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PROFIBUS controls Europe´s most modern sewage plant
Austria
PROFIBUS PA

Project
In 2000 it has been decided to significantly expand and modernize Vienna‘s main sewage treatment plant. When the project was completed in 2005, the plant was soon recognized   as being Europe’s most modern sewage treatment facility. The main objectives of the modernization project were (a) to improve water effluent quality by adding a second biological purification stage and (b) to install state-of-the-art automation and electrical systems for both the new and existing parts of the plant.
PROFIBUS was selected to handle data communications at the extensive site, and to serve as ideal link between the old and the new sections of the plant. The decision in favour of Profibus was based on

  • the user´s overall strategy of installing proven, state-of-the-art technology,
  • the large physical size of the plant and hence the need to keep cabling costs low and provide high-speed communication services,
  • the unique feature of Profibus to support hybrid automation (perform continuous processing as well as discrete operations at the same bus)
  • the use of PCS7 control system.


Main sewage treatment plant in Vienna

Solution
The process control systems were standardized for the old and new facilities at the site. PROFIBUS was installed on all units of the new part of the plant while conventional technology (4-20mA) remained in place for the existing facilities. The main demand on the new process control system were reliable operational monitoring of the purification process and extremely high availability. Both of these requirements are of the upmost importance at sewage treatment plants, because the plant has to treat the full volume of sewage 24/7 under any conditions. Other requirements included ease of operation and a sophisticated diagnostic strategy to support cost-effective repair and maintenance.
Topology includes field level, central and local control levels and two higher Ethernet communication systems. 27 “process control stations” are distributed throughout the plant, and allocated to different subsystems such as thickening, pump stations or transformer stations. A total of 5000 devices are installed at the field level through the site. Around 500 are PA devices to measure temperature, pressure and differential pressure.
 
Conclusion
The list of major benefits includes unrestricted functional system management at this very large facility, significantly faster reaction times, and lower (cabling) costs compared to conventional technology. In addition, extensive diagnostic functionality and event-driven maintenance increase the efficiency and reduce the cost of maintenance activity. Centralized data storage and simple expandability also offer significant benefit.