P-CIM Aqua

P-CIM offers customized SCADA/HMI packages for virtually any industrial endeavor. One prominent example is P-CIM Aqua - a specialized control system for wastewater management as is currently in use in Düsseldorf, Germany.

When the German government introduced rigorous new ATV standards (Abwasser Technische Verordnung, Wastewater Technical Regulation) such as the M-260 standard for reporting and documenting contaminants released to public water systems, engineers had to implement new secondary treatment processes to meet the requirements.

It is well known that health problems can be caused by high levels of nitrate in drinking water supplies. Thus, it seems prudent to set new lower levels for the presence of these pollutants.

The Düsseldorf South Water Treatment Facility, originally completed in 1975, had to perform an upgrade to its plant in order to satisfy the new ATV regulations. Construction began in 1994 on the Belebungsbecken, a secondary wastewater treatment process in which bacteria consume the organic parts of the waste.

The innovative technology at the Düsseldorf water plant was to bring the nitrification together in a simultaneous process. Wastewater swirls through five 23,200 m3 flat, open air tanks, each tank divided into four narrow channels where compressed air is blown into the bottom to supply oxygen. The compressed air is supplied by four large turbines. Control of the turbines, the amount of air injected into the process, the flow of water, water temperature, pH, bacteria, and many other parameters associated with the process is a science that is not completely understood.

P-CIM SCADA software is used to track and plot the variables with the intention of converting what is now largely an empirical process into engineering science. Some of the process variation can be reduced through technology and co-operation of local industry, and this reduction contributes to the cost effectiveness of the plant.

The main contractor for the control system was Schneider Electric Germany, who in turn chose AFCON Software and Electronics Ltd. as a subcontractor together with system integrator Inotronics GmbH to carry out the process control system with its P-CIM software. Twenty workstations running P-CIM are used for supervision, management, collection and displaying of process data. Half of them are in the central control room and the others are scattered about the site. The control system currently handles 16,000 I/O points and will be expanded to 35,000.

The entire control system upgrade with communication links was installed in the first five months of 1999. Eighteen redundant pairs of Telemecanique TSX-7 PLCs working in a redundancy configuration carry out the job of process control. Each controller is linked to the central control room with fiber-optic cable.

At night, when input variations are lowest, the entire plant is controlled by three operators. The PC-based visualization system consists of 20 operator workstations connected to two sets of data servers, which are also working in a redundancy configuration. A redundant 100 MB Ethernet fiber-optic communications network connects all stations to the data servers. Response time, it is claimed, is less than half a second.

Two of the workstations project large images onto the wall of the control room. A single operator can work with as many as ten different screens. Reliability and performance of the communication system is understandably a major requirement. To ensure high reliability, dual network cables, hubs, PLCs and above all, software redirecting support, are implemented.
Real time data are read into the communication server, stored in the archive server, and distributed to the operation workstations.

Many enhanced features of P-CIM point out the advantages of a PC-based SCADA system. Historical data collection into an SQL data server, for example, allows engineers to store and analyze vast quantities of data, which will allow them to study and refine the process. As the process moves from continuous control to batch control, recipe management becomes more important. Recipe management allows users to dynamically modify a recipe's structure and values.

Producing reports for various government agencies is also a major and obvious requirement. It is relatively easy to configure reports that satisfy the new ATV M-260 standard with the software's Windows-based system. The software has built-in Internet access, which allows authorized users to view plant data from across the globe.

It is estimated that nearly 20% of total project costs were saved as a result of industry co-operation and the use of state-of-the-art PLC and PC SCADA technology.
So far, advanced wastewater treatment technology, coupled with good co-operation with industrial neighbors and modern control system have produced a very efficient system, and Düsseldorf residents enjoy a low water-usage rate of €2 per cubic meter.