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CASE STUDY-Efficient purification through automation modernization
CASE STUDY

Efficient purification through automation modernization

The modernization of the wastewater treatment plant in Suwałki, carried out by ATER Logic, enabled the implementation of a unified control system for the individual installations.

The use of Siemens equipment and software in the process helped streamline plant operation, enabled diagnostics and process monitoring, and increased the operational safety of the installation.

The Water and Sewerage Company in Suwałki (PWiK Suwałki Sp. z o.o.) is responsible for supplying water to the city’s residents as well as collecting and treating wastewater. The plant receives wastewater from the entire city, nearby villages, and non‑sewered areas. Until 2024, the treatment plant operated using a dispersed and outdated control and process visualization system. As a result of necessary but uncoordinated automation expansions, different parts of the facility were operated using various controllers, software platforms, and supervision systems. This situation made day‑to‑day operation difficult and hindered effective fault detection.

"The most serious issue at the treatment plant was the diversity and inefficiency of the control systems in use. Each installation had a different user interface, there was no unified method of data presentation, and process data archiving was incomplete. In addition, the lack of technological support and the inability to introduce modifications significantly hindered day‑to‑day operation,”
- recalls Łukasz Kurzyna, CEO of PWiK Suwałki Sp. z o.o.

Another key aspect for the wastewater treatment plant operators was the aeration process in the biological chambers, which plays a crucial role in the proper course of nitrification and denitrification. Improper control of the blowers, diffusers, and air valves resulted in suboptimal energy consumption, caused fluctuations in oxygen levels, and led to instability in the parameters of the treated wastewater. This increased the risk of failing to meet applicable environmental standards.

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One of the key tasks in the modernization process was to increase the efficiency of controlling the operation of the blowers, diffusers, and air valves.

Implementation goal: a unified automation system

The main reason for initiating the modernization of the treatment plant was the need to unify the control system by replacing the existing dispersed setups with one cohesive system. The implementation was also intended to improve the aeration process and increase the reliability and operational safety of the facility.
The project, which lasted a total of ten months, began with the signing of the contract in July 2024. The first stage included the design, prefabrication, and delivery of the supervisory system.

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After the modernization, the proper operation of the blowers and valves ensures stabilization of technological parameters in the biological chambers and precise optimization of energy consumption.

As part of the planned work, an industrial network was delivered and commissioned, and specialized control and instrumentation switchboards (AKPiA) were gradually supplied for ten technological areas. In the following stages, the entire system was commissioned and optimized. The project concluded with staff training in May 2025.
It is worth emphasizing that all work was carried out while the facility remained fully operational. All systems and software were implemented without interrupting the technological process.‘The new solutions, based on Siemens components, have contributed to increasing the reliability and operational safety of the treatment plant.

"Centralized real‑time monitoring of all facilities from a single workstation helps us detect and resolve failures and also enables remote supervision. The development of new control algorithms for all plant systems has delivered concrete, expected results. In particular, the new operation of blowers and valves provides, among other things, stabilization of technological parameters in the biological chambers and precise optimization of energy consumption"
explains Andrzej Maziarz, Technical and Development Director at PWiK Suwałki.

Quality improvements in the control area

The modernization of the control system at the wastewater treatment plant in Suwałki was based on redundant S7‑1500 series controllers (S7‑1517H‑3PN). The redundancy of key devices has significantly increased the reliability and stability of the entire system. Thanks to the use of Siemens equipment, technological processes are now controlled in a consistent manner, with minimal risk of failure.‘

'As part of the modernization, ATER Logic specialists carried out a comprehensive replacement and expansion of the control infrastructure. The previously dispersed system, based on multiple computers and inconsistent solutions, was replaced with a single, modern, redundant setup. This solution ensures continuous system operation even in the event of a controller failure, a higher level of process safety, and a significantly reduced risk of unplanned downtime, which translates into greater stability and efficiency of the entire installation. All technological facilities have been connected to a single supervision center. As a result, plant operation has become simpler, the risk of human error has been reduced, and failure diagnostics and response to threats are much faster,"
- evaluates Sławomir Kalita, Sales Manager at Siemens Poland.

Another important area of the implementation was the change in the aeration control logic.

“Before the modernization, the system was imprecise and unstable — technological parameters often deviated from process requirements, and the blowers and valves operated inefficiently, resulting in high energy consumption. Thanks to the implementation of new control algorithms, we have stabilized oxygen levels, introduced dynamic blower regulation, and enabled automatic control of the aeration valves. As a result of our work, smooth and precise control of the aeration system is now possible,”
- emphasizes Tomasz Prusinowski, CEO of ATER Logic, the integrator responsible for the implementation.

The third area covered by the modernization involved improving operational safety. The previously incompatible systems increased the risk of failures, made optimization and necessary modifications impossible, and lacked comprehensive equipment monitoring. The implementation resulted in a unified alarm and diagnostics system, enabling remote supervision of most of the facilities. As a result, the software and controllers now operate within a single, standardized environment. Downtime and repair costs have been reduced, equipment reliability has improved, and operational safety has been significantly enhanced.

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As part of the planned work, an industrial network was delivered and commissioned, and specialized control cabinets were supplied progressively.

Effects of the control algorithm modernization

As part of the modernization, controllers from various manufacturers were replaced with redundant Siemens SIMATIC S7‑1500H controllers that manage the entire facility. In addition, an engineering workstation equipped with TIA Portal software was delivered and commissioned. This workstation enables full operation of the main controller, analysis of algorithm performance, and the ability to introduce modifications to the control logic for the entire site.

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The previously dispersed system, based on multiple computers and inconsistent solutions, was replaced with a single modern, redundant setup built on the SIMATIC S7‑1500 controller.

“Previously, implementing changes in the algorithms was difficult — there were no engineering tools such as TIA Portal, and each part of the control system operated in a separate environment. The new architecture provides full control, development capabilities, and the ability to maintain a consistent control system,”
- notes Tomasz Prusinowski.

Along with the replacement of the control algorithm, the entire control layer was also unified. Thanks to TIA Portal software, standardized control logics were implemented for the entire facility. This made it possible to introduce one coherent system. All technological units now share a unified interface, alarms, control structure, and data archiving. As a result, operator work is more efficient, response to deviations is faster, and the complete process history enables thorough optimization analysis.

The most important innovation in the control system was the implementation of a fuzzy logic controller. It simultaneously analyzes multiple process parameters, including oxygen concentration, organic load, wastewater flow, sludge concentration, the condition of the activated sludge, and the load on the biological chambers. Based on this data, it determines the optimal oxygen demand. The controller smoothly regulates the blowers, air valves, and the distribution of air between the biological zones.

"Unlike the previous system, the controller does not react in a binary on/off manner — instead, it anticipates and adapts to process changes. It maintains a stable oxygen level even under rapidly changing conditions,"
- emphasizes Tomasz Prusinowski.

Key benefits of the modernization

As part of the modernization, all equipment responsible for supervising technological processes was completely replaced.
A key element of the new infrastructure was the addition of a server cabinet housing two redundant Siemens S7‑1500H controllers along with a high‑availability computer system.
This solution ensures continuous operation of the control system — in the event of a failure of one controller, the other immediately takes over its functions without affecting ongoing control processes.

The unification of the user interface across the entire facility, the centralization of process data archiving, and the implementation of an engineering workstation have significantly improved the reliability, transparency, and analytical capabilities of the control system. These measures have also simplified operation and technical maintenance.

The hardware replacement carried out by ATER Logic aimed to ensure high reliability and uninterrupted system operation. The modernization was largely based on Siemens hardware and software solutions. Redundant PLC controllers minimize the risk of downtime, while SITOP power supplies and UPS modules keep the system running even in the event of a power failure. Thanks to distributed ET200SP I/O stations and the new communication network, the system can be easily expanded and integrated with additional devices. Meanwhile, the implemented protective devices safeguard operators and equipment against failures and voltage surges, and the new communication infrastructure and SQL Server Reporting Services reporting system enable faster operation as well as efficient creation of process analyses and reports.

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The implementation of an engineering workstation based on TIA Portal has improved the reliability of the control system and simplified operation and technical maintenance.

Siemens played a key role in the modernization of the control and communication system, providing both technical support and the delivery of automation solutions. The company served as a project partner, advising on system architecture and the selection of optimal components.
Łukasz Kurzyna, CEO, PWiK in Suwałkach Sp. z o.o.
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SITOP power supplies and UPS modules keep the system running even in the event of a power failure.

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Thanks to the distributed ET200SP I/O stations and the new communication network, the system can be easily expanded and integrated with additional devices.

As a result of the implementation, a uniform user interface has been ensured across all facilities, making operation, diagnostics, and monitoring significantly easier. An important element that increased usability was also the improvement and automation of the purification process in the biological section.
The modernization of the control algorithms for the blowers and valves made it possible to stabilize oxygen levels in the biological chambers and optimize energy consumption.

"Aeration typically accounts for 50–60% of a treatment plant’s operating costs, which is why improving these processes has significantly increased the plant’s efficiency and delivered substantial energy savings for its operation,"
- emphasizes Tomasz Prusinowski of ATER Logic

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The work carried out has translated into an even better ability to meet the needs of the residents of Suwałki and the surrounding areas.

The modernization has enabled real‑time monitoring of all facilities from a single workstation, accelerated fault detection and resolution, and allowed for remote supervision of the installation. It has also opened new opportunities for PWiK Suwałki in terms of automated supervision, autonomous operation, and the implementation of intelligent control strategies.

"An important objective of the implementation was also to prepare the treatment plant for future upgrades. Thanks to excellent cooperation between the client, integrator, and technology provider, we have created conditions for further expansion of automation in the future. We have ensured better integration with other systems at the facility, such as sludge management, the biogas plant, and receiving stations,"
- explains Sławomir Kalita from Siemens.

The modernization has brought our facility into the era of intelligent, autonomous resource management. All of this will translate into even better achievement of our goals, improved system reliability, noticeable energy savings, and—above all—the ability to even better meet the needs of the residents of Suwałki and the surrounding areas.
Andrzej Maziarz, PWiK Suwałki