The modernization of water management systems usually only involves individual process steps. The Monsheim wastewater treatment plant, however, is undergoing a complete overhaul. The main focus of the new concept is on achieving a more process-oriented way of working, as well as reducing energy consumption, 100 percent of which is to be self-generated in future.

The Monsheim wastewater treatment plant

The Monsheim wastewater treatment plant has a treatment capacity of 46,500 population equivalents, although this number can rise to 120,000 from September to December due to grape harvesting in the Rhineland palatinate. Therefore, a great deal of energy is required to treat the water. As a part of the automation technology modernization program, the project management team therefore intends to optimize energy utilization in addition to improving technical processes. As a basis for this, a modular and powerful control technology via which the field devices can be easily connected to the control system was required.

A modular and powerful control technology Axiocontrol

After the retrofit, ten Axioline controllers distributed throughout the entire system will control all processes within the sewage treatment plant. The measurement values from the intake to the exhaust fans through to the combined heat and power plants will be recorded via analog and digital interfaces, and processed in the decentralized controllers so that they are subsequently available for an energy analysis and other evaluations. To achieve the objective of a high degree of efficiency, a redundant fiber-optics based network ring with intelligent Factoryline switches has been installed throughout the entire system. Network and transmission errors therefore lead to process failures much less often than in the past.

All processes at a glance

 Operating panels installed throughout the plant provide employees with an overview of the status of the individual processes and components based on the powerful network. Employees can now intervene in the respective process as and when necessary. The Quint uninterruptible power supplies (UPS) have been coupled to the control system, so that important battery operating states – such as the current state of the power supply – can now be read off. Furthermore, the UPS provides information on the charging state and the remaining runtime of its energy storage system, and issues preemptive failure warnings.

A further objective of the modernization program was to save costs during the engineering process. One option here is to link the automation and visualization level. The wastewater treatment plant employees therefore use the Waterworx function block library to program and create applications. The different field devices can be easily integrated into the application using the blocks. The integrated visualization interface enables fast connection of the process parameters to the control system.

Consistent concept as an essential foundation

“Modernizing the individual treatment steps combined with the new automation technology and intelligent field devices provides us with a consistent concept that forms the foundation for the efficient operation of our wastewater treatment plant”, explains Ralf Schmidt, head of the Mittleres Pfrimmtal municipal wastewater association. A modern control system and reliable components alone are not enough to achieve the highest possible degree of efficiency after the modernization program. Rather, the focus needs to be on the solution as a whole.

Coupling complex field devices to the control system is often associated with considerable costs and a high susceptibility to faults. If the user employs the preconfigured blocks tested by the manufacturer, the different components can be integrated easily and the availability of the application during operation increased. The information provided by the intelligent sensors and actuators is displayed in the control system and is thus taken into consideration for the efficient operation of the Monsheim wastewater treatment plant.

• By Joel Stratemann, Industry Management Water employee, Phoenix Contact Electronics GmbH, Bad Pyrmont