Dresden-Kaditz sewage treatment plant
The Dresden-Kaditz sewage treatment plant is the main sewage treatment plant in the Saxon capital of Dresden . It is located in the Kaditz district on the right bank of the Elbe on both sides of the federal motorway 4 . It is operated by Stadtentwässerung Dresden GmbH.
Technical development
prehistory
In the course of the removal of the fortifications in Dresden, the drainage had to be reorganized by backfilling the moats. For the first time, a planned drainage system was built in Dresden, the drainage channels (locks) flowed directly into the Elbe. These were viewed as structures of subordinate importance and accordingly executed with inferior quality and depth, but they met the requirements for receiving and draining rainwater from the road locks and the water of the Kaitzbach. The disposal of the faeces continued to be carried out in lavatory pits, the contents of which were regularly emptied using manure trucks and disposed of outside the city. This was done from 1871 by the "Dresdner Düngerexport-Actiengesellschaft".
In the 19th century, this system no longer met the growing demands of industrialization and population growth . So around 1855 a "basement water plague" was found, which had its cause in the leaky street locks and pits, hygienic problems such as the cholera epidemic of 1874 were the reason for a complete reorganization of the drainage and comprehensive introduction of the floodplain sewerage system, which is part of the building code of the city of Dresden , announced on March 17, 1906 was officially regulated.
The introduction of the alluvial sewer system was the result of extensive discussions that took place in the last third of the 19th century. Town planning officer Hermann Klette (1847 to 1909) and the long-standing head of Dresden's city council, Dr. Stöckel deservedly. With regard to the discharge of sewage and faeces into the Elbe, an expert opinion from the “Reichs-Gesundheitsrath” was obtained on February 8, 1902, which defined the following requirements for discharges from the alluvial sewer system into the Elbe and thus also the cleaning performance of the future cleaning system:
- Removal of coarse floating and sinking matter up to particles of 3 mm. The residues excreted in the process must be removed in a manner that is both healthy and aesthetic.
- Creation of the possibility of general disinfection of the wastewater in exceptional cases
- Installation of interception devices for coarse floating and sinking materials at all emergency outlets
- Construction of a central wastewater treatment plant on the Kaditzer Flur
- Continuation of the final outlet of the treated wastewater as a closed pipe to the middle of the Elbe river
1st epoch (1910–1952): Mechanical cleaning system and pumping station on the Kaditz corridor
Wastewater treatment
The construction of the mechanical cleaning system and pumping station on the Kaditz corridor began in 1909. The planning was in the hands of the aforementioned Hermann Klette, as head of the municipal civil engineering department, responsible for technology, and city planning officer Hans Erlwein (1872–1914), as head of the municipal civil engineering department, responsible for architecture .
From 1906 to 1907 the civil engineering office operated a test facility for testing different cleaning methods and units on a site below the Marienbrücke. The mechanical clarification system based on the Riensch patent and the so-called Kramer apparatus were tested. At the entrance to the system there was a sand trap with a diameter of 6 m and a hand-cleared coarse screen. The subsequent Riensch separator disk had a diameter of 4.6 m and groove-like openings of 2 × 30 mm. The disk was inclined 15 ° to the horizontal, partially submerged and rotated 1.5 times per minute. A spider-like rotating brush set with eight brushes was attached above the disc, which swept the substances deposited on the disc into a channel. From there, the contaminants were conveyed into a container with a rake-like conveyor device. The system was driven by a steam engine with an output of 1.91 kW. The results were in some cases unsatisfactory, the pane bent under the impact of mud and sewage, and the brush set was difficult to clean. The cleaning performance amounted to approx. 10% of the coarse soiling.
Based on these results, the sieve discs improved by Maschinenfabrik Wilhelm Wurl, Berlin, were used in the mechanical cleaning system. These had a diameter of eight meters and plunged into the wastewater at an angle of 22.5 °. This made it possible to remove approx. 34% of the undissolved substances, an important achievement at the time. The Riensch-Wurlschen sieve discs were, in addition to a hand-cleared upstream coarse screen system, the sole cleaning stage, which was a very common procedure at the time. So had z. B. the places Glatz , Herford , Lauenburg, Ludwigshafen am Rhein , Magdeburg , Mainz , Ragnit , Ratibor , Stettin , Torgau and Wurzen also screen discs as the sole wastewater treatment plant.
The four sieve discs were arranged in a hall 59 m long and 10.6 m wide so that the discs could be connected in parallel or two in series.
Furthermore, a pumping station was built to ensure the drainage of the wastewater in the city area in accordance with the Elbe water level. In a hall 46 m long and 18 m wide, eleven pumps of various sizes could lift up to 22.3 m 3 / s of water.
The treated wastewater was led to the Elbe via a 450 meter long canal, which ended there with a wrought iron pipe with a diameter of 2 m in the middle of the river. This is still in operation today.
Screening material treatment
After several days of storage, the separated screenings had the following composition according to an analysis by the Agricultural Chemical Research Institute Promnitz:
| Water content | 67.660% | |
| organic substance | 17.240% | |
| of which nitrogen | 0.628% | |
| mineral substances | 15.100% | |
| from that | Potash | 0.080% |
| phosphorus | 0.182% | |
| lime | 0.586% | |
The screenings were given to agriculture and used there for soil improvement. Since this use was only possible temporarily, it was essential to treat the material to be sieved to improve its shelf life. After various attempts at drying or degreasing, the construction of a processing plant was planned in 1914, but this was prevented by the First World War .
After several attempts, the construction of a closed digester with a volume of 2500 m³ was finally started in 1936. This was heated to 33 ° and was the third heated digester in Germany after Essen-Rellinghausen. The screenings were digested until they were odorless and then drained on open "drying beds". The solid material was then made available to the farmers as fertilizer. The digester gas produced during digestion was stored in a gasometer and later used to heat the digester.
2nd epoch (1952–1987): Dresden-Kaditz primary sewage treatment plant
Wastewater treatment
The purely mechanical cleaning by means of sieve disks could not meet the increasing demands on the water quality in the long run. Starting in 1936, plans were drawn up in the civil engineering department to increase the cleaning performance by means of biological processes such as the trickling filter process or the activated sludge process, but these could not be continued due to the Second World War .
The food shortage of the post-war years shifted the focus of wastewater treatment to agricultural wastewater utilization in order to increase yields. This would have resulted in a 100% reduction in pollution loads for the Elbe, as no more wastewater would have been discharged during the growing season. The funds for the conversion of the sewage treatment plant were therefore only made available for agricultural wastewater recycling.
The basic idea of this solution was to use the nutrient content of the wastewater as much as possible, so the wastewater should be cleaned in mechanical primary clarifiers with a residence time of only one hour to the extent necessary for further use or discharge into the Elbe. In a gravity channel , it should be directed to Sörnewitz and pumped from there to the fields in the Grossenhain area. It was planned to rain about 110,000 m 3 / d. Two expansion sections were planned for the system, with only the 1st expansion section, the reconstruction of the sewage treatment plant, being carried out; the second expansion phase failed due to a lack of money and material.
The operation of the sieve discs turned out to be more and more difficult due to the material wear and tear after the war, from 1952 onwards they were gradually dismantled. Instead of the 4th sieve disc, a rake with a bar width of 35 mm was installed. To protect the pumps, a sand trap (two chambers 36 m long and 4 m deep) was placed between the sieve disc hall and the pumping station. By reducing the flow speed to 0.3 m / s, the heavy sands settle while the lighter suspended matter is carried on.
The basic concept of the pumping station was retained, but what was new was that the arrangement of the settling basins meant that the wastewater now had to be pumped continuously. From a water level of 4.50 m, the free outlet from the sedimentation basin into the Elbe no longer worked, so that all of the coarsely treated wastewater was then pumped into the Elbe with a higher water level via the rainy weather pumps.
For the main cleaning of the wastewater, which used to be done through the sieve disks, five rectangular settling basins, each 60 m long, 10 m wide and 2.4 m deep, were built, the cleaning effect of which was many times that of the sieve disks. 90% of the pollutants that could be deposited sank to the ground, the dissolved substances, especially nitrogen and phosphorus, were retained and should benefit agriculture. The wastewater treated in this way flowed through a fall structure into the existing wastewater sewer and then into the Elbe, as the discharge to the fields in the direction of Grossenhain was not implemented (see above).
The converted plant was put into operation in May 1956.
Sludge treatment
Approx. 600 m³ of sludge per day accumulated in the settling basins, which were pushed into the sludge pockets of the settling basins with the bottom sliding plate of the mechanical clearing device and from there pumped into the sludge treatment plant. The existing digester with a capacity of 2,500 m³ was too small for this amount of sludge with a residence time of approx. Four days. A variant of the extension was the arrangement of another digester with a capacity of 5,000 m³ towards the Elbe below the existing one. In the end, however, another digester with 2,500 m³ was implemented in a mirror image of the existing one.
The now existing digester volume of 5,000 m³ was not enough to achieve digestion, so that two unheated, open digesters with 13,000 and 18,000 m³ contents were arranged. The digested sludge was drained via drying beds, which were expanded to an area of 25,000 m². The farmers and gardeners showed great interest in the solid mud. In order to ensure continuous sales of the sludge, a pipeline network was built and operated from 1964 to 1986 together with the “Kaditz Horticultural Production Cooperative”, which later became the early vegetable center, which cultivated the fields adjacent to the sewage treatment plant.
- State in the 1980s
Large building
Pumping station
Settling basin
Digestion towers
Mud pool
Residential buildings
3rd epoch (1987 - present): From the communal sewage treatment plant to the sewage park
Wastewater treatment
Due to the planned economic framework in the GDR, the investments to maintain the facility could not be realized to the extent required after the renovation. This led to the fact that the plant gradually fell into disrepair during operation and, in a catastrophically worn condition, it completely failed on January 2, 1987 during a power failure due to flooding on the Elbe. The construction work started in 1986, which was due to the "action plan for the implementation of the resolution of the Presidium of the Council of Ministers of the GDR to increase water use in the upper Elbe section Pirna / Dresden / Riesa of October 20, 1983" of December 5, 1983 (PMR resolution no . 02/108 / I / 83), arrived too late and could not prevent the disaster.
- 1987 average
Said action plan was necessary due to the increasing pollution of the Elbe water by the non-existent or inadequate wastewater treatment plants of industry and municipalities on the upper reaches of the Elbe, but the city of Dresden u. a. a large part of the drinking water required from the Elbe. This action plan also states:
- "Point I. 2. It is necessary to create political and ideological clarity that the improvement of the water quality of the Elbe is an important prerequisite in order to guarantee the drinking water supply, irrigation and service water supply in the upper Elbe in the long term, important results in the recovery of valuable substances from the Wastewater in the field of environmental protection in the interest of the citizens of the republic as well as reserves for further use of the Elbe water are developed and that the active cooperation of all managers and production collectives of the companies involved is then required.
- Item II. Planning, preparation and implementation of the joint sewage treatment plant “Dresden-Kaditz” and the Radeburg waterworks including the pipeline
- 1. The further preparation and implementation of the investment complex joint sewage treatment plant "Dresden-Kaditz" with its sub-projects
- - Reconstruction and intensification of the existing mechanical sewage treatment plants,
- - New construction of a plant for the biological treatment of the waste water pretreated in the detoxification plant of the Drugs Plant Dresden and the municipal waste water of the cities of Dresden and Freital
- - sludge treatment plant
- - Biogas utilization
- takes place in the responsibility of the director of the VEB water supply and wastewater treatment Dresden as the main client. "
- 1. The further preparation and implementation of the investment complex joint sewage treatment plant "Dresden-Kaditz" with its sub-projects
VEB Hoch- und Tiefbau Pirna was designated as the main contractor for the structures in the aforementioned action plan and VEB Kombinat Wassertechnik und Projektierung Wasserwirtschaft as the main contractor for the equipment. With the decision of the Council of Ministers 7 / II. 4. b / 86 of August 7, 1986 was used as the main contractor for the structures of VEB BMK Coal and Energy .
In 1984 planning began for the joint sewage treatment plant "Dresden-Kaditz" as a biological wastewater treatment plant with partial nitrification. In 1990, in view of the political and associated economic upheavals, which on the one hand resulted in a reduction in the pollution load, on the other hand in the change in the water law situation in the unified Germany as part of the EEC , the expansion plans with further demands for nitrogen and phosphorus elimination revised. The mechanical and 1st biological stage were made fully functional; construction of the 2nd biological stage was not started. The Dresden-Kaditz sewage treatment plant was put back into operation on November 1, 1991 with a partial capacity.
Since then, the sewage treatment plant has been continuously expanded. Only the essential steps are mentioned at this point, for further information please refer to the homepage of Stadtentwässerung Dresden:
- July 1993: complete commissioning of the 1st biological stage of wastewater treatment (high load activation)
- February 1994: Commissioning of a plant for chemical phosphate precipitation
- December 2000: Commissioning of a sand washing machine for processing the resulting sand
- August 2003: Completion of the construction work to convert the old digestion towers into offices, for archiving purposes and as a technical station
- February 2004: Commissioning of the rain overflow basin with a volume of 24,000 m³
- June 2005: Inauguration of the new biological stage with nitrogen removal
- January 1, 2006: The quality of the treated wastewater complies with the applicable EU regulations
- August 2, 2006: Commissioning of an upstream anaerobic denitrification in converted basins of the former 1st biological stage
- September 5, 2018: Commissioning of the expansion of the biological stage, consisting of
- two circulation distributors, each with a capacity of 8,000 m³
- two aeration basins each with a capacity of 16,000 m³ and a water depth of 7.50 m; 2,200 aeration plates with rubber membrane are installed on the bottom of each basin. The capacity of the aeration basins grew 1.5 times.
Sludge treatment
With the political change in 1989/90, the decades-long practice of agricultural utilization of sewage sludge was increasingly questioned. The modern ecologically oriented agriculture feared the entry of pollutants on their land. With regard to the heavy metal content in the Dresden sewage sludge at the beginning of the 1990s, these fears were certainly justified; accordingly, sludge incineration with upstream thermal drying was planned as the sludge treatment. Due to the decline in industry in the subsequent period and the associated decline in the heavy metal content, sludge incineration was no longer necessary and instead of the planned partial drying, full drying was implemented, which was in operation from 1994 to the end of 2011.
In the years 2008 to 2012 a digestion plant was built in which the sludge is digested and biogas is extracted in two 10,500 m³ digestion towers using the anaerobic sludge stabilization process (cf. anaerobic wastewater treatment) . This biogas is used in a block-type thermal power station (CHP) to generate electrical energy and local heating , thus improving the energy balance and the CO 2 balance of the sewage treatment plant. In three CHP modules with a total of approx. 3 MW output, so much electrical energy and heat is produced that approx. 70% of the electrical energy requirement of the sewage treatment plant and the entire heat requirement of the sludge treatment can be covered. The digestion also reduces the amount of sludge produced by approx. 30%, which in turn has a beneficial effect on disposal costs.
The digested sewage sludge is dewatered in centrifuges to 25% dry matter content and transferred to disposal companies via a sludge loading facility, which was also completed in 2012. So 150 tons of sludge are a daily composting fed. The composts are used for the recultivation of open-cast lignite mining areas and for general landscaping. Due to the quality of the sewage sludge, it is suitable for agricultural use.
The sludge treatment with thickening, digestion, drainage and loading is located on an area west of the BAB 4 motorway . The striking digestion towers with their gray-blue matrix facade next to the motorway cannot be overlooked.
Sewage park
In addition to the tasks described for wastewater purification and sludge treatment, the sewage treatment plant is also characterized by other functions, so it can be referred to as a sewage treatment park .
Regenerative energy generation
Hydropower
At the outlet of the sewage treatment plant, there is a height difference of 6 m to the Elbe, which is used to generate energy. A turbine is installed here that delivers 650 MWh per year.
solar power
A photovoltaic system with an average annual yield of 160 MWh is located on the roof of the rain overflow basin.
natural reserve
Wild bird sanctuary
Since 2007, Saxony's first wild bird sanctuary has been located on the site of the sewage treatment plant, which is supported by the Dresden Environment Center . Five aviaries, a cage for ground brooders and several functional containers were created on an area of 300 m². By June 2010, 652 injured birds, from blackbirds to storks to buzzards, had been nursed back to health and released into the wild.
Biotopes
As part of compensatory measures, wet biotopes were created in the area near the Elbe and on the site of the sewage treatment plant, several dry biotopes as a habitat for protected plants and animals. For this purpose, among other things, a cycle path in operation was demolished without replacement. The biotope was created on this three meter wide strip that has now been created.
Art and education
education
The wastewater treatment plant is opened to the interested public through regular "open days", also in connection with inaugurations or anniversaries. In 2005, 12,000 visitors came to the inauguration of the new biology and in 2010 10,000 visitors on the occasion of the anniversary “100 years of the Dresden-Kaditz sewage treatment plant”. The sewage treatment plant is also a regular destination for school and preschool school excursions; in 2006 alone 2,500 schoolchildren were able to visit the plant.
art
The female artists' association “ Dresdner Sezession 89 e. V. "realized various objects in the sewage treatment plant with the artists Heidemarie Dreßel, Kerstin Franke-Gneuss, Angela Hampel and Kerstin Quandt under the project name" Mnemosyne ", the Greek goddess of memory:
- Heidemarie Dreßel realized an 11 m high metal installation at the sewage treatment plant outlet. Filigree stainless steel nets with nozzles conjure up a fine veil of water on the Elbe under the name "Viva Fluvia".
- Kerstin Franke-Gneuss arranged an installation of bent aluminum tubes coated in green and blue at the transformer station. These "waves of color" embody the movement of the nearby Elbe.
- Angela Hampel placed three sculptures, the "undines", as female, virgin water spirits near the three ponds at the entrance to the sewage treatment plant.
- Kerstin Quandt arranged colored glass stones with lyrical quotes on the wide reception avenue, which as "currents" admonish the careful handling of the life-giving water.
literature
- Rudolf Böhm, Torsten Fiedler, Siegfried Schäfer, Rainer Wiesinger: On the history of urban drainage in Dresden. 3rd revised and expanded edition. Owned by Stadtentwässerung, Dresden 2007, OCLC 699515359 .
- Karl Imhoff, Joseph Brix, R. Weldert: The urban drainage in Germany. 2 volumes. Fischer, Jena 1934, DNB 560937199 .
Individual evidence
- ^ Dresdner Journal , March 17, 1906, ZDB -ID 1153352-3
- ↑ Ryszard Lidzbarski, Feliks Lewandowski: Clarification of municipal wastewater - Historical connections between Dresden and Tczew (Dirschau). In: DWA circular. No. 35, October 2009, ZDB -ID 2398731-5 , pp. 13-14.
- ^ Imhoff et al.: Stadtentwässerung Deutschland. 1934.
- ↑ Böhm et al.: History of urban drainage. 2007.
- ↑ Site plan of the Dresden-Kaditz pre-treatment plant from September 27, 1952, Association of German Water and Soil Associations, Technical Office Dresden
- ↑ Action plan for the implementation of the resolution of the Presidium of the Council of Ministers of the GDR to increase the water use in the upper Elbe section Pirna / Dresden / Riesa of October 20, 1983.
- ↑ Dresden's virtual sewage treatment plant. on: stadtentwaesserung-dresden.de , accessed on March 14, 2014
- ↑ from: KA - correspondence waste water, waste . No. 10/2018, p. 861
- ↑ Telephone information from Stadtentwässerung Dresden from June 26, 2012.
Web links
- Dresden-Kaditz sewage park at stadtentwaesserung-dresden.de , accessed on March 14, 2014
- Walter Hahn: Dresden-Briesnitz. View from the west-south-west of Briesnitz, Kaditz and Übigau, in the middle distance the sewage treatment plant and airfield with air barracks, 1925
- Kaditz sewage treatment plant, May 1956
Coordinates: 51 ° 4 ′ 23 " N , 13 ° 40 ′ 46" E