CASE STUDY

Optimization of wastewater treatment plant control

The MACS system, developed by DP System based on Siemens technologies, enables energy savings and provides additional load capacity for wastewater treatment plants. The solution implemented in Słupsk and Iława allows for serving a larger number of residents.

DP System has developed a tool that combines technological and software solutions. The goal of MACS (Model-based Advanced Control System) is to maximize the technological efficiency of wastewater treatment plants and reduce energy consumption. The system can operate in nearly any treatment plant equipped with automation systems. The solution has already been implemented, among others, in wastewater treatment plants in Iława and Słupsk.

Model-based predictive control

Developed since 2018, MACS is designed to support the operation of biological wastewater treatment plants based on integrated removal systems for organic compounds and nutrients. Individual components of the solution optimize the performance of technological processes. One of the key functions is carried out by the module responsible for controlling biological reactors."

A wastewater treatment plant is required to achieve a level of purification that meets standardized parameters for nitrogen and phosphorus content. The MACS system optimizes the wastewater treatment process, making it easier to meet environmental discharge requirements. The applied algorithms ensure that these targets are achieved with minimal energy consumption. The system also supports efficient biomass management by optimizing external recirculation and prevents the carryover of activated sludge into treated wastewater,"
says Robert Wlaźlak, Director of the Industrial Automation Department at DP System.

DP System - Optimization of wastewater treatment plant control - OpenGraph

The MACS system enables the maximization of technological efficiency in wastewater treatment plants while reducing energy consumption.

The MACS system has been implemented, among others, at the wastewater treatment plant in Słupsk.

The implemented technologies make it possible to optimize the amount of chemicals used in treatment processes. The solution developed by DP System also enables energy savings in the biochemical processes carried out by the treatment plant."

Biochemical reactions in wastewater treatment plants are among the most difficult to control because they involve living organisms. These processes also have a high demand for electrical energy,"
says Adam Paczesny, Commercial Director of the Industrial Automation Department at DP System.

The algorithms and mathematical models of the treatment plant used in the MACS solution enable predictive management—acting in advance—of the environment for the living organisms performing treatment processes. This results in increased efficiency, particularly in terms of energy consumption. This approach also makes it possible to optimize the use of the existing treatment plant infrastructure.

Modernization of the wastewater treatment plant

“The starting point for the modernization work was the need to meet emission standards, which was linked to reducing energy expenditures. As a result of the implemented changes, efficiency improved by 25 to 35%. About 14% of this was due to improved control, while the remaining part resulted from replacing blowers with modern, more energy-efficient units. Under normal operation, the plant achieves an 80% level of self-sufficiency, but at times this even reaches 100%. This means we are energy independent. This is a direct result of implementing the DP System solution,”
says Kazimierz Stachyra, Manager of the wastewater treatment plant in Słupsk.

The MACS solution implemented in Słupsk is used to control aeration, internal and external recirculation, and to regulate the operation of key actuators such as blowers and mixers. A coagulant dosing module has also been implemented. An essential role in ensuring the efficient operation of the control system is played by comprehensive instrumentation of the installation.

“The effectiveness of the applied control results from combining in-depth technological knowledge of treatment plant processes, expertise in automation principles, and engineering based on mathematical models and predictive control,”
says Kazimierz Stachyra.

The MACS system is used to control aeration, internal and external recirculation, and to regulate the operation of actuators such as blowers and mixers.

MACS was designed using Siemens technology that combines a traditional PLC controller with an industrial computer.

The solution was designed using Siemens technology that integrates a traditional PLC controller with an industrial computer. A SIMATIC Box PC, along with communication modules, was used for control. Siemens industrial PCs are characterized by high performance, a wide operating temperature range, and resistance to vibrations, while occupying minimal space in the control cabinet. They are also designed to operate reliably in harsh environmental conditions.

“We chose a Siemens solution because it is a versatile platform combining the capabilities of a programmable logic controller with a high-performance industrial computer. This computing power is essential for integration with the MATLAB environment, which is used to implement mathematical models, reproduce the biochemical processes of the treatment plant, and perform calculations for process control. This approach allowed us to easily integrate the optimization layer with the control system within the same environment,”
explains Robert Wlaźlak, Director of the Industrial Automation Department at DP System.

A compact industrial computer, the SIMATIC Box PC, along with communication modules, is used to control the system.

Benefits in the area of energy efficiency

A significant benefit of implementing the MACS system is the broadly understood increase in the safety of the processes carried out by the facility that uses it.

The modernization was carried out in such a way that replacing the existing infrastructure of the treatment plant was not necessary. The existing measurement devices, supplemented with additional missing measurements, were integrated and provide the data required for the operation of the MACS system. In turn, the control signals generated by the DP System solution are executed by the plant’s existing control infrastructure, which underwent only minor upgrades. As a result, despite relatively low investment, significant financial and environmental benefits were achieved.

“During the modernization of the treatment plant, we introduced an additional, higher-level control layer serving as support for the operator. After implementation, the MACS system selects and automatically sets optimal process control parameters,”
says Tomasz Chrześcijanek, Project Manager at DP System.

The implementation of the solution took approximately six months, while its calibration lasted about one year, allowing for consideration of the facility’s operational specifics across different seasons.

The most important benefits include energy savings resulting from reduced electricity consumption. It has also been possible to increase the stability of processes in the biological section. In addition, employees, supported by information from the system, are now less involved in process supervision, allowing their time to be used more effectively.

Kazimierz Stachyra, Manager, wastewater treatment plant in Słupsk

Another benefit achieved through the modernization is the broadly understood increase in the safety of the processes carried out by the facility. The implemented solution makes it possible to achieve an additional load capacity reserve of approximately 20,000 PE (Population Equivalent). This allows the treatment plant to accept a greater volume of wastewater for processing using the already existing reactor.

“Before the modernization, the treatment plant was capable of receiving wastewater from 250,000 inhabitants, whereas now it serves 350,000. This result was achieved, among other things, thanks to the implementation of optimization solutions. We are satisfied with DP System’s involvement in the implementation work, as well as with the system’s performance. The solutions applied prove effective both in the day-to-day operation of our treatment plant and in critical situations, such as periods of heavy inflow of wastewater following rainfall,”
summarizes Kazimierz Stachyra from the treatment plant in Słupsk.

Modernization of wastewater treatment plant in Iława

Another facility where the MACS solution, running on Siemens devices, has been implemented is the Wastewater Treatment Plant in Iława. In this case, the primary reason for implementation was the need to reduce nitrogen content in treated wastewater. DP System won the tender and began work involving the replacement of control elements, dampers, and drive components responsible for recirculation control.

The modernization covered internal and external recirculation, aeration control, and dosing of PIX coagulants. As part of the completed work, the external recirculation system was changed from a control algorithm based on incoming wastewater volume to one based on sludge levels in secondary clarifiers. As a result of these changes, it was necessary to automate the outlet gates installed in the secondary clarifiers. The modernization led to improved quality of treated wastewater. Noticeable benefits in terms of energy savings have also been achieved.

“Energy consumption largely depends on the type of wastewater flowing into the treatment plant. A more difficult load requires more air and the use of blowers that consume significant amounts of electricity. Due to the variability of incoming wastewater with different concentrations, it is difficult to precisely assess how energy-efficient the new solution is. However, during stable operation we observe a significant improvement in performance and increased energy efficiency of the installation. Controlling dampers and switching off blowers at the right moments makes it possible to clearly reduce electricity consumption. Thanks to optimization, we are now able to fully utilize the capabilities of the wastewater treatment system,”
says Krzysztof Draszewski, Deputy Head of the Wastewater Treatment Plant in Iława.

The MACS system has been in use in Iława for several years. Similar to the treatment plant in Słupsk, its implementation took about six months, followed by approximately one year of adaptation to the facility’s specific conditions. Over an annual cycle, all seasonal phenomena that could occur at the facility were analyzed. Currently, the applied solution enables energy reduction of around 12%. Improved process efficiency also means higher throughput of the entire plant and the ability to process larger volumes of wastewater.

“Instead of standard PID controllers, we implemented solutions using a process model and resulting predictions, i.e., MPC (Model Predictive Control) algorithms. Operating points for this type of controller are much closer to technological limits, which automatically translates into higher process efficiency and improved plant throughput,” explains Robert Wlaźlak from DP System.

“The solutions provided by Siemens not only take into account the broad capabilities of model-based control but also offer support for artificial intelligence: Machine Learning (Deep Learning). All of this enables higher control efficiency and provides additional opportunities to optimize energy consumption and achieve better process performance,” emphasizes Michał Urliński from Siemens Polska.

The implemented solution facilitates maximizing the amount of biogas obtained in chemical processes. Another benefit of the MACS system is the reduction in the time required for certain tasks.

“In some aspects, it has been possible to reduce labor input. This applies, among other things, to control in secondary clarifiers, which before modernization required manual adjustment of gates to regulate sludge levels, whereas now this process is fully automated,”
notes Krzysztof Draszewski.

“The MACS system enables continuous monitoring of measurement devices. It allows, among other things, the assessment of the reliability of current measurements. If the system determines that a given measurement is unreliable, it informs the user and switches to an alternative measurement or bases the control algorithm on historical values,”
adds Tomasz Chrześcijanek from DP System.