In the summer of 2012, traces of per- and polyfluorinated chemicals (PFC) were detected in the raw water for the first time. The waterworks underwent extensive modernization, employing ABB’s drive and control technology to ensure a reliable water supply.
The waterworks ceased all operations in July 2013 following the discovery of elevated PFC levels in the raw water in 2012. From November 2016 to February 2018, the Rauental waterworks was completely renovated to remove the pollutants. The renovation entailed partial flow hardening and the installation of an activated carbon filtration system alongside ABB’s control and drive technology.
A clean process
Thanks to its new highly efficient activated carbon filtration system, Stadtwerke Rastatt now complies with the strict PFC limits of the EU Drinking Water Directive. The system comprises four tanks filled with activated carbon, one of which serves as a reserve. Each tank has a diameter of three meters and a height of almost seven meters. Each filter can purify around 1.5 million liters of drinking water per day. This means that up to 6,000 cubic meters per day can be extracted from the water catchments in Rauental. The treated water is hardened to reach the same level of water hardness as the drinking water provided by Ottersdorf waterworks with which it is mixed. Subsequently, the water is deacidified before it is fed into the network.
An AC500 PLC controls the entire purification technology of the water extraction and the water transport in the waterworks (Image: ABB). 
Tobias Meisch, water technician at the Rauental waterworks, praises the user-friendliness of ABB technology. (Image: ABB)
AC500 PLC ensures a reliable water supply
The waterworks uses an ABB AC500 PLC with a CP676 operator panel to control all water treatment and transport. The AC500 is ABB’s most powerful controller with extensive communication options and I/O capabilities. Decentralized sub-distribution boards are connected to the PLC via PROFINET and PROFIBUS. ABB provides dedicated water libraries for the PLC, enabling advanced pump functions, data storage, remote access, and reliable data transmission. ABB’s efficient drives control all the waterworks’ pumps, including deep well pumps, intermediate pumps, and greywater pumps.
The right choice
The engineering company Alwin Eppler provided the engineering services and the technical equipment for the conversion of the waterworks. Jürgen Kieninger, project manager at Alwin Eppler, is satisfied with the choice of ABB technology:
„We opted for a scalable and powerful AC500 PLC due to its high availability, fail-safety, and reliability. Furthermore, it has proven its worth in the water industry. The plant supplier suggested the AC500, which the client then accepted. The use of IE5 synchronous reluctance motors for the submersible deep well pumps, intermediate pumps, and network pumps necessitated appropriate drives. To meet this special requirement, we chose ABB drives to ensure safe operation and thus guarantee process reliability and reduce energy consumption.”
Regarding energy input, the entire main distribution system has undergone an upgrade, featuring transformer and emergency power infeed alongside ABB components (main switches, etc.). Tobias Meisch, water technician at the Rauental waterworks, praises the user-friendliness of ABB technology: “We’ve had positive experiences with ABB technology so far. The drives are easy to operate. The detachable displays are interchangeable to upload parameters to other drives, which is very convenient.”
Smooth service provided by ABB
He praises ABB’s service in particular: “We were pleasantly surprised by the customer service. In the rare case of a fault, the hotline worked smoothly. And when the parameters of a drive had to be adjusted on a replacement pump, a service technician was available to assist us promptly.”
About Stadtwerke Rastatt
Stadtwerke Rastatt operates two waterworks of its own – at Ottersdorf and Rauental – and provides drinking water to the city center and the districts of Ottersdorf, Wintersdorf, Plittersdorf, Rauental and Niederbühl. Furthermore, they manage the Förch waterworks on behalf of the Vorderes Murgtal water supply association. In 2021, they distributed 2.536 million cubic meters of drinking water, of which 1.2 million liters were supplied by the Rauental waterworks.
