flowmeters.

Another known from DE-OS 35 09 031 mixing device uses a multi-chamber mixing tank with partitions and overflow edges between the individual chambers. First mixing component 1 is introduced into the mixing container, to a number corresponding to the desired mixing ratio filled by chambers, with the filling of a subsequent Chamber over the overflow edge of the partition to the previous, already filled chamber takes place. After that, the second one Top up the mixture component until the multi-chamber mixing tank is completely filled. Also in this known device is a preliminary metering of the mixture components by means of a control loop required. Of the first mixture component may only filled so much, as many chambers as desired, filled are. The filling with the first mixture component must then be broken off exactly before this mixture component overflows into the subsequent chamber. The filling process with the second mixture component must be stopped when the multi-chamber Mixing tank is full.

The invention is based on the object Applicable method for producing more accurate Mixing ratios between at least 2 samples as well an apparatus for carrying out this method to accomplish. The procedure to be created should be easy be manageable and require only a small amount of equipment.

The task is done with a procedure solved, as characterized in claim 1. A Apparatus for carrying out the Ver driving is described in claim 4. further developments The invention are described in the subclaims.

By the method according to the invention are at For example, from the aeration tank of a sewage treatment plant withdrawn activated sludge and that from the secondary clarifier extracted clear water in containers promoted, whose Capacity up to an overflow in the same ver ratio as the desired mixing ratio stands. The content of the samples filled up to the overflows container is then placed in a common mixing tank submitted. The obtained mixing ratio is exact and corresponds to the capacity of the samples container to its overflow. By means of an adjustment Baren overflow can the capacity and thus the Mixing ratio to be changed. As usual a limited number of mixing ratios is necessary, can on the sample containers more Overflows can be arranged at appropriate heights,  in each case only the overflow corresponding to the ge wished mixing ratio is opened. A long way re possibility to vary the mixing ratio It consists of containers of different sizes ability to exchange. The flow over the overflows Send activated sludge and the clear water become Bele recirculated.

Because the mixing ratio of the samples alone determined by the capacity of the sample container is a dosage of the production volume to mixing samples not required. Rather, le just make sure that a sample volume för is sufficient, the sample container until the Fill overflow. This can be done by time-controlled Pumps are ensured.

The inventive method and the Vorrich to carry out the process are general applicable everywhere, where exact mixing ratios of at least 2 samples should be prepared.

The invention will be described below with reference Drawing explained in more detail, the example of animated mud and clear water schematically a device to produce exact mixing ratios shows.

An activated sludge tank 1 is connected via an inlet 2 with the (not shown) aeration tank a sewage treatment plant and a clear water tank 3 via a to 4 with the (also not shown) Nachklär tank the sewage treatment plant in connection. In the inlet 2 to the activated sludge tank 1 sits a control valve 5 with a branch 6 to an activated sludge pump 7 , the output 8 is returned to the aeration tank. In the inlet 4 to the clear water tank 3 , a clear water pump 9 is arranged, and between the pump 9 and clear water tank 3 sits in the inlet 4, a control valve 10 with a branch 11 to the inlet 2 to the activated sludge tank. 1

The activated sludge tank 1 is connected via a STEU erventil 12 and the clear water tank 3 via a control valve 13 with a measuring cylinder 14 with a measuring scale 15 and a height-adjustable optical detector 16 in conjunction. A piston 23 in the measuring cylinder 14 ge equips the ejection of the Meßzylinderinhalts via a return line 17 to the aeration tank.

Both the activated sludge tank 1 and the clear water tank 3 are equipped with an adjustable overflow channel 18 and 19 , which are also returned to the aeration tank via a return line 20 and 21 respectively. With a total container volume of 1000 ml make this ÜberIaufgerinne 18 and 19, an adjustment of the container volume in each case up to the overflow channel, for example, 100 ml-1000 ml possible.

Control electronics plus a recorder are shown at 22 .

The device described operates as follows: In the basic position of the measuring cylinder 14 , the piston 23 is in the lowest position. The piston is only used to "press" the mud-water mixture from the measuring cylinder after the measuring cycle. The activated sludge pump 7 and the clear water pump 9 promote with an adjustable time at least 1000 ml in the respective containers 1 and 3 with ÜberIaufgerinne. The activated sludge pump 7 is in a side branch of the inlet 2 arranged so that un indirectly flows and, after an induction activated sludge in the activated sludge tank 1 thus entering into the container 1 sludge flocs are not chaffed from the feed pump.

In the containers 1 and 3 can be made with the ver adjustable overflow channels 18 and 19, the desired dilution ratio, z. B .:

Activated sludge tank 1 | 250 ml Clear water tank 3 750 ml or @ Activated sludge tank 1 500 ml Clear water tank 3 500 ml

Now, as in the laboratory, the clear water is first introduced into the measuring cylinder 14 by the valve 13 opens. Thereafter, the valve 12 opens, so that the activated sludge can flow into the measuring cylinder 14 . After the containers 1 and 3 are empty, the valves 12 and 13 close again. The valve 10 in the clean water inlet 4 via the branch 11 a connection to Belebtschlammbe container 1 ago, after which the pump 9 timed the Be lives sludge tank 1 fills with clear water. This measure takes place so that no sludge residues cake on the container wall.

After a residence time of the sludge-water Ge mixture in the measuring cylinder 14 of z. B. 30 minutes is determined on the measuring scale 15 or by means of the optical detector 16, the height of the deposited sludge and thus the sludge volume. Now the piston 23 pushes the mud-water mixture from the measuring cylinder 14 via the line 17 back to the aeration tank. In the upper (dash-dotted lines) position of the piston 23 , ie, when the piston 23 in the amount of a mouth of the line 17 , the valve 12 opens, so that the water in the activated sludge tank 1 with ge dissolved sludge residues also flows via line 17 from , Thereafter, the valve 12 closes again and the piston 23 returns to its lower starting position. The valve 10 has also taken its starting position.

Now a new measuring cycle begins and the pumps 7 and 9 start again to fill the containers 1 and 3 .

Claims (8)

1. A method for generating exact mixing ratios between at least two samples, characterized in that the samples to be mixed in containers ( 1 , 3 ) whose variable capacity up to an overflow ( 18 , 19 ) in the same ratio as the desired Mixing ratio is, and that the content of the filled up to the overflow sample container in a common mixing container ( 14 ) is discharged. 2. The method according to claim 1, characterized by the use of sample containers ( 1 , 3 ) of different capacity to the overflow ( 18 , 19 ). 3. The method according to claim 1 or 2, for Ver Dilution of activated sludge with clarified water for bestim the sludge volume after the sludge in the Has dropped off mixing container. 4. Apparatus for carrying out the method according to one of claims 1 to 3, characterized by at least two sample containers ( 1 , 3 ) whose variable capacity up to an overflow ( 18 , 19 ) is in the same ratio as the mixing ratio of the samples to be generated , and by a mixing container ( 14 ) for receiving the contents of each filled to the overflow sample container. 5. Apparatus according to claim 4, characterized in that the capacity of a sample container ( 1 , 3 ), by different Liche height arrangement of the overflow ( 18 , 19 ) is variable. 6. Apparatus according to claim 4 or 5, characterized in that in the feed of the sample container ( 1 , 3 ) each a time-controlled pump ( 7 , 9 ) and in the course of the sample container to the mixing container ( 14 ) a control valve ( 12 , 13 ) is arranged , 7. Device according to one of claims 4 to 6 for the dilution of activated sludge with clear water, characterized in that a conveyor pump ( 7 ) in a side branch ( 6 ) of the activated sludge inlet ( 2 ) to the sample container ( 1 ) and arranged via a control valve ( 5 ) is connected to this inlet. 8. Apparatus according to claim 7, characterized by a Verbindungslei device ( 11 ) between the activated sludge inlet ( 2 ), which connecting line via a control valve ( 10 ) to the clear water inlet ( 4 ).