Water treatment plant for Switzerland
SPANGLER – the Plus of Modernization.
The water treatment system of our customer Bertschi AG in Switzerland actually works perfectly after the tank has been cleaned. The water added with chemical substances is treated and can therefore flow back into the sewer system. However, most components, including the control units, are outdated. So, it was time to bring the plant up to the latest technical standard so that the process can continue to run smoothly in the future, according to the customer’s statement. Spangler Automation was then commissioned to modernize the water treatment plant with the Retrofit-Service.
Demanding process of water treatment
With the cleaning of the tanks, chemical substances are added to the water. Therefore, it must not be returned to the sewer system without prior treatment. During treatment it passes through various areas, one of them is the treatment in the supply container. Here, the waste water pre-treated by the reaction tank is gradually fed into five supply tanks, aired and the sediment deposited on the bottom is removed. In the next step the waste water flows into so-called aeration tanks in the biology area. Here, urea, defoamer and phosphoric acid is added manually for the correct pH-value. Afterwards the pretreated waste water flows into the two ultra filtration streets and is pumped through the filtration circle for cleaning and filtering. The filtered waste water flows into the permeated tank. After previous fine treatment, the water is now clean and can flow back into the sewer system.
Extensive retrofit of the control technology
In agreement with the customer, a functional specification sheet of the plant process was established. Thanks to the detailed pre-planning the visualization and programming could be implemented smoothly. The special aspect about this order was the short-term and simultaneous application of two PLCs running in parallel in one plant. It was possible to switch between both controls. This made it possible to switch to a new redundant control system quickly and safely. Before the final conversion to the new PLC was concluded, the plant was tested intensively in advance with the help of a remote simulation. After the first test run, it was already possible to switch from the old control system to the new one. Two Siemens PLC S7-1500-R and one ET200SP as decentral periphery were applied. Additionally, two Siemens operation devices HMI TP1500 were installed.