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Water supply Osterburken - Nano technology for Drinking water treatment
Nano technology makes soft drinking water out of extremely calcareous well water, in order to protect household equipment and pipe work. Since October 2010 one of the most modern water softening plants has been in operation, reliably controlled with VIPA hardware.
Nano technology replaces chemicals
The fountains in the city of Osterburken in Neckar-Odenwald unearth only extremely calcareous well water on account of the geological conditions in the region. A far-reaching water softening was therefore compulsory. The traditional water softening occurred in the past with the help of chemical processes. Here, for a long time, expenditure and results have not corresponded to what is expected of drinking water. So it was decided in Osterburken to adopt a new approach. With the help of the company Kuhn GmbH Höpfingen, who have dealt with the treatment of drinking and waste water for many years, they found a very modern solution. The whole project was simplified by the fact that Kuhn, in addition to the pipeline construction and the mechanical engineering equipment, also supplied all the electrical and control engineering. Here Kuhn was also able to use their experience with nanotechnology. Nanotechnology allows solutes, that make the water hard, to be removed from the water by osmotic filtration without the need of chemical additives. The treatment of the well water was carried out at different stages until the desired water quality was reached.
Process sequence in several stages
The water softening process described is only one part of the whole process of obtaining drinking water. It begins with the precisely regulated removal and transfer of raw water from different wells into the raw water storage tank of the treatment plant. For the operation of the nano-filtration system, it is very important that the pumps produce a well-defined system pressure, because otherwise the high sensitive membrane filter may be damaged. In the filtration system itself further processes, such as pre-filtration, membrane filtration, decontamination, and the collection of treated water in two pure water chambers, take place. At the end of the water treatment another UV sterilization of the pure water takes place before the clean water is pumped into in the local reservoir in drinking water quality. The processing performance of the plant is 650 cubic meters in 14 hours - equivalent to the average daily consumption of the city Osterburken. The degree of hardness is reduced from 26 to the present 11-13 ° d H..
Complex process sequences demand precise control technology
Starting from the pumping in the well house up to the feed-in into the drinking water supply there are a number of processes that must run reliably to ensure the availability of safe drinking water at all times. As a central controller, the CPU 314SC/DPM from the 300S-C-Class with integrated SPEED7 technology, which has both a PROFIBUS interface and an Ethernet interface for coupling the panel and programming, was used. This saves on expensive communications processors, which would have to be connected directly to the CPU. The CPU allows cycle times of 2 ms, so that the numerous programmed software controllers can easily be handled. In addition, the integrated digital and analog inputs and outputs in the CPU contribute to saving space in the control cabinet. In the central units as well as in three decentralized stations the compact SLIO modules provide for fast and space-saving connection of sensor and actuator via a PROFIBUS network. The visualization of the system was also realized with VIPA components. The 12" touch panel used is connected via Ethernet to the PLC. Besides the on-site display and operation, the panel permits the recording of data in the integrated ring or circular buffer. Likewise it is equipped with a qualified alarm management in the case of exceeded limits or error messages.
Familiar technology completely from one source
That the technology used - from the PLC components to the operator terminal - comes completely from VIPA, was a decisive argument for Thomas Schäfer, project manager at plant supplier Kuhn: "It makes work much easier for us as system manufacturer, if we can get everything from a single source." After all, Kuhn has been working with VIPA for many years.